Geomorphology of Alluvial Fans from the Hindu Kush Range, Chitral Valley, North Pakistan, with Emphasis on Evaluation of Debris-Flow Hazards

GEOMORPHOLOGY OF ALLUVIAL FANS FROM THE HINDU KUSH RANGE, CHITRAL VALLEY, NORTH PAKISTAN, WITH EMPHASIS ON EVALUATION OF DEBRIS-FLOW HAZARDS

ANWAR SAEED KHAN

NATIONAL CENTRE OF EXCELLENCE IN GEOLOGY, UNIVERSITY OF PESHAWAR, PESHAWAR, PAKISTAN (2015)

ACKNOWLEDGMENT

In the name of Allah, the most merciful and the beneficent.

I am very thankful to Almighty Allah who enables me to complete this research work successfully.

Let me proceed to acknowledge and express with thanks to my sincere and deep gratitude to my advisor, Prof. Dr. M. Asif Khan (T.I), Vice Chancellor, Karakuram International University Gilgit Baltistan for his valuable supervision, guidance and encouragement in completion of this research study. I am also very thankful to my co-supervisor Mr.M. Haneef Associate Professor, Department of Geology, University of Peshawar for his time to time guidance and encouragement.

Beside this I am also very thankful to Prof. Dr.M.Tahir Shah, the Director, Prof. Dr. Irshad Ahmad, Prof.Dr. Nimatullah Khattak, Prof.Dr. Tazeem Tahirkheli, Dr. Rubina Bilqees GSA,Dr. Muhammad Shafique, Mr. M. Sufyan Qazi Research Associate, Mr. Asif Majeed Additional Director Finance, Ms. Farhidoon Sahar Supdt/Acad., Mr. Ishtiaq Ahmad Asstt:Acad. and all staff members of the National Center of Excellence in Geology, University of Peshawar for their co-operation, processing and finally organizing the public defense.

I have no words to place on my record my deep sense of gratitude to Prof. Dr. Amir Khan, Dr. Fazlur Rahman, Associate Professor, Dr. M. Jamal Nasir, Dr. Iffat Tabassum, , Assistant Professors and Mr. Zahid Khan, Cartographer, Department of Geography, University of Peshawar for their help and encouragement.

My sincere thanks goes to Prof. Dr. Hizbullah Khan, the Director Admissions, Mr. Shah Nazir, Mr. Kamran, Mr. Shamsher Khan (Supdt.), Mr. Sajjadullah (Asstt.) and Mr. Shakeel Directorate of admission, University of Peshawar for their cooperation and help in the whole process.

Lastly I am thankful to all my friends and best wishers who helped me in this research work.

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ABSTRACT

The Chitral District of northern Pakistan straddles the Hindu Kush Range in the SW Pamir Syntaxis. The district covers an area of 14850 km2 in a mountainous terrain with an elevation range from ~1000 m to ~7700 m. The late Quaternary glaciations broadened the river valleys up to ~4 km wide (e.g., at Mastuj and Chitral). Proximity to steep valley slopes renders these fans prone to hydrogeomorphic hazards, including landslides, floods, mud flows and debris flows. This dissertation focuses on Geomorphology of alluvial fans from the Hindu Kush range in Chitral valley, north Pakistan, with emphasis on evaluation of debris flow hazards. It is addresses the issue of debris-flow related geohazards in the Chitral district, especially on the valley slopes of the Yarkhun (Chitral) River. In general, slopes in the Hindu Kush and Karakoram are so heavily laden with debris that it appears that in the event of a heavy rain or glacial outburst-flood (GLOF), every tributary stream is capable of generating debris and mud flows. The inventory of debris flow in Chitral valley covers road/river stretch along the main trunk river i.e., Kunar-Chitral-Yarkhun river between Drosh in the south-west and Brep (north of Mastuj) in the northwest, described in terms of sites which have experienced Debris flow hazards in the past or have potential for future debris flow hazard.Field observations, topographical maps andsatellite-image analyseswas carried out by applying the Arc GIS 9.3.software in laboratory. For classification of tributary stream types and their associated landforms and geomorphological characteristics of the various landform types, morphometric parameters of watersheds, their resultant streams and associated fans were measured, analyzed and use them to differentiate between various landforms. A preliminary morphometry of the tributary-junction fans in the Chitral valley are classified into 1) discrete and 2) composite. The discrete fans are modern-day active landforms and include debris cones associated with ephemeral gullies, debris fans associated with ephemeral channels and alluvial fans formed by perennial streams. The composite fans are a collage of sediment deposits of widely different ages and formed by diverse alluvial-fan forming processes. These include fans formed predominantly during MIS-2/Holocene interglacial stages superimposed by modern-day alluvial and debris fans. Composite fans are turned

iv into relict fans when entrenched by modern-day perennial streams. These deeply incised channels discharge their sediment load directly into the trunk river without significant spread on fan surface. In comparison, when associated with ephemeral streams, active debris fans develop directly at composite-fan surfaces. Major settlements in Chitral are located on composite fans, as they provide large tracts of levelled land with easy accesses to water from the tributary streams. These fan surfaces are relatively more stable, especially when they are entrenched by perennial streams (e.g., Chitral, Ayun, Reshun). When associated with ephemeral streams (e.g., Snowghar) or a combination of ephemeral and perennial streams (e.g., Drosh), these fans are subject to frequent debris-flow hazards. Fans associated with ephemeral streams are prone to high-frequency (~10 years return period) debris-flow hazards. By comparison, fans associated with perennial streams are impacted by debris-flow hazards during exceptionally large events with return periods of ~30 years. This study has utility for quick debris-flow hazard assessment in high-relief mountainous regions, especially in arid- to semi-arid south-central Asia where hazard zonation maps are generally lacking. Several factors, such as, presence of a water source from rainstorms or glacial melting), density of vegetation, gradient of slopes, nature of the stream (perennial or ephemeral) contribute to debris-flow hazards. However, they greatly vary in the amount of debris- flow hazard due to the nature of the fan and nature of the feeding tributary stream. Finally, two fans with equivalent hazard shall have different vulnerability depending upon the size of population and associated infrastructure.

Based on the geomorphological and morphometric analysis carried out during this study, hazard and vulnerability maps were developed for the Chitral valley. These maps of the Chitral valley provide evidence for debris flow hazard and vulnerability.

TABLE OF CONTENTS

CONTENTS PAGE Nos. Approval sheet ……………………………………………………………………………ii Acknowledgement…………………………………………………..………………...... iii Abstract ……………………………………………………………………………...…...iv Table of contents ……………………………….…………………………………....…...vi Illustration…………………………………………………………………………....…...xi List of Table……………………………………………………………………...... …...xvii CHAPTER 1 ENVIRONMENTAL SETTING………………………….…...... 01 1.1 Introduction………………………………………………………………….…….01 1.2. Statement of the Problem………………………………………………...... ……02 1.3. Location of the Chitral Valley ……………………………………………...... 03 1.4 Physiography……………………………………………………………….…...... 04 1.4.1. Quaternary landforms…………………………………………....…...... 06 1.5. Climate: ……………………………………………………………..….....…...... 07 1.5.1. Precipitation ……………………………………………………...... 09 1.5.2. Temperature ………………………………………………….………...... 11 1.6. Settlement pattern: ………………………………………………………………...13 1.7. Demographic characteristics:………………………………………………...... 13 1.8. Communication & transport system …………………………………….………14 CHAPTER 2 RESEARCH METHODOLOGY……..……………….….…...15 2.1 Introductionto the Study…………………………………………..………...…...15 2.2 Aims and Objectives……………………………………………….………...... 19 2.3 Research methodology ………………………………………………...……...... 19 2.4 Scope of the Study ………………………………………………………...…...... 22

CHAPTER 3 ASSESSMENT/INVENTORY OF DEBRIS FLOW HAZARD IN CHITRAL VALLEY……………………………….…...... 23

3.1 Introduction…………………………………………………………….…...... 23

3.2 SEGMENT-A (DROSH-CHITRAL……… ..………………………………....23 3.2.1 SITE A1. Nagar Alluvial Fan...... 25 3.2.2 SITE A2. Alluvial Fan, Left Bank of the ChitralGol, Opposite UrsunGol…………………………………………………………………...... 26 3.2.3 Site A3. Right Bank Upstream Nagar Fort……………………..…27 3.2.4 Site A4. Drosh Alluvial Fan…………………………………….....28 3.2.5a Site A5a. Jushaba Gol (Drosh) ...... 28 3.2.5b Site A5b. Kaldam Gol (Drosh) ...... 32 3.2.6 SiteA6. IchharGol-MuyahGol Alluvial Fan (Right Bank)...…...... 33 3.2.7 Site A7. Kesu Fan (Left Bank)……………………...…….……….33 3.2.8 Site A8. Girat Debris Fan (Left Bank)…………...………….…….36 3.2.9 Site A9. Ayun Alluvial Fan (Right Bank) ……………...…………37 3.2.10 Site A10. Chitral Flood Plain-Alluvial Fan ……………………..…37 3.2.11a Site A11a. Chitral City (Left Bank): Scouts Post Bridge...... 39 3.2.11b Site A11b. Chitral City (Right Bank): Airport Road……...... 39 3.2.11c Site A11c. Chitral City (Right Bank): Airport Area………...40 3.3. SEGMENT B FROM CHITRAL CITY TOWARDS BARENIS……..……..42 3.3.1 Site B1. Danin, Chitral City – Start of Chitral-Mastuj Road…..…42 3.3.2. Site B2. Kari Gol Fan……………………………………………..42 3.3.3. Site B3. Ragh………………………………………………….…..43 3.3.4. Site B4. TurenKuju, Right Bank, Yarkhun River……………..….45 3.3.5. Site B5. More LashtBala, Right Bank………………………..…...45 3.3.6. Site B6. Parait Alluvial Fan, Right Bank Yarkhun River…….…..47

3.4. SEGMENT-C BARENIS TO MASTUJ……………………………….48 3.4.1. Site C-1 Barenis...... 48 3.4.2. Site C-2 Shil Gol...... 50 3.4.3. Site C-3. Right Bank, Yarkhun River-Parpish Alluvial Fan and Next Channel Upstream………………………….…51 3.4.4. Site C-4. Right Bank, Yarkhun River, Debris-Flow Channel

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next Upstream from Parpish…………………………….53 3.4.5. Site C-5. Lon Creeping Debris Flow, Opposite Reshun, Right Bank-Yarkhun River………………………………53 3.4.6. Site C- 6 Reshun Alluvial Fan……………………………………..55 3.4.7. Site C- 7 ShogramGol Alluvial Fan, Right Bank Mastuj River…...57 3.4.8. Site C- 8 Zait Alluvial Fan, Left Bank of Mastuj River…………...58 3.4.9. Site C- 9 Active Creeping Debris Flow, Channel next upstream of ShogramGol, Right Bank, Mastuj River………..….…59 3.4.10. Site C-10. Koragh Gol...... 60 3.4.11. Site C- 11 Confluence of Mastuj and Turko River………….……....62 3.4.12. Site C- 12. CharanGol fan, Left bank of Mastuj River….…………64 3.4.13. Site C- 13. Duryano Debris Fan……………………………………...65 3.4.14 Site C- 14. Buni Alluvial Fan………………………………….…..…66 3.4.15. Site C- 15. Right Bank, Mastuj River, Opposite Buni…………….....68 3.4.16. Site C- 16. Right Bank, Mastuj River, Opposite AwiGol…………...70 3.4.17. Site C- 17 Miragram Gol fan...... 70 3.4.18. SiteC- 18 Snoghar Debris Fan...... 71 3.4.19. Site C- 19 Nisr Gol Fan...... 74 3.4.20. Site C- 20. Sarghoz Debris fan, Left Bank Mastuj River…………….75

3.5. Segment-D MASTUJ – BREP, YARKHUN RIVER VALLEY ..………...77 3.5.1. Site D-1 PasumGol (Chinar Village); Left Bank Yarkhun River...78

Prersent channel 3.5.2. Site D-2 PurkasapGol Debris Fan; Right Bank Yarkhun River...... 79 3.5.3. SiteD-3. Chunj Composite fan…………………………………….80 3.5.4. Site D-4. Mori Khuz-TuriKuzh Debris Fans, Right Bank, Yarkhun River……………………………………………83 3.5.5. Site D-5 Brep-DahrKotGol Fan, Left Bank, Yarkhun River……...84

3.6. SEGMENT-E FROM MASTUJ TO LASPUR………………………..86 3.6.1 Site E-1. OnshitGol Fan, Left Bank……………………….……....87 3.6.2 Site E-2. Shaidas Gol Aluuvial fan...... 88

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3.6.3. Site E-3 MuriGol fan:…………………………………………….89 3.6.4. Site E-4 Gasht Fan Terrace……………………………………....91 3.6.5. Site E-5 Loh Gol Fan (Kamshai-Harchin Village)...... 92 3.6.6. Site E-6 Rahman-Phorth Settlement (PhargamGol)…..…………93 3.6.7. Site E-7 Baruk village...... 94 3.6.8. Site E-8. Baum, Huzun, and Rizhun Settlements at RizhunGol-Laspur Confluence……………...…………..95 3.6.9. SiteE-9. SorLaspur………………………………..………………96

CHAPTER 4 LANDFORM CHARACTERISTICS AND MORPHOMETRIC ANALYSIS ……………………………..98 4.1. Introduction………………………………………………………………………98 4.2. Tributary stream types and associated landforms …………………………..….98 4. 3. Landform characteristics………………………………………………………..100

4.3.1. Debris cones ……………………………………………………………..100

4.3.2 Fans …………………………………………………………………….101

4.3.3 Discrete fans…………………………………………………………….102

4.3.4 Composite fans………………………………………………………….103 4.4. Watershed and Fan Morphometry……………………………………………...104 4.5. Assessment of Tributary Streams for Debris Flow, Debris Flood a and Flood Potential………………………….……………………………….…109

Chapter 5 Evaluation of Debris flow Hazard Assessment on Alluvial Fans.…118

5.1 Introduction……………………………………………………...... 118 5.2 Debris-flow Hazard Case Studies…………………………………………………..119 5.2.1 Active Debris fans……………………………………………………....119 5.2.2 Composite Fans…………………………………………………..……..121 5.3 Debris-flow hazard return period……………………………………………….130 5.4. Hazard and Vulnerability Assessments………………………………………...134 5.4.1. Active Fans……………………………………………………………..134

5.4.2. Relict Fans……………………………………………………………..134

CHAPTER 6 FINDINGS& CONCLUSION………..……………………....142

6.1. Findings………………………………………………………………………...142 6.2. Conclusions…..………………………………………………………………….147 6.3. Recommendations ………………………………………………………………147 References……...……………………………………………………………….148

ILLUSTRATION Figure 1.1 Location map of Chitral District, northern Pakistan………………………....04 Figure. 1.2 Map of Chitral District, northern Pakistan showing topography…………....05 Figure 2.1. Map showing location of the Chitral valley in the eastern Hindu Kush of northern Pakistan ( after Kamp et.al.,2004)……………………………………………....18 Figure 2.2. Showing various morphometric parameters which were measured for morphometric analysis in this study………………………………………………….….20 Figure 3.1 Index map of Drosh-Chitral Segment, showing major settlements………....24 Figure 3.2a)Satellite Image and b)field photographs of the Nagar Fan, Lower Chitral....25 Figure 3.3. Young alluvial fan characterized by deeply entrenched multichannel flow...26 Figure 3.4. Satellite image of a settlement at right bank of the Chitral River, midway between Nagar and Drosh………………………………………………………………..27 Figure 3.5. a) Image showing Drosh Alluvial Fan on the left bank of the Chitral River. b) Geomorphological map of the Drosh Alluvial Fan……………………………...…...30 Figure 3.6. 1) Aerial view of the JoshabaGol and its debris-f;low channel. 2) A close-up aerial view of the debris-flow channel 3) Close-up aerial view of JoshabaGol as it enters head of the debris fan. 4) Field photo of recent (2005) debris flow in JoshabaGol (upstream view) near the road level. 5) Downstream view of JoshabaGol……………...31 Figure 3.7. 1). Upstream view of KaldamGol from road. 2) Retaining walls along the channel side to restrict the debris flow in the main channel…………………..32 Figure 3.8.IchharGol-MuyahGol Alluvial Fan (Right Bank of Chitral River)………...34

Debris flow Figure 3.9. Kesu alluvial fan, on the left bank of the Chitral River……………………..35 Figure. 3.10. An aerial view of the Ghirat alluvial fan…………………………………..37 Figure. 3.11. Aerial view of the Ayun village settlement on a flood-plain cum alluvial fan composite terrace……………………………………………………....38 Figure 3.12a. A view of Southern Chitral City (Scouts Post Bridge)…………………..39 Figure. 3.12b Airport Road, Right bank Chitral River………………………………….40 Figure 3.13 a) A broad aerial view of the surroundings of the Chitral Airport. b) Close- up of an ephemeral channel north of the Airport, with recent debris flow damage to the Chitral-GaramChashma road. c) Close-up of an ephemeral channel at the northern edge of the runway, with recent debris flow damage to the road……………..41

Figure. 3.14. A view of the Danian alluvial fan, northern part of the Chitral city……...42 Figure 3.15. Kari GolAluvial fan, left bank Yarkhun River…………………………....43 Figure 3.16.1. A broad view of the Ragh Flood Plain-Alluvial Fan Settlement. …….….44 Figure. 3.16.2. Close-up of the Ragh settlement………………………………………....44 Figure 3.17. TurenKuju settlement. Two channels draining the settlement………….….45 Figure 3.18.1. A view of More LashtBala, Right Bank Yarkhun River. (Fig. 3.18.2). In the event of torrential rains, the channel has a history of blockage by its own debris. (Fig. 3.18.3).In 1986, such debris-flow blocked the main channel and ran through the settlement as a flash flood together with reasonable large amount of debris that destroyed many houses……………………………………………………………………………...46 Figure 3.19.1. Topographic map showing location of the Parait Alluvial……………...47 Figure 3.19.2. Satellite image of the Parait Alluvial Fan showing the main channel…..47 Figure 3.19.3. Field photo of the Parait Alluvial Fan………………………………...…47 Figure 3.20. Location map of segment C from Barenis to Mastuj………………….…..48 Figure 3.21.1. Aerial view of the Barenis settlement compositely formed by flood-plain deposit partially overlain by the alluvial fan………………………………………….....49 Figure 3.21.2. View looking northwest of Mastuj river valley……………………….....50 Figure 3.22. Aerial view of the ShilGol, an ephemeral channel…………………….…51 Figure 3.22.2. (on left) View upstream ShilGol……………………………………...... 51 Figure 3.22.3. (above) Downstream view of ShilGol………………………………...... 51 Figure. 3.23. A view of the BarumGol on the right bank of the Yarkhun River……..…52 Figure 3.24. Active debris flow………………………………………………………….53 Figure 3.25.1. Topographic map showing location and position of the Lon village……54 Figure3.25.2. A view of creeping debris-flow deposit………………………………….54 Figure 3.26. Satellite image of ReshunGol and Reshun Fan, left bank, Mastuj River supplemented with topographic map of the same, showing extent of the stream length and catchment area……………………………………………………...... 56 Figure 3.27.1. Topographic map showing location of the ShogramGol and associated settlement on alluvial fan………………………………………………..57 Figure 3.27.2. A distant view of the Shogram alluvial fan…………………………...... 57 Figure 3.28. A side view of the Zait debris fan at the mouth of the ZaitGol………...... 58

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Figure 3.29. Location map of major actively creeping debris-flow, upstream of Shogram and Zait…………………………………………………59 Figure 3.30. A field photograph of the active creeping debris flow in a channel hanging about 2000 feet above the river level………………………..60 Figure 3.31. View of the ephemeral Koragh channel, left bank Mastug River………..61 Figure 3.32.1. (Left) Location map of the Torikho-Mastuj rivers confluence………...62 Figure 3.32.2. Satellite image of the Torikho-Mastuj Rivers……………………….....62 Figure 3.32.3. Field photograph of the settlements on creping debris fans on the northern side of the Torikho-Mastuj confluence…………………….....62 Figure 3.33. A view of the CharanGol and the associated debris fan………………....64 Figure 3.34.1. A satellite image of the Daryano Debris Fan…………………….…….65 Figure 3.34.2. A view of the Daryano Debris Fan……………………………….……66 Figure 3.35.1. ETM Satellite image of the Buni alluvial fan……………………….…67 Figure 3.35.2a. (Upper Left). Partially mature and stabilized, BuniGol fan…………..68 Figure 3.35.2b. (Upper Right). Distal end of the Buni Alluvial Fan………………..…68 Figure 3.35.2c. (Lower Left). A view of the eastern part of the Buni Alluvial Fan…..68 Figure 3.35.2d. (Lower Right). Another view of the eastern most edge of the BuniAlluvial Fan……………………………………………………...... 68 Figure 3.36.1. ETM Satellite image of a major landslide opposite the Buni………….69 Figure 3.36.2. A field view of unconsolidated mass of fine grained clayey sediments enclosing large pointed boulders probably representing the body of an old land slide..69 Figure 3.37. A view of an immature debris fan with steep ephemeral channel……….70 Figure 3.38.1. (Left). ETM satellite image of the Miragram alluvial fan……………..71 Figure 3.38.2. (Right Up). A field photograph of the Miragram Alluvial Fan………..71 Figure 3.39.1. Satellite image of the Snoghar alluvial, U-shaped debris-laden feeder channel and the glacial catchment area…………………………………73 Figure 3.39.2. Field photograph of the Snoghar fan showing the same features as observed on the satellite image…………………………………….73 Figure 3.40.1. (Left). ETM Satellite Image of the Nisar Alluvial Fan, right bank , Mastuj River………………………………………………………74 Figure 3.40.2. (Right Above) Field photograph of a portion of the Nisr alluvial fan….74

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Figure 3.41.1. Satelite image of the Sarghoz alluvial fan………………………………..75 Figure 3.41.2. A field view of the Sarghoz debris fan…………………………………...76 Figure-3.42. A) Location map of Segment D Mastuj to Brep, District Chitral……...... 77 Figure 3.42(B). Terrain map of Mastuj- Brep Segment……………………………..…...78 Figure 3.43.1. (Left) ETM Satellite image of the Pasum debris fan, left bank Yarkhun River…………………………………………………….…...79 Figure 3.43.2. (Right). Field photo of the Pasum debris-flow channel comprising clast -supported debris………………………………………...... 79 Figure 3.44. A field view of the Purkasap alluvial fan on the right bank of the Yarkhun River………………………………………………………...…..80 Figure 3.45.1. ETM Satellite image of the Chunj and Chapalai debris fans on the left bank of the Yarkhun River…………………………….....81 Figure 3.45.2. (above). A view of the active debris fan overhanging the Chunj village...82 Figure 3.45.3. (below). The flat debris fan at the mouth of the ShanoGol…………...….82 Figure 3.46.1. ETM satellite image of the twin Mori and TuriKuzh fans on the right bank of the Yarkhun River………………………………………….84 Figure 3.46.2. Field view of the Mori Kuzh debris fan………………………………….84 Figure 3.46.3. Field view of the TuriKuzh debris fan……………………………….…..84 Figure 3.47. ETM image of Brepcompsite fan at the confluence of ChhikanGol with Yarkhun River at left bank…………………………………...85 Figure- 3.48. Location map of Segment-G Mastuj to SorLaspur, District Chitral……...86 Figure 3.49. View of the Onshit Fan on the left bank of the SorLaspur River………….87 Figure-3.50.1. The Shaidas alluvial fan, fed by a shallowly entrenched ephemeral channel……………………………………………………………….88 Figure-3.50.2. Close up of ShaidasGol fan……………………………………………...89 Figure. 3.51.1. A satellite image view of the MurriGol on the left bank of the Laspur River………………………………………………………...90 Figure. 3.51.2. A close-up of the Murri Debris Fan……………………………………..90 Figure. 3.51..3. Photograph of the Murri Debris Fan showing shallow perennial channel. (upstream view)……………………………………………...90 Figure 3.52.1. Satellite-image view showing the location of the Gasht village…………91

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Figure 3.52.2. Gasht village on flat flood-plain deposit…………………………………91 Figure. 3.53.1. Satellite image view of the LohGol alluvial fan, with adjacent Harchin village…………………………………………………...92 Figure.3.53.2. A photographic view of the LohGol and associated alluvial fan. …….…93 Figure. 3.54. ETM Satellite image of the Rahman-Phorth settlement, left bank of Laspur River………………………………………………………..94 Figure 3.55. Downstream view of Baruk village showing active debris flow on steep slope……………………………………………………………………95 Figure. 3.56. ETM satellite image of the Baum-Huzun-Rizhun settlement at the confluence of the RizhunGol with Laspur river…….………...96 Figure 3.57.1, 2. Downstream views of the Laspur settlement from Shadur Road……...97 Figure 4.1. Tributary-junction fan types in Chitral. (A) An ephemeral-stream related active debris fan. (B) A relict fan associated with a perennial stream…………………...99 Figure 4.2. Examples of active fan types from Chitral…………………………………100 Figure 4.3 Relationship between various morphometric parameters for drainage and depositional basins for tributary-junction sediment fans from Chitral District, northern Pakistan…………………………………………………………………………………109 Figure 4.4. Watershed morphometry of the Chitral fans. (a) Interrelationship between watershed relief and Melton’s ratios (MRs) (b) Interrelationship between Melton’s ratio (MR) and watershed length…………………………………..…116 Figure 5.1. Satellite images of Chuinj (A) and Brep (B) villages located upstream from Mastuj………………………………………………….120 Figure 5.2. Satellite image, post 2007 debris-flow event (A) and pre-debris flow field photograph (B) of the Snowghar village, Upper Chitral………..…...120 Figure 5.3 (A) Geomorphological map of the Drosh fan terraces on the left bank of the Chitral River. (B) Field photograph of the Joshaba Goldebris fan perched on Drosh composite…………………………………….123 Figure. 5.4. (A) Field photograph of the Pret fan. Large perennial stream. (B) A satellite image of the Buni composite fan drained by a through-going incised perennial stream hosting a major settlement……………………….…125

Figure 5.5 Successive potograph of an eyewitness account of a debris flood event in ReshunGol, upper Chitral.(A) Turbulent phase intervening successive debris flood surges. (B) Boulders with diameters up to 2 m floating through debris flood surge. (C) Debris-flood aftermath…………………………….……………………………….126 Figure 5.6 A) A panoramic view of MorLushtBala, a large fan with a sizable population and associated agriculture. (see B) has potential of being clogged in a debris-flow event………….………………………………………128 Figure 5.7 View of ShishiGol showing active alluvial fan associated with perennial stream…………………………...………………………….…..130 Figure 5.8 A. Map shows from Drosh to Chitral area of Chitral Valley based on fan types and feeder tributary streams………………………………………136 Figure 5.8 B. Map shows from Chitral to Barenes area of ChitralValley based on fan types and feeder tributary streams……………………………….137 Figure 5.8 C. Map shows from Barenes to Mastuj to Laspur area of Chitra Valley based on fan types and feeder tributary streams……………………….138 Figure 5.8 D. Map shows from Mastuj to Brep area of Chitral Valley based on fan types and feeder tributary streams………………………………..139 Figure 5.9 A preliminary debris-flow hazard map of Chitral Valley based on fan types and feeder tributary streams………………………………..140

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LIST OF TABLES

Table No. 1.1 Classification of Late Quaternary and younger landforms in the

Chitral valley, northern Pakistan ( modified after Kamp, et el., 2004)….…07

Table No. 1.2 Average monthly Rainfall for Chitral and Drosh Rainfall in mm……….10 Table No. 1.3 Average monthly Temperature for Chitral and Drosh………………...... 12 Table No. 1.4 Population of Chitral District, 1972,1981, 1998………………….……...14 Table No. 2.1 Watershed/Drainage basin attributes used in the analysis………...……..21 Table No. 4.1 Showing the Analysis of Morphometric Parameters……………..…….106 Table No.4.2 Morphometry of tributary streams and their associated landforms, Chitral District………………………………………………………….108 Table No.4.3 Distinguishing features of the various hydrogeomorphic hazards (debris flows, debris floods and water floods……………...... 110 Table No.4.4. Hydrogeomorphic parameters of the watersheds associated with various tributary streams/channels, Chitral Valley………….……112 Table No.4.5 Hydrogeomorphic Properties of the Drainage Basin in Chitral Valley….115 Table No.4.6 showing class limits for hydrogeomorphic processes……………………115 Table No.5.1 Events Data of Debris Flows Hazard in Chitral Valley N.Pakistan……..131 Table No.6.1.Geomorphic characteristics of tributary-junction sediment fans and associated natural hazards, Chitral Valley, N. Pakistan…..……………143

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CHAPTER 1

ENVIRONMENTAL SETTING

1.2 Introduction

The Chitral District of northern Pakistan straddles the Hindu Kush Range in the SW Pamir Syntaxes. The district covers an area of 14850 km2 in a mountainous terrain with an elevation range from ~1000 m to ~7700 m. The Late Quaternary glaciations broadened the river valleys up to ~4 km wide (e.g., at Mastuj and Chitral). It is within the flanks of these valleys where the cropland, orchards and human settlement are mainly located.

A common geomorphic feature of the Chitral region is valley-facing slopes associated with high-relief Mountains, which merge into broad, relatively flat, floodplains. Valley slopes are drained by a dense network of tributary streams of several orders and magnitudes. They unload sediment on entering valley floors forming a range of tributary- junction landforms including debris- and alluvial fans. The modern-day sediment fans commonly rest upon relict sediments of morainic, glaciofluvial, fluvial and lacustrine origin forming terraces on the valley flanks (Kamp 1999; Kamp et al. 2004). In a region, where flat land for settlement (and especially cultivation) is scarce, these terraces are popular, if not the only available site for habitation. Growing population, coupled with advances in irrigation technology and road building, has led to a spread of settlements and cropland on an increasing number of terraces. The area is prone to occasional heavy precipitation that causes flooding of the terraced fans, damaging life, property and crops. At least a dozen human causalities are associated with floods, avalanches and debris flow every year (Haq 2007).

Geohazards in the Karakoram have been subject of several studies in the past (e.g., Derbyshire and Owen 1990; Derbyshire et al. 2001), but the adjacent eastern Hindu Kush remained unexplored due to inaccessibility. Haserodt (1968, 1982) and Buchroithner (1980) pioneered descriptions of Quaternary sediments from the region. Except for Iturrizaga (1999), who addressed the post-glacial debris accumulations in High Asia (including the eastern Hindu Kush), most of the subsequent studies concentrated on reconstructing the glacial history of the region (Haserodt 1989; Owen et

1 al. 2002; Kamp et al. 2004). Kamp (1999; 2001a, b) modelled the Quaternary glaciations and recognized Quaternary terraces in the Chitral Valley in terms of their origin and mutual stratigraphic relations. This work was able to set the foundation for subsequent geomorphologic studies in the region.

Whereas debris-flow has been recognized as a major agent of landscape evolution and landform origin, debris-flow as a geohazard in the Hindu Kush region was first documented by Wasson (1978) who described an eye-witness account of a debris-flow event on August 14, 1975 at Reshun, NE Chitral.

1.2. Statement of the Problem

This thesis addresses the issue of debris-flow related geohazards in the Chitral District, especially on the valley slopes of the Yarkhun (Chitral) River. In general, slopes in the Hindu Kush and Karakoram are so heavily laden with debris that it appears that in the event of a rain or glacial outburst-flood (GLOF), every tributary stream is capable of generating debris flows. However, in details, debris flow processes are highly variable from place to place and depend heavily on morphometric characteristics of the tributary streams and interaction of the tributary streams with pre-existing landforms (glacial moraine, flood plain) at trunk-river valley flanks. Therefore, every habitat at flanks of the Yakhun river has a different level of susceptibility to debris-flow hazards that needs to be differentiated. Additionally, in the present course of study, debris-flow is not only considered as an important geohazard capable of damaging life, property and critical infrastructure such as roads, bridges and water channels, but also as an agent of landform development. As will be seen in later chapters, the geomoprophological studies demonstrate that debris-flow deposits i.e., debris fans are an important landform in the Chitral valley. This thesis tends to identify these debris fans and tries to understand their relationship with other landforms on the trunk-valley flanks in order to evaluate debris- flow hazard. In this background, the major scientific objectives of this thesis include:

1. The classification of landforms on the flanks of the Yarkhun River and its major tributaries in order to understand their origin (i.e.;, glacial, fluvial).

2. Distinction of landforms formed by deposition of sediments transported by tributary streams from those formed by other processes such as fluvial or glacial (e.g., glacial moraines, flood plains)?

3. Understanding inter-relationship between river-flank landforms and tributary streams.

4. Understanding typology of tributary streams in terms of morphometric characteristics and their potential for floods versus debris flow.

5. Classification of Yarkhun-River flank landforms/platforms in terms of their susceptibility to debris-flow and flood hazards.

Quantification of return period for debris-flow hazards for different classes of landforms (and associated settlements).Vulnerability analysis for various towns and villages in Chitral valley in terms of their risk to debris-flow hazards. Development of a preliminary debris-flow hazard/vulnerability map for Chitral valley.

1.3. Location of the Chitral Valley

Geographically, the study area is located between 71-12’ to 71-53’ East longitude and 35-13’ to 36-55’ North latitude. The Chitral valley has a maximum length of 320 Kms its width ranges upto ~4 kms Height of the valley is ranging from 1129 meters above sea level (Arandu in the south) to 3636 meters (Baroghal in the north). The Chitral district is bounded on the northwest by Afghanistan, on the south by upper Dir district and Kunar province of Afghanistan and on the east by Ghizer district of northern areas and Swat district. The total area of Chitral district is approximately 14850 square kilometers (Fig 1.1).

Fig. 1.1 Location map of Chitral District, northern Pakistan (After Kamp et al. 2004).

1.4 Physiography

The Chitral District of northern Pakistan is traversed by the Hindu Kush Mountains, which terminate to the southwest in Afghanistan. To the east, the Hindu Kush Mountains merge with the E-SE trending Karakoram Ranges of northern Pakistan. The Pamirs of the Central Asia border the Hindu Kush Range to the north and the Kohistan Ranges of Swat and Dir bound it to the south.

The Chitral River originates from the Karambar glacier at an altitude of 4500 m in the northeast. After some 300 km through the district, the river flows into Afghanistan as the Kunar River. The Chitral River separates the higher Hindu Kush in the NW from the Lesser Hindu Kush in the SE (Fig.1.2). The Higher Hindu Kush at the NW flank of the Chitral Valley is characterized by altitudes between 5500 and 7500 m and hosts the highest peak of the range, the Tirich Mir (7706 m). The Lesser Hindu Kush, at the SE flanks of the Chitral Valley, has altitudes between 5000 and 7000 m (Kamp et al. 2004).

Relief is commonly greater than 2500 m and, locally, greater than 4500 m. More than 34% of the Chitral District lies above 4500 m (Kolb 1994). Several major tributaries join the main river including Sor Laspur River at Mastuj, Tirich-Torikho River near Buni, Lutkho River at Chitral and Shishi River at Drosh.

Figure. 1.2 Map of Chitral District, northern Pakistan showing topography.

In the study area, geology largely controls topography. The High Hindu Kush, NW of the Chitral River, comprises an axial granite batholith (Tirich Mir and Kafiristan Plutons; Hildebrand et al. 2000, 2001). The SE flank of the Chitral Valley is underlain by axial granite called Kesu-Buni Zome-Zargar-Umalsit pluton (Calkins et al. 1981; Pudsey et al. 1985). The region between these NE-SW trending plutonic belts comprises metasedimentary rocks of various ages, of which the Chitral slates make the principal lithology underlying the middle Chitral Valley between Reshun and Gahiret (Calkins et al. 1981; Pudsey et al. 1985). Part of the valley from Reshun upstream is underlain by relatively weak lithologies including conglomerates and shales belonging to the Cretaceous Reshun Formation and the Devonian-Permian Lun Shale (Pudsey et al. 1985). The topography of the region is strongly influenced by Himalayan orogeny. Three

5 regional fault structures (each trending NE-SW) are (from north to south): the Tirich Boundary Zone (Zanchi et al. 2000); the Reshun Fault (Calkins et al. 1981) and the Karakoram-Kohistan Suture Zone (Tahirkheli et al. 1979; Heuberger 2004). These faults traverse the eastern Hindu Kush, marking the collisions between the three micro- continents/island arc terrains from Late Jurassic to middle Cretaceous. This composite terrain at the southern margin of Eurasia underwent a phase of tectonic uplift and related deformation at the time of Eocene India-Eurasia collision. With a pronounced tectonic activity at 24-17 Ma (Hildebrand et al. 2001; Heuberger 2004), the region is subsequently deforming through an anti-clockwise rotation associated with the active left lateral strike- slip tectonics at the SW margin of the Pamir Syntaxis (Hildebrand et al. 2001). Active Hindu Kush-Pamir Seismic Zone (Searle et al. 2001) is located 80-150 km northwest of Chitral .

1.4.1 Quaternary landforms

Rugged mountains with deeply dissected U- and V-shaped valleys characterize the landscape of the eastern Hindu Kush. Since the Late-Quaternary Glacial Maximum (MIS- 3, ca 65-33 ky; Owen et al. 2002), a wide variety of sediments including glacial, fluvial, aeolian and mass-movement debris accumulations filled the valleys and intermountain basins. Remnants of this period occur as preserved terraces on valley sides. Kamp (1999) and Kamp et al. (2004) classified the Late Quaternary and younger deposits of the Chitral region into six types of terraces: morainic, glaciofluvial, fluvial, lacustrine, mass- movement debris and fan terraces (Table 1.1). The morainic, glaciofluvial and paraglacial fluvial terraces are related to two principal stages of Late Quaternary glaciations in the eastern Hindu Kush termed Drosh Glacial Stage (MIS 3) and Pret Glacial Stage (MIS 2/Early Holocene) (Kamp 1999; Owen et al. 2002; Kamp et al. 2004). These glaciation stages are interpreted to have been characterized by large trunk glaciers, each more than 500 m thick and 200 km long, which gave rise to U-shaped valleys of Chitral River and its tributaries. After the last glaciation, these valleys, with terraces comprising glacial, glaciofluvial and paraglacial deposits, were subjected to present fluvial regime. These terraces, together with the younger flood-plain deposits, form the centre-stage for the deposition of mass-movement derived debris in the form of tributary-junction talus cones and debris fans. The same landforms are the principal sites of habitation as they provide flat land for cultivation and human settlements with tributary streams providing water for

domestic and irrigation use. At times, the tributary streams turn into potential natural hazards caused by flooding and debris flows.

Table1.1

Classification of Late Quaternary and younger landforms in the Chitral valley, northern Pakistan ( modified after Kamp, et el., 2004)

Formation Description Process Sediment Age Lowest, active, alluvial-fan terraces Fluvial-flow Coarse (gravel-dominated, Shishi Fan at the distal toe of incised perennial dominated subordinate sand and rare Recent Formation streams, adjacent to main riverbed. sediment fans. boulders), river-reworked, Contempo Active toe erosion by trunk river. well sorted debris. rary Active debris fans associated with Mass-movement Variable (silt, sand, gravels Recent Daryano Fan ephemeral streams. Variable supported debris and boulders). Contempo Formation thickness up to 100 m. flow. rary Lower, relict fan terraces Tributary-junction Slope debris, redeposited MIS-2 Urghuch Fan Variable thickness up to 200 m. fans, mass- diamictons. and Formation movement younger dominant. Middle, relict fan terraces. Fluvial. Silt and sand mixed with Ayun Fan 70-200 m thick. slope debris and re- MIS-2 Formation deposited diamicton. Upper, relict fan terraces. ~350 m Glaciofluvial and Diamictons with sharp, Broz Fan thick. mass-movement. angular boulders in fine 55-31Ky Formation Paraglacial, formed between the matrix. (MIS-3-2) trunk glacier and valley slopes.

1.5. Climate:

The few descriptions of climate that exist are far too generalized to be of much use in a region that varies locally so much in altitude. The most useful account is that by Rafiq (1976) who describe various type of climate in Pakistan. Hamid et al (1969) also applied the various climate classification system of Koppen, together with those of Papadakis (1966) and Walter et al (1975) that all place Northern areas and Chitral into one-category-basically a dry continental Mediterranean climate. However, even to the casual observer, within this region, that spans two degrees of latitude (35°-13’-36o--55N) and three degrees of Longitude (71°-73oE), there is a significant variation in temperature and precipitation imposed by topography.

The climate has the following general features:

1. The aridity causes the absence of vegetation to insulate the bare rocky mountains slopes that act as a storage heaters. At 37oN latitude the days are quite long in summer, the

night are correspondingly shorter, there is insufficient time for the extra heat load to be lost by back radiation, resulting in warm weather in the Chitral valley for much of the summer.

2. It is a rain shadow area receiving the attenuated effects of both the summer monsoon and the winter's western depressions. However within the rain shadow area, topography still exerts a strong local orographic influence.

3. There is a strong gradient of rainfall with altitude. Most valleys receive between 100-200 mm/year, but the adjacent ridges, 1000m higher receive 400 mm, supporting juniper and alpine pastures at 3000 m. It has been estimated that in the high mountains above 6000 m, the rainfall should be of the order of 2000 mm. It is actually this snowfall at high altitude, through its subsequent melting that sustains human settlements in the area, which is otherwise a "mountainous desert.

The climate of Chitral is distinctly continental. It is hot in summer ranging from very hot in their lowlands to warm in the uplands and cool in the higher elevations. The extreme maximum temperature recorded in Drosh is 45 C for the month of July while in Chitral it is 44 C for the same month. The mean maximum temperature for the same month for Drosh is 36 C and the mean minimum temperature is 23-26 C. The summers at high altitudes such as Baroghil, Sor Laspur, Gobur, Bogusht, Kiyar, Arkari, Ovir, and Rech etc. are cool and windy with extremely cold nights (GOP. 1999).

In winter most of the valleys are in the grip of cold, northerly winds and blizzard. The winter is less severe in the lowlands as compared to the uplands. The extreme minimum temperature recorded at Drosh and Chitarl stations is -3.8 C for the month of January and February. The mean minimum temperature for the same stations has been 0.2 C and -1.3 C for the months of January and February, respectively.

The Chitral district receives annual rainfall in the range of 250 mm to 1000mm. It increases in January; the maximum is reached in March when 135.9 mm and 135 mm rainfall is obtained in Drosh and Chitral respectively. The rainfall from December to April amounts to 448.2 mm in Drosh or 68% of the total annual rainfall. The rainfall in the upper parts of Chitral is low; winter and spring rain is more or less the same. The winter and spring precipitation is very important because it firstly provides moisture to rabbi season and secondly the whole years flow of spring, streams and rivers depend on the snow-fall in these seasons.

The summer and autumn rains form only about 32% of the total annual rainfall. It is received from the thunderstorms, which often gives torrential rains and cause great damage due to floods. Dust storms also occur during July and August and rarely bring showers in the afternoons. Nearly all the moisture of the monsoon winds becomes almost exhausted over the plains of India and Pakistan before reaching these remote valleys thus Chitral benefits very little from the monsoons (GOP. 1999).

1.5.1. Precipitation:

In Chitral district evaporation rates greatly exceed the rainfall. Table 1.2 shows the rainfall data for Chitral station. It shows the following pattern:

 March, April and May are consistently the wettest months whereas the pre and post monsoon months i.e., June, October and November are the driest.'

 Gilgit is at the same height as Chitral but experiences for less rain from the winter depressions.

 The winter spring rains are more widespread and universal as compared with the much more localized summer rains.

 Thunderstorms are occasional and hails rare. Occasionally, a shower in July and August can be heavy and according to the condition of upper catchment of nallahs, the run off may reach a threshold to trigger mass movement. It is also a fact that heavy rain in summer on glaciers may cause rapid melting, resulting in the high discharge of the sheaths.

 Snowfall is heavy in winter and forms the main source of water in the area, but its data is not recorded in the region. Similarly the record of hailstorms that occur in September to October, is also not available. It contributes very little to water and harmful to the agriculture crops (Whiteman, 1992).

Table No. 1.2 Average monthly Rainfall for Chitral and Drosh. Rainfall in mm

Chitral Drosh

Month Mean* Heaviest Fall Mean* Heaviest Fall

January 32.0 37.3 87.1 95.3

February 75.7 61.7 74.7 80.8

March 153.4 39.0 135.9 72.4

April 155.7 34.8 109.7 86.4

May 47.0 35.6 61.0 50.8

Jun 6.9 6.1 21.8 38.6

July 7.9 7.4 21.3 35.1

August 9.1 8.6 23.9 115.3

September 16.3 29.7 26.4 95.3

October 18.5 24.1 34.8 64.8

November 16.3 24.4 22.4 52.8

December 49.0 33.0 39.9 77.7

Average 48.9 54.9

Source: Regional Meteorological Office Lahore.

Heaviest Rainfall in 24 hours of rainfall *Average upto 12 years.

1.5.2. Temperature

Climatic data is available only for the lower part of the valley. As, in all, mountainous regions, temperature condition vary in different parts of the valleys especially in those areas, which are situated at higher altitudes. Beside the width of the valley, orography, valley winds and altitude of the surrounding heights are of immense importance in determining temperature condition and its variation in different areas. The latitude determines the seasonal range in temperatures. Table 1.3 gives the mean monthly temperature for Chitral and Drosh. From the analysis of the table one can observe the following.

Most conspicuous is the very large annual range of temperature (28-30°C). The local climate of Chitral is hotter in summer and cooler in winter. This large diurnal range is excellent for crop growth as it encourage accumulation of photosynthesis, during the period of low night temperature.

Variation in the normal temperature experienced during the season is important. Their influence on the rate of melting of snow in spring has already been mentioned as an important factor in controlling the availability of irrigation water. A small difference in temperature can have a much larger effect on growth. A cool April can delay the first cut of fodder upto two weeks and a cool May can slow the rate of regrowth. As many farmers have finished their straw winter feeding reserves this can be critical to the survival of livestock’s. Secondly, at the upper end of the double crop region (200-2200 m) and the upper limit of wheat cultivation (3000-3300 m) a cooler than average season will prevent the crop maturing in time (Whiteman 1992)

Table No. 1.3 Average monthly Temperature for Chitral and Drosh Temperature in C°

Chitral Drosh

Month Maximum Minimum Maximum Minimum

January 8.7 -1.3 7.1 0.2

February 10.6 0.3 10.2 1.4

March 16.1 5.1 15.1 4.9

April 21.7 8.4 21.3 9.8

May 27.3 12.8 28.1 15.3

Jun 34.8 18.7 33.8 20.3

July 36.7 20.7 36.0 23.2

August 35.7 14.7 35.1 22.7

September 31.7 13.6 32.1 18.7

October 24.7 8.2 25.6 11.9

November 17.9 3.4 17.8 6.4

December 11.5 0.1 11.1 2.4

Average 23.1 22.7

Source: Regional Meteorological Office Lahore.

1.6. Settlement pattern:

In Chitral settlements spread from 1,129m elevation at Arundu, the lowest point in the region to the 3,636m contour line at Baroghil. As mentioned earlier most settlements are found on the alluvial fans or on river terraces wherever soil fertility coincides with easily available water. Villages are also located in the beds of abandoned river courses where similar conditions persist. Besides the vast tracts of uninhabited areas due to adverse physical factors there are many habitable stretches scattered in the region which are at present not settled because of precarious conditions of water supply. Settlements are generally sited on the raised site of alluvial fans, which contain mostly infertile and stony lands. Thus the fertile lands are spared for cultivation. Hill torrents and streams are also important determining, they are avoided because they are prone to flooding. The banks of deeper and less dangerous streams are on the other hand favored sites for settlements (GOP. 1999).

Dispersion of individual hamlets and dwellings can also be observed which is a result of many factors such as socio-economic, population increase, feudal system, inheritance system, fragmentation of agricultural land, population pressure in the central villages, preference of land owners to build their houses close to their agricultural lands have resulted in dispersion of settlements in the valleys .

1.7. Demographic characteristics:

The total population of the district according to the 1998 census is 317,198. The distribution of population follows the lines of streams and rivers and is concentrated on the alluvial fans where water can be easily obtained, or on the gentle slopes or river terraces, which have fertile stretches and where water is also available.

The density of population is 21 person sq. km. The density is low because of the vast tracts of barren mountains and glacier bound valleys, which are uninhabited.

The population of the district has increased by 427 % since 1900. The first official census of the area was carried out in 1941. Since then the growth has been 192 %, while the last decade has shown the highest rate of increase so far, which is 3.4% per annum. This growth rate compared to the same decade for the whole country (3.1%) is quite high. Table

1.4. Table No. 1.4 Population of Chitral District, 1972,1981, 1998

S.No Area Total Population Male Female Pop./sq. 1998 1998 km.1998 1972 1981 1998

1 Chitral District 159000 208560 318689 162082 156607 21.5

2 Chitral Sub. Div. 87617 121648 184874 95499 89375 28.6

3 Mastuj Sub.Div. 71383 86919 133815 66583 67232 15.9

Source: Census of Population 1998. 1.8. Communication & transport system:

Chitral has inadequate means of transportation and communication, which have been a main hindrance in the economic and social progress of the district. The difficult topographic conditions and lack of resources greatly hampered the construction of roads. The mileage of roads for vehicular traffic remained limited till late. Since the merger of the state with Pakistan in 1969, a number of roads have been constructed making most of the remote areas accessible. Among these, Ashrat -Chitral -Buni road is a metalled and negotiable by heavy vehicle. The rest of the valleys in Mulkhow, Torkhow, Mastuj, Yarkhun, Laspar, Garam Chashma, Kalash Goom etc. have been connected by unmetalled jeep-able roads. Only certain remote parts e.g.; Baroghil, Bagusht, and Shah Jinali lack any road links (GOP. 1999).

Motorized vehicles include mostly jeeps, small bodied truck, pickups, Jeeps, due to difficult terrain, however, play an important role in the transportation of different commodities and people to the remotest parts of the district. The people have to depend entirely on jeeps for their daily journeys and trade purposes. With gradual increase in the widths of roads passenger wagons are also being introduced to the area lately. Heavy or large bodied trucks can only ply between Dir and Buni bringing different commodities to the district from the down country. To the still inaccessible parts of the district animal drawn.

CHAPTER 2

RESEARCH METHODOLOGY

2.1 Introduction to the Study

Geomorphology is the description and interpretation of landforms (Morrison, 1985). Geomorphic analysis is a base for understanding of processes involved in landform origin and evolution. Practical applications of geomorphology include measuring the effects of climate change as well as hazard assessments including landslide/debris flow prediction and mitigation. (Bridges, 1990).

The role of geomorphology in controlling landform is displayed at its best in alpine mountain ranges such as Alps and Himalayas. The Hindu Kush Range, one of the principal mountain ranges in the Himalayan system, is among the most dynamically active tectonic and geomorphic areas in the world. The valley fill sediments of great thickness have been deposited by glacial, fluvial and mass movement processes, forming different types of landforms including moraines, alluvial fans, fluvial terraces, debris flows, talus and scree cones, and floodplain deposits (Kamp, et al. 2004).

The Hindu Kush and Himalayas being the highest mountain chain on the earth are marked by very high relief and intense erosional activity under extreme climatic conditions. A number of variables control the formation and initiation of extensive debris in the region i.e. precipitation, glaciations, drainage, lithology, slope and gravity. These processes generate enormous amount of debris, which ultimately find its way down slopes to reach the valley floor as a debris flow. In the Hindu Kush and Himalayan mountainous terrain, it constitutes a significant natural hazard that can cause fatalities, damage infrastructures and settlements and diminish land productivity (Giraud, 2005).

Being part of the Hindu Kush range, the Chitral valley is no exception. The vast alluvial plain carved by the glacial valley is subjected to devastating floods and debris-flows from the tributary streams almost on annual basis. (Said, 1992).

Debris flows are fast moving flow type landslides composed of slurry of rock, mud, organic matter and water that move down drainage-basin channel onto alluvial fan (Giraud, 2005). Debris flows can travel great distances down valleys and debris-flow fronts can move at high speeds as much as 85 kilometers per hour (Macdonald, 1972). Several contributing processes including stream gradient and length, slope in the drainage basin, sediment availability from catchments area determine the nature and extent of debris flow. A debris flow ultimately deposits its sediment load whenever a stream emerges from the steep mountainous slope area into a gentle valley floor forming an alluvial fan. These natural processes are important factors for landscape evolution. However if human settlements come in the way, these natural events turn to natural hazards with the potential to cause disasters (Glade, 2005).

One of the principal landform in the Chitral valley include alluvial fans. As opposed to mountain-front fans, those in the Chitral valley are formed at the junction of tributary streams with the trunk river and therefore termed tributory-junction alluvial fans (Harvey, 1997). The morphometric analysis of the alluvial fans is the base for relating alluvial fan area and slope to drainage basin area in order to understand if and to what extent the alluvial fans are dependent on the physical environment including characteristics and processes of the drainage basin and depositional site (Villar and Ruiz, 2000).

Various authors have developed empirical relationship between debris flow characteristics and conditioning parameters. A review of the worldwide study has been published by Rickenmann (1999). Numerous other authors have developed site-specific relationship for debris flow hazards for example Evans and Hungr, (1993); Corominas, (1996); Bathurst et al., (1997); Wieczorek et al., (2000); Okunishi and Suwa (2001); Glade (2005),

Similarly, researchers have described various types of natural hazards associated with Quaternary deposits of the eastern Hindu Kush and Himalayas. These include Burton et al., (1964), Burton and Kate, (1964), Burton et al., (1978); Cunny, (1983); Owen, (1989), Said, (1992); Khan, (1993); Khan, (1994); Khan, (2000); Kamp et.al., (2004); Dardner and Sakzuc, (2004). Several researchers focused on debris flow hazards at selected localities in

16 the eastern Hindu Kush and Himalayas (e.g. Wasson, 1978; Itturrizaga, 1999; Case, 2000). However, none of these studies describe debris flow dynamics and its associated hazards in relationship with morphometric parameters for the Chitral valley. The present study will be first of its kind in the region concerning research on the type, nature and origin of debris flow in the Chitral valley and associated hazards.

5933 3804 72° 73° Baroghil- Karambar- 74° 6317 Pass Pass • Shah Jinali- Yarkhun Lasht 4343 Pass Fig. 2.1. Map of District Moghlang 6940 4260 6872 Chitral Showing Study Area 6523 Darkot-Pass 6225 6416 Ishkashim 6030 Thui-Pass Darkot 6244 • 4499 6677 (2609) Torkhow Rech N 7038 Zebak 7106 Paur (2606) UzhnuKhot- 6518 Pass Khot Ishkoman 36°30' 7349 Zanglasht 4323 Mastuj 5852• 6005 Washich Yakhdiz 7485 Shotkhar 5532 5798 Shagram Buzund 6320 Chatar- Rayeen Brep khand 6293 5708 Shagrom Odier 5660 Zadar-Pass Yasin Werkup 5009 (2260) Owirdeh i Mulkhow Istaru Chunj 7706 M 5873 Booni Mastuj 4328 5628 5823 (2279) 5798 5950 5167 Barum Gupis Reshun 6550 Dorah-Pass (2170) Lotkuh o Ghizer Chhachi Gakuch 4554 5056 Shandur-Pass Singal Barenis 3720 5815 5393 5308 Garam Chashma Sor 36° 5905 Laspur Shoghor Kuju Koghuzi 4995 4894 Ustur 5722 6259 Chitral Ragh 4377 5942 5001 5405 Chitral Kari 4684 Town Chumurkhon Dadarili- (14 75) 5871 Pass International T A J I - K I S T A N Madaklasht 5060 Boundary C H I N A 5749 Faizabad 5142 Broz 5813 District Boundary Ayun Gahiret Tahsil Boundary Kesu 5110 4662 4955 Altitude in m Gilgit Drosh Glaciers and Skardu 4664 35°30' Drosh Regions above 4367 Kalam Snow-line Kabul Mirkhani (2100) Study Area Srinagar Ashret 0 10 20 30 40 km Kamdesh 4955 4103 Lowari- 4821 Peshawar Islamabad Pass Draft: 3118 K. Haserodt (1988), Arandu A. Holdschlag (2003) 4277 4287 Cartography: Fliessbach/Kamp/Hengstmann- Reusch (TU Berlin) (1998), 3814 Dir 72° A. Holdschlag (2003) Figure 2.1. Map showing location of the Chitral valley in the eastern Hindu Kush of northern Pakistan ( after Kamp et.al., 2004)

2.2 Aims and Objectives

The aims and objectives of the study are as follows:

1. To recognize and map various types of landforms in the Chitral Valley with emphasis on alluvial fans. 2. To identify major debris-flow prone areas based on previous history and present landscape configuration. 3. To diffetentiate various landforms based on morphometric analysis of the contributing tributory streams. 4. To carryout debris flow hazard and vulnerability analysis using GIS and Remote Sensing. 5. To classify alluvial fans in terms of hazard potential and to suggest measures for mitigation and control.

2.3 Research methodology

1. This research work is focused on debris-flow hazards on tributary-junction fans along Chitral River and its major tributaries including Mustuj, Sor Laspur and Torikho Rivers (Fig. 2.1).

2. For detailed mapping of thevarious Quaternary landforms, topographic maps (Survey of Pakistan, 1:50,000) and satellite images (Landsat 7 ETM, 30 m resolution and SPOT 5, 2.5 m resolution) were used. Quaternary landform map developed by Kamp et al. (2004) was made as base map for recording field observations in this study.

3. An inventory was developed for most of the Quaternary landforms flanking the Yarkhun River and its tributaries.

4. A total of 100 Alluvial fans were studied in the field and described in terms of catchments area, availability of sediment, stream gradient, relief, fan morphology, distributaries streams, and nature of stream incision, stream discharge and land use for geomorphic analysis. These data were used for hazard zonation and classification. Geomorphic features such as fan axial and cross profiles and nature of constituent sediments were recorded. Tributary feeder channels associated with fans were recognized

as gullies, ephemeral channels and perennial streams and their associated tributary- junction fans were evaluated for signs of recent debris-flow events by identifying channel levees and debris-flow lobes.

5. Morphometric data regarding measurement of various stream parameters like watershed area, feeder-channel length and gradient and fan-surface or depositional basin area and gradient are measured for each fan using ETM satellite images georeferenced and processed through ArcGIS® 9.3, together with topographic maps and field survey. Parameters for watershed like Melton ratio, relief ratio and length (Wilford et al., 2004; de Scally et al., 2010) were used to distinguished feeder channels capable of generating floods, debris floods and debris flows at fans

Figure. 2.2. Showing various morphometric parameters which were measured for morphometric analysis in this study.

The following attributes were used in the analysis. Table 2.1 Watershed/Drainage basin attributes used in the analysis Attributes Description Units Basin/watershed Topographically defined area of the basin Km2 Area Basin/watershed The planimetric straight line length from the most distant point (crest) Km length of the basin boundary to the fan apex Channel length The total length of the channel identified on the image Km Relief The elevation difference between highest point and lowest point in a Km basin. Melton ratio Basin relief (km) divided by the square root of Basin area(km) Km/Km (Melton, 1957) Relief ratio Basin relief divided by basin length (km) (Costa, 1988) Km/Km Slope% Elevation difference(Max.-Mini) divided slope line length*100 % Slope o =Degree(ATAN(Fan slope% / 100)) Degree Mean, Standard deviation and range were also calculated through statistical formulas of all fans and watershed/drainage basin.

6. Historical accounts of hydrogeomorphic hazard events were compiled from newspaper archives, unpublished records of the district government (relief department) and from interviews with locals. The district government records span entire Chitral district, and include data archives from 1970 onward. The data include location, cause (snow avalanche, landslide, debris flow, tributary-stream flood and riverine flood), casualties, and relief supply details. Interviews were conducted in 40 settlements along the Chitral River from north of Mastuj to south to Drosh. The questionnaire included nature of the event, approximate year of occurrence, magnitude, and damage. These were supplemented with field observations for signs of debris flow remnants (e.g., levees, lobes and poorly sorted sediment deposits) to distinguish debris-flow events from those of flash floods. 7. For thematic data preparation software’s of geographic information system (Arc View 3.3, Arc GIS 9.3) were applied in developing, manipulating, zonation and analyzing the digital data for preparation of the hazard mapping.Global positioning system (GPS) was used to record the location of fans. For the preliminary hazard mapping attempted in this study, two classes; high and low based on frequency of the debris-flood/flow events

21 were used. Fans with debris-flood/flow events ~10 years return period are classified as high hazard and those with ~30 years return period as low hazard. For vulnerability assessment simple parameter i.e., presence or absence of a human settlement were used. Landforms with a sizable settlement on the fan surface or adjacent to it are classified as highly vulnerable and those with no or negligible settlement, as least vulnerable. Finally the analyzed data were presented in the form of maps, tables, statistical diagrams and descriptions.

2.4 Scope of the Study As a result of this study, the following goals will be achieved:

1. For the first time, a complete inventory of large and more significant debris flow/fans in the Chitral valley will be carried out. This data bank thus generated will be useful for any type of future work on geomorphology, landscape evolution and hazard assessment. 2. Morphometric data on drainage and depositional basin of all major alluvial and debris fans were used to recognize various geomorphic types and develop a debris flow hazard classification. Recognizing the most important controlling factors for the generation of debris flows in Chitral valley, an area-specific debris-flow hazard classification will be developed. This classification will not only be useful for general awareness of the inhabitants but also serve as important guide for land-use planning, infra-structure development, hazard assessment, mitigation and control and where possible, designing engineering solutions for mitigating debris-flow hazard. 3. Although extensive literature is available on almost every aspect of debris flow worldwide but debris fan/flow research in high altitude mountainous terrain of Himalayas and Hindu Kush has not received due attention for lack of accessibility and hostile terrain conditions. This study will document very pertinent data on high altitude, continental geomorphic setting with its unique physiographic set up.

CHAPTER 3

ASSESSMENT/ INVENTORY OF DEBRIS FLOW HAZARD IN CHITRAL VALLEY

3.1 Introduction This chapter encompasses an inventory of debris flow hazard in Chitral Valley of N. Pakistan. This district is part of the Hindukush-Himalaya Mountain System of the Himalayas, which itself speaks volumes about the extent of natural disasters threatening this district. The study aims at contributing to natural disaster management in this district and it is expected that this inventory will make a basis for future planning for mitigation strategies to cope with the threat of debris flow hazards in this area. This assessment/inventory of debris flow in Chitral valley covers road/river stretch along the main trunk river i.e., Kunar-Chitral-Yarkhun river between Drosh in the south-west and Brep (north of Mastuj) in the northwest. The inventory is divided into five sections comprising road/river segments. The first segment deals with assessment of debris flow from Drosh-Chitral. The second segment from Chitral-Barenes. Third segment from Barenes-Mastuj. Segment four from Mastuj-Brep. The fifth segment describes from Mastuj to Laspur area. Each segment is described in terms of sites which have experienced Debris Flow Hazards in the past or have potential for future Debris Flow Hazard.

3.2 Segment A (Drosh-Chitral)

The Drosh-Chitral Segment is approximately 40 km long along the Chitral-Kunar River. Several major and minor streams join the Chitral-Kunar River from both east and west. Of the prominent streams include Nagar, Urshun, ,Singur, Chitral, Mulen, Ayun on the right bank Drosh, Joshaba, Kaldam, Shishi, kesu, Damin, Pandori, Jughar, Chchu, Chamarkan, Kolo, Gumbas, Pashan, Ghirat, Kesu and Shishi on the left bank. In the following a list of important debris flow fans in this segment with significant debris-flow hazard are described.

SEGMENT A. DROSH-CHITRAL

Figure 3.1 Index map of Drosh-Chitral Segment, showing major settlements, Drainage Basin area and important streams.

3.2.1 Site A1. Nagar Alluvial Fan 35o 28’ 44.7” N, 71o 44’ 47.3” E Large alluvial fan on the right bank of Chitral River with well developed cultivation and human settlements. The Chitral River is deeply entrenched in a narrow, sinous channel. The fan has moderate gradient (<10) and is incised by few deeply dissected debris flow channels. Fan morphology: Mature(stabilized) with settlements and cultivation. Raised distal (peripheral) slopes with entrenched drainage. Fan lies above normal flood level in the river Chitral. Drainage Basin: Deeply dissected with steep slope bounded mountain ranges. Debris Flow hazard: Low. Localized ground subsidence under high rain fall conditions is probable.

a Fig. 3.2 a) Satellite Image and b) field Chitral R. photographs of the Nagar Fan, Lower Chitral. Note that perennial streams Isrit Gol and Ursun Gol are deeply entrenched through their associated alluvial fans, so that in case of a debris flow event, the sediments are Ursun Gol directly flushed in the N river, without posing hazard to habitation on the alluvial fan.

b c

Chitral River

3.2.2 Site A2. Alluvial Fan, Left Bank of the Chitral Gol, Opposite Ursun Gol

Drainage: Dendritic, ephemeral stream with high flow during rains or under snow-melt conditions (seasonal). Lack of vegetative cover in the mountainous catchment area.

Slope profile: Moderate to steep, free slope in the upper reaches, followed by talus or scree slope with convex up lower slope profile.

Lithology: Silty, clayey sand with low clast to matrix ratio, derived from hillslope debris blanket, bedrock weathering in the catchment area and channel bank failure.

Fan Morphology: Gentle to moderate (<150 ), stabilized with settlements and cultivation. Flow through deeply entrenched channels with occasional spillover on the banks under higher than normal discharge conditions. Hazard type: Debris flow, liquefaction and ground subsidence Hazard Vulnerability: Road, human settlements and cultivation.

Incised

channels Fan

Fig. 3.3. Young alluvial fan characterized by deeply entrenched multichannel flow. Note that settlement confined to edge of the fan, as the medial part highly unstable and prone not only to flooding, debris flow but gully erosion. The topographic break furnished by road hazardous for road through debris flow deposition. 3.2.3 Site A3. Right Bank Upstream Nagar Fort.

35o,30’,36.10”N , 71o,44’,24.28”E

Two streams drain through this alluvial fan developed on the flood-plain deposits. Not that the southern stream has a long dendritic course with large catchment area. Despite being perennial/ephemeral, this stream has a relatively well developed/entrenched channel resulting in an efficient flushing/discharge of debris flow directly into the river. The northern smaller stream, associated with recent debris flow that has partially damaged the cropland is shorter, steeper and has only a limited catchment area. This immature stream has less entrenched channel, which is itself filled with its own debris flow. This makes the valley floor at higher or equal level to the surround cultivated, inhabited fan. A torrential rain event makes this stream highly hazardous as the debris flow has no escape rout but to spill sideward into the cropland and settlement.

Recent Debris Flow

Figure. 3.4. Satellite image of a settlement at right bank of the Chitral River, midway between Nagar and Drosh. Note that major ephemeral stream is associated with some debris flow hazard but smaller northern stream with limted catchment area and immature channel has clear evidence of recent debris flow history.

3.2.4 Site A4. Drosh Alluvial Fan

The largest alluvial fan with a major settlement in this segment is defined by the Drosh alluvial fan on the left bank of Chitral River (Fig. 3.5a.). The composite fan drained by four major streams including Drosh Gol, Joshaba Gol, Kaldam Gol and Shishi Gol has a total length of 4 km along the left bank of the river with average width of 1 km. The fan comprises five sets of debris flow terraces overlying the floodplain sediments of the river terraces, which onlap from south to north with successively lower altitudes. Of these four terraces are vegetated and used for settlement while the fifth, which is the youngest and the most recent comprises alluvial sediments deposited by the Shishi River at its confluence with the Chitral River as a delta fan (Fig. 3.5b).

As mentioned above, the Drosh Fan is drained by at least four streams. Of these the southernmost is Drosh Gol, that passes right through the shopping centre of the town.The northern edge of the fan is drained by the Shishi Gol. These two are major streams in the area with catchment areas, respectively being 22,420 km2 and 501,054 km2. The respective stream length is Drosh Gol, 10.6 km and Shishhi Gol 40.57 km. Because of their perennial nature, the two streams are characterized by deeply entrenched channel, both capable of flushing any debris directly into the Chitral river without posing hazard to the settlement and cropland on the Drsosh fan. From debris-flow hazard, relatively less mature, ephemeral streams draining the Drosh fan in its middle parts are most important.

3.2.5a Site A5a. Jushaba Gol (Drosh)

35o 34’ 29” N, 72o 48’ 17” E

The Joshaba Gol is a typical immature, ephemeral stream. The catchment area is 8547 km2 with the major sediment-feeding channel length of 6.2 km. The upper reaches of the stream lie in steep, snow-covered mountain range running parallel to Chitral river valley. Several paleo-flow channels, now clogged and abandoned can be recognized on the satellite imagery. The fan has steep slope towards the river with deeply entrenched streams with channel-restricted flow in the proximal part of the fan while the middle and distal part of the fan the streams are shallow and broad having potential for frequent over bank spillovers. During seasonal discharges in the Joshaba Gol, the sediment-laden streams gush down the steeply sloping fan carrying huge sediment load. The sediment-

28 laden discharges either get deposited in the channel on its way down or spilled over the adjacent settlement and cropland. To restrict the flow to its main channel, retaining walls and gabions have been constructed which have, to some extent helped to control/mitigate overbank spill over, reducing damage to life and property. However, spillover under higher than normal discharges commonly takes place disrupting the existing measures. History: The most recent debris flow occurred in 2005 causing damage to seven houses, disrupting infra structure (main road, electricity) and cultivated land. Stream Characteristics: Ephemeral stream with straight channel and steep gradient marked by shallow, incised, channellized flow. Deep, narrow channel in the upper reaches grading downstream into shallow and broad channel near the Chitral river.

Slope Characteristics: Straight, steep to moderate slopes (> 15-250) along channels/valleys marked by long stretches extending from snow-clad, mountain peaks down to valley floor.

Sediment type: Coarse, clast-dominated, reworked floodplain/older terrace- sediment substantiated by predominantly matrix-supported sediment derived from bedrock in the surrounding mountains and hillslope debris. Hazard type: Debris mud flow Hazard vulnerability: Human settlements, cultivation, cattle, road and infra structure. Risk Factor: High

Fig. 3.5. a) Image showing Drosh Alluvial Fan on the left bank of the Chitral River. Four streams, Drosh, Jioshaba, Kaldam and Shishi Gols drain the alluvial fan. Of these Joshaba and Kaldam Gols are sites of frequent debris flow, as detailed in the text. b) Geomorphological map of the Drosh Alluvial Fan.

2 3 Clogged Debris Present Flow Channel Channel

4 5 Chitral River

Levee s

Down stream Road

Fig. 3.6. 1) Aerial view of the Joshaba Gol and its debris-f;low channel. Note the catchment area characterized by steep landslide scarps and filled with debris. Insets show close-ups of lower reaches of the channel.2) A close-up aerial view of the debris-flow channel it passes through the settlement crossing the chitral-Drosh road. Several recent debris- flow spillovers from the main channel into surrounding settlement are clearly visible. 3) Close-up aerial view of Joshaba Gol as it enters head of the debris fan. Note ill-defined main channel, with several paleo-channels marked by past debris flows.4) Field photo of recent (2005) debris flow in Joshaba Gol (upstream view) near the road level. Note the debris-filled channel being higher than the surrounding inhabited fan. 5) Downstream view of Joshaba Gol, downslope from road. 31

3.2.5b Site A5b. Kaldam Gol (Drosh) 35o 34’ 67.0” N, 71o 48’ 33.0” E The Kadam Gol is an ephemeral stream with seasonal flow restricted to heavy rain fall/snow melt conditions in the catchment area. The stream is braided in the lower reaches of the fan. High, coarse, sediment discharges result in clogging or shallowing of the existing channels which results either in channel abandonment or alteration in stream gradient profile. As a controlling measure retaining walls and gabions have been constructed to restrict the flow to its channel. The catchment area is wide and extensive with high sediment source from bedrock erosion of the surrounding steep and barren mountains, substantiated by morainic debris and hillslope deposits, the channel has a huge sediment-input potential to defy temporary remedial measures. It is high risk area and a potential threat to life, settlements, roads and crops.

Steep barren slopes with talus cones Retaining walls Debris Flow Scree slopes

Figure 3.7. (1). Upstream view of Kaldam Gol from road. Note the flat and wider channel floor compared to the Joshaba Gol (Site A7a), yet the stream is comprised of recent debris flow. In the even of torrential rain the channel has potential of being clogged by its own debris-flow load, with chances of spilling over on the sides into cropland and settlement. 2) Retaining walls along the channel side to restrict the debris Debris flow flow in the main channel.

3.2.6 Site A6. Ichhar Gol-Muyah Gol Alluvial Fan (Right Bank of Chitral River) 35o, 36’, 42.67” N, 71o, 47’, 47.99” E First small settlement with associated cropland on right bank of the Chitral-Kunar River is on alluvial fans fed by a set of streams from western valley slopes (Fig. 3.8a). Of these Icchar and Muyah Gols are the main streams associated with several minor channels. The composite alluvial fan is about 1.5 km long (along the river) and at 0.6 km wide at its maximum. About 30% of the fan is cropland, with about 100 houses while rest comprises barren debris-flow deposits (Fig. 3.8b). The abundance of scree slopes in catchment area, immature nature of the feeding channels makes this fan susceptible to debris flow. The channel floor typically at higher elevation than the surrounding cropland and settlements. Torrential rain events can be catastrophic and may damage parts of the cropland as well as the cropland through spill over of the debris/mud flow from the clogged channel floor.

3.2.7 Site A7. Kesu Fan (Left Bank) 35o, 37’, 54.46” N, 71o, 47’, 36.26” E The Kesu alluvial fan, on the left bank of the Chitral River is 3 km long and 1.14 km wide at its maximum. The fan is almost fully covered with cropland and the combined settlement scattered on the fan exceeds 1000 houses. The Kesu Gol is major channel, while two smaller channels and many steep gullies face the fan from eastern valley

Figure 3.8 B1 . a) Ichhar-Muyah Alluvial Fan, Right Bank Chitral River. Two relatively

larger streams with associated steep gullies feeding the alluvial fan. Channels typically

ephemeral and immature without deep entrenching. Channel floor at higher elevation than surrounding settlement-cropland. Combined with scree-laden slopes, torrential rain event likely to spill over the debris-mud flow onto the cropland and N settlement. b) Close up.

Large alluvial fan with irregular slope profile, steep mountains in the catchment with

1 Km slopes. Most importantly, as shown in Fig. 3.9 B2a, the Kesu debris fan owes its origin not to the Kesu Gol rather to the relatively smaller channel to the south. This can be explained through a through understanding of the processes controlling debris fan formation and the associated debris-flow hazards. The difference in maturity, channel length, extent of catchment area are the factors which determine the extent of the resultant debris fan.

Figure 3.9 Figure B2. a) An overview of the Kesu alluvial fan 34 on left bank. Three fan terraces at different elevations make the campsite fan. The main channel passing through the fan is Kesu Gol. However, the fan is clrealy a product of the relatively smaller channel next to the south. The difference in maturity, channel length, extent of catchment area are N the factors which determine the extent of the resultant debris fan. b) A close up of the debris flow channel (next south of the Kesu Gol). Despite being subordinate to Kesu Stream, this stream is responsible for the formation of the Kesu Debris Fan. Though much of the fan is stabilized, there are clear evidences of debris flow events in recent past. c) Close up aerial view of the southern end of the Kesu Fan. Dense settlement right at the toe of debris-laden gullies make the area prone to debris flow hazard.

Obviously, the Kesu Gol with larger channel length and catchment area carries greater load of debris than the other stream. However, the same factors determine the amount of water draining through the two stream. The greater amount of surface water flow in the Kesu stream has resulted in maturity of the stream reflected in greater entrenchment of the channel floor. This enables this stream an effective and efficient discharge of its debris-load directly into the river. In comparison, the next stream to the south (Fig. 3.9

B2a,b), despite relatively smaller catchment area and the channel length and thus lesser overall debris load is capable of making large debris fans such as Kesu. The controlling factor is again the net amount of water available. Being a smaller channel and catchment area, this debris load almost always exceeds the water, resulting deposition of much of the material onto the channel floor at the head of the fan. The successive events, by clogging the main channel, result into several radiating channels carrying the spilled over debris flows on sides of the main channel. Not only the entire debris fan has formed through this process by recent and future debris-flow hazards can be explained in terms of this process. Figure (3.9 B2b) shows recent examples of spill-over debris flow deposits associated with this stream. Figure (3.9 B2c) shows severe threat of debris-flow hazard to the road and the dense settlement right at the toe of the steep debris-laden channels. An unusually large debris flow event will result in considerable damage to these elements.

3.2.8 Site A8. Girat Debris Fan (Left Bank) 35o, 37’, 54.46” N, 71o, 47’, 36.26” E Girat alluvial fan occupies the left bank of the Chitral River. The Ghirat stream is a mature channel, with deeply entrenched channel with efficient debris discharge capacity, that furnishes a low hazard potential. Several minor streams and gullies, however drain through the alluvial fan. These minor channels are immature and therefore are characterized by shallow channel course. In the event of torrential rain event, debris flows are expected threatening the settlement and cropland.

Minor Recent Debris Flows Figure. 3.10. An aerial view of the Ghirat alluvial fan. N Deeply entrenched perennial stream capable of inundation at stream banks and flooding of settlement/ cropland located within the stream channel near the confluence. Minor channels above the settlement are associated with small recent debris flows.

3.2.9 Site A9. Ayun Alluvial Fan (Right Bank) 35o, 42’, 51.58” N, 71o, 46’, 37.55” E A 5km long and 2 km wide stretch on the right bank of the Chitral River is occupied by the village Ayun. The settlement is perched on the flood-plain on the immediate bank of the river which is overlain in the west by alluvial fan terraces. The Ayun River drains the settlement with several minor channels feeding the alluvial fan. There is no evidence of recent debris flow, suggesting that the alluvial fan-floodplain terraces are highly stabilized by thick vegetation. Debris flow hazard is rated low for this settlement.

3.2.10 Site A10. Chitral Flood Plain-Alluvial Fan The Chitral Town and its suburbs are sprawled on a relatively flat plain stretched on the river banks of the Chitral River. This plain is 13 km long and up to 2 km wide. Much of the plain comprises flood-plain deposits on the river banks, but the plain has a past history of glacial action that contributed to widening of the valley floor. More than a dozen major tributaries join the river on either side which has contributed to widening of the valley floor. The flood plain is overlapped by alluvial and debris fans at its outer edges. Despite the fact that Chitral is surrounded by mountains comprising a relatively

Figure. 3.11. Aerial view of the Ayun village settlement on a flood-plain cum alluvial fan composite terrace. The main feeding channel i.e., Ayun River is characterized by perennial water flow with deep-entrenchment furnishing the channel with an efficient mechanism of transportation and disposal off of the debris. The terrace is stable with well developed cropland and other vegetation. Debris-flow hazard is rated low. week rock i.e., Chitral Slates, which have weathering properties capable of generating abundant debris, the signs of recent debris flow are relatively uncommon. Two factors are determine this apparent lack of debris flows. Firstly the slopes facing the river (or its tributaries) are generally highly steep, with a constant steep gradient from ridge top to the slope toe, which prevents accumulation of scree on slopes, resulting in barren, scree-free slopes. Secondly, the streams surrounding the township and its suburbs are mostly perennial fed by glaciers, resulting an efficient flow and discharge of the debris direct into the main trunk river. These two factors have made Chitral township and its surrounds virtually free of debris-flow hazard, although flash flooding in case of torrential rains cannot be ruled out.

3.2.11 a Site A11a. Chitral City (Left Bank): Scouts Post Bridge

N 38 Steep Debris-

laden Slopes

Mulen Gol

Figure 3.12a. A view of Southern Chitral City (Scouts Post Bridge). Note steep scree slopes laden with loose debris capable of conversion into debris/mud flow in the event of an unusual torrential rain.

The steep slopes facing the settlement in southern Chitral town (opposite Scouts Post Bridge) have low to moderate accumulation of fresh unconsolidated debris material. There is no evidence of recent debris-flow but in case of torrential rains these slopes have potential for generating debris-flow threatening the irrigation channel, settlement and the cropland.

3.2.11 b Site A11b. Chitral City (Right Bank): Airport Road

The Airport Road segment immediately next to the Main Chitral Bridge (Fig. 3.12b1) is bounded by moderately steep slopes. Several ephemeral, immature channels drain through these slopes, laden with recent fresh debris. Clear evidence of recent debris flow along these channels is seen suggesting that these channels are capable of generating debris and mud flow with potential hazard to the minor settlement but especially the important road, linking the city centre with the airport.

Recent Debris Flows damaging the road Chitral River

3.2.11 c Site A11c. Chitral City (Right Bank): Airport Area The Singur composite fan on the right bank of the Chitral River is one of the major plain areas in Chitral City (Fig. 3.13-a). The fan is drained by the Singur Stream from west which is a perennial channel. Downstream of Singur stream, there are several ephemeral channels which are debris filled and have clear evidence of recent debris flow(Fig. 3.13 a,b,c,d,e). Of these, two channels are of particular interest, one at the northern end of the runway (Fig. 3.13-c,e) and the other south of the Airport near Balach Village (Fig. 3.13-b,d). Both these channels are immature and ephemeral. Both are filled with recent debris flow. The debris filled channel floor is at least a meter high above the road and the natural levees are as high as 1.5 meters. Both the channels are potential debris-flow hazard of moderate level, capable of over spilling from their banks into surrounding settlement and cropland which are lower elevation than the channel floor. At their toe, they cause damage to Garam Chashma-Chitral road but are capable of cusing damage to the runway and other Airport building in case of an unusually high spell of torrential rain.

3.3. SEGMENT B FROM CHITRAL CITY TOWARDS BARANUS

3.3.1 Site B1. Danin, Chitral City – Start of Chitral-Mastuj Road

The road through Danin area of the Chitral City on way to Mastuj passes through the Danin Alluvial fan. The fan is thoroughly vegetated and densely settled with a generally good stability. The Dannin Ridge overhanging the settlement comprises several gullies and steep channels with talus cones. In case of torrential rains, chances of debris flow are there threatening the settlement in the part of the city. The area can be classified to be characterized by low debris-flow hazard.

Chitral N

Danin Gol Chitral-Mastuj Rd

Figure. 3.14. A view of the Danian alluvial fan, northern part of the Chitral city. Stabilized alluvial fan with low debris flow hazard from talus cones.

3.3.2. Site B2. Kari Gol Fan

Kari Gol Alluvial fan, left bank Yarkhun River is a stabilized, highly vegetated settlement. The main channel is perennial with year-round water flow, resulting in directed flow in a well-entrenched channel. The debris-flows from the main channel as well as its tributaries are directly discharged in the main river. An active fan overlaps the main fan, associated with a minor, ephemeral channel with clear evidence of recent debris-flow (Fig. 3.15). This channel is capable of generation of significant debris-flow hazard in an unusually high torrential rain posing serious threat to the settlement and the cropland.

Active Debris Fan

Active Debris Flow

Kari Gol Stable Alluvial Fan

Figure 3.15. Kari Gol Aluvial fan, left bank Yarkhun River. The stabilized fan is mainly drained by the perennial Kari Gol, with efficient discharge of debris flow into the trunk river. Minor ephemeral channel at the head of fan associated with recent debris flow, posing high-debris-flow hazard to the settlement.

3.3.3. Site B3. Ragh

Ragh village, on the left bank of the Yarkhun River is apparently a stabilized, highly vegetated settlement. The aerial view on a satellite image however reveals that the settlement is prone to high debris-flow hazard. The settlement is divisible into two parts. The riverside area all the way to almost the road level is a flood-plain deposit that provides a fertile land for crops. The much of the area above the road level is built on active debris fans. These debris fans are fed by two ephemeral channels each associated with recent debris flows. These channels are characterized by an immature drainage. Since entrenchment is not deep, the channels are capable of blocking the main course and overflow sideward into the settlement in case of debris-flow events during the torrential rains.

3.3.4. Site B4. Turen Kuju, Right Bank, Yarkhun River

The Turen Kuju settlement on the right bank of the Yarkhun River is characterized by a composite alluvial fan cum flood-plain flat land, densely vegetated and apparently well

44 stabilized. The two streams draining the settlement (Fig. 3.17) are characterized by narrow channels which are further subjected to confinement by settlement and cropland. In the event of a torrential rain, debris flow may block and choke the main channels resulting flooding and spread of debris flow in the settlement and cropland. Some evidences of recent flow suggest medium-grade hazard associated with this settlement.

N N

Turen Kaju Kuju

Recent Debris Flow Recent Channels with debris flows immature drainage

Figure 3.17. Turen Kuju settlement. Two channels draining the settlement are characterized by under-developed drainage prone to blockage by debris deposits in an event of debris flow, which may cause substantial hazard to the settlement and the cropland.

3.3.5. Site B5. More Lasht Bala, Right Bank

35o 59’ 94” N, 71o 58’ 63” E

More Lasht Bala is an alluvial fan about a km wide with almost of same length from fan apex to its distal end cut by the river. The fan has a reasonable settlement as well as the cropland. The ephemeral channel draining the fan is very narrow at its apex and is characterized by a meandering path while passing through the fan. The channel has a history of blockage especially at the apex by its own debris load. This results in diversion of the channel flow through the main settlement as a flash flood/debris flow. In 1986 such diverted debris flow from the apex passed through the main village and destroyed several dozens of houses and destroyed many croplands (Fig. 3.18.1, 2, 3). The site is highly hazardous for the reason of similar debris flows in future.

Fig. 3.18.1

Diverted Main Debris Ephemeral Flow 1986

3.3.6. Site B6. Parait Alluvial Fan, Right Bank Yarkhun River

36o 02’ 97” N, 72o 02’ 22” E

The Parait Alluvial Fan, located on the right bank of the Yarkhun River is 2 km wide with apex to river distance of about 1 km. The Parait Gol is a perennial channel with regular water flow resulting in maturity of the stram as reflected in its deep entrenchment. This main channel lacks any debris-flow hazard. However, immediately next to the south, thee is an immture ephemeral chanel with an active debris fan with clear evidence of recent debris-flow events. This channel poses a high debris-flow hazard to the souther two-third of the fan thretening the settlement and the cropland (Fig. 3.19.1, 2, 3).

Ephemeral Channel with Active Debris Parait Gol N Fan

Figure 3.19.1. Topographic map showing location of the Parait Alluvial fan on right bank of the Yarkhun River.

Figure 3.19.2. Satellite image of the Parait Alluvial Fan showing the main channel i.e., Parait Gol characterized by lack of recent debris flow and the ephemeral channel to the south with recent debris fan.

Figure 3.19.3. Field photo of the Parait Alluvial Fan.

The stream opposite the Parait Gol, is also ephemeral. The channel is characterized by active debris flow at the road level. The channel downstream from the road is deeply incised.

3.4. SEGMENT-C BARENIS TO MASTUJ

Turkho R iv Mastuj River er Parwak Mastuj Sanoghar

Reshun Barum Gol Parpesh CHITRAL Barenis-Mastuj

0 15 Kms Barenis

Fig. 3.20. Location map of segment C from Barenis to Mastuj

3.4.1. Site C-1 Barenis 36o 04’ 42.9” N; 72o 02’ 29.1” E Brenis settlement is located on the left bank of the Yarkhun River. The settlement is located on a composite alluvial fan cum flood-plain landform. The Berenis Gol is a perennial stream with deep entrenchment resulting in no obvious debris-flow hazard for the settlement (Fig. 3.21).

Barenis

Active N Debris Flow Fig. 3.21.1. Aerial view of the Barenis settlement compositely formed by flood-plain deposit partially overlain by the alluvial fan. The perennial entrenched Barenis Gol well directed capable of flushing any debris-flow direct to the river, rather than threatening the settlement.

On the right bank, opposite Berenis (Figure 3.21.1, 2) an extended alluvial fan exists at the toe of barren, intensely weathered, steep mountain range. The catchment area is east-facing, high angle slopes blanketed with unconsolidated, morainic sediments and talus cones dropping down to a moderately sloping, small but laterally-stretched debris fan along the banks of a broad river valley. The surface drainage on the fan is dendritic with several branching tributaries. The streams are slightly entrenched in the distal part of the fan where small triangular facets along the ledge have developed. Frequent flows activity is evident from a recent, small mudflow on the fan. High instability of the fan is evident from lack of settlement and cultivation. Despite existence of active debris flow hazard, there is no vulnerability due to lack of population or cropland.

Recent debris flow

Barenis Village

Fig. 3.21.2. View looking northwest of Mastuj river valley, upstream of Barenis, a large alluvial fan on the right bank of the river having a catchment area of barren steep slopes mantled with debris. Recent debris flow is visible.

3.4.2. Site C-2 Shil Gol 36o 06’ 41.1” N; 72o 03’ 38.4” E Older debris flow comprised of morainic sediment deeply incised by recent debris flow. The debris is coarse clast-dominated with subordinate fine matrix (Fig. 3.22). In 2004, a debris flow along this gol inflicted damage to road, settlement and agricultural land. Downslope from the road the entire population is still at risk (Fig. 3.22.2). The direction of Gol is from east towards the Mastuj river, which cuts the moraine deeply.

Figure 3.22.

Aerial view of the Active debris-flow N Shil Gol, an channels ephemeral channel characterized by recent debris flow. Another steep, debris flow channel on the southern end of the settlement is also associated with recent debris flow.

Shil Gol debris flow

Figure 3.22.2. (on left) View upstream Shil Gol debris flow intersection at Chitral-Buni road. Noteworthy are steep, unstable slopes in the catchment area with high sediment production potential, steep gol gradient and coarse morainic flow. Figure 3.22.3. (above) Downstream view of Shil Gol, showing vulnerable settlement.

3.4.3. Site C-3. Right Bank, Yarkhun River-Parpish Alluvial Fan and Next Channel Upstream

36o 06’ 41.1” N; 72o 03’ 38.4” E

The Barum Gol is major stream at the right bank of the Yarkhun River. The channel has an overall length of about 19 km and is fed by major glaciers from Tirich Mir. Further, the stream drains through a lithology comprising loose shale which is highly susceptible to mass movement. However because of a large catchment area fed by glaciers and overall stream length, the stream is characterized by perennial water flow resulting in

51 directed flow in a well entrenched channel. Parpish is the major settlement at the mouth of the stream but there is considerable settlements and cropland upstream (Fig. 3.23).

Because of the confined flow in deeply-entrenched stream the debris flows into the stream are transported directly to the river without threatening the settlement and the cropland. However, since the stream is fed by major glaciers, which are capable of generating avalanches, which might result in unusually large debris-flow which might exceed the capacity of the stream and can spillover onto the settlement. The chances of such a catastrophe are moderately high because abundance of lithologies comprising loose shale. The channel may be classified as moderately hazardous from the debris-flow point of view.

Debris- Parpish Flow Stream Barum Fig.E.4.1 Gol

Fig. 3.23. A view of the Barum Gol on the right bank of the Yarkhun River. Note the presence of major glaciers from Tirich Mir in the catchment area, which furnishes the stream with a perennial flow. Directed flow in an deeply-entrenched valley produces an efficit system for debris-flow flushing direct into the river. This results in no major fan development and lack of any debris-flow hazard, unless in an unusual event of avalanche which might produce debris flow beyond the capacity of the channel. 3.4.4. Site C-4. Right Bank, Yarkhun River, Debris-Flow Channel next Upstream from Parpish. (36o 08’ 14.7” N; 72o 04’ 25.0” E)

An ephemeral channel draining the western slopes of the Yarkhun River, next and upstream to the Barum Gol is source of a spectacular debris flow (Figure 3.24). The huge

52 amount of debris associated with this channel is result of the shale lithology exposed in the catchment area of this channel. Other sources of the debris include colluvium and morainic sediments. Although this stream is associated with high debris-flow hazard, the lack of any settlement or cropland at this site makes it low risk site.

3.4.5. Site C-5. Lon Creeping Debris Flow, Opposite Reshun, Right Bank-Yarkhun River

A large settlement termed Lon is located in a saddle-shaped basin about 2000 feet above the river level, on the right bank of the Mastuj River. The topographic map (Fig. 3.25.1) shows that the several ephemeral and some perennial (spring water) stream drain into the basin. Interestingly, the streams out-letting from the basin are all ephemeral suggesting that all the water is internally absorbed into the basin. The village Lon is the type locality of famous geological formation called Lon Shale. The Lon Shale is typically loose clayey material with minimum internal cohesion. This lithology underlying the Lon settlement, by absorbing water from spring-fed perennial further looses its cohesion and is capable of creep like a glacier. (Fig. 3.25.1, 2) shows the irregular shaped creeping mass at the ridge directly below the Lon village. Whereas this creeping debris-flow does not pose a major threat to any settlement on the river bank, the Lon settlement being located on such an unstable mass is under a permanent threat by hazards like fissuring, sinking and liquefaction. In case of torrential rains, some of the streams draining into the Lon village may turn into debris flows and may cause damage to property and land in this settlement. The settlement is therefore rated as high hazarad cum high risk.

Spring-fed perennial streams

Creeping- debris flow Fig.5.25.1,2

Figure 3.25.1. Topographic map showing location and position of the Lon village, opposite Reshun.

Thick colluvium on slopes Settlement

Mastuj River

Figure 3.25.2. A view of creeping debris-flow deposit opposite Reshun.

3.4.6. Site C- 6 Reshun Alluvial Fan 36o 09’ 32.06” N, 72o 05’ 58.34” E The Reshun alluvial fan, on the left bank of the Mastuj River is a major settlement in mid-upper Chitral district. The fan is about 2 km wide and 0.9 km across from apex to its toe at Mastuj River. The Reshun Gol is a perennial stream about 12 km in length fed by glaciers (Fig. 3.26). Because of perennial character attained by large stream length, large catchment area and presence of glaciers as feeders, the Reshun Gol has well entrenched channel that traverses across the Reshun Alluvial fan. This furnishes the stream capability of efficient discharge of any debris flow direct into the river in normal circumstances. However, every 30 to fifty years a rainstorm may cause landsliding in the catchment area generating substantial amount of debris which when mixed with stream and rain water can produce debris flow of substantial dimensions. Wason (1978) has documented once such unusually large debris-flow event in the Reshun Gol on August 14, 1975. According to this eye-witness account, on 14th August, 28 hours after the start of the rain in the catchment area of the Reshun Gol a major debris-flow event happened in the evening at 7 pm that lasted for about one hour. The debris-flow owed its origin to a major rain-triggered landslide probably 5 km upstream in Reshun Gol at Shkuh Garhi. The debris-flow carried timber and a major sediment load including boulders as big as 2 meters. Despite being a well entrenched channel, the debris-flow was so huge that it not only damaged the one abutment of the across-the-channel bridge but destroyed several houses and cropland near the apex of the fan. This example provides insight into extreme cases of debris-flow hazard. The main theme developed in this report, which has been supplemented by dozens of field observations is that that deeply entrenched perennial streams pose no or little debris-flow hazard due to their efficiency of direct discharge of any debris direct into the river without being capable of threatening the surrounding settlement. The Reshun Gol 1975 debris-flow event suggests that even such deeply-entrenched channels may be hazardous in unusual cases where rainstorms can be accompanied by landslides in the catchment area where the flood as well as the enormous amount of debris may still result in debris flow hazards.

Reshun

Figure 3.26. Satellite image of Reshun Gol and Reshun Fan, left bank, Mastuj River supplemented with topographic map of the same, showing extent of the stream length and catchment area.

3.4.7. Site C- 7 Shogram Gol Alluvial Fan, Right Bank Mastuj River. 36o 10’ 22.06” N, 72o 07’ 00.66” E

The Shogram alluvial fan (Fig. 3.27.1), located on the right bank of the Mastuj River is about 1 km in length along the river, and 0.3 km wide from apex to its toe near the river. The alluvial fan is built on flood-palin terraces and is associated with the Shogram Gol, which is an ephemeral channel(Fig. 3.27.2). Unlike most ephemeral channels in the region, the Shogram Gol is a low gradient deeply entrenched stream. The sediment source in the catchment area is from mass wasting produced hillslope deposits. The gently sloping fan is incised by two streams oriented perpendicular to each other. The fan is partially stabilized but vulnerable to higher than normal discharges along the feeding streams. Moderate debris-flow hazard is associated with this settlement. Figure 3.27.1. Topographic map showing location of the Shogram Gol and associated settlement on alluvial fan. Figure 3.27.2. A distant view of the Shogram alluvial fan looking upstream from Reshun. Note the built of the typical alluvial fan on a flood-plain deposit.

Steep bedrock slope

Talus cone Scree slope

Flood plain Road Flood plain

3.4.8. Site C- 8 Zait Alluvial Fan, Left Bank of Mastuj River.

36o 09’ 35.5” N; 72o 06’ 26.5” E

Zait is a typical alluvial fan deposited on flood-plain deposits on the left bank of the Mastuj River. The partially stabilized fan along the stretch of the river is being fed by

57 a long, entrenched stream bringing in sediment from a wide catchment area with appreciable contribution from gulley erosion of the talus cones and landslides of the unstable steep slopes. Hazard type Debris flow, mudflow, landslides.

Risk Elements Settlement and cultivated land during peak flood conditions.

Risk Level Moderate.

Debris Terrace Fluvial Terrace Glacial moraine

River erosion

Figure 3.28. A side view of the Zait debris fan at the mouth of the Zait Gol. The Debris fan is built on the flood-plain terrace. The red colour is due to derivation of debris material from the Reshun Formation (red conglomerate and shale), exposed in the catchment area.

3.4.9. Site C- 9 Active Creeping Debris Flow, Channel next upstream of Shogram Gol, Right Bank, Mastuj River.

Active Creeping Debris-Flow

Upstream of Shogram and Zait, there is a spectacular debris-flow exposed on the right bank of the Mastuj River. The debris-flow is associated with a narrow hanging valley about 2000 feet above the Mastuj River. The topographic map of the channel (Fig. 3.29) shows that the feeder stream is perennial, but looses its water content into the basin feeding the active debris flow, rather than reaching the river. This special situation arises due to presence of the unique lithology i.e., the Lon Shale in the basin area. Being a week, in-cohesive lithology, the shale absorbs all the awater and turns into a viscous material that moves downstream through an active creep rather than flow. In case of rainstorm, this material can easily turn in to a mud flow. The creeping debris-flow is typically associated with ground failure, sinking, bulging, fissuring. This phenomenon is a close analogue of a moving glacier. Obviously, the basinal area in the catchment as well as the active creeping debris flow both are highly hazardous for any settlement, road or cropland.

Bedrock Scree Slope slopes failur e

Ground failure

Active Debris flow

Figure 3.30. A field photograph of the active creeping debris flow in a channel hanging about 2000 feet above the river level. The water absorption in the basinal area makes the bedrock lithology i.e., the Lon Shale turn into a viscous mud that creeps downslope. Note the presence of fissures, slums, sinks in the creeping debris flow.

3.4.10. Site Site C-10. Koragh Gol 36o 12’ 53.01” N; 72o 09’ 24.1” E

Koragh Gol is a shallow, ephemeral stream that joins the Mastuj River on its left bank almost at the confluence with the Torikho River. The ephemeral stream has evidence of frequent debris flow as shown by debris-flow levees. The channel is bounded by scree slopes, which in case of rain mix with water to form the debris flow. The Mustuj road is under a constant threat from the debris flow from this channel.

Vertical cliffs Scree of jointed cone bedrock

Debris 60 flow channel Stablized toe of slopes

Levee

Road

3.4.11. Site C- 11 Confluence of Mastuj and Turko River

36o 13’ 18.3” N; 72o 10’13.0” E

Figure 3.32.1. (Left) Location map of the Torikho-Mastuj rivers confluence.

Figure 3.32.2. Satellite image of the Torikho- Mastuj Rivers. The red arrow shows direction of view of field photo-Fig.3.32.3. Note concentration of cropland and settlements (green) on the northern ridges of the Mastuj River.

Photo E11.2 Mustuj R.

Torikho R.

Debris fans with hummocky surface characterized by ground subsidence, Figure 3.32.3. slumping and land sliding. Field photograph of the settlements on Turkho river creping debris fans on the northern side of the Torikho- Mastuj Mastuj river confluence.

The terrain bounding the northern side of the Mastuj River comprises a lithology characterized by week engineering properties like strength and cohesion. The lithology is named after the Lon village (opposite Reshun) and is called Lon Shale. Two competent lithologies (limestones and quartzites) bound this lithology from two sides, one from north along the sky-line ridges and the second along the northern side of Mastuj River. The distribution of rock types has resulted in the formation of a depression between the two ridges. This depression occupies the middle reaches of the noerthern valley slopes of the Mastuj River and runs almost parallel to the river from Lon to Torikho confluence. This depression formed by week lithologies of Lon Shale is subject to concentration f settlements and cropland for several reasons 1) availability of relatively flat land; 2) easy excavation helps in development of fields, roads, water channelsetc; 3) the clay-rich lithology provides ready soil for crops, 4) the drainage into the basin is mostly completely absorbed that raises the moisture content of the soil often generating springs, readily useable for drinking and irrigation purposes. Whereas these factors have been effectively used by locals for concentration of settlements and cropland, the same factors pose serious hazards to their sustainable living and livelihood. Firstly the clay-rich lithology with week porosity absorbs all the water draining into it without allowing its safe passage as surface flow. When soaked with water, the lithology virtually turns into a highly viscous mud which results into creeping debris flow. Several examples of this creeping debris-flow have been noticed and described in previous pages (e.g., Site E5, E9). Settlements and croplands located on such sites are therefore highly unstable and are under a constant threat of damage. Secondly, even those places where no such active creeping debris-flow is present, the lithology is prone to instability due to ground subsidence, fissuring, slumping and land sliding.

At this particular site (Fig. 3.32.1, 2), the northern valley slopes at the confluence of the Torikho-Mastuj Rivers are characterized by a similar hazard. As is obvious from Fig.3.32.2 and 3.32.3, the northern valley slopes at this site are characterized by settlements and cropland perched on large debris-fans which owe their origin to creeping debris flows. The hummocky surface appearance of these fans clearly owe to processes such as ground subsidence, slumping, and land sliding. The area can be classified as high hazard high risk zone. 3.4.12. Site C- 12. Charan Gol fan, Left bank of Mastuj River.

36o 13’ 45.3” N; 72o 10’ 30.0” E The Charan Gol, on the left bank of the Mastuj River, immediately upstream of the confluence with Torikho River, is characterized by a stabilized debris fan. The maturity of the fan is indicated by low gradient major feeding streams in the catchment area, deeply entrenched channels (10’s of meters) on a gently sloping fan and thick vegetative cover on the fan (Fig. 3.33) . Apparently no hazard to settlement and cultivation except under catastrophic, high sediment-laden discharges may cause choking-or inundation- induced spillover inflicting damage to life and property. The high-gradient tributary on the left bank of Charan Gol, in the apex area of the debris fan is capable of blocking the narrow channel at this site, which in case of a major rain storm can result in high debris- flow hazard to the settlement and cropland.

Steep bedrock slopes with talus cones Tributary

Main stream

Stablized fan

Charan Gol

Figure 3.33. A view of the Charan Gol and the associated debris fan. The deeply incised channel has efficient discharge capacity for any debris flow. However, unusually large debris-flows from side streams may block the channel at the apex and can cuse spilling over of the debris-mud flows onto settlement and cropland.

3.4.13. Site C- 13. Duryano Debris Fan 36o 15’ 10.5” N; 72o 13’ 15.5” E

Duryano Debris Fan is located on the left bank of the Mastuj River, formed by an immature channel called Daryano Gol. The immature channel is characterized by a steep gradient with a dendritic to trellis pattern in a deeply weathered bedrock cliffs blanketed with thick morainic and hillslope deposits (Fig. 3.34.1). The debris fan is fed by several high gradient streams capable of transporting huge amount of sediment substantiated by landslides and slumps during the rainstorms. The steep sloping fan has poorly developed surface drainage with few shallow-entrenched channels (Fig. 3.34.2). Switching of streams courses as a result of sediment dumping in the existing channels is evident from newly formed sideward flow. The fan is immature and is at high risk of damage from debris flow during the rainstorms. The risk elements include settlement, cropland and the road. Hazard type Debris flow, subsidence and ground failure, shifting of surface flow. Risk elements Life, settlement and cultivated land.

Figure 3.34.1. A satellite image of the Daryano Debris Fan. The image clearly shows the immature nature of the debris-fan with poor drainage. Such Daryano type of poorly developed Debris Fan drainage, in case of rainstorms leads to major debris- flow hazard for settlements, cropland and Mastuj R. other infrastructural elements built on unstable N debris fans.

Landslide Talus slope Recent flow

Floodplain

3.4.14. Site C- 14. Buni Alluvial Fan 36o 16’ 51.0” N; 72o 15’ 44.3” E

Buni village is a major settlement in mid-upper Chitral district. The settlement is located on an alluvial fan which is biggest in the Chitral district. It is 5 km long along the river with apex to river width of 2.25 km. Buni Gol, the feeding channel of the alluvial fan is a mature, perennial streams with approximately 13 km in length and over 75 km2 in terms of catchment area. The Buni Gol being a perennial stream fed by large catchment area including glaciers (Fig 3.35.1) is well-directed, deeply entrenched channel capable of discharge of large amount of debris material direct into the river without endangering the settlement and cropland on the alluvial fan (Fig. 3.35.2a). However, since the large alluvial fan is bounded on its south by steep ridges, there are several scree slopes with steep immature ephemeral channels, capable of debris flow hazard during the rainstorms (Fig. 3.35.2b, 2c). One such ephemeral channel in the eastern part of the alluvial fan has a clear evidence of recent debris flow that invades the settlement. Therefore, whereas the Buni Gol can be source of debris-flow hazard only in extreme cases (recurrence interval as high as 50 years), the smaller ephemeral channels from the southern ridge slopes,

66 especially in the eastern parts of the settlement can be a source of smaller but frequent debris-flow hazard. Since the alluvial fan is thickly populated and well vegetated, risk in the eastern part of the Buni settlement can be rated high.

Mustuj R. Figure E-11.1 View of partly stabilized Buni alluvial fan with main feeding channels and tributaries. The debris is derived from deeply weathered bedrocks and hill slope sediments.

Recent Debris Flow

BUNI N

Figure 3.35.1. ETM Satellite image of the Buni alluvial fan covering the catchment area. Note the steep ridges bounding the fan at its southern side are lined by talus cones with steep debris-flow channels, some of which have evidence of recent debris flows invading the settlement.

Buni Gol Distal end of the Alluvial Fan

Steep, immature debris-flow channel

Deeply entrenched channel

Talus slope

Debris cones

Grooved Steep sloping front ridge fan ridge of fan

Figure 3.35.2a. (Upper Left). Partially mature and stabilized, gently sloping Buni Gol fan, with deep entrenched channels and thick vegetation. Figure 3.35.2b. (Upper Right). Distal end of the Buni Alluvial Fan along the Mastuj River showing predominantly coarse clast-supported fabric. Figure 3.35.2c. (Lower Left). A view of the eastern part of the Buni Alluvial Fan. The steep ridge south of the fan is characterized by several ephemeral channels developing talus cones. The dendritic drainage pattern through the fan is capable of debris-flow derived from these talus cones causing hazard for the settlement and the cropland. Figure 3.35.2d. (Lower Right). Another view of the eastern most edge of the Buni Alluvial Fan. The steeply sloping fan edge marked with steep ephemeral channels is source of recent debris flow hazards.

3.4.15. Site C- 15. Right Bank, Mastuj River, Opposite Buni

A major tract of the Mastuj road opposite to Buni passes through an unstable ground. A close view of the satellite image (Fig.3.36.1) shows that opposite the Buni fan there is a scarp of a major landslide and the unconsolidated material traversed by the road is, in fact the body of the landslide. The excavation related with construction of the road destabilized the land slide body and caused it to reactivate as loose debris. Steep road cuts through this unconsolidated material are subjected to constant down-slope movement of this unconsolidated mass of material (Fig. 3.36.2), which, in case of rainstorms, turns into debris/mud flow.

3.4.16. Site C- 16. Right Bank, Mastuj River, Opposite Awi Gol

Directly opposite to the Awi Alluvial Fan, the right bank of the Mastuj River has several immature debris fans associated with steep, ephemeral channels with limited channel length and catchment area. These type debris fans (Fig. 3.37) are characterized by poorly developed surface drainage (dotted lines), high gradient stream, non-

69 channelized flow, sparse vegetation and steep fan slopes. Any settlement or cultivation on such debris fans is prone to high debris-flow hazard.

Fan drainage

Settlement with high hazard risk

Figure 3.37. A view of an immature debris fan characterized by steep ephemeral channel, steep fan slope, poor drainage and highiest level of debris-flow hazard for settlements and cropland. 3.4.17. Site C- 17 Miragram Gol fan 36o 15’ 31.04” N, 72o 21’ 58.25” E The Miragram alluvial fan is partially stable with thick vegetation and reasonably large settlement. The fan is about 2 km long along the river and 1.6 km wide from apex to fan toe on riverside (Fig. 3.38.1). The current course of the Miragram Gol follows the western edge of the fan. The channel is well entrenched and under normal circumstances is capable of flushing any debris flow direct into the river. In unusual circumstances, such as in the event of torrential rainstorm or avalanche, the availability of abundant debris material on the channel floor upstream of the settlement (Fig. 3.38.2) may cause unusually large debris flow which can block the main channel and run over the main settlement east of the channel. The settlement therefore can be rated prone to high debris- flow hazard.

Entrenched stream

Morainic debris deposit

3.4.18. Site C- 18. Snoghar Debris Fan 36o 1’ 27.04” N; 72o 24’ 44.25” E

The snowghar alluvial fan located on the left bank of the Mastuj River and is a 2.5 x 1.5 km2 in area. The fan is thickly populated with well developed cropland. The Snoghar Gol, the feeder channel of the alluvial fan is relatively short in length (6 km) and has a relatively small catchment area (20km2). It is characterized by a wide U-shaped valley, laden with enormous amount of debris (Fig. 3.39.1, 2). The channel is typically ephemeral fed by melting glaciers only in the summer times. The catchment area comprises glaciers. A radial array of channels branch out from the apex area, none being well entrenched, resulting in an overall extremely poor drainage. Despite an absence of a perennial source of water, the well developed settlement and cropland suggests that that water melting from glaciers soaks into the debris at high reaches of the channel and emerges in the fan area in the form of springs which not only provide drinking water but are efficiently used for irrigation purposes.

The availability of a wide plain formed by the alluvial fan surface, abundance of spring- water and fantastic view of overhanging glaciers has made Snoghar a popular habitation. However, several physiographic features make Snoghar one of the most vulnerable habitates in Chitral district. The abundance of debris in the U-shaped valley overhanging the settlement, the presence of glaciers at steep slopes at the channel head and a poor to virtually absent drainage at the fan surface are the major factors which pose a serious debris-flow threat to the settlement. The most recent example of this vulnerability to debris-flow hazard dates back only to June 29, 2007 when an avalanche broke at the channel head. The avalanche catastrophically melted and the resultant water mixed with abundantly available loose debris on the channel floor gushed down through the settlement washing away scores of houses, the road and three bridges.

The theme built through out this report, based on satellite-image analysis, field observations and historical perception i.e., the settlements built on alluvial fan fed by immature channels (short stream length, small catchment area) are characterized by poor drainage through the fan surface and are most vulnerable to debris-flow hazard in the even of rainstorm, avalanche or glacial outburst flood. Snoghar is the most typical example of this type of hazard and vulnerability. In caparison, alluvial fans associated with streams with perennial flow of water due to their large stream length and large catchment area are mostly well entrenched and provide an efficient drainage. In case of a debris-flow event such streams are capable of efficiently discharging their debris load direct into the river instead of spilling over the fan surface and hence the settlement.

Figure 3.39.1. Satellite image of the Snoghar alluvial, U-shaped debris- laden feeder channel and the glacial catchment area. Note the poor development of drainage in the fan area.

Figure 3.39.2. Field photograph of the Snoghar fan showing the same features as observed on the satellite

3.4.19. Site C- 19 Nisr Gol Fan 36o 17’ 13.20” N; 72o 36’ 09.22” E Nisr alluvial fan, associated with Nisr Gol is located on the right bank of the Mastuj River. The fan is 3.8 km wide along the river and from apex to toe is 2.5 km. The deeply entrenched Nisr Gol divides the fan into two parts, one downstream of the Nisr-Mastuj confluence is thickly vegetated (red colour on the satellite image; Fig. 3.40.1) and one upstream of the confluence being barren. The barren half of the fan, unlike other alluvial/debris fans in the region comprises thick sand layers in the bottom and thick muddy layers in the upper half (Fig. 3.40.2). These sediments suggest fluvio-lacustrine sedimentary environments. However, distinct fan shape and morphology point to development of these lithologies point to their origin in alluvial fan setting. The presence

73 of thick muddy beds alternating with sandy layers suggest that the fan was developed in static conditions possibly in a lacustrine (lake) setting.

Nisr Alluvial fan

Figure 3.40.1. (Left). ETM Satellite Image of the Nisar Alluvial Fan, right bank , Mastuj River. Figure 3.40.2. (Right Above) Field photograph of a portion of the Nisr alluvial fan. Unlike other fans in the Chitral District, the Nisr alluvial fan is dominated Figure-E-15.3a, b. View of Nisar Golby lacustrine thick clay sedimebeds alternatingnts displaying with sandy alternating beds. The sequence of sand andfan wasclay. probably developed in static conditions probably akin to lacustrine (lack) sedimentary environments.

It is most probable that the Sanoghar debris fan, immediately downstream of the Nisr fan once, probably in pre-historic times, completely blocked the Mastuj river turning it into a lack that persisted for a long time. The ongoing deposition from the Nisr Gol led to a deltaic fan deposited in lacustrine settings. In terms of the present-day hazards, the fan is now well stabilized assicaited with a deeply entrenched channel, without any significant threat from debris flow hazard.

3.4.20. Site C- 20. Sarghoz Debris fan, Left Bank Mastuj River 36o 16’ 37.2” N; 72o 26’ 55.8” E

The Sarghoz debris fan is located on the left bank of the Mastuj River. The fan is mostly barren, except for about 15 houses and a limited cropland on the western edge of the fan (Fig. 3.41.1). The fan is a typical debris fan associated with an ephemeral channel with a steep gradient. The upper part of the channel floor in the catchment area is extensively debris laden, which flows as a viscous debris flow in rainstorms or glacial melting. The fan is typically immature without any entrenched channel; rather there is dendritic

74 drainage pattern radiating from the apex area and traversing the fan surface as shallow channels (Fig. 3.41.2). In case of debris flow all or some channels become active and can spread the debris-flow material on all parts of the fan. The limited settlement, the cropland and the Mastuj road are under a serious threat from debris flow hazards.

1 km

Figure 3.41.1. Satelite image of the Sarghoz alluvial fan.

Figure E-16.2 Thick stratified sandy fluvial terrace in Mastuj valley.

Figure 3.41.2. A field view of the Sarghoz debris fan. Note the sloping fan surface with shallow sufacial ephemeral channels capable of threatening the populace, cropland and the road with debris-flow hazard in case of rainstorm or glacier melting.

3.5. SEGMENT-D MASTUJ – BREP, YARKHUN RIVER VALLEY

Brep

Dahr Kot Turi Khuz

Muli Khuz

Chunj

Mastuj-Brep Mastuj

0 10 Kms KmsKms

Figure-3.42. A) Location map of Segment D Mastuj to Brep, District Chitral.

Figure 3.42(B). Terrain map of Mastuj- Brep Segment (Figure D-1A) showing major physiographic features, cultivated area and drainage pattern.

The Mastuj-Brep Segment is approximately 25 km long along the Yarkhun River. Several major and minor streams join the Yarkun River from east and west. The prominent left bank streams include Pasum, Shano, Chapalli, Dahr Kot and Chhikan while joining from the right bank are Purkasap, Shagus, Muli Khuz, Turi Khuz. Detailed description of various debris flow fans with significant hazard potential, located along this segment is given below.

3.5.1. Site D-1 Pasum Gol (Chinar Village); Left Bank Yarkhun R. 36o 18, 32.4” N; 72o 33, 11.9” E

Stream Characteristics Located on the left bank of the Yarkhun River, first upstream from Mastuj, the stream is intermittent and is characterized by a debris fan about 2.5 km long and 1.5 km wide. Stream Gradient Low in the upper catchment area, moderately steep in the lower catchment area as well as on the fan. Channel Profile Broad and shallow Lithology Coarse, boulder-size sediments derived dominantly from granitic catchment area.

Hazard type Debris flow Risk Agricultural land and settlement.

N Debris-Flow Terrace

Present Debris-Flow Pasum Channel

Yarkhun R.

Figure 3.43.1. (Left) ETM Satellite image of the Pasum debris fan, left bank Yarkhun River. Figure 3.43.2. (Right). Field photo of the Pasum debris -flow channel comprising clast -supported debris. The terraces bounding the current channel represent older debris-flow deposits.

Prersent channel 3.5.2. Site D-2 Purkasap Gol Debris Fan; Right Bank Yarkhun River. 36o 19, 32.4” N; 72o 34, 11.9” E

Fan morphology Partially stabilized, 3 km wide sloping fan with a length of 6kms with several incised channels. Stream characteristics Intermittent, steep and narrow with deep entrenched channels Catchment Area Mountain front with talus cones

Debris type Matrix-supported

Hazard type Mud flow, debris flow, potential for high hazard after heavy downpour. Risk elements Settlements and cultivation

3.5.3. Site D-3. Chunj Composite fan 36o 19’ 39.4” N; 72o 35’ 02.6”E The Pasam and Shano Gol are torrential streams about 3 km apart. In between the two there is a smaller debris-flow channel that makes an active debris fan overhanging the Chunj village (Figure 3.45.1). These streams originate as gulleys in the upper, steeper part of the mountainous catchement area becoming wider and shallowly incised into the middle and deeply incised in the lower reaches. The vast vegetated plain area around Chunj village lies in the middle of both streams. The composite fan covers about 6 km2 area which is sparsely populated but thickly vegetated. It is frequently invaded by torrential debris flow at the toe of the debris-fans that overhang the Chunj settlement, damaging land and property.

Fan Morphology Small, recent, non-stabilized, steep sloping fan with several incised channels with multiple overlapping flow lobes Stream Characteristics Shallow, ephemeral Hazard type Debris flow Debris type Matrix-supported to clast-supported Risk element Settlement, agriculture History Loss of life and property from debris flow in 2005.

Active debris fan with several 80 depositional lobes

Scree slopes

Active debris-flow damages crops & vegetation

Shano Gol

Gulley erosion

Coarse debris

Figure 3.45.2. (above). A view of the active debris fan overhanging the Chunj village. The steep immature fan associated with a ephemeral gully channel is highly active during rainstorms and has invaded the village at the fan toe as recently as 2005. Figure 3.45.3. (below). The flat debris fan at the mouth of the Shano Gol. The deeply entrenched channel is associated with common clast and matrix supported debris flow.

3.5.4. Site D-4. Mori Khuz-Turi Kuzh Debris Fans, Right Bank, Yarkhun River

A five-km long stretch on the right bank of the Yarkhun River is thickly vegetated and is a host to a reasonably large settlement. Much of the stretch is formed from flood-plain deposits from Yarkhun River. However, two prominent debris fans Mori Kuzh and Turi Kuzh are associated with two ephemeral streams, overlap the flood-plain deposits. Both the fans are immature and are regularly subjected to debris flow. Despite similar general characteristics like extent, shape and sedimentation, the two fans differ in location of current distributary channels which determine location of the settlement and cropland. The Mori Gol fan is almost exclusively barren from apex to the toe, the cropland and settlement being restricted to its two sides. This suggests the immature distributary channels span the entire fan. Apparently all the debris-flow material is deposited on the main fan surface, there is a possibility that in case of a bigger rainstorm event, the frontal channels are obstructed by the debris material and the flow diverts sideways which can seriously threaten the settlements and cropland located at the lateral peripheries of the fan. In comparison, the Turi Gol fan has its frontal/distal part stabilized and is host to settlements and cropland. This is because the current distributery channels, instead of flowing straight to the toe of the fan are directed side-wards from the apex along the axes separating the ridges and the fan. Since both the debris fans are immature and highly unstable, there is no guarantee for the distributary channels to persist with their current courses in the case of future debris flow events. So the settlements on or in the vicinity of both the fans are highly vulnerable to future debris-flow hazards.

Figure 3.46.1. ETM satellite image of the twin Mori and Turi Frontward directed Kuzh fans on the right current bank of the Yarkhun distributery River. Red colour channels Mori shows the distribution Kuzh of the settlement/cropland and blackish brown colour marks the active parts of the fans. In case of the Mori Kuzh fan, the distal part of the fan is active, while in the case of the Turi Turi Kuzh fan, flanks are Kuzh marked by recent debris flows while the distal part of the fan is stabilized.

Sideward directed current distributery channels

Figure 3.46.2. Field view of the Mori Kuzh Figure 3.46.3. Field view of the Turi Kuzh debris fan. Note active distal fan with debris fan. Note distal part of stable distal fan. cropland/settlement on the flanks. Current active debris-flow channels are restricted to the flanks of the fan. 3.5.5. Site D-5 Brep-Dahr Kot Gol Fan, Left Bank, Yarkhun River 36o 25o 08.7o N; 72o 39o 17.3o E

A large debris fan formed by two adjacent streams i.e., Dahr Kot and Chhikan Gol is located on the left bank of the Yarkhun River. The Brep village is located on the eastern end of the fan. Despite extensive vegetation and sizable settlement, the fan is typically unstable characterized by a poor drainage on the fan surface. Lack of perennial water flow and high debris vs water ratio has hindered development of any entrenched channel

84 which could have directed the flow directly into river. Rather, the channels feeding the fan are divided into several distributary channels as they enter the fan surface from the apex point. These distributery channels are typically shallow, often laden by debris material characterized by a poor discharge capacity. In the event of a debris flow, one or more of these channels host the fresh debris flow and since they have a poor discharge capacity instead of directing the flow direct into the river, overflow and spill over their material sideward into the settlements, causing loss to life, property and the cropland.

On this alluvial fan the most recent debris events occurred in 2005 and again on 27th July 2006. The 2006 debris flow resulted in total destruction of 103 homes, 5 schools, bazaar and road. The debris flow initiated after heavy rain fall. The flash flood ultimately got converted into coarse sediment-charged debris flow roaring down the steep slopes from the catchment area, destroying everything that came under its way. As a result, the fertile agricultural land and human dwellings got buried under thick cover of debris.

Bebris Flow 2005, 2006

Dharkot Gol

Chhikan Gol Brep

Figure 3.47. ETM image of Brep compsite fan at the confluence of Chhikan Gol with Yarkhun River 3.6.at left SEGMENT bank. The two- channelsE feedingFRO Mthis MASTUJ composite debris TO LASPUR fan are characterized by steep drainage fed by glaciers. Both the streams are ephemeral and are shallow and immature, vulnerable to common Thedebris Sor flow. Laspur River is a southern tributary of the Mastuj River, entering the Mastuj River at Mastuj. The river valley is bounded by high ridges occupied by glaciers. The tributaries of the Sor Laspur River are mostly loaded with debris fed by glacial moraines. Right bank major tributaries and stream channels include from upstream to downstream

Shandur Gol, Loh Gol, and Dodargaz Gol; while on the left bank the major stream channels are Rizhan Gol, Phargam Gol, Gashit Gol, and Murri Gol. Settlements in the valley include Sor Laspur, Boum, Baruk, Rahman, Harchin, Gashit, Shaidas and Onshit (Fig. 3.48). The key debris flow fans in this valley are described below in detail.

5 Km

Yarkhun R. Mastuj

Laspur R.

Shaidas Murri Gol

Gasht

Harchin

Baruk Dehr Baruk

Laspur

Figure. 3.48. Location map of Segment-G Mastuj to Sor Laspur, District Chitral.

3.6.1 Site E-1. Onshit Gol Fan, Left Bank

36o 13’ 32.4” N; 72o 29’ 58.3” East

Onshit gol fan is located on the left bank of Laspur River (Fig. 3.49). The Onshit Gol is primarily an ephemeral channel marked by steep gradient. It gives rise to a large fan comprising debris at the channel mouth. The fan is mostly barren without any settlement or cropland, which is restricted to its northern end only. The fan is clearly active marked by shallow distributary channels. Whereas all the distributery channels are laden with past debris flows, the current course of debris-flow is restricted to the southern end of the fan. The presence of unstable scree slopes in the catchment area, steep ephemeral non- channelized drainage has made this area more susceptible to hazardous debris flow. Torrential rain events can be catastrophic and may damage parts of the cropland as well as the settlement. Since the cropland and settlement is limited, the fan can be characterized as high hazard, low risk.

. Current Debris- Flow Channel

Laspur R. Onshit

Figure 3.49. View of the Onshit Fan on the left bank of the Sor Laspur River. Much of the scree-debris fan is active therefore inhabited. Only the northern part of the fan is used for settlement and cropland. The scree-slopes overhanging the village are prone to debris-flow hazard during rainstorms.

3.6.2 Site E-2. Shaidas Gol Aluuvial fan

36o 12’ 34.4” N; 72o 29’ 58.3” E The Shaidas alluvial fan (Fig. 3.50.1, 2, 3), on the right bank of the Laspur River is 2 km long and 1.25 km wide at its maximum. The fan is covered with vegetation and settlement is scattered on the fan. The Shaidas Gol is an ephemeral channel, which is though apparently well channelized but is shallowly entrenched, with channel floor at higher height than the surrounding outward sloping fan (Fig. 3.50.2). Note that tributaries of the Shaidas Gol are debris laden and continuously supply debris load to the main channel. Presence of signs of past debris-flow deposits adjacent to main channel suggest that the channel is susceptible to blockage by its own debris load leading to flow in outward distributery channels, which pass through the settlement and the cropland. There is a high debris-flow hazard and medium-level risk for this village.

Figure-3.50.1. The Shaidas alluvial fan, fed by a shallowly entrenched ephemeral channel. On both sides of the stream the fan is covered by vegetation and scattered settlement.

Figure-3.50.2. Close up of Shaidas Gol fan. Note preservations of several N distributary channels with minor to large past debris flow events.

Past Debris N Flow

Past Debris Flow distributary channels

Shaidas Gol

Figure 3.50.3.A photographic view of the Shaidas Gol as it cuts the Sahidas fan. Note the presence of debris load deposits on the channel floor. Such higher intensity debris-flow events may block the main channel resulting in overspill from the main channel endangering the settlements and cropland. The road segment (culvert) is under constant threat.

3.6.3. Site E-3 Muri Gol fan: The Mori Gol fan is located on the left bank of the river and is about 1.25 km long (along the river) and at 1 km wide at its maximum. The channel floor is typically at higher elevation than the surrounding fan area. Muri Gol comprises two active channels passing through the middle of the debris fan. Both the channels are perennial but debris laden (Fig. 3.51.1, 2, 3). There is clear evidence of several distributery channels subject of debris flow in the past (Fig. 3.51.2). This is a type example of channel evulsions in response to choking of the channels through deposition of debris load. The fan has steep surface with a network of shallow (often debris filled) channels. Due to unstable nature of the active debris fan, only a limited settlement and cropland has developed on the fan. Much off the settlement is located upstream of the Murri fan on Gasht flood-plain. The fan is characterized as high hazard but low risk, due to limited cropland and settlement.

3.6.4. Site E-4 Gasht Fan Terrace The Gasht village is a large settlement (3 x 0.6 km) on the left bank of the Laspur River. It is bounded by two debris-flow channels on its both sides; Gasht Gol on the upstream side and the Murri Gol on the downstream side (Fig. 3.52.1). Both the Gasht Gol and the Murri Gol fans are active prone to common debris flow hazard. However, much of the settlement and cropland in the Gash village is sprawled on flood-plain deposits of the Laspur River in between the two active debris fans (Fig. 3.52.2). The hazard and risk levels are variable. The two ends of the village, northern and southern, both lying adjacent to the active debris fans are prone to high debris-flow hazard and a medium level of risk. The central part of the village is not in direct path of any major debris flow channel and is thus relatively much safter, except for scree-slope deposits overhanging this part of the village, which might activate as debris flows in exceptionally strong rainfall. This part of the village is therefore is characterized by low debris-flow hazard but medium level of risk.

Figure 3.52.1. Satellite- Dasht Gol image view showing the Murri Gol location of the Gasht village which lies between two major ephemeral streams. The area is relatively safe and stabilized by vegetation cover.

Gasht Gol

Figure 3.52.2. Gasht village on flat flood-plain deposit. The village is a suitable example of

locals understanding about Stabilize fan safer site selection on a flood plain between the two active debris fans. Note some level of hazard because of debris- ladden scree slopes which may rarely activate as small debris flows.

3.6.5. Site E-5 Loh Gol Fan (Kamshai-Harchin Village) The Loh Gol debris fan is located on the right bank of the Laspur River (Fig. 3.53.1). The fan and adjacent settlement (Harchin) are together about 3 km long along the river valley and up to 2 km wide. The fan is built from debris material coming from the Loh Gol, which is an perennial channel. The Loh Gol is a mature channel, characterized by a steep-channel gradient and a shallow channel floor characterized by an efficient discharge into river. There are signs of common channel avulsion and occurrence of distributaries away from the main channel suggesting common past debris flow events on the fan surface. Due to instability of the fan surface, only the northern part of the fan is used for cropland and settlement. Much of the settlement and cropland is concentrated on the adjacent (upstream side) flood plain i.e., Harchin, which provides relatively more stable, flat landform suitable for such purposes. In terms of debris flow hazard, in normal circumstances there is a wide medial channel through the fan that transports the debris directly into the river. However, in case of catastrophic downpour, there are chances that the main channel is choked by its own debris load and some old channels on the northern edge of the fan are reactivated for over spilled debris flow. In such case the settlements on the northern edge of the fan and the adjacent Harchin village are prone to partial damage. The area can be therefore characterized as medium hazard and medium risk.

Kashmai N

Loh Gol

Harchin

Figure. 3.53.1. Satellite image view of the Loh Gol alluvial fan, with adjacent Harchin village. Note the sparse vegetation on the fan surface and dense vegetation in the Harchin village. The fan is characterized as medium debris-flow hazard. The Harchin village has medium level of risk from debris flow in unusually strong rainstorm.

3.6.6. Site E-6 Rahman-Phorth Settlement (Phargam Gol) A major settlement namely Rahaman-Phorth village occurs on the left bank on the either side of the Pharagam Gol. The settlement sprawls upon an area of 5 x 2 km along the left bank of the river. The settlement is primarily built upon a wide flood plain, overlapped by alluvial fan associated with the Phargam Gol. Since the Pharagam Gol is a large stream with large catchment area and channel length and is fed by glaciers, the channel is furnished by a constant water supply (perennial) indicating maturity of the channel. The channel is deeply entrenched and no debris fan is currently associated with the channel due to efficient discharge system characteristic of this channel. Upstream there are several alluvial fans formed by tributaries of the Pharagam Gol which are fed by glacial moraines. This implies that the stream is supplied by an enormous amount of debris load in its catchment area. However, equally or more abundant supply of water has rendered the Pharagam Gol with an efficient discharge capability which transports all the debris carried by the stream directly into the river, without forming a debris fan spreading on to the settlement.

In terms of hazard, the Ramna-Phorth settlement is characterized as low-level debris flow hazard. However, the Pharagam Gol is characterized by a large channel length and large catchment area which is fed by at least five major glaciers. Each of te glaciers is associated with huge debris material in the form of glacial moraines. Additionally, the satellite image shows presence of at least four glacial lakes. In unusual weather

93 conditions, catastrophic melting of glaciers may cause natural damming of the Phargam Gol in the catchment area forming natural lakes. These lakes or the already existing glacial lakes may be subject of outburst floods which will exceed the capacity of discharge by the Pharagam Gol leading to spill over to the settlement. Therefore, whereas the settlement is reletaively safe from debris flow hazards, there is high hazard level for natural lakes or glacial lakes outburst floods. Since the area is densely settled, the risk level is theefore high.

Phorth

Phragam Gol

Rahman Harchin

Figure. 3.54. ETM Satellite image of the Rahman-Phorth settlement, left bank of Laspur River. Note the deep etrenchment of the Phragam Gol with efficient discharge capcity, furnishing low level of debris-flow hazard for the settlement. However, the settlement is under high risk from glacial lake outburstt flood (GLOF).

3.6.7. Site E-7 Baruk village 36o 04’ 5401” N; 72o 27’ 03.2” E

The Baruk village is located on the right bank of the Laspur River. It is a relatively smaller settlement on the flood plain of the Lapur River. An immature, debris laden channel opens faces the village directly. In case of unusual rainstorms, this channel is capable of generating debris flows which can invade the settlement capable of causing major damage. The village is characterized by medium level of debris-flow hazard with a medium risk level..

Debris flow

Hazard prone area

Figure 3.55. Downstream view of Baruk village showing active debris flow on steep slope. The area in front of the debris flow laden stream is at continuous potential risk.

3.6.8. Site E-8. Baum, Huzun, and Rizhun Settlements at Rizhun Gol- Laspur Confluence.

The composite flood-plain deposits, and alluvial fan material associated with Rizhun Gol constitute a flat landform at the confluence of the Rizhun Gol-Laspur River confluence, which is densely vegetated with a sizable settlement in three small villages i.e., Baum, Huzun and Rizhun (Fig. 3.56). All the three villages have at their back scree- ladden steep channels which can in unusually strong storm conditions can generate small debris flows. The Rizhun Gol is a perennial channel fed by glaciers which is deeply entrenched mature channel capable of discharging its debris directly into the river. However, major, though rare hazard is from avalanches in the catchment area of the glacier-fed Rizhun Gol. This combined with rare events when glaciers block a part of the Rizhun Gol forming natural lakes; outburst of such lakes may cause major damage to these settlements

3.6.9. Site E-9 Sor Laspur

This is the major settlement in the area. The settlement is located on a stable alluvial fan with thick vegetation cover, cropland and sizable settlement. Although the upper reaches of the Shandur Gol are heavily laden by glacial moraine material yielding thick debris deposits, the mature, deeply entrenched Shandur Gol is characterized by an efficient discharge which directly flushes out any debris flowing in the stream, without causing any threat to the settlement. The settlement is therefore graded as low debris-flow hazard and thus low risk.

Muri Gol

Figure 3.57.1, 2. Downstream views of the Laspur settlement from Shadur Road. Note the stable settlement, despite scree slopes and talus cones on valley sides and morainc debris on fan head.

CHAPTER#4 LANDFORM CHARACTERISTICS AND MORPHOMETRIC ANALYSIS

4.1. Introduction This chapter focuses on classification of tributary stream types and their associated landforms. The geomorphological characteristics of the various landform types are highlighted to ultimately evaluate their hazards potential. In the same process, morphometric parameters of watersheds, their resultant streams and associated fans are measured and analyzed to use them to differentiate between various landforms. As noted by several previous workers, notably Wilford et al (2004) and de Scally (2010), all the tributary streams do not have identical potential for debris flows. These authors have demonstrated that tributary streams with rugged catchments (high relief, limited stream length) are the ones, which are prone to debris flows. In comparison, streams with less rugged catchment topography are not capable to transport debris flows to stream mouths (i.e., fan surfaces). Such streams are therefore, only capable of generating water floods and rarely debris floods but no debris flow. This recognition and classification of tributary streams is vital as the hazard level posed by these three hydrogeomorphic process namely water floods, debris floods and debris flows are enormously different. Hungr et al. (2001) noted considerable difference in relative peak discharge between water floods, debris floods and debris flow, being up to 40 times higher in the case of debris flows making them one of the most dangerous of the hydrogeomorphic hazards. 4.2. Tributary stream types and associated landforms

Tributary streams in the Chitral region are either ephemeral or perennial (Fig. 4.1). Each of these is associated with specific tributary-junction fans. The ephemeral rills and gullies are commonly associated with debris cones; while the ephemeral channels form debris fans. Both these landforms are active landforms (Fig. 4.1A). The perennial streams, in comparison, are associated with two types of fans: 1) relict fans with deeply incised channels characterized by confined-channelized flow, and 2) active alluvial fans forming at the terminal end of the perennial stream-trunk river junction (Fig. 4.1B).

Relict fans in the Chitral valley are mostly composite comprising sediments deposited in multiple phases through multiple alluvial processes.

Relict fans are far more abundant than the active fans, especially in middle and lower Chitral (Mastuj downstream). Amongst the active fans, debris cones and fans are preponderant over the active alluvial fans formed at perennial-stream terminal ends.

The sediment supply to these fans involves gravity-controlled rock fall (talus/scree), sediment-gravity flow and fluid-gravity flow (cf., Blair and McPherson, 1994). The debris cones in Chitral are an outgrowth of talus cones and include scree deposited through rock falls as well as sediment-gravity flows. In comparison, debris fans are exclusively gravity-flow deposits, while the alluvial fans are predominated by fluid- gravity flow deposits.

Figure 4.1. Tributary-junction fan types in Chitral. (A) An ephemeral-stream related active debris fan. (B) A relict fan associated with a perennial stream. Note the feeder stream incised through the relict fan forms an active alluvial fan at stream’s terminal end.

Figure 4.2. Examples of active fan types from Chitral. (A) A panoramic view of the Daryano debris fan, left bank, Chitral River, associated with an ephemeral stream. The fan is characterized by mass-movement dominated deposition from a steep-gradient ephemeral stream originating in a debris-laden watershed. Hummocky fan surface is drained by a bird-foot shaped drainage with several abandoned distributaries and some active channels. (B) A satellite image of the perennial Shishi Gol tributary stream incised through the Drosh composite fan forming an active alluvial fan at its confluence with the Chitral River. Braided channel pattern typical of coarse-sediment deposits dominates the channel course and the fan surface.

4.3. Landform characteristics

4.3.1. Debris cones

The valley flanks in Chitral are characterized by steep slopes resulting from Late Quaternary glaciations and subsequent intense weathering and fluvial incision. These slopes are mantled with a thick blanket of gravity-derived, poorly-sorted mix of sediment, with metre-scale angular blocks contributed by rock falls. Debris cones generally swarm around steep gullies on valley slopes. These are piles of sediment derived mostly from adjacent slopes and reworked debris of older terraces perched high on valley slopes (Iturrizaga, 1999). The primary origin of debris cones is gravity-controlled down-slope movement of debris material. Water, when available, enhances transport of such material through the rills and gullies. Wasson (1979) recognized the role of both sheet and leveed debris flows, in addition to mass movements and fragmental rock fall in the formation of these slope deposits. Steepness of the talus slopes at the angle of repose, combined with loose grain-stacking within the debris renders these landforms prone to debris flows in the events of downpour. Modern debris-flow deposits with channel levees and lobes

100 intermixed with scree-slope deposits are a common observation on debris-cone surfaces in the Chitral valley. In terms of morphometry, the debris cones are characterized by a limited watershed area (< 4 km2), while the cone area is even more limited, i.e., < 0.3 km2 (Table 4.2; Fig. 4.2). The gradient of the feeder gullies in the catchment area is generally the same as that of the cone’s slopes. The steepness of this gradient both for the cone surface and the feeder gullies conforms to the dominant role of gravity in their development.

4.3.2 Fans

The Chitral valley is characterized by a great variety of fan sediments of Holocene and younger age associated with tributary streams draining into the trunk river. These fan deposits are typically perched on the valley sides, where the confined tributary streams enter the broad valley floors, depositing their debris load as both the gradient and stream energy rapidly decreases (Drew 1873; Lecce, 1990). In majority of the cases, these deposits conform to the definition of Bull (1968, 1977) in that they comprise a mix of coarse and fine sediments and are fan-shaped, radiating down slope from the point (apex) where the stream leaves the source area. Owen (1988) and Derbyshire and Owen (1990) demonstrated from the nearby Karakoram Mountains that fan deposits are not typically alluvial, but rather they comprise a variety of sedimentary facies including debris-flow, mudflow, fluvial, till, lacustrine, aeolian and glaciofluvial. Iturrizaga (1999) and Kamp et al. (2004) corroborated these observations with examples from the eastern Hindu Kush ranges. In concurrence with these observations, we classify these fans involving sedimentary deposits of multiple ages and origin as the composite fans. Being older in age and commonly deposited on morainic terraces on valley sides, these fans are characterized by large fan size and surface area. Toe trimming by trunk river and entrenching by traversing perennial streams has modified their original fan outline as well as their radial shape. In comparison, modern-day fans are discrete as they retain their fan- shaped outline and involve sediment deposition driven by one dominant processes i.e., either sediment-gravity flow or fluid-gravity flow (cf., Blair and McPherson, 1994).

Discrete fans are commonly perched direct on valley floor or valley-side flood plain, but

101 instances are common where they are superimposed on composite fans, especially when the later lie at the foot of the ephemeral streams.

4.3.3 Discrete fans

Discrete tributary-junction fans are modern and active and are formed both by ephemeral and perennial streams. Debris fans constitute the major output of ephemeral streams (Fig. 4.2A), while the active alluvial fans are associated with perennial streams (Fig. 4.2B, 4.4B).

The debris fans are characterized by convex cross profiles, resulting in higher elevation of the radial axial parts relative to the lateral flanks. In young, immature debris fans, fan surfaces are drained by shallow distributary channels radiating out from the apex. The relatively older fans, by comparison, are characterized by fewer incised channels with some degree of confined flow. However through-going entrenched channels capable of discharging debris load directly into the trunk river are uncommon. The dominant sedimentation mode in these fans is debris flow with some contribution from other mass movement processes including rock fall and land sliding. The resultant fans are massive, rarely stratified and poorly sorted. They are characterized by a silt-sand matrix containing angular to sub-rounded rock fragments ranging in size from pebbles to boulders. In terms of morphometry, the debris fans are commonly associated with small watershed areas (~7 km2), steep feeder channel gradients in the source area (~24o) and, a moderately steep fan gradient (~9o). Active fans are also formed by the perennial streams especially at their terminal ends at their junctions with the trunk river. These deeply entrenched streams, incising through relict fans transport their sediment load to be deposited near or onto the trunk riverbed (Fig. 4.1B, 4.2B). The resultant active alluvial fans are mostly sorted and hence, stratified, dominantly comprising sands and gravels, with rare cobbles and boulders, testifying to their fluvial origin.

102

The active alluvial fans formed at the distal end of the perennial streams are rarely preserved. When present, they are typically smaller in size than the debris fans formed by ephemeral streams (Fig. 4.4B). This is despite the fact that the feeder perennial streams transport a greater sediment load compared to their ephemeral counterparts. Their preservation is controlled by; 1) the availability of depositional space at the distal ends of the stream where it joins the trunk river and 2) the flow characteristics of the trunk river. The steep-gradient, high-energy trunk rivers tend to wash away all the debris delivered by the tributary stream, hindering fan development/preservation. This situation is characteristic of narrow (V-shaped) trunk-river valleys (e.g., the Dammal Nasar confluence, lower Chitral). In comparison, where the valley floor is wide and the tributary stream joins the trunk river inside of a meander, active alluvial fans may form at the toes of the perennial streams. The best example of active alluvial fans of this type is near Drosh (lower Chitral), at the confluence of the Shishi Gol and Chitral River (Fig. 4.4B). This 0.18 km2 active alluvial fan is formed by 48 km long Shishi Gol (watershed area ~650 km2) as it enters Chitral River. Under exceptionally high sediment-laden discharges, these fans are capable of temporarily damming the trunk river. The morphometric parameters for the active alluvial fans associated with the perennial streams appear to include large watershed areas and feeder channel lengths, but a small fan size (Table 4.2). This contrasts with active debris fans associated with ephemeral streams characterized by a direct proportional relation between the fan area, watershed area and feeder-channel length.

4.3.4 Composite fans

The ancient landforms at valley flanks of the Chitral River comprise two types of terraces: 1) remnant from Late Quaternary glacial and interglacial stages (e.g., morainic, glaciofluvial, fluvial, and lacustrine terraces) and 2) modern fans formed through alluvial processes. Commonly, the later are perched on surfaces carved out from stratigraphically older terraces. These fans are not only composite in terms of their constituent material and origin but also overlap laterally forming coalesced fans (bajada) resulting in large terraces at valley flanks in Chitral. They are commonly eroded and deeply dissected,

103 especially by perennial streams to which they probably owe their origin in their earlier history. They occur at higher elevations compared to the adjacent trunk valley floor as well as the floor of the entrenched tributary perennial streams traversing them. The composite fans are devoid of active deposition when associated exclusively with perennial streams. Instead, the entrenched perennial streams deliver their seasonal sediment load directly to the trunk river. However, as shown by watershed morphometry analysis, perennial streams entrenched through composite fans are capable of carrying debris floods, which may surge through apex areas of composite fans and inundate fans surface. Composite fans, when located at the toes of ephemeral streams are prone to debris flows. These result in active debris fans formed on top of the composite fans. As will be shown later, this is the highest risk setting as debris-flow hazards are frequent and population is high. 4.4 Watershed and Fan Morphometry

Morphometric analysis is a standard technique used for quantitative characterization of the surface geomorphology of landforms, especially alluvial fans (Horton, 1945; Strahler, 1957). Fan morphometry involves measurement of various fan parameters such as area and slope and their comparison with the parameters defining the watershed in terms of watershed area, feeder-channel length and feeder-channel slope. Drew (1873) observed that fans with gentle average slope had larger watershed areas compared to those with steeper slopes, an inverse relationship that was later quantified by Bull (1962). Bull (1962) demonstrated that fan size, measured in terms of area, is directly proportional to the watershed area. Subsequent studies generally corroborate these findings but also demonstrate geographic variations (Hooke, 1967; Hooke and Rohrer, 1979) and list several controlling factors including bedrock lithology, tectonic activity, climate and local base levels (Cooke et al., 1993; Harvey, 1997; Al-Faraj and Harvey, 2005).

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In the studied area, morphometric parameters have been measured for the three feeder channel types: 1) ephemeral rills and gullies, 2) ephemeral channels, and 3) perennial streams and their resultant landforms (cones, fans) (Table 4.1, 4.2). There is a direct proportional relationship between the watershed area, the feeder-channel length and fan- surface area (Fig. 4.2a, b). All these three parameters have highest values for composite fans, intermediate for debris fans and lowest for debris cones. Variations in these parameters are accompanied by decrease in channel gradients from gullies, ephemeral channels to perennial streams. The fan-surface slope, which has a ~ 1:1 ratio with the gradient of the feeding gullies in the case of debris cones, decreases proportionally from cones to fans (Fig. 4.2c). However, as noted by previous workers (e.g., Blair and McPherson, 1994), there is an inverse relationship between the watershed area and the surface slope on associated fans (Fig. 4.2d). The morphometric characteristics of active alluvial fans associated with perennial streams formed at their toes in close vicinity or on the riverbed of the trunk river are conspicuous. They are typically small in size irrespective of the size of the watershed and length of their feeder streams. They are also highly unstable and short lived due to continuous erosive action of the trunk river. They contrast with typical alluvial fans formed in stable baseline setting (e.g., Death Valley, California; Blair, 1999), which grow large and their fan area has a direct proportional relationship with watershed area and stream length (Kostaschuk et al., 1986; Blair and McPherson, 1994).

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Table 4.1 Showing the Analysis of Morphometric Parameters.

Cone/Fan Watershed Watershed Watershed Area Cone/Fan S# Channel/Stream Area(sq.kms) Slopeo Stream L_Km (sq.kms) Slopeo Fan Type Stream type 1 Kari 0.59 32.82 1.23 0.12 27.19 Debris cone Ephemeral 2 Mulen Kolo 0.14 47.98 0.72 0.07 30.71 Debris cone Ephemeral 3 Ragh 0.48 39.86 1.12 0.07 23.85 Debris cone Ephemeral 4 Ragh1 0.39 34.22 1.16 0.08 22.05 Debris cone Ephemeral 5 Opposite Mastuj R. bank 3.80 13.17 5.52 0.06 32.94 Debris cone Ephemeral 6 Near Mastuj Down Stream 3.70 25.41 3.12 0.29 28.86 Debris cone Ephemeral 7 Mastuj R. bank Laspur 1.30 33.26 2.19 0.12 33.42 Debris cone Ephemeral 8 Near Chinar L. bank 1.50 32.30 2.21 0.13 51.12 Debris cone Ephemeral 9 Kao Gol 5.66 21.31 4.40 0.63 7.97 Debris Fan Ephemeral 10 Joshaba Gol 8.09 24.23 3.44 0.96 14.04 Debris Fan Ephemeral 11 Kaldam Gol 13.21 15.11 6.94 1.00 5.71 Debris Fan Ephemeral 12 Kandak Gol (Broz) 10.81 25.64 5.74 0.80 15.11 Debris Fan Ephemeral 13 Kolo Gol 5.66 29.68 3.90 0.50 5.14 Debris Fan Ephemeral 14 Kolo Gol1 2.06 29.68 3.90 0.07 5.14 Debris Fan Ephemeral 15 Urghuch Gol 9.75 15.11 5.30 0.90 4.57 Debris Fan Ephemeral 16 Chuchu Gol1 6.80 20.30 4.75 0.87 2.86 Debris Fan Ephemeral 17 Singur 9.80 10.76 5.94 0.74 3.43 Debris Fan Ephemeral 18 Singur Gol 12.08 11.86 5.96 0.51 7.97 Debris Fan Ephemeral 19 Turen Kulu Gol 15.78 19.80 5.70 0.38 16.70 Debris Fan Ephemeral 20 Borghozi 4.30 32.21 2.89 0.12 2.29 Debris Fan Ephemeral 21 Kaghozi1 1.05 21.31 1.41 0.09 17.74 Debris Fan Ephemeral 22 Mori Parwak 3.93 27.47 2.91 1.09 9.09 Debris Fan Ephemeral 23 Nisar Gol 17.87 17.22 7.13 1.49 10.20 Debris Fan Ephemeral 24 Snowghar Gol 17.04 23.27 6.07 1.33 9.65 Debris Fan Ephemeral 25 Diwan Gol 8.88 17.22 4.44 0.57 2.29 Debris Fan Ephemeral 26 Istacho Gol 13.92 17.22 4.45 2.26 4.57 Debris Fan Ephemeral 27 Khutan Gol 13.09 15.64 4.85 2.71 6.28 Debris Fan Ephemeral 28 Dahrkot Gol (Brep) 39.37 18.78 7.14 2.73 7.41 Debris Fan Ephemeral 29 Khunz 8.45 15.64 4.68 2.39 5.14 Debris Fan Ephemeral 30 Khuruz Gol 6.51 17.22 5.11 1.13 7.35 Debris Fan Ephemeral 31 Shich 11.41 17.22 6.30 0.36 1.72 Debris Fan Ephemeral 32 Pardan Gol 7.17 22.78 4.73 0.96 10.20 Debris Fan Ephemeral 33 Paranggaz 3.82 34.61 2.91 0.97 0.57 Debris Fan Ephemeral 34 Muli Kirkiz 8.42 20.30 5.22 0.08 17.22 Debris Fan Ephemeral 35 Guzhgal 3.92 38.31 2.33 1.12 9.73 Debris Fan Ephemeral 36 Urshun Gol 74.24 7.97 16.11 0.21 4.57 Alluvial Fan Perenial 37 Dam Gol 21.93 10.76 10.13 0.34 4.00 Alluvial Fan Perenial 38 Swir Gol 48.81 7.97 16.75 0.80 4.00 Alluvial Fan Perenial 39 Drosh Gol 21.08 14.57 9.33 0.99 9.65 Alluvial Fan Perenial 40 Shishi Gol 524.00 4.72 48.01 0.43 2.86 Alluvial Fan Perenial 41 Kesu Gol 21.79 17.22 7.26 0.96 6.84 Alluvial Fan Perenial 42 Gahirat Gol 38.61 7.41 16.27 0.49 8.53 Alluvial Fan Perenial Cone/Fan Watershed Watershed Watershed Area Cone/Fan S# Channel/Stream Area(sq.kms) Slopeo Stream L_Km (sq.kms) Slopeo Fan Type Stream type 43 Birir Gol 99.30 4.57 17.98 0.07 5.71 Alluvial Fan Perenial 44 Rumbur Gol (Ayun) 388.55 5.14 34.92 1.58 5.65 Alluvial Fan Perenial

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45 Gumbas Gol 21.62 19.80 8.00 0.61 15.11 Alluvial Fan Perenial 46 Jughur Gol 64.76 6.84 16.31 2.36 3.43 Alluvial Fan Perenial 47 Ochusht Gol 22.40 11.86 7.07 0.60 12.95 Alluvial Fan Perenial 48 Mulen Gol 19.38 14.04 8.69 3.04 6.28 Alluvial Fan Perenial 49 Chitral Gol 23.06 10.20 8.01 1.31 8.53 Alluvial Fan Perenial 50 Danin Gol 21.26 14.57 8.31 0.99 5.14 Alluvial Fan Perenial 51 Lusht Gol 3.58 20.30 4.21 0.38 9.65 Alluvial Fan Perenial 52 Kari Gol 11.30 26.10 4.42 0.48 6.84 Alluvial Fan Perenial 53 Ragh 4.73 19.80 2.86 0.34 2.86 Alluvial Fan Perenial 54 Mulen Kulu Gol 23.92 8.53 13.62 0.20 9.65 Alluvial Fan Perenial 55 Kaghozi Gol 36.11 19.29 8.26 0.80 7.41 Alluvial Fan Perenial 56 Moren More 3.40 30.11 2.85 0.32 1.72 Alluvial Fan Perenial 57 Istan Gol 15.33 18.78 7.69 0.06 30.11 Alluvial Fan Perenial 58 Turen More 1.38 21.31 1.80 0.34 4.00 Alluvial Fan Perenial 59 Chamuruk 5.58 26.10 4.34 0.41 2.86 Alluvial Fan Perenial 60 More Gol (Kham Koru) 7.93 16.70 5.03 0.23 18.26 Alluvial Fan Perenial 61 Morisan Gol (Turen Mori) 11.86 16.70 6.81 1.18 5.71 Alluvial Fan Perenial 62 Gokhtan Gol 25.86 20.81 10.35 0.90 6.28 Alluvial Fan Perenial 63 Molen Gol (Molen) 12.14 13.50 6.63 0.68 9.09 Alluvial Fan Perenial 64 Toren Gol (Moroi) 16.17 22.78 5.49 0.97 7.97 Alluvial Fan Perenial 65 Darom Gol 5.45 26.10 3.35 0.39 10.20 Alluvial Fan Perenial 66 Parait Gol 60.09 9.09 13.03 1.01 5.14 Alluvial Fan Perenial 67 Barenis Gol 58.77 12.95 10.59 0.85 4.00 Alluvial Fan Perenial 68 Shil Gol 18.03 17.74 6.81 0.29 8.19 Alluvial Fan Perenial 69 Parpish Gol 260.60 9.65 17.36 0.14 39.01 Alluvial Fan Perenial 70 Shogram Gol 50.56 4.57 12.39 0.39 7.97 Alluvial Fan Perenial 71 Reshun Gol 78.64 20.81 7.72 1.15 1.72 Alluvial Fan Perenial 72 Koragh Gol 23.39 17.22 9.38 0.71 9.65 Alluvial Fan Perenial 73 Charan Gol 12.92 17.22 4.51 0.84 6.84 Alluvial Fan Perenial 74 Kosht Gol 30.54 17.22 7.14 10.65 6.84 Alluvial Fan Perenial 75 Diryano Gol 6.66 26.10 2.71 0.49 9.65 Alluvial Fan Perenial 76 Buni Gol 48.98 15.11 9.62 5.96 4.57 Alluvial Fan Perenial 77 Awi Gol 19.07 18.26 6.46 0.65 7.97 Alluvial Fan Perenial 78 Miragram Gol 14.56 18.78 6.73 0.56 22.29 Alluvial Fan Perenial 79 Dodargaz Gol (Mastuj) 15.31 19.29 6.13 1.87 8.53 Alluvial Fan Perenial 80 Pasum Gol 14.23 19.80 4.79 1.33 8.53 Alluvial Fan Perenial 81 Chunj Gol 3.17 23.27 3.17 1.85 20.81 Alluvial Fan Perenial 82 Shagul Gol (Parkasap) 12.51 12.95 5.60 0.79 7.97 Alluvial Fan Perenial 83 Shano Gol 9.45 16.17 6.52 1.16 6.50 Alluvial Fan Perenial 84 Chapalli 51.38 12.95 9.59 1.06 3.89 Alluvial Fan Perenial 85 Shaguno Gol 1.94 28.81 2.55 0.66 12.41 Alluvial Fan Perenial 86 Muli Khuz Gol 14.64 20.81 4.89 1.96 12.95 Alluvial Fan Perenial 87 Turi Khuz 14.57 15.64 5.69 1.12 1.60 Alluvial Fan Perenial Cone/Fan Watershed Watershed Watershed Area Cone/Fan S# Channel/Stream Area(sq.kms) Slopeo Stream L_Km (sq.kms) Slopeo Fan Type Stream type 88 Dahrkot Gol (Miragram) 26.82 17.22 6.84 0.94 11.86 Alluvial Fan Perenial 89 Dahrkot Gol (Miragram1) 9.95 17.22 6.84 0.87 11.86 Alluvial Fan Perenial 90 Bang Gol 55.81 6.84 9.88 1.29 4.57 Alluvial Fan Perenial 91 Muli Ghall (Paur) 54.80 7.97 9.09 0.36 15.64 Alluvial Fan Perenial 92 Donich Gol (Dirsir) 9.95 24.23 3.97 1.76 15.11 Alluvial Fan Perenial 93 Shulkuch Gol 4.19 30.54 3.01 1.21 14.57 Alluvial Fan Perenial

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94 Shaidas Gol 11.53 22.29 5.23 0.96 10.76 Alluvial Fan Perenial 95 Onshit Gol 8.40 18.26 4.07 0.55 15.11 Alluvial Fan Perenial 96 Murri Gol (Gusht) 13.51 19.80 3.95 1.25 9.09 Alluvial Fan Perenial 97 Shandur Gol 9.46 17.74 6.09 1.01 9.65 Alluvial Fan Perenial 98 Up stream Shandur Gol 3.81 28.37 2.97 1.67 10.20 Alluvial Fan Perenial 99 Loh Gol 22.78 13.50 7.65 2.52 6.28 Alluvial Fan Perenial 100 Rahman Gol 17.46 25.64 4.58 3.15 4.80 Alluvial Fan Perenial

Table 4.2. Morphometry of tributary streams and their associated landforms, Chitral District, Watershed Fan Tributary Feeder Landform Length Fan Area Fan Stream Area (km2) Channel Type (km) (km2) Slope(o)*4 Type Slope(o) Ephemeral Debris Cones 0.1-3.8*2 0.7-5.5 13.1-47.9 0.06-0.29 22-51.12 Gully (8)*1 1.491.47*3 2.161.57 32.310.1 0.120.07 31.38.9 Ephemeral Debris Fans 1.05-39.3 1.4-7.1 10.8-38.3 0.07-2.7 0.6-17.8 Channel (27) 9.97.4 4.81.5 21.56.88 0.990.76 7.84.9 Alluvial Fans 1.05-524 1.41-48 4.6-38.3 0.06-10.65 7.9-39 Perennial (65) Stream 38.0283.5 8.237.24 17.627.37 1.051.51 8.146.4 (Discrete/Perch

ed /composite) *1Number of fans measured in each class *2Range *3AverageStandard Deviation *4Longitudinal average along the fan axis

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Figure 4.3 Relationship between various morphometric parameters for drainage and depositional basins for tributary-junction sediment fans from Chitral District, northern Pakistan. 4.5. Assessment of Tributary Streams for Debris Flow, Debris Flood and Flood Potential Debris flow is commonly used as a general term for mass movements characterized by a mix of debris and water (commonly with organic material in the form of wooden chunks and logs). However, the two components (debris and water) are highly variable in mutual proportions so that their different proportions yield vastly different types of mass movements. The two end members are water floods (exclusively or predominantly water) and landslides (exclusively or predominantly debris). The two intermediate members include debris floods and debris flows. Costa (1988) differentiated debris flows, debris floods and water floods on the basis of nature of flow (turbulent vs laminar), sediment

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concentration, sediment distribution (uniform or non-uniform) and shear strength (N/m2). Hungr et al. (2001) noted considerable contrast in terms of relative peak discharge between water floods, debris floods and debris flow, being up to 40 times higher in the case of debris flows making them one of the most dangerous of the hydrogeomorphic hazards (Table 4.5). Table 4.3 Distinguishing features of the various hydrogeomorphic hazards (debris flows, debris floods and water floods; after Costa (1988), Santangelo et al.(2011) and Wilford et al. (2004).. Hydrogeomorphic Sediment Shear Flow Type Sediment Geomorp- Sedimentological features Peak Hzarad concentr- Strength Distribution hological Discharge ation (by (N/m2) features volume) Debris Flow 47 to 70% 40 Non- Uniform Marginal Poorly to normal peak Newtonian sediment levees or sorted deposits. Can discharges visco-plastic concentrati terminal have reverse 5 to 40 or dilatant on profiles lobes grading, but also can times of fluids with range from absent to water laminar flow. normal. flood long-axis (A-axis) orientation of clasts is dominantly parallel to flow.

Debris Flood/ 20% to 10-40 non- non- bars, Clast orientation in Up to Hyperconcent- 47% Newtonian uniform to fans, debris-flood deposits twice rated Floods fluids, uniform sheets, are mixed, with the of water moderately sediment and A-axes of large flood turbulent to concentrati splays, cobble to boulder discharges laminar on profiles and the clasts stream usually perpendicular channels to the flow and have a pebbles to small large cobbles usually width-to- parallel to flow. depth ratio

Water Flood About < 10 Newtonian nonuniform well sorted and the 20% fluids with sediment clasts are usually well turbulent flow concentrati imbricated. The A- on profiles, axes of all clasts in flood deposits are oriented perpendicular to flow.

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Melton (1965) noticed a crucial relationship between morphometry of fans, feeder channels and watershed catchment areas. He noticed that ruggedness of the watersheds plays an important role in type of hydrogeomorphic processes prevalent on a fan surface. As a general rule, streams and channels associated with rugged watersheds (high watershed relief and Melton ratios and short watershed lengths) are considered prone to debris flows (cf., Jackson et al., 1987, de Scally et al., 2010, Wilford et al., 2004). Watersheds with lower ruggedness (defined by low relief and Melton ratios and long watershed lengths) are less prone to debris-flow hazards and instead are susceptible to water- or debris floods. In the light of this background, three morphometric parameters were additionally measured in this study. These included Melton ratio (MR: watershed relief divided by square root of watershed area), watershed-relief ratio (watershed relief divided by watershed length) and watershed length to assess hydrogeomorphic processes associated with tributary streams in the Chitral valley. Fig. (4.3a) shows relationship between watershed relief and Melton ratios for Chitral fans and associated tributary channels. de Scally et al. (2010) demonstrated from their studies from the Schist Ranges, Southern Alps, New Zealand that channels and fans associated with fluvial floods are characterized by an upper threshold of MR 0.67 and relief ratio 0.38, while those prone to debris flows have lower threshold of MR 0.45 and relief ratio 0.25. The data, in general conform to the classification scheme of de Scally et al. (2010). Of a total of 24 perennial streams, 21 classify as fluvial with only three having values for MR and relief ratio higher than the upper threshold. In the case of ephemeral streams, 5 out of 32 plot within the threshold of debris flows. As is the case with the Schist Ranges, New Zealand (de Scally et al., 2010), there is a considerable overlap between the debris fans and fluvial fans in the Chitral valley in the range of MR 0.45-0.67 and relief ratio 0.25-0.38. These include several composite fans entrenched by perennial streams, composite fans located at the toes of epheremeral channels, as well as discrete debris fans formed exclusively by ephemeral channels. Wilford et al. (2004) used relationship between watershed Melton ratio (MR) and watershed length to discriminate fans prone to debris flows, debris floods and floods.

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Fans and tributary streams from the Chitral Valley are used to evaluate this relationship (Fig.4.4b). Perennial- stream watersheds in the Chitral valley are characterized by lengths > 5 km and MR <0.68, while those for ephermal streams have lengths <8 km and MR > 0.36. The Wilford et al. (2004) classification of exclusively debris flow fans (i.e., MR >0.6 and watershed length < 2.6 km) only encompasses the debris cones from the Chitral valley (Fig. 4.3b). Since the discrete debris fans from the Chitral valley, with demonstrable debris-flow origin, plot outside the debris-flow field, this classification does not appear to carry universal applications. However, this suggests that a great majority of the perennial streams (with the exception of 4) in the Chitral valley are capable of debris floods, while the ephemeral streams especially those draining onto the composite fans are prone to debris floods as well as debris flows.

Table 4.4. Hydrogeomorphic parameters of the watersheds associated with various tributary streams/channels, Chitral Valley. Stream Type Fan Type Watershed (Elev_diff_ Basin Sqr of Basin Watershed Length Km) Basin Relief Basin Melton S# Stream Name Area in sq.kms (kms) Relief Ratio Area Ratio 1 Urshun Gol 74.24 13.50 2.26 0.17 8.62 0.26 Perennial Alluvial Fan 2 Dam Gol 21.93 9.50 1.93 0.20 4.68 0.41 Perennial Alluvial Fan 3 Swir Gol 48.81 12.40 2.35 0.19 6.99 0.34 Perennial Alluvial Fan 4 Kao Gol 5.66 4.10 1.72 0.42 2.38 0.72 Ephemeral Debris Fan 5 Drosh Gol 21.08 8.80 2.43 0.28 4.59 0.53 Perennial Alluvial Fan 6 Joshaba Gol 8.09 5.30 1.55 0.29 2.84 0.54 Ephemeral Debris Fan 7 Kaldam Gol 13.21 8.00 1.87 0.23 3.63 0.52 Ephemeral Debris Fan 8 Shishi G0l 524 43 3.96 .09 22.89 0.17 Perennial Alluvial Fan 9 Kesu Gol 21.79 7.90 2.25 0.28 4.67 0.48 Perennial Alluvial Fan 10 Gahirat Gol 38.61 15.00 2.12 0.14 6.21 0.34 Perennial Alluvial Fan 11 Birir Gol 99.30 15.50 1.44 0.09 9.96 0.14 Perennial Alluvial Fan 12 Rumbur Gol 388.55 23.90 3.14 0.13 19.71 0.16 Perennial Alluvial Fan 13 Kandak Gol 10.81 7.10 2.76 0.39 3.29 0.84 Ephemeral Debris Fan 14 Gumbas Gol 21.62 8.50 2.88 0.34 4.65 0.62 Perennial Alluvial Fan 15 Kolo Gol 5.66 4.80 2.22 0.46 2.38 0.93 Ephemeral Debris Fan 16 Kolo Gol1 2.06 2.30 2.22 0.97 1.43 1.55 Ephemeral Debris Fan 17 Urghuch Gol 9.75 6.40 1.43 0.22 3.12 0.46 Ephemeral Debris Fan 18 Chuchu Gol1 6.80 9.70 1.76 0.18 2.61 0.67 Ephemeral Debris Fan 19 Jughur Gol 64.76 12.70 1.96 0.15 8.05 0.24 Perennial Alluvial Fan 20 Ochusht Gol 22.40 8.00 1.49 0.19 4.73 0.31 Perennial Alluvial Fan 21 Mulen Gol 19.38 8.50 2.17 0.26 4.40 0.49 Perennial Alluvial Fan 22 Chitral Gol 23.06 7.50 1.44 0.19 4.80 0.30 Perennial Alluvial Fan 23 Danin Gol 21.26 8.00 2.16 0.27 4.61 0.47 Perennial Alluvial Fan 24 Singur 9.80 6.00 1.13 0.19 3.13 0.36 Ephemeral Debris Fan 25 Singur Gol 12.08 6.50 1.25 0.19 3.48 0.36 Ephemeral Debris Fan 26 Lusht Gol 3.58 4.80 1.56 0.32 1.89 0.82 Perennial Alluvial Fan 27 Kari Gol 11.30 5.20 2.17 0.42 3.36 0.64 Perennial Alluvial Fan

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28 Ragh 4.73 3.20 1.03 0.32 2.17 0.47 Perennial Alluvial Fan Mulen Kulu Perennial Alluvial Fan 29 Gol 23.92 10.10 2.04 0.20 4.89 0.42 Turen Kulu Perennial Alluvial Fan 30 Gol 15.78 5.20 2.05 0.39 3.97 0.52 31 Borghozi 4.30 3.30 1.82 0.55 2.07 0.88 Perennial Alluvial Fan 32 Kaghozi Gol 36.11 7.70 2.89 0.38 6.01 0.48 Perennial Alluvial Fan 33 Kaghozi1 1.05 1.60 0.55 0.34 1.02 0.54 Perennial Alluvial Fan 34 Moren More 3.40 3.00 1.65 0.55 1.84 0.90 Perennial Alluvial Fan 35 Istan Gol 15.33 6.90 2.61 0.38 3.92 0.67 Perennial Alluvial Fan 36 Turen More 1.38 1.70 0.70 0.41 1.18 0.60 Perennial Alluvial Fan 37 Chamuruk 5.58 4.30 2.13 0.49 2.36 0.90 Perennial Alluvial Fan 38 More Gol 7.93 4.90 1.51 0.31 2.82 0.54 Perennial Alluvial Fan 39 Morisan Gol 11.86 6.30 2.04 0.32 3.44 0.59 Perennial Alluvial Fan 40 Gokhtan Gol 25.86 8.40 1.76 0.21 5.09 0.35 Perennial Alluvial Fan 41 Molen Gol 12.14 5.70 1.59 0.28 3.48 0.46 Perennial Alluvial Fan 42 Toren Gol 16.17 5.40 2.30 0.43 4.02 0.57 Perennial Alluvial Fan 43 Darom Gol 5.45 3.50 1.64 0.47 2.34 0.70 Perennial Alluvial Fan 44 Parait Gol 60.09 11.60 2.09 0.18 7.75 0.27 Perennial Alluvial Fan 45 Barenis Gol 58.77 9.10 2.44 0.27 7.67 0.32 Perennial Alluvial Fan 46 Shil Gol 18.03 7.00 2.18 0.31 4.25 0.51 Perennial Alluvial Fan 47 Parpish Gol 260.60 21.80 2.95 0.14 16.14 0.18 Perennial Alluvial Fan 48 Shogram Gol 50.56 11.10 0.99 0.09 7.11 0.14 Perennial Alluvial Fan 49 Reshun Gol 78.64 13.50 2.93 0.22 8.87 0.33 Perennial Alluvial Fan 50 Koragh Gol 23.39 8.30 2.91 0.35 4.84 0.60 Perennial Alluvial Fan 51 Charan Gol 12.92 4.30 1.40 0.33 3.59 0.39 Perennial Alluvial Fan 52 Kosht Gol 30.54 6.70 2.21 0.33 5.53 0.40 Perennial Alluvial Fan 53 Diryano Gol 6.66 3.50 1.33 0.38 2.58 0.51 Ephemeral Debris Fan 54 Buni Gol 48.98 8.80 2.60 0.30 7.00 0.37 Perennial Alluvial Fan 55 Awi Gol 19.07 7.20 2.13 0.30 4.37 0.49 Perennial Alluvial Fan 56 Miragram Gol 14.56 5.80 2.29 0.39 3.82 0.60 Perennial Alluvial Fan 57 Mori Parwak 3.93 2.20 1.52 0.69 1.98 0.76 Ephemeral Debris Fan 58 Nisar Gol 17.87 6.00 2.21 0.37 4.23 0.52 Ephemeral Debris Fan 59 Snowghar Gol 17.04 5.50 2.61 0.47 4.13 0.63 Ephemeral Debris Fan 60 Dodargaz Gol 15.31 7.00 2.15 0.31 3.91 0.55 Perennial Alluvial Fan 61 Pasum Gol 14.23 5.20 1.72 0.33 3.77 0.46 Perennial Alluvial Fan 62 Chunj Gol 3.17 2.80 1.36 0.49 1.78 0.77 Ephemeral Debris Fan 63 Shagul Gol 12.51 5.20 1.29 0.25 3.54 0.36 Ephemeral Debris Fan 64 Shagul Gol1 18.10 6.20 1.48 0.24 4.25 0.35 Perennial Alluvial Fan 65 Shano Gol 9.45 5.20 1.89 0.36 3.07 0.62 Perennial Alluvial Fan 66 Chapalli 51.38 9.40 2.21 0.23 7.17 0.31 Perennial Alluvial Fan 67 Shaguno Gol 1.94 2.50 1.40 0.56 1.39 1.01 Ephemeral Debris Fan 68 Muli Khuz Gol 14.64 4.40 1.86 0.42 3.83 0.49 Ephemeral Debris Fan 69 Turi Khuz 14.57 5.00 1.59 0.32 3.82 0.42 Ephemeral Debris Fan 70 Diwan Gol 8.88 4.50 1.64 0.36 2.98 0.55 Perennial Alluvial Fan 71 Istacho Gol 13.92 4.40 1.38 0.31 3.73 0.37 Ephemeral Debris Fan 72 Khutan Gol 13.09 4.70 1.36 0.29 3.62 0.38 Ephemeral Debris Fan 73 Khunz 8.45 4.30 1.31 0.30 2.91 0.45 Ephemeral Debris Fan 74 Khuruz Gol 6.51 4.20 1.58 0.38 2.55 0.62 Ephemeral Debris Fan 75 Shich 11.41 6.90 1.95 0.28 3.38 0.58 Ephemeral Debris Fan 76 Dahrkot Gol 26.82 6.50 2.12 0.33 5.18 0.41 Ephemeral Debris Fan 77 Pardan Gol 7.17 5.00 1.99 0.40 2.68 0.74 Ephemeral Debris Fan

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78 Bang Gol 55.81 10.00 1.19 0.12 7.47 0.16 Perennial Alluvial Fan 79 Paranggaz 3.82 3.00 2.01 0.67 1.95 1.03 Ephemeral Debris Fan 80 Muli Ghall 54.80 9.40 1.27 0.14 7.40 0.17 Perennial Alluvial Fan 81 Donich Gol 9.95 3.80 1.79 0.47 3.15 0.57 Perennial Alluvial Fan 82 Shulkuch Gol 4.19 3.30 1.78 0.54 2.05 0.87 Ephemeral Debris Fan 83 Shaidas Gol 11.53 5.20 2.14 0.41 3.40 0.63 Perennial Alluvial Fan 84 Onshit Gol 8.40 3.10 1.34 0.43 2.90 0.46 Ephemeral Debris Fan 85 Murri Gol 13.51 4.40 1.42 0.32 3.68 0.39 Perennial Alluvial Fan 86 Shandur Gol 9.46 5.50 1.95 0.35 3.07 0.63 Perennial Alluvial Fan Up-stream Perennial Alluvial Fan 87 Shandur Gol 3.81 2.50 1.61 0.64 1.95 0.82 88 Guzhgal 3.92 2.50 1.84 0.74 1.98 0.93 Ephemeral Debris Fan 89 Loh Gol 22.78 5.80 1.84 0.32 4.77 0.38 Perennial Alluvial Fan 90 Rahman Gol 17.46 4.80 2.20 0.46 4.18 0.53 Perennial Alluvial Fan 91 Muli Kirkiz 8.42 4.50 1.93 0.43 2.90 0.67 Ephemeral Debris Fan 92 Kari 0.6 1.2 0.8 0.6 0.8 1 Ephemeral Debris cone 93 Mulen Kolo .1 0.7 0.8 0.7 0.4 2.1 Ephemeral Debris cone 94 Ragh 0.5 1.1 0.9 0.7 0.7 1.4 Ephemeral Debris cone 95 Ragh1 0.4 1.2 0.8 0.6 0.6 1.3 Ephemeral Debris cone 96 Awi Lusht 1.08 1.8 1.2 0.66 1.04 1.2 Ephemeral Debris cone Opposite Ephemeral Debris cone Mastuj R. 97 bank 9.5 5.5 1.3 0.3 3.1 0.4 Near Mastuj Ephemeral Debris cone 98 Down Stream 3.9 3.1 1.5 0.6 2.0 0.7 Mastuj R. Ephemeral Debris cone 99 bank Laspur 1.3 2.2 1.4 0.8 1.1 1.3 10 Near Chinar L. Ephemeral Debris cone 0 bank 1.5 2.2 1.4 0.7 1.2 1.1

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Table 4.5 Hydrogeomorphic Properties of the Drainage Basin in Chitral Valley

Watershed Tributary Length Stream Landform Type Area (km2) Relief Ratio Melton’s Ratio (km) Type Ephemeral 0.1-3.8*2 0.7-5.5 0.8-0.3 2.1-0.4 Debris Cones (8)*1 Gully 1.491.47*3 2.161.57 0.60.1 1.20.5 Ephemeral 1.05-39.3 1.4-7.1 1.0-0.2 1.5-0.4 Debris Fans (27) Channel 9.97.4 4.81.5 0.40.2 0.60.3 Perennial Alluvial Fans (65) 1.05-524 1.41-48 1.0-0.1 1.5-0.1 Stream (Discrete/Perched/ 38.0283.5 8.237.24 0.30.2 0.50.2 composite) 1Number of fans measured in each class *2Range *3AverageStandard Deviation

Table 4.6 showing class limits for hydrogeomorphic processes Variable Flood Perennial stream (Debris Ephemeral Stream Flood) (Debris Flow) Melton Melton <0.3 Melton 0.3 to 0.6 Melton >0.6 and length Melton >0.6 and length >2.7 Length <2.7 km km Melton Melton <0.3 Melton 0.3 to 0.77 Melton >0.77 and relief ratio Melton >0.77 and relief ratio and relief ratio >0.42 <0.42 km Relief ratio Relief ratio Relief ratio 0.15 to 0.35 Relief ratio>0.35 and length <0.15 Relief ratio >0.35 then length And length <2.7 km >2.7 km

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Figure 4.4. Watershed morphometry of the Chitral fans. (a) Interrelationship between watershed relief and Melton’s ratios (MRs) for debris-flow prone ephemeral and floodprone perennial streams. Basin relief ratio of 0.38 and MR of 0.67 define the upper threshold for streams characterized by fluvial flows (f) and 0.25 and 0.45 values for the same parameters define the lower threshold for debris flows (after de Scally et al., 2010). (b) Interrelationship between Melton’s ratio (MR) and watershed length. Box with MR 0.6 and length of 2.7 km defining the field for streams associated with debris flows, and the vertical line demarcating streams characterized by fluvial floods (MR <0.3) and debris floods (MR >0.3) are from Wilford et al. (2004).

To differentiate between floods, perennial stream and ephemeral stream in the study area a standard Melton techniques were used (Wilford, et al. 2004). For this purpose field work and GIS analysis were carried out on 100 fans/cone from the main Chitral valley. The Melton ratio and basin length provided the best identification of hydrogeomorphic processes (Fig. 4.4a). The class boundaries fit well that flood watershed have Melton ratio <0.3 (Jackson, et al.1987) and basin/watershed associated with perennial stream have Melton ratio 0.3 to 0.6 and basin/watershed associated with ephemeral stream have Melton ratio >0.6. The addition of basin/watershed length effectively differentiated ephemeral stream (debris flows) and perennial stream (debris flood) (Table 4.6). From the hazard point of view it is important to differentiate basin/watershed with ephemeral streams from perennial streams as ephemeral streams can have up to 40 time greater sediments discharge than perennial streams (Hungr et al., 2001).

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Basin/watershed length and Melton ratio were used as the most suitable differentiating attributes because they correctly identified majority of the basin/watershed and relatively simple to determine. The Melton ratio was also used as a differentiate attribute in the past. Table 4.4 shows all details of basin/watershed in the study area.

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CHAPTER # 5

EVALUATION OF DEBRIS FLOW HAZARD ASSESSMENT ON ALLUVIAL FANS

5.1 Introduction

This chapter focuses on the evaluation of debris flow hazard assessment on alluvial fans in Chitral valley. Those familiar with the Karakoram landscape, know that amount of debris on slopes of Karakoram and associated mountain ranges is some of the highest in the world (Iturrizaga, 1999). Most of this debris is attributed to frost weathering but a large contribution is production through glacial processes. Nonetheless, irrespective of origin, the debris abundance leads to debris flow; a hydrogeomorphic hazard characterized by tens of times greater than the floods that make them highly dangerous to human settlements and related infrastructures. However, its not just about the presence or abundance of the debris on mountain slopes that make a geographic location vulnerable to debris flow. Several factors such as presence of a water source (e.g., rainstorms or glacial melting), density of vegetation, gradient of slopes, nature of the stream (perennial or ephemeral) contribute to debris-flow hazards. As is shown in previous chapters, fans on valley sides in the Chitral valley are the major site of human settlements. However, they greatly vary in the amount of debris-flow hazard due to the nature of the fan and nature of the feeding tributary stream. Finally, two fans with equivalent hazard shall have different vulnerability depending upon the size of population and associated infrastructure.

This chapter, based on the geomorphological and morphometric analysis carried out during this study (Chapters 3-4), evaluates Chitral valley for debris flow hazard and vulnerability. In the first section, the debris-flow hazard case studies are described to highlight differences in landscape, nature of fans and associated tributary streams. In the second section, attempt is made to evaluate return period for debris flow hazards associated with each of the fan and tributary stream type. And finally, hazard and vulnerability maps are developed for the Chitral valley.

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Iturrizaga, L. (1999). Typical debris accumulation forms and formations in High Asia–A glacial-history-based concept of the origin of Postglacial debris accumulation landscapes in subtropical high mountains with selected examples from the Hindu Kush, the Karakoram and the Himalayas. GeoJournal, 47(1-2), 277-339.

5.2 Debris-flow Hazard Case Studies:

The observations show that tributary-junction fans in the Chitral valley (with the exception of modern alluvial fans at the toes of perennial stream) are prone to debris-flow hazards but with varying magnitudes and frequency. Active debris cones and debris fans are characterized by high debris-flow hazards. Hazards are of the highest order where composite fans occupy toes of the ephemeral streams. Composite fans associated with and drained by perennial streams present a different scenario from the point of view hydrogeomorphic hazards. Through-going, deeply incised perennial streams traversing the composite fans are essentially canyons in their morphology, with channel floors several tens of meters deeper than the surfaces of fans they traverse. In seasonal flood conditions, these streams are capable of transporting the sediment load through channel course until it is shed into the trunk river. Fan surfaces are prone to debris-flood hazards only under induced conditions of high sediment-laden unconfined flows during exceptionally high-magnitude events.

5.2.1 Active Debris fans

Being active sites deposition, these fan surfaces are unsuitable for habitation and development. Locals realized their susceptibility to debris-flow hazards and in the past avoided them for habitations and developments. With growing population and associated economic pressure, there is an increasing tendency to develop these large tracts of un- used land without considering the associated dangers. Two types of new settlements developing along active debris fans include: 1) at the relatively stable outer peripheral edges of the fan on overbank areas adjacent to debris cones and debris fans (Fig. 5.1A). Both these situations are susceptible to debris-flow hazards in torrential rains and snow avalanches. Chuinj and Brep, two sizable settlements upstream from Mastuj, were

119 devastated by debris-flow events in two successive years (2005 and 2006). Chuinj village is mainly located over flood-plain deposits, but lies in close proximity to an active debris fan on mountainside (Fig. 5.1A). Brep village (Fig. 5.1B) is located on a coalesced debris fan formed by two adjacent ephemeral streams (Dahrkot and Chhikan Gol). This is by far the most populated of the active debris fans in the studied area. Debris-flow events of 2005 and 2006 damaged a large portion of these two villages.

Figure 5.1. Satellite images of Chuinj (A) and Brep (B) villages located upstream from Mastuj. The Chuinj settlement is located on floodplain adjacent to two active debris fans. Brep is built upon an active debris fan. Active lobes from 2005 to 2006 debris-flow events are visible in the photographs.

Fig. 5.2. Satellite image, post 2007 debris-flow event (A) and pre-debris flow field photograph (B) of the Snowghar village, Upper Chitral. Densely populated composite fan is linked to an avalanche-prone glacially carved watershed through a broad but short debris-laden ephemeral stream. Together with a poor drainage on the fan surface, this setting renders the village to frequent debris flow hazards. (1) Confirmed debris-flow hazard zone (from 2007 event), (2) potential hazard zone, and (3) hazard free zone

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5.2.2 Composite Fans

Most major settlements at the banks of the Chitral River are on composite fans drained by through-going and entrenched perennial tributary streams. Broad platforms comprising remnants of morainic or glaciofluvial fan terraces (e.g., Snowghar, Reshun) or subsequently stabilized alluvial-fans (e.g., Chitral, Drosh and Ayun) are the most popular sites for settlements, infrastructure and agriculture. Ephemeral streams draining onto older, low relief, wide and apparently stable fans occupying the space between the fan toe and the trunk river are active sites of debris flows. The Snowghar settlement in upper Chitral is a typical example of this kind (Fig. 5.2A, B). Kamp et al. (2004) attributed the landform at Snowghar to a relict end-moraine, surrounded and covered by an alluvial fan (i.e., the Urghuch Fan Formation). A large modern-day debris fan is perched on this ancient fan surface. Together, these landforms form a terrace occupying an area of 1.66 km2 at the foot of the debris-laden Snowghar ephemeral stream (watershed area 19.57 km2, channel length 6.5 km) with a steep gradient/slope (~49%, 26o). The fan is densely populated with well-developed cropland and orchards. The fan surface is poorly drained, in line with the characteristics of debris fans in the region. Short, shallow distributaries on the fan surface, combined with a large volume of debris material in the watershed area and a steep feeder channel have triggered several debris-flow events in the past. The most recent of these events occurred between June 29 and July 1, 2007, when a snow avalanche in the watershed triggered debris flows in the Snowghar village, sweeping away more than 200 houses, a school, and a dispensary, overall displacing more than 400 families. About 30% of the settlement was covered by debris flow (Fig. 8A). Apart from some remnant morainic terraces (5% of the fan surface), the entire settlement is exposed to potential future debris-flow hazards. Drosh is another major settlement on the left bank of the Chitral River that is inhabited by ~50,000 people due to the availability of large flat land and a well-developed irrigation system. The fan is typically composite, comprising five fan-terraces characterized by a series of varying topographic heights relative to each other and the trunk riverbed (Fig. 5.3A). Kamp et al. (2004) assigned the upper-most terraces (FT1) to the Ayun Fan Formation of fluvial origin and the lower terraces (FT 2 to 4) to the Urghuch Fan

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Formation, remnants of a tributary-related alluvial fan. We recognize that a younger set of alluvial fans (FT-5) is presently forming at the distal ends of the present-day tributary streams. Of these, the ones associated with the ephemeral channels (FT-5a) are perched on top of the older terraces, while those related with the perennial streams are being deposited directly on to the trunk riverbed (FT-5b). Of the five tributary streams draining the Drosh fan complex, Drosh Gol in the south and the Shishi Gol in the north are confined, deeply-incised, through-going perennial streams capable of discharging their debris load into the trunk river, without endangering the fan surface under low to moderate flood conditions. The intervening part of the fan terrace is drained by three ephemeral streams. The two in the middle (namely Joshaba Gol and Gormal Gol; Fig. 5.3A) are associated with recent debris-flow events. Unlike the radial, multi-stream distributary drainage pattern characteristics of active debris fans, these ephemeral streams on older landforms have a single channel course. However, these levee-bound, broad, shallow channels are perched high on the fan surface (Fig. 5.3B). In debris-flow events, these distributary channels are clogged by debris material resulting in levee breach/overflow, followed by inundation of the adjacent lowlands on the fan surfaces. The latest debris-flow event of this type happened during the summer of 2005 along the ephemeral stream of Joshaba Gol, blocking the Drosh-Chitral road for several days besides damaging cultivated land and settlement (Fig. 5.3B).

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Figure 5.3 (A) Geomorphological map of the Drosh fan terraces on the left bank of the Chitral River. Four streams, Drosh, Joshaba, Kaldam and Shishi drain the terrace. Of these Joshaba and Kaldam are subjected to frequent debris flow, as detailed in the text. Geological formations: PF = Purit Formation, DF = Drosh Formation, MZ = Melange Zone; Fan terraces: FT 1–4 = Composite fan components, FT-5a = Perennialstream related active alluvial fan, FT-5b = Ephemeral-stream related active debris flows. (B) Field photograph of the Joshaba Gol debris fan perched on Drosh composite. The levee-bound channel with remnants of a debris-flow event in 2005 is perched on the aggrading radial axis of the fan, at higher elevations than the fan flanks. The successive debris flow events choke the channel leading to spillages through levee breaches.

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The Pret village is located on a wide, flat fan surface (2.7 km2 in area) on the right bank of the Chitral River (Fig. 5.4A). The fan is perched on a morainic remnant terrace (Kamp et al., 2004) and lies 30 m above the trunk riverbed. Two right-bank tributaries of the Chitral River drain the fan. Of these, the northern tributary (Pret Gol) is a 14.6 km long perennial stream with a catchment area of ~60 km2. The perennial stream has incised through its own alluvial fan in the apex area as well as the underlying morainic terrace, and drains its sediment load directly into the Chitral River. The settlement and the associated cropland located on the upper fan terraces are well above the normal flood level and, therefore, are relatively safer from low intensity debris-flood activity. In comparison, adjacent ephemeral stream (catchment area 8.83 km2 and stream length 4.65 km) deposits its debris load directly on top of the Pret fan forming a small (0.13 km2) but active debris fan (Fig. 5.4A).The part of the Pret fan down slope from the toe of this perched debris-fan is susceptible to frequent debris-flow hazards. Buni village (~60 km upstream from Chitral town) is located on the surface of the largest composite fan in the Chitral valley drained by the 12 km long perennial, deeply-incised, through-going stream, the Buni Gol (Fig. 5.4B). The ~7 km2 large fan comprising the Middle/Late Holocene Urghuch Fan Formation (Kamp et al., 2004) is primarily a product of detritus derived from the Buni Gol. With successive morphological changes in the drainage basin, as the Buni Gol evolved into a mature perennial stream fed by a large catchment area (47 km2), water flow on the fan surface became confined into one of the distributary channels, which, with passage of time incised and entrenched through the fan surface (from 5 m at the fan apex to 10 meters at the fan toe) resulting in an efficient discharge of the debris load directly into the Chitral River. Abandoned distributary channels (remnants from the early, immature stage) are still recognizable on the Buni fan. Unusually strong monsoon rainstorms in northern Pakistan in 2010 triggered a major snow avalanche in the upper reaches of Buni Gol that led to a catastrophic debris flood event at Buni fan on July 26, 2010 (Uddin, 2010).

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Figure 5.4. (A) Field photograph of the Pret fan. Large perennial stream (1) incises the composite fan. Apparently stable settlement is prone to debris-flow hazard from an ephemeral-stream related active debris fan (2). (B) A satellite image of the Buni composite fan drained by a through-going incised perennial stream hosting a major settlement.

A significant debris-flood event associated with the perennial Reshun Gol was witnessed and elaborately documented by Wasson (1978). The Reshun fan, on the left bank of the Chitral River, hosts a major settlement in the mid-upper Chitral valley (Fig.5.5). The 1.2 km2 fan is drained by the 12 km long, glacier-fed Reshun Gol, which originates at an altitude of 3700 m asl. Draining through a narrow gorge, the stream traverses through the valley fills and the fan as an entrenched channel (which is about 2 m deep in the apex area and as much as 15m deep at the fan toe). According to the eye-witness account (Wasson, 1978), on 14th August, 1975, twenty-eight hours after the start of the rain in the catchment area, a major debris-flood event was initiated in the Reshun Gol (Fig. 5.5). The debris-flood owed its origin to a major rain-triggered landslide 5 km upstream in the feeder stream. The debris-flood carried dislodged trees and a substantial sediment load, including boulders as large as 2 m (Fig. 5.5C). Despite being a well-entrenched channel, the debris-flood not only damaged the wooden bridge on Reshun Gol but also wiped out several houses and cropland on the fan surface especially near the fan apex.

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Figure 5.5 Successive potograph of an eyewitness account of a debris flood event in Reshun Gol, upper Chitral on the evening of August 14, 1975 (from Wasson, 1978).

(A) Turbulent phase intervening successive debris flood surges. (B) Boulders with diameters up to 2 m floating through debris flood surge. (C) Debris-flood aftermath .

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Remnants of a 1986 debris-flow event of comparable magnitude were observed at Mor Lasht Bala (~ 12 km upstream from Chitral) during this study. Here, a relict, stabilized alluvial fan traversed by a deep incised intermittent stream, is host to a sizable village, associated orchards and cropland (Fig. 12A,B). The stream is less than 2 m deep in the narrow apex area, though it attains a depth of about 10 meters while meandering through the fan surface. The stream has a history of blockage, especially at its apex, caused by its own debris load. When this happens, channel-course avulsion drives debris flows through the village. In 1986, one such debris flow diverted from the apex, swept through the main village destroying several dozens of houses and surrounding cropland (Fig. 5.6). Although, no debris-flow hazard has struck the village since then, remnant debris deposits from the event have considerably reduced the channel width in the apex area, developing a potential for future hazards.

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Figure 5.6 A) A panoramic view of Mor Lusht Bala, a large fan with a sizable population and associated agriculture. Apparently, the settlement is safe and has a good agriculture fields surrounding the village. However, the ephemeral stream (see B) has potential of being clogged in a debris-flow event and capable of diverting debris flow on to fan surface damaging property and agriculture land. In 1986, exactly this happened as a debris-flow pulse diverted from the clogged channel spread into the village and agriculture land on the fan surface.

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The debris-flow hazard on the fan surfaces drained by through-going, deeply-entrenched perennial streams (e.g., Buni, Pret) are significantly less than those fan surfaces that are subject of active erosion/deposition in response to debris flows associated with ephemeral/intermittent channels. This however, does not imply that perennial streams are devoid of debris flows. In essence, the perennial streams transport greater sediment load compared to their ephemeral counterparts. Firstly, the catchment basin of the perennial streams has greater amount of unconsolidated debris material available due to factors like great aerial extent, presence of snow covered peaks and glaciers, intense weathering/erosion caused by extreme temperature variations, slope-instabilities and glacial action. Secondly, the perennial streams have a permanent flow of snow-melt or spring water as an efficient transport mechanism and thirdly, the established channel course provides a through-going passageway. While the ephemeral streams, being broad and shallow, have the tendency of spreading sediment load onto the fan surface, the perennial stream tend to deposit their sediment load at the distal end of the existing fan.

The preservation of newly formed fan and subsequent stacking of fan lobes depends upon 1) availability of depositional space at the terminal end of the stream where it joins the trunk river and 2) the flow characteristics of the trunk river. The steep-gradient, high- energy trunk rivers tend to wash away all the debris delivered by the tributary stream, disallowing any localized deposition/ accumulation of sediments forming fans at the interface of tributary stream and the trunk river. This situation is characteristic of trunk rivers flowing through V-shaped valley, which is the case downstream from Mirkhani in Chitral valley (e.g., Dammal Nasar confluence). In comparison, where valley floor is wide, and the tributary stream joins the trunk river at the low-energy concave side of a meander bend, active alluvial fans are formed at the mouth of the perennial tributary streams. The best example of active alluvial fans of this type is witnessed near Drosh (Lower Chitral), at the confluence of the Shishi Gol with the Chitral River (Fig. 6.7). The 40 km long Shishi Gol is one of the major tributaries of the Chitral River with a large glacier-fed catchment area (~640 km2). The confluence of the Shishi Gol with Chitral River is characterized by a 0.18 km2 active alluvial fan. Such alluvial fans are rarely used for any human activity in the Chitral valley because of their extremely active nature. In

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exceptional cases, such active fans can partially or wholly block the trunk river, but considering the high-energy flow characteristics of the Chitral River, probabilities of such events are extremely low.

N Shishi Gol

Remnant Fan Terraces Drosh

Active Tributary Alluvial Fan

Chitral River

FigFigure 15 .6.7 View of Shishi Gol showing active alluvial fan associated with perennial stream.

5.3 Debris-flow Hazard Return Period

Hindu Kush-Karakoram region lacks historical record of hydrogeomorphic events like floods, debris floods and debris flows. The two meteorological stations in the Chitral District (Drosh and Chitral) are located at the valley floor and do not portray precipitation conditions for isolated rainstorms that occur mostly in the upper reaches of the tributary streams. Haserodt (2008) presented annual precipitation data for Drosh (1940-1992) and Chitral (1964-1987). We additionally processed monthly rainfall data for the Chitral meteorological station from 1964 to 1996. None of these datasets prove suitable for distinguishing isolated rainstorms responsible for debris-flow hazards in Chitral. We therefore resorted to literature, newspaper archives, district government records and individual survey reports based on interview with locals. Wasson (1978), while recording

130 an eye-witness account of a 1975 debris-flood event at Reshun, a settlement on a composite fan drained by the perennial Reshun Gol, used information from locals to determine a return- period of ~30 years for debris-flood recurrence at Resun. Our survey for settlements on similar composite fans associated with perennial streams (e.g., Mori Lusht, Pret, Buni) suggest that large debris-flood events equivalent to those at Reshun (1975) or Buni (2010) occurred once or at the most twice in living memories, which corroborate findings of Wasson (1978). Khan (2004) compiled a dataset for debris flood/debris flow events and related damages covering 35 fans in Chitral region. When combined with reported events compiled from newspaper archives and district- government records, the record of debris flood and debris flow events amounts to 42, spanning 1972-2009. These included only those events which preserved evidence for debris flood/flow in the form of debris remnants. According to these data, a hazardous debris flood/flow event occurs in Chitral region every two years. For individual fans, the return periods vary from place to place but generally fall into two categories. For composite fans drained by perennial streams (e.g., Chitral, Reshun, Ayun, Broz, Buni, Pret and Mori Lust), the recorded events are one or at the most two in the last ~40 years, which corroborate findings of Wasson (1978). For active debris fans (including those located on riverbank flood plains e.g., Brep, Chuinj, Daryano or those perched on composite fan surfaces e.g., Drosh, Kesu, Snowghar) up to four events are recorded for the last ~40 years, suggesting a return period of ~10 years (Table 5.1). Table 5.1 Events Data of Debris Flows Hazard in Chitral Valley N.Pakistan S# Location Date Duration Damages 1 Chitral Gol 27-30th July, 3 days Houses partially damaged and this event occur 2010 after 26 years 2 Ochusht 24 June 2010, 1 day Death cases=13, Houses=15 completely 2007, 1976, damaged, Partially=25, 1972 3 Bunni 28th July 2010, 1 day Houses, Forest and Orchard were damaged, May, 1988 Land=4.5 hectares Houses= 2 injuries= 5 Animal death= 25 Fruit Trees= 500 Canal Heads=1 Road= 242 meters

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4 Shishi kooh Shishi kooh valley road has blocked due to 11-Sep-08 flash floods. (GH Farooqi) 5 Ghaghor 3 days Land=1.5 hectares Canal Heads=8 August, 1992 Road=1936 meters 6 Shangas Gol August 1989 - Land=3.5 hectares Houses=8 Animal death=15 August 1990 Fruit Trees=50 Canal Heads=8 7 Broz 1 day Land= 1.51 hectares Houses= 15 August,1992 Road=1600 meter 8 Gahrait 2 days Land= 0.5 hectares Houses=20 May, 1997 Canal Heads=2 9 Kesu 1 day Land= 10.12 hectares Houses= 1 Animal August 1997 death= 3 10 Drosh Jun, 1997 - Land=30 hectares Houses= 50 Death cases= 3 Joshaba August,1998 Animal death= 17 Fruit Trees= 400 Kaldam Jul, 2005-06 Canal Heads=1 Road=240 meters 11 Kari 1 day School=1 Animal death= 15 Fruit Trees= 1000 Canal Heads=1 1992 Road= 241 meters 12 Ragh - Land= 5 hectares, Canal Heads=4 Road=725 1990 meters 13 Koghozi 1994, 1997 1 day Houses= 7 14 Birmugh August 1997 - Fruit trees=22 January 1998 15 Moroi 1 day Fruit Trees= 500 Canal Heads=2 Road=240 August 1997 meters 16 Moroi Payan 1 day Land=0.5 hectares Fruit Trees= 200 August 1997 Road=1200 meters 17 Barnes - Land=10.12 hectares Fruit Trees= 3000 July, 1987 Canal Heads=3 Road=240 meters 18 Green Lusht 1987, 1988 - Houses=10-15 19 Reshun Land=2.5 hectares Fruit trees=4000 Road=3870 meters Canal head=9 Animal 1978 death= 3 School= 1 Main Booni Chitral August, 1997 road has been blocked at Reshun after flash sep.2008 flood. 20 Zait - Land= 20.24 hectares Injuries= 2 Death cases= 2 Animal death= 56 Fruit Trees= 1000 July, 1997 Canal Heads=25 Road=240 meters 21 Koragh July 1997 - Land= 81hectares Houses= 2 Animal death= 5

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Fruit Trees= 400 Canal Heads=1 22 Charan Aug. 1997 - Land=10.12 hectares Houses= 25 23 Awi Last July, 1997 2 days Land= 1.6 hectares Houses=1Road=242 meters 24 Awi 1 day Land=3.2 hectares Houses= 1 Death cases= 1 Animal death= 17 Fruit Trees= 20 Jun, 1994 Canal Heads=8 Road=12100 meters 25 Miragram - Land=0.1 hectares Fruit Trees= 60 July, 1980 Canal Heads=2 Road=110 meters 26 Sonoghur Hundreds of villagers were stranded in the Sonoghur village on Saturday, a day after a large chunk of glacier broke loose in a remote 1-Jul-07 area of Chitral district because of heavy rains. 27 Muli Parwak Aug. 1984 - Land=24.2 hectares Fruit Trees= 150 Road=725 meters 28 Turi Parwak Sep. 1991 3 hrs Land= 8 hectares Houses= 10 Death cases= 1 Aug.1992 Fruit Trees= 200 Canal Heads=1 Road= 1690 meters 29 Nisar Gol March, 1998 - Land=0.8 hectares 30 Sarghoz Aug. 1996 - Land=4.5 hectares Houses= 3 Death cases Injuries=3 Fruit Trees= 300 Road=482 meters 31 Mastuj July, 1978 - Houses= 51 Death cases= 1 Dodargaz Animal death= 100 Pasam Gol 32 Shano Gol 2005 - High level flood/debris flow caused damages to houses. 33 Dahrkot Gol Jun, 2005 - School=5, Houses= 103 Shops= 10 Brep Death cases= 3 Source: Field Survey 2007 and 2012.

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5.4 Hazard and Vulnerability Assessments

As demonstrated amply in this study, debris flow hazards are mainly associated with ephemeral tributary streams compared to perennial streams. Likewise, it is clear from this study that active debris cones and fans are most hazardous in terms of debris flow. The composite, mostly relict fans are mostly entrenched and incised by perennial streams, which are capable of transporting debris material from catchment directly into the trunk river with disturbing fan surfaces. There are however exceptions, where large composite fans lie at footsteps of ephemeral streams. Such fan surfaces are hazardous in terms of debris flows. Figure (5.8 ) show a classification of the Chitral valley in terms of this landform classification. These maps additionally classify the tributary streams into perennial and ephemeral and show their relationship with the fan types. For the preliminary hazard mapping attempted in this study, we have used two classes; high and low based on frequency of the debris-flow events. Landforms with debris-flow events of less than 10 years return period are classified as high hazard and those with over 30 years return period as low hazard. For vulnerability assessment we have used simple parameter i.e., presence or absence of a human settlement. Landforms with a sizable settlement on the fan surface or adjacent to it are classified as highly vulnerable and those with no or negligible settlement, as least vulnerable.

5.4.1. Active Fans

The young sediment fans, which include landforms like talus cones, debris fans and active alluvial fans being active sites of erosion/deposition are unsuitable for habitation and hence, avoided by the locals. These landforms are characterized by high hazard but low vulnerability. With increasing population pressure, and technology advances in heavy machinery, there are increasing attempts to capture these active fans for agriculture and farm houses. As these surfaces are characterized by high hazards, using these fans for any kinds of habitation increases their vulnerability.

5.4.2. Relict Fans Commonly in the Chitral valley, large tracts of pre-existing landforms occur between the trunk river and the valley slopes, which are attractive sites of habitation and cultivation. If

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drained by deeply entrenched, perennial streams capable of efficiently discharging the debris loads direct into the trunk river rather than on the fan surface, such landforms provide relatively stable sites for these purposes and thus are characterized by low hazard. However, being an attractive site for habitation and agriculture, this setting has high vulnerability, especially in case of exceptionally large events. The example of the Reshun and Bunni fans described above are typically of this nature. These fans drained by large, well-entrenched deeply-incised streams provide low hazard conditions that has resulted extensive developments on these fans. However, both Bunni and Reshun have documented evidences (Bunni in 2010 and Reshun in 1978) of debris flows and debris floods with well documented damages to life, property and agriculture land. Due to presence of high population, these fans, despite a low hazard represent a case of high vulnerability. The fans were classified into active alluvial fans, active debris fans, Relict fans, talus cones, flood plain along with its watershed/drainage basin area of Chitral Valley segment wise from Drosh to Chitral (Fig. 5.8A) Chitral to Barenes (Fig. 5.8B) Barenes to Mastuj (Fig. 5.8C) and Mustuj to Brep (5.8D). Arc GIS 9.3 version was used for classification of fan types and associated hazards.

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Figure 5.8 A. Map shows from Drosh to Chitral area of Chitral Valley based on fan types and feeder tributary streams

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Figure 5.8 B. Map shows from Chitral to Barenes area of Chitral Valley based on fan types and feeder tributary streams

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Figure 5.8 C. Map shows from Barenes to Mastuj to Laspur area of Chitral Valley based on fan types and feeder tributary streams.

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Figure 5.8 D. Map shows from Mastuj to Brep area of Chitral Valley based on fan types and feeder tributary streams.

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Based on (Fig. 5.8 A, B, C,D) a preliminary debris-flow hazard map of Chitral Valley (Fig. 5.9) was prepared with help of symbols.

Figure 5.9 A preliminary debris-flow hazard map of Chitral Valley based on fan types and feeder tributary streams. 1. Active debris fans mostly associated with ephemeral streams, 2. Relict fans incised by perennial streams, 3) Relict fans partially drained by ephemeral streams with active debris fans forming on relict-fan surfaces, 4) Active alluvial fans forming at the terminal end of perennial streams, 5) active debris/talus cones.

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There are cases in Chitral, whereby the relict terraces occur at the footsteps of debris- flow prone ephemeral streams. These combinations of well-populated pre-existing large tracts of landforms at trunk-river banks drained by debris-flow prone ephemeral streams are the highest hazard and vulnerability areas in the Chitral Valley. As described, the Snowghar in upper Chitral valley is a classical example, where the debris-ladden slope with an ephemeral stream drains directly onto the surface of the large fan terrace. Any rainfalls above normal or abnormally high melting of glaciers, or in the case of glacial- lake outbreak, this fan is highly prone to debris flow hazard. Despite this, the Snowghar in one of the most populated fan surfaces. This combination of high hazard with high population renders Snowghar as one of the most vulnerable population centres in the Chitral valley. Othe examples of high hazard and high vulnerability include Drosh and Mor Lasht Bala. Our studies demonstrate that it is possible to conduct a preliminary assessment of tributary-junction landforms in terms of their relative hazard and vulnerability using simple parameters such as landform type, nature of the feeder stream and presence/absence of human settlement (Fig. 5.9).

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CHAPTER 6 FINDINGS& CONCLUSIONS

6.1. Findings

The Chitral District of northern Pakistan comprises high-altitude Mountains with steep slopes and deeply incised valleys. Despite the extreme ruggedness of the terrain, the district hosts a sizable population (~0.5 millions) mainly spread on Late Quaternary to modern-day gently sloping landformson the flanks of the Chitral River. These are the only relatively flat and partially stable surfaces with surface- and groundwater resources and organic-rich soils to support cultivation and habitation. The landforms, because of their location at the footsteps of the steep valley slopes, are drained by tributary streams, which unload their sediment forming fans overlapping modern flood plains or pre-existing landforms on river flanks (Owen et al., 2002; Kamp et al., 2004).

These debris and alluvial fans, perched on other landforms on valley flanks are commonly vulnerable to hydrogeomorphic hazards. Our field observations, coupled with limited historical data, show that the debris-flow hazards on tributary fans in the Chitral valley are greatly controlled by the contributing watershed and tributary-stream characteristics coupled with fan- surface drainage (i.e., shallow distributaries vs. entrenched channels). Table (6.1)summarizes physical characteristics and associated hazards on various fan landforms in the Chitral valley.

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Table 6.1Geomorphic characteristics of tributary-junction sediment fans and associated natural hazards, Chitral Valley, N. Pakistan.

Landform Composite Fan Active Alluvial Fan Debris Fan Debris Cone Contributory feeder Perennial Perennial Ephemeral Ephemeral Rills and gullies stream Physical Characteristics: Watershed: Area (Average) Large (54 km2) Medium (13 km2) Small (4 km2) Very small (0.65 km2) Drainage pattern ------Dendritic------Parallel ------Length (Average) Extensive (10.7 km) Intermediate (5.7 km) Intermediate (~3.43km) Limited (1.4 km) Feeder-channel slope 16.2o 20o 24o 33o angle (average) Fan Surface: Area (average) Large (2.2 km2) Very Small (~0.21 km2) Small (~0.7 km2) Very Small (0.2 km2) Slope angle (average) 7.5o 7o 9.3o 33 o Distributary channel Linear (single entrenched) Branching, braided Radial, bird-foot type Linear pattern Narrow, straight to sinuous, Braided, shallow Broad, shallow, levee-bound Channel morphology deeply incised with confined Steep, shallow, levee-bound (unconfined flow) (unconfined flow) flow Fan surface deposition Rare, only through spillage at Mostly on the terminal end On the fan surface as debris flow On cone surface as debris flow lobes apex in exceptionally debris- of the tributary stream lobes flood events Hazards: Channel avulsion Uncommon ------Common, channel choking switching flows to new channels------Uncommon Exclusively fluvial floods Exclusively debris floods Exclusively debris flows Mass movements and debris flows Events Frequent Rare (return period ~30 years) Common (return period ~10 years) Common

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The ephemeral streams with steep gradient and high sediment/water ratios tend to shed their sediment load soon after they leave the fan apex. The resultant landforms are primarily debris fans characterized by convex radial and cross-profiles. The drainage pattern on these fans is typically bird-foot shaped radial, with distributary channels radiating out from the apex (Fig. 4.1A). The shallow channels bounded by levees are typically perched high relative to the rest of the fan surface used for cultivation and habitation. Such shallow channels on fan surface are prone to processes such as channel choking, avulsion and levees breach by successive debris-flows that constitute high potential hazard for habitats located on such fans. In comparison, high-energy perennial streams with higher water/sediment ratio are capable of greater erosive action relative to their ephemeral counterparts. This enables them to carve through the landforms they pass, including the tributary fans formed in their earlier history. This results in switching of active deposition from fan surface to the stream course especially at its distal end, where it joins the trunk river. Two sets of perennial streams are differentiated based on watershed morphometries. The perennial streams characterized by exceptionally large watershed areas and lengths (and correspondingly low watershed-relief and Melton ruggedness ratios) are capable of only fluvial floods and therefore do not pose debris flow/flood hazard to fans associated with them (e.g., ShishiGol). Others (e.g., DroshGol, BuniGol, PretGol), characterized by watershed morphometries intermediate between those for very large perennial streams on one hand, and the ephemeral streams on the other, are prone to generating debris floods. In normal seasonal discharge, such entrenched perennial streams transport their debris material directly to the trunk river. Exceptional rainstorms, triggering avalanches, GLOFs or landslides cause debris floods that exceed the capacity of the channels resulting in surge through the fan apex to inundate the fan surface. The ReshunGol in is an exception. The watershed morphometric characteristics classify this perennial stream as fluvial- flood prone but lacking potential for debris floods/flows to reach the stream toe. However, Wason (1978) recorded an eyewitness account of a 1975 debris-flood event in the ReshunGol, caused by a rainstorm-triggered landslide in a sub-tributary five km upstream from the fan apex. This shows that in addition to watershed area and length, triggering site distance relative to the fan apex may be an important factor governing debris flood/flow hazards on perennial-stream fans.

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The situations described above are commonly encountered in the Chitral valley, but represent merely end-member cases of an otherwise variable and continuously evolving landscape. Hindu Kush Ranges like the adjacent Karakoram and Himalayas are characterized by neotectonics and associated high uplift rates resulting from the ongoing Himalayan orogeny (Hildebrand et al., 2000; Mahmood et al., 2009). In response, the Himalayan rivers are incising at rates as much as 12 mm/yr (e.g., Indus River; Burbank et al., 1996). Data to quantify fluvial incision rates for the Chitral River are lacking, but as is the case with the Indus River, it can be postulated that incision rates are generally equal to the uplift rates (Zeitler et al., 2001). Mahmood et al. (2009) calculated uplift rates of up to 0.7 mm/yr for the Chitral region indicating an active fluvial incision for the Chitral River. In the backdrop of this active tectonic setting, we observe an evolutionary continuum in tributary stream types and their associated landforms. Erosion carves rills and gullies on slopes which produce debris flows superimposed on debris cones when supplied with water. Continuous headwarderosion in the catchments, transition these gullies into ephemeral streams and ultimately into perennial streams. In our model, the immature debris fans are in essence more evolved versions of the debris cones. Likewise, the debris fans are capable of evolving into alluvial fans. One amongst the several distributary channels radiating out of the debris-fan apex may confine into a main channel that serves as the principal conduit for sediment discharge. Processes like fan- toe trimming by trunk river (cf. Leeder, 2001) lead to fan-head trenching and ultimately fan-wide incision of this originally confined but shallow channel. As the channel is entrenched, the deposition switches from the fan surface to the distal end of the fan, often resulting in considerable elevation difference between the remnant fan surfaces and the active alluvial fans forming at the toe of the perennial stream (Fig. 4.2B).

The modern debris fans are unsuitable for habitation and hence, avoided by the locals. These landforms are characterized by high hazard but low vulnerability. In some cases, however, large fans occupy landscape between the trunk river and the valley slopes, which are attractive sites for habitation and cultivation. If drained by deeply entrenched perennial streams, such landforms provide relatively stable sites for these purposes and thus are characterized by low hazard. However, this setting has high vulnerability. There are cases in Chitral, whereby composite fans occur at the footsteps of debris-flow prone ephemeral streams (e.g., Snowghar; Fig.5.2). This combination of well-populated fans at

145 the toes of debris-flow prone ephemeral streams is the highest risk setting in the Chitral valley. Our studies demonstrate that it is possible to conduct a preliminary assessment of tributary-junction fans in terms of their relative hazard and vulnerability using simple parameters such as modern depositional processes, nature of the feeder stream and presence/absence of human settlement (Fig. 5.9).The frequency of debris-flow events is climate dependent. The Chitral valley, due to location in the Eastern Hindu Kush Mountains, is in monsoon rain shadow, leading to prolonged periods of droughts. Occasional heavy rainstorms, together with local snow avalanches, glacial-lake outbursts and catastrophic melting occur in individual watersheds. Based on a survey by Khan (2004), we have estimated that the debris fans perched on composite fans are prone to debris-flow events with a return period of ~10 years. When populated, these fan surfaces are rated as the most vulnerable and require immediate remedial measures. In comparison, the composite fans drained by perennial streams, are relatively less hazardous, as the debris material from the watersheds is directly flushed into the trunk river. However, the high-relief active mountainous environment is susceptible to rare high-intensity rainstorms that may activate avalanches, catastrophic melting, land sliding and glacial-lake outbursts. The resulting debris-laden floods exceed the capacity of even the most well entrenched perennial streams. Wasson (1978) described an eyewitness account of a debris-flood event from Reshun. This testifies to the risk to settlements within the low-hazard zones. The hazard level for such settlements differs from those on composite fans superimposed by the ephemeral-stream debris fans in terms of their lower probabilities of occurrence. As noted by Wasson (1978), debris-flow hazards on composite fans drained by the through-going entrenched perennial streams are characterized by long return periods, i.e., ~30 years.

Mitigation against debris-flow hazards is beyond the scope of this work. However, this study identifies simple parameters, which can be used to classify landforms in the Chitral valley in terms of their level of debris-flow hazards. The ephemeral-stream fans are characterized by the highest probability of debris-flow hazards and necessitate effective landuse planning at the minimum.

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6.2 Conclusions 1. A great majority of settlements in Chitral, located on or adjacent to tributary- junction fans, are exposed to debris-flow hazards. 2. Depositional landforms (debris cones and debris fans) associated with ephemeral gullies and channels are active and prone to frequent debris-flow hazards. Densely-populated composite fans drained by ephemeral streams are at the highest risk from debris-flow hazards. Individual ephemeral-stream debris fans have a chance of a debris-flow event at least once in ~10 years. 3. Fans incised by perennial streams transport a confined flow of debris material directly into the trunk river rather than at the fan surface. Such fans are susceptible to debris-flood hazards in exceptionally large events. Return period for such events is ~30 years. 4. Although debris-flow hazards are a product of multiple factors, knowledge about the nature of the watershed, feeding channel and associated fans allows quick assessment of debris-flow hazards in remote regions lacking detailed hazard zonation mapping.

6.3 Recommendations 1. It is recommended to elaborate engineering solutions to trap debris in the catchments or route the flows through specified channels on fan surface may serve additional remedies if logistically feasible. 2. The probability of debris-flow hazard in case of perennial-stream fans is relatively lower, except in the events of exceptionally high magnitude. However, occasional clearing of channel courses is recommended especially in parts of the channels in the fan’s apex areas may significantly reduce spillage to fan surface.

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References Al-Faraj, A., Harvey, A.M., 2005.Morphometry and depositional style of Late Pleistocene alluvial fans: Wadi Al-Bih, northern UAE and Oman. Geological Society London, Special Publications 251, 85–94. Bathurst, J.C.; Burton, A.; Ward, T,J. 1997, Debris-flow run-out and Landslide Sediment delivery model tests. ASCE Journal of hydraulic Engineering, 123: 410-419. Blair, T.C., 1999. Cause of dominance by sheet flood vs. debris-flow processes on two adjoining alluvial fans, Death Valley, California.Geomorphology 46, 1015-1028. Blair, T.C., McPherson, J.G., 1994. Alluvial fan process and form.In:Geomorphology of Desert Environments, Abrahams, A.D., Parsons, A.J. (eds). Chapman and Hall, London, 354–402. Bridges, E.M. 1990. World Geomorphology, Cambridge University Press, P.257. Burton, I..; Kate, R.W.; White, G.F, 1964.The Perception of Natural Hazards in Resource Management. Natural Resources Journal, 3: 412-41. Burton, I.; Kate, R.W.; White, G.F, 1978.The Environment as Hazard. New York. Oxford University Press, London, , P.240. Burton, I.; Kate, R.W, 1964.The flood plain and the sea shore-A Comparative Analysis of Hazard Zone Occupance. Geographical Review, 54: 336-85. Buchroithner, M., 1980.An outline of the geology of the Afghan Pamirs.Tectonophysics 62, 13–35. Bull, W.B., 1962. Relations of alluvial fan size and slope to drainage basin size and lithology in western Fresno County, California. United States Geological Survey, Professional Paper 450-B, 51-53. Bull, W.B., 1968. Alluvial fans.Journal of Geological Education16, 101–106. Bull, W.B., 1977. The alluvial fan environment.Progress in Physical Geography 1, 222- 270. Burbank, D.W., Leland, J., Fielding, E., Anderson, R.S., Brozovic, N., Reid, M.R. Duncan, C., 1996. Bedrock incision, rock uplift and threshold hillslopes in the northwesternHimalaya.Nature 379, 505-510. Case, W.F., 1996.Debris-Flow Hazards, Utah Geological Survey, Public Information, 2000, Series 70. Cooke, R.U., Warren, A., Goudie, A.S., 1993. Desert Geomorphology. University College Press, London.

148

Costa, J.E., 1988.Rheologic, geomorphic and sedimentologic differentiation of water floods, hyperconcentrated flows and debis flows. In: Baker VR, Kochel RC, Patton PC (eds) floog geomorphology. Wily, New York. Cunny, F.C., 1983. Disasters and Development.Oxford University Press, LondonP.278. Corominas, J. The Angle of Reach as a Mobility Index for Small and Large Landslides. Canadian Geotechnical Journal,, 33: 260-271. Crandell, D.R., 1971. Post-glacial Lahars from Mount Rainier volcano, Washington, U.S. Geol. Surv. Prof. Pap, 677, 1–75. de Scally, F.A., Owens, I.F., Louis, J., 2010. Controls on fan depositional processes in the schist ranges of the Southern Alps, New Zealand, and implications for debris-flow hazard assessment. Geomorphology 122, 99–116. Dardner, J.S.; Sakzuc, E., 2004.System of Hazard Identification in High Mountain areas: An Example of the Kullu District, Western Himalaya. Journal of Mountain Sciences,2: 115- 127. Derbyshire, E., Fort, M., Owen, L.A., 2001.Geomorphological hazards along the Karakoram Highway; Khunjerab Pass to the Gilgit River, Northwest Pakistan.Erdkunde, Arcive Fur WissenschftlicheGeographie, Boss Verlag Kleve, 49- 71. Derbyshire, E., Owen, L.A., 1990. Quaternary alluvial fans in the Karakoram Mountains. In: Rachocki, A.H., Church, M. (eds), Alluvial Fans: A field Approach. John Wiley and Sons, Chichester, 27–53. Drew, F., 1873.Alluvial and lacustrine deposits and glacial records of the Upper Indus Basin.Geological Society of London, Quarterly Journal29, 441-471. Evans, S.G.; Hungr, O., 1993. The Assessment of Rock fall Hazard at the Base of Talus Slopes. Canadian Geotechnical Journal,30: 620-636. Giraud, R.E., 2005. Guidelines for the Geologic Evaluation of Debris-flow Hazards n Alluvial Fans in Utah, Utah Geological Survey, 1-14. Glade, T., 2005.Linking Debris-Flow Hazard Assessment with Geomorphology. Geomorphology, 66: 189-213. Haq, I.,2007. Community Response to Climatic Hazards in Northern Pakistan.Mountain Research and Development 27 (4), doi:10.1659/mrd.0947.

149

Harvey, A.M., 1997. The Role of Alluvial Fan in Arid Zone Fluvial Syestem. In: Thomas, D.S.G (Ed), Arid Zone Geomorphology, Processes, Form and Change in Dry Lands. Wiley, Chichister, ,pp 231-259. Harvey A.M, Silva, P.G., Mather, A.E., Goy, J.L., Stokes, M., Zazo, C., 1999.The impact of Quaternary sea-level and climatic change on coastal alluvial fans in the Cabo de Gata ranges, southeast Spain. Geomorphology 28, 1–22. Haserodt, K., 1968. ZurquartärenVergletscherung des PakistanischenHindukusch (Chitral).EiszeitalterGgw 19, 302-303. Haserodt, K., 1982. Die quartäreVergletscherung am PakistanischenHindukusch (Chitral). Sitzungsber Mitt BraunschweigerWiss Gesell Sbd 6 (mitKarte): Braunschweig, 25– 27. Haserodt, K., 1989. Zurpleistozänen und postglazialenVergletscherungzwischenHindukusch, Karakorum und Westhimalaya. In: HochgebirgsräumeNordpakistansimHindukusch, Karakorum und Westhimalaya. Haserodt, K. (ed). Beitrage Mat Regional Geography 2, 181– 233. Haserodt, K., 2008. Change of the climate in the Hindu Kush region-facts, trends, and necessary oberservations of the environment. In: Proceedings of the third international Hindu Kush cultural conference. Din, I. (ed).Oxford Press, 15-29. Hildebrand, P.R., Searle, M.P., Shakirullah, Khan, Z.A., Van Heijst, H.J., 2000. Geological evolution of the Hindu Kush, NW Frontier Pakistan: active margin to continent-continent collision zone. In: Tectonics of Nanga-Parbat Syntaxis and Western Himalayas. Khan, M. A., Treloar, P.J., Searle, M.P., Jan, M.Q. (eds).Geological Society London, Special Publications 170, 277-293. Hooke, R.LeB.,1967. Processes on arid regions alluvial fans.Journal of Geology 75, 438- 460. Hooke, R.LeB., Rohrer, W.L., 1979. Geometry of alluvial fans; effect of discharge and sediment size.Earth Surface Processes 4,147-166. Horton, R.E., 1945. Erosional development of streams and their drainage basins: hydrophysical approach to quantitative morphology. Geological Society of America Bulletin 56, 275-370. Hungr, O., Morgan, G.C., Kellerhals, R., 1984.Quantitative analysis of debris torrent hazards for design of remedial measures. Canadian Geotechnical Journal 21, 663–677.

150

Itturrizaga, L.,1999, Typical Debris Accumulation Forms and Formation in High Asia. A Glacial-History-based Concept of the Origin of Post-glacial Accumulation Debris Landscape in the Sub-tropical High Mountains with Selected Examples from the Hindu Kush, the Karakoram and the Himalayas. Geo-Journal, 47: 277-239. Ives, J.D., Shrestha, R.B., Mool, P.K., 2010. Formation of glacial lakes in the Hindu Kush-Himalayas and GLOF risk assessment. Kathmandu: ICIMOD, 1-56. Jackson, L.E. Kostaschuk, R.A. MacDonald ,G.M., 1987. Identification of debris flow hazard on alluvial fans in the Canadian Rocky Mountains. In: Debris flows/avalanches: process, recognition, and mitigation. Costa, J.E., Wieczorek, G.F. (eds). Reviews in Engineering Geology VII, 115–124. Kamp, U., 1999.,JungquartäreGeomorphologie und VergletscherungimöstlichenHindukusch, Chitral, Nordpakistan. Berliner geographischeStudien 50. Kamp, U., 2001a.JungquartäreTerrassen und Talentwicklung in Chitral, ostlicherHindukusch.ZeitschriftfuerGeomorphologie45, 453-475. Kamp, U.,2001b. Die jungquartäreVergletscherungChitralsimöstlichenHindukusch, Pakistan. ZeitschriftfürGletscherkundeundGlazial-géologie 37, 81-100. Kamp, U., Haserodt, K., Shroder, J.F., 2004. Quaternary landscape evolution in the eastern Hindu Kush, Pakistan.Geomorphology 57, 1-27. Khan, A.S., 2004.An evaluation of natural hazards in the Chitral valley (A case study along Drosh-Mastuj and Chitral-GaramChashma roads).Masters Dissertation, University of Peshawar, Pakistan. Khan, A. N., 1993.An Evaluation of Natural Hazard Reduction Policies in Developing Countries with Special Reference to Pakistan. Pakistan Journal of Geography, 3: 81- 97. Khan, A.N., 1994.Extent and Evaluation of the Adverse Effects of Landslides on Housing in Murree, Pakistan. Journal of Rural Development and Administration, 26, 1: 119-141. Kolb, H.,1994. Abflußverhalten von Flűssen in den HochgebirgenNordpakistans. In: Physisch-geographischeBeitragezu den HochgebirgsräumenNordpakistans und der Alpen. Haserodt, K. (ed.). Beitr u Mat z RegGeogr, Technical University Berlin 7, 21- 114.

151

Kostaschuk, R.A., MacDonald, G.M., Putnam, P.E., 1986. Depositional processes and alluvial fan-drainage basin morphometric relationships near Banff, Alberta, Canada.EarthSurface Processes andLandforms11, 471-484. Lecce, S.A., 1990. The alluvial fan problem. In: Alluvial Fans: A Field Approach. Rachocki, A.H., Church, M. (eds). John Wiley and Sons, Chichester, UK, 3-24. Leeder, M.R., 1999. Sedimentology and sedimentary basins: from turbulence to tectonics. John Wiley and Sons, Meldon, USA, pp. 592. Leeder, M.R., Mack, G.H., 2001. Lateral erosion (“toe cutting”) of alluvial fans by axial rivers: implications for basin analysis and architecture. Journal of the Geological Society, London 156, 665-893. Macdonald,G.A., 1985.Macdonald, Volcanoes, Prentice-Hall, Englewood Cliffs, NJ (1972). Morrison, W.G. A Dictionary of Geology, CBS Publishers and Distributors Delhi India, P.506. Mahmood, S.A., Shahzad, F., Gloaguen, R., 2009.Remote sensing analysis of quaternary deformation using river networks in Hindukushregion.Geoscience and Remote Sensing Symposium, IEEE International, IGARSS2, II 369-II 372. Melton, M.A., 1965.The geomorphic and paleoclimatic significance of alluvial deposits in southern Arizona. Journal of Geology 73, 1–38. Melton, M.A., 1957.An analysis of the relation among elements of climate, surface properties and geomorphology.Office of the Nav Res DeptGeol Columbia Uni, NY, Tech Rep 11. Okunishi, K.; Suwa, H., 2001.Assessment of Debris-Flow Hazard of Alluvial Fans.DPRI, Kyoto University, Uji-City, 611-0011 Japan. Natural Hazards, 23: 259-269. Owen, L.A., 1988. Terraces, uplift and climate in the Karakoram Mountains, Northern Pakistan.PhD thesis, University of Leicester, UK. Owen, L.A., Kamp, U., Spencer, J., Haserodt, K.,2002. Timing and style of Late Quaternary glaciation in the eastern Hindu Kush, Chitral, northern Pakistan: a review and revision of the glacial chronology based on new optically stimulated luminescence dating. QuaternaryInternational97/98, 41-55. Roohi, R., Ashraf, R., Naz, R., Hussain, S.A., Chaudhry, M.H.,2005. Inventory of glaciers and glacial lakes outburst floods (GLOFs) affected by global warming in the

152

mountains of Himalayan region, Indus Basin, Pakistan Himalaya. ICIMOD Report, Kathmandu, Nepal. Rickenmann, D., 1999. Empirical Relationship for debris flows. Natural Hazards, 19: 47-77. Said, M. 1992.Natural Hazards of the Hunza valley. Proceedings of the National Seminar on Progress of Geography in Pakistan, 75-83. Santangelo N, Daunis-i-Estadella. J., Crescenzo G., V. Di Donato V., Faillace P.I.,1 J. A. Martín-Fernández J.A.& P. Romano P. 2011. Topographic predictors of susceptibility to alluvial fan flooding, Southern Apennines. Earth Surface Processes and Landforms. John Wiley & Sons, Ltd.Published online in Wiley Online Library(wileyonlinelibrary.com) DOI: 10.1002/esp.3197. A. Santo3 and V. Scorpio1Santo A, Di Crescenzo G, Foscari G, Liuzza V, Sciarrotta S,& Scorpio V. 2011. Flood susceptibility assessment in a highly urbanizedalluvial fan: the case study of SalaConsilina (southern Italy). NaturalHazard and Earth System Science, 11: 2765–2780. Strahler, A.N., 1957. Quantitative analysis of watershed geomorphology.Transactions, American Geophysical Union38, 913-920. Uddin, S.,2010. Booni, the day the glacier broke. Chitral News (http://www.chitralnews.com/Letter-05-8-10.htm) Wasson, R.J., 1978. A Debris Flow at Reshūn, Pakistan Hindu Kush, GeografiskaAnnaler. Series A, Physical Geography, Vol. 60, No. 3/4, pp. 151-159 Wasson, R.J., 1979. Stratified debris slope deposits in the Hindu Kush, Pakistan.ZeitschriftfuerGeomorphologie 23(3), 301-320. Wilford, D.J., Sakals, M.E., Innes, J.L., Sidle, R.C., Bergerud, W.A., 2004.Recognition of debris flow, debris flood and flood hazard through watershed morphometrics. Landslides 1, 61–66. doi:10.1007/s10346-003-0002-0. Wieczorek, G.F.; Morgan, B.A., 2000.Campbell, R.H. Debris Flow Hazard in the Blue Ridge of Central Virginia. Environmental and Engineering Geosciences, 6: 3-23. Yar, M.K.; Mumtaz, K., 1980. Integrated Land Resource Survey Report of Chitral Sub- project, District Chitral NWFP: Pre-investment center Peshawar. Zeitler, P.K., Koons, P.O., Bishop, M.P., Chamberlain, C.P., Craw, D., Edwards, M.E., Hamidullah, S., Jan, M.Q., Khan, M.A., Khattak, M.U.K., Kidd, W.S.F., Mackie, R.L., Metamorphic consequences of thermomechanical coupling facilitated by erosion, Tectonics 20, 712 – 728.

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