SAND AUDIT IN DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of

SAND AUDIT OF RIVER IN

VALLUVAN KADAVE AT CHIRAKKAL GRAMA PANCHAYAT

RE-COMPUTED SAND AUDIT REPORT

Submitted to

THE SECRETARY, GRAMA PANCHAYAT

GOVERNMENT OF KERALA

By

CENTRE FOR ENVIRONMENT AND DEVELOPMENT

THIRUVANANTHAPURAM

November 2016

Centre for Environment and Development 1 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala

TABLE OF CONTENTS

Page No

FOREWORD 3

1.0 INTRODUCTION 4

1.1 Background 4

1.2 Environmental Impact of Excessive Sand Mining in Streams 4

1.3 Sand and Gravel Mining Policy and Guideline 6

1.4 Sand Audit or Budget 9

1.5 Sand and Gravel Mining Management 9

2.0 OBJECTIVES OF THE PRESENT STUDY 12

3.0 STUDY AREA 12

4.0 METHOD OF STUDY 13

4.1 14 STUDY BY GIS APPLICATIONS

5.0 RESULTS AND RECOMMENDATION OF THE STUDY 20

RESULT FROM GIS APPLICATIONS 5.1. 20

6.0 RE- COMPUTATION 25

7.0. DRAWINGS

Centre for Environment and Development 2 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala

FOREWORD

Kannur district is located in the northern part of the Kerala State with a geographical area of2966 sq.km. It is bounded by the Western Ghats in the east and Lakshadweep Sea in the west.The major rivers of the district are Perumba, Kuppam, Valapatnam, , Mahi, andAncharakandy originated in the highlands of Western Ghats and drain in to the sea.

In recent years, rapid development has led to an increased demand for river sand as a source of construction material. This has resulted in a mushrooming of illegal river sand mining activities which have given rise to various problems that require urgent action by the authorities. These include river bank erosion, river bed degradation, river buffer zone encroachment and deterioration of river water quality. Very often, over-mining occurs which jeopardises the health of the river and the environment in general.

There is a need for the Revenue Department, Local Administration Department (LAD) and Irrigation Department to be equipped with the necessary planning and management tools to deal with the problems that arise from river sand mining and the preparation of this guideline is an effort in this direction. The District Collector, Kannur has conducted a DLEC meeting in his chamber on 24-02-2014 and taken a decision for carry out River Bank Mapping and Sand Auditing of 4 rivers in Kannur District and requested the Centre For Environment and Development, Thiruvananthapuram to carry out the study and submit the report based on it. Based on the above The CED has completed the study and submitted the detailed report to the District Collector, Kannur.

River Bank Mapping and Sand Auditing of the Valapattanam river from Neendunokki Bridge to Pazhasinikadave Bridge Has been completed and report submitted as per the request of the River Management Cell of Revenue Department.

As requested by the District Collector, Kannur, we carried out the study of the balance stretch of the Valapattanam river from Pazhasinikadave Bridge to Valapattanam Bridge and report has been submitted on June 2015. This report was prepared on the basis of the detailed Total Station survey and investigation carried out by our experts.

Again the District Collector requested to re-compute the volume of sand in the stretch of Valapattanam river from Pazhasinikadave Bridge to Valapattanam Bridge and submit the report. Accordingly the report is prepared and submitted on September 2016 based on the previous study and the volume of sand mined after the study. GIS application also adopted for the computation.

Now the Secretary, Chirakkal Grama Panchayat requested to prepare the volume of sand in the stretch of Valluvan Kadave in Valapattanam River in the area of Chirakkal Panchayat. Accordingly the report is prepared based on the previous study and the report of September 2016. We sincerely hope that this report will be very useful for planning and management of sand mining in the above stretch of Valapattanam river of Kannur District. Dr. Babu Ambat Executive Director Centre for Environment and Development Centre for Environment and Development 3 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala

1.0 INTRODUCTION

1.1 Background

Sand and gravel have long been used as aggregate for construction of roads and buildings. Today, the demand for these materials continues to rise. In Kerala, the main source of sand is from in-stream mining. In-stream sand mining is a common practice in the streams and rivers of Kerala.

In-stream sand mining can damage private and public properties as well as aquatic habitats. Excessive removal of sand may significantly distort the natural equilibrium of a stream channel. By removing sediment from the active channel bed, in-stream mines interrupt the continuity of sediment transport through the river system, disrupting the sediment mass balance in the river downstream and inducing channel adjustments extending considerable distances (commonly 1 km or more) beyond the extraction site itself. The magnitude of the impact basically depends on the magnitudes of the extraction relative to bed load sediment supply and transport through the reach.

1.2 Environmental Impact of Excessive Sand Mining in Streams

Excessive in-stream sand-and-gravel mining causes the degradation of rivers. In-stream mining lowers the stream bottom, which may lead to bank erosion. Depletion of sand in the streambed and along coastal areas causes the deepening of rivers and estuaries, and the enlargement of river mouths and coastal inlets. It may also lead to saline-water intrusion from the nearby sea. The effect of mining is compounded by the effect of sea level rise. Any volume of sand exported from streambeds and coastal areas is a loss to the system. The major impacts in Kerala due to excessive and illegal sand mining are :

 Sand mining from almost all the rivers in Kerala goes on unabated despite the restrictions and controls imposed by the State Government;

 It has not only deepened the river beds to below the sea level but threatens the existence of several road bridges across these rivers;

Centre for Environment and Development 4 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala

 As a result of the fall in the riverbed level to below the sea level, the water available in 20-30 km stretch of several rivers from their confluences to upward has become saline;

 Besides, the water level in the wells on the embankments has fallen sharply after the monsoon season ;

 Another concern is that the indiscriminate mining has bared the bases of the pillars of the

bridges to the extent that the well Fig 1 : Indiscriminate sand mining has exposed the foundation that are supposed to foundations of the bridge remain under the riverbed are now exposed by several metres;

 When the extraction rate exceeds the replenishment rate, significant and potentially irreversible changes occur in the hydraulic conditions and channel stability;

 Slumping of river banks, marked changes in riverbed configuration, mining of sand from prohibited areas close to engineering structures and over- deepening of river channels are Fig 2: Bared well-foundations of a bridge facing threat of collapse some of the problems that need immediate attention;

 Apart from in-stream mining, mining of sand from land areas such as paddy fields and floodplains is also practised in many panchayats;

 The layers of sand inter-bedded within floodplain areas have been exploited as an alternative to river sand;

 The floodplain mining also damages the environmental setting of the area;

 The removal of sediments and creation of deep pits by way of mining sand will result in lowering of water table to deeper levels.

Centre for Environment and Development 5 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala

Many bridges across rivers are facing threat of collapsing owing indiscriminate sand- mining. Though sand-mining from the 500-metre limits of bridges is strictly prohibited as per the River Bank Protection and Regulation of Sand Mining Act-2001, sand is being mined illegally even from the close vicinity of the bridge piers, Figure 3: Exposed bank of a river due to unrestricted mining activities leaving the concrete structures in a precarious condition.

1.3 Sand and Gravel Mining Policy and Guideline

The following policies should be taken into consideration before approving sand and gravel mining permits.

a) Ensure conservation of the river equilibrium and its natural environment

b) Avoid aggradations at the downstream reach especially those with hydraulic structures such as jetties, water Figure 4: Exposed bridge foundation due to intakes etc. unrestricted mining activities c) Ensure that the rivers are protected from bank and bed erosion beyond its stable profile.

d) Avoid interfering the river maintenance work by Department of Irrigation and Revenue Department or other agencies.

e) No obstruction should be done to the river flow and water transport.

f) Avoid pollution of river water leading to water quality deterioration.

g) Outline the process required in determining the locations, periods and quantity for sand and gravel mining.

Centre for Environment and Development 6 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala

The general guidelines for sand and gravel mining are as follows:

a) Parts of the river reaches that experience deposition or aggradations shall be identified first. Operators may be allowed to extract the sand and gravel deposit in these locations to lessen aggradation problem.

b) The distance between sites for sand and gravel mining shall depend on the replenishment rate of the river. Sediment rating curve for the potential sites shall be developed and checked against the extracted volumes of sand and gravel.

c) Sand and gravel may be extracted across the entire active channel during the dry season (January to May and August to November).

d) Layers of sand and gravel which could be removed from the river bed shall depend on the width of the river and replenishment rate of the river.

e) Sand and gravel shall not be allowed to be extracted where erosion may occur, such as at the concave bank.

f) Sand and gravel shall not be extracted within 500 meter from any crucial hydraulic structure such as pumping station, water intakes, bridges, buildings and such structures.

g) Sand and gravel mining could be extracted from the downstream of the sand bar at

river bends.

g) Flood discharge capacity of the river could be maintained in areas where there are significant flood hazard to existing structures or infrastructure. Sand and gravel mining may be allowed to maintain the natural flow capacity based on surveyed cross- section history

Centre for Environment and Development 7 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala

Details of the criteria needed to ensure that sand and gravel extraction is carried out in a sustainable way are given in Chapter 6 of this guidelines

Start

The Cross – section survey should cover the entire length of the river except the CRZ zone at River Survey downstream. Minimum intervals of the cross section is twice the width of the river subject to the minimum of 500 M. Sediment Sampling The sediment sampling should be verified on the each cross-sections including the depth of the sand deposit by penetration of iron rod. Preparation of Cross Sections Cross section should be prepared with highlighting the cross section area of sand deposit and area of sand up to the depth of 2.00 M from the water level to be marked. Quantity Calculation Calculate the quality of the sand deposit for mining by Panchayat wise. Submission of the Proposal Submit the proposal with all cross sections longitudinal section of the river with quantity calculation and necessary instructions. Management Plan Concerned Local Body and Revenue Department should manage the sand mining as per the prepared management plan.

End

Centre for Environment and Development 8 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala

1.4 Sand Audit or Budget

Determining the sand budget for a particular stream reach requires site-specific topographic, hydrologic, and hydraulic information. This information is used to determine the amount of sand that can be removed from the area without causing undue erosion or degradation, either at the site or at a nearby location, upstream or downstream

1.5 Sand and Gravel Mining Management

A summary of recommendations for the management of sand and gravel mining is given herein. a) Permit mining volume based on measured annual replenishment

A volume equal to the estimated annual replenishment could be extracted from the reach of the channel. Replenishment (up to the elevation of the selected channel configuration) would need to occur before subsequent extraction could take place.

Maintain a record of annual replenishment accounts for the episodic nature of sediment transport. For example, during wet periods with high stream flows, and a high contribution of sediment from hillslopes and tributaries, the data through monitoring would show that sand and gravel bars are replenished quickly. During drought periods with low stream flow, and little sediment supply or transport, the data would likely show that bars were replenished at a slower rate. The use of monitoring data is essential in measuring when actual replenishment occurs. The use of the concept of annual replenishment protects long-term channel stability as well as aquatic and riparian habitat by extracting a volume sustainable by watershed processes.

It is important to develop a system to allocate the total estimated annual replenishment between all of the operators. b) Establish an absolute elevation below which no extraction may occur

(Minimum Enveloped Level or Redline)

The absolute elevation below which no mining could occur or “redline” would be surveyed on a site-specific basis in order to avoid impacts to structures such as bridges and to avoid impacts on vegetation associated with downcutting due to excessive removal of sediment. An extraction site can be determined after setting the deposition level at 2 m below the summer water level. c) Review cumulative effects of sand and gravel extraction

Centre for Environment and Development 9 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala

The cumulative impact of all mining proposals should be reviewed on an annual basis to determine if cumulative revering effects are likely and to ensure that permits are distributed in a manner that minimizes long-term impacts and inequities in permits between adjacent mining operations. d) Maintain flood capacity

Flood capacity in the river should be maintained in areas where there are significant flood hazards to existing structures or infrastructure. e) Establish a long-term monitoring program

Monitoring of changes in bed elevation and channel morphology, and aquatic and riparian habitat upstream and downstream of the extraction would identify any impacts of sand and gravel extraction to biologic resources. i) Retain vegetation buffer at edge of water and against river bank

Riparian vegetation performs several functions essential to the proper maintenance of geomorphic and biological processes in rivers. It shields river banks and bars from erosion. Additionally, riparian vegetation, including roots and downed trees, serves as cover for fish, provides food source, works as a filter against sediment inputs, and aids in nutrient cycling. More broadly, the riparian zone is necessary to the integrity of the ecosystem providing habitat for invertebrates, birds and other wildlife. So removal of the vegetation from the river bank while mining should be strictly restricted. j) Limit in-stream operations to the period between January to May and September to November.

The in-stream mining should only be allowed during the dry season. k) An annual Status and Trends Report

This report should review permitted extraction quantities in the light of results of the monitoring program, or as improved estimates of replenishment become available. The report should document changes in bed elevation, channel morphology and aquatic and riparian habitat. The report should also include a record of extraction volumes permitted and excavation location. Finally, recommendations for reclamation, if needed should be documented.

Centre for Environment and Development 10 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala

Setbacks and Mining Envelope Levels for In-Stream Mining

. The excavation must be carried out giving a setback of minimum of 5 m from the main channel bank toward the flow channel (Figure 5).

. The stockpile must be located beyond 20 m to the left or right of the main

channel bank (Figure 5). Figure 5: Setback, “dead line” and Maximum Allowable Mining Depth for In-Stream Mining . The maximum allowable mining depth is 2 m from the water level as shown in Figure 5.

Centre for Environment and Development 11 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala

2.0 OBJECTIVES OF THE PRESENT STUDY

The District Administration is responsible to ensure that sand and gravel extraction is carried out in a sustainable way in the rivers, to maintain the river equilibrium with the application of sediment transport principles in determining the locations, period and quantity to be extracted and also to identify the suitable locations, period and quantity that can be extracted. Generation of necessary information is essential to plan the above mentioned activities.

The basic objectives of the present study and re-computing of sand volume are

(i) Re-compute the volume of sand deposit and the amount of possible extraction in the area of Valluvan Kadave in Valapattanam river from Valluvan Kadave to Chakkasupy Kadave in Chirakkal Panchayat, Kannur District.

(ii) To set up guidelines for controlling and management of sand mining by the authorities and to formulate policies for sand and gravel mining.

(iii) To ensure conservation of the river equilibrium and its natural environment.

3.0 STUDY AREA

Kannur district is located in the northern part of the Kerala State with a geographical area of 2966 sq.km within the latitudes 110 40‟ to 120 48‟ North and longitudes 750 52‟ to 760 07‟ East. The boundary of the district are Kasargod district in the north, Western Ghats in the east (Karnataka) Kozhikode and Wayanad districts in the south and Lakshadweep Sea in the west. More than 50% of its residents living in urban areas. The district has good biodiversity including wetlands, Rivers, Mangroves and evergreen forests.

The district has two distinct monsoon seasons- South West Monsoon starts in June and continues till the end of September and the North East monsoon season is from October to end of February.

The study area is Valluvan Kadave, Chirakkal Grama Panchayat in Valapattanam River starts from Parassinikadavu Bridge to Valapattanam Bridge.

Centre for Environment and Development 12 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala

Table 1

Details of the Study Area No Name of River District Panchayat Kadave Starting point End point

1 Valapattanam Kannur Chirakkal Valluvan Parassinikadavu Valapattanam River Kadave. Bridge Bridge

4.0 METHOD OF STUDY

The following methodology was adopted for the assessment of volume of sand

 Volume of the sand is assessed by re-computing the volume of sand submitted along with the previous report of 2015 and GIS studies. The methodology of the previous study is as follows.

 Divided the river channel in to segments, based on the reaches panchayat-wise;

 Calculated the thickness of the sand resource in the river channel using methods such as pitting, coring and spiking (measure the depth of sand deposit by penetrating an iron rod);

 Took profiles across the river at an interval of two times the width of the river or 500 m, whichever is less using leveling equipment;

 The profile should have a reading at the middle and two edges and in between every 20 m distance;

Centre for Environment and Development 13 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala

 Took the water level during the time of survey and connected it to a permanent identified bench mark.

 Noted the thickness of the sand bed up to 2 m depth from the summer water level for computation purposes;

 Computed the volume of sand in Prohibited areas each reaches  Notified biological hot spots and sensitive areas  Reaches with placers and other economic minerals panchayat- wise;  River reaches critically affected by bank  Deducted the sliding/slumping/bank erosion  Constructed areas such as bridges, water intake, volume of sand tanks etc. deposit available in  Any other reach that need protection as decided by experts prohibited areas.  Areas mentioned in the Act (Kerala Protection of River Banks and Regulation of Removal of Sand  A map (longitudinal Act, 2001) section) of the river has been prepared marking the locations of all bench marks, profiles, permanent structures like bridges, water intake point, waste water/drainage discharge points, ferry gat/ boat landing centre, road very near to river, dam, check dam, kadave etc

 Compute the volume of sand in Kadave wise.

4.1 STUDY BY GIS APPLICATIONS Instream Minable Sand Supply to the River Channel between Parassinikadavu an Valapatnam Bridge

The in stream minable river sand in Valapatanam River (VR) channel between Parassinikadavu (N.Lat. 11.9847850 and E.Long. 75.4041560 ) and Valapatanam Bridge (N.Lat. 11.9307370 and E/Long. 75.3531480 ) over a channel length of 9.0 km, is scrutinized here in the following. [The river basin data set used is download from DIVA GIS data base.]

The VRB (Valapatnam River Basin), a six order interstate basin (area= 1867 km2 area) has 546 km2 in Karnataka and 1321 km2 in Kerala. The VR rises from Brahmagiri (elv.= 1350 m amsl) in the Western Ghats. Annual water discharge is 4779 Mm3. The av. annual rain fall stands at 3622 mm. The drainage net work of the VRB is fairly large and sum of the lengths of stream segments of all orders (1-6) is measured as 3036 km. and hence a stream density of

Centre for Environment and Development 14 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala

1.62 km/km2. Out of this, major tributaries (viz., Srikandapuram puzha, Valiapuzha, Veni Puzha and Aralampuzha) contribute to a river channel length 625 km.

The Pazhassi Dam at (N.Lat 11.9991020 and E.Long. 75.6091320) at Kuyilur is only a barrage and not a dam across the VR, commissioned in 1979 has a maximum spillway capacity of 3510 m3/sec and a catchment area of 1028 km2.

During the monsoon season in Kerala, unlike a dam, this Barrage allows free flow of sediment and water through all or some of the sluice gates freely to maintain a through flow of water and sediment to the downstream section of the VR channel to finally reach the ultimate sink or the ocean.

The barrage however has not blocked the free flow of sediment and water during bankful or flood flows. Interestingly the reservoir on the upstream side of the reservoir is also not threatened by sediment accumulation and consequent decline of storage, compared to the other lower head dams and reservoirs.

MINABLE SEDIMENT VOLUME ESTIMATION Sediment storage sites Bed load of the rivers is the class of natural fine aggregates. Obviously, flood plains or alluvial plains are customarily the largest sites of bed load sediment in respect of rivers. However, these deposits are not available for active downstream transport as the stream or water surface gradient is so low that the channel swings laterally forming a meandering channel.

Critical shear stress This parameter is what determines the efficacy of sediment transport in channels and is related to shield‟s criterion. The critical shear stress is a function of flow depth, flow gradient and constant of gravitation. In stream segments with higher gradients the critical shear stress is larger (e.g., in stream channels of highland and midland of Kerala) and the opposite is true in channel segments with low gradient (e.g., alluvial plains). Obviously, flood and bankful flows (with higher depths of flow) are the events with higher critical shear stress.

In the upper reaches, due to the higher channel gradients the critical shear stress is a relatively larger number or has a higher value and hence higher the efficiency to transport of sediment Centre for Environment and Development 15 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala as bed load. At any point of time the sediment that covers the bed is a signature of the competence of the river flow at that site.

In the upper reaches the channel is a vast storage site of sediment in the form of different types channel bars, and sediment fill in the channels. In addition, the debris flow into channel shaped as cones and fans are also examples of accumulated sediment available for transport.

We need to see the channel main stem as the transport zone much similar to a conveyor belt. The tributary net work of various orders in the source zone are „gatherers‟ of sediment load for throughput in the transport zone, and is headed to the sink zone- ultimate or the penultimate sink.

Role of Kuyilur (Pazhassi) Barrage As was pointed out earlier this barrage is a structure allowing through flow of sediment and water and consequently does not make the downstream channel to starve for water and sediment. To put this in another way, the VR system has not been significantly affected by the barrage in respect of hydrology or sediment discharge. All the suspended and dissolved load yielded from the VRB of 1867 km2 area is conveyed through the main stem to the ultimate sink. The bed load travelling down stream through the net work of lower order channels and finally through the main stem are under transport only intermittently. Huge volume of sand grade or coarser sediment is thus stores in the channel as fills and bars.

This process of sediment transport modeled in the foregoing therefore does not deprive the Valapatanam Bridge to Prassinikadavu segment from sediment trough put in respect of volumes year after year as long as the water discharge during the monsoon season stays nearly the same.

Role of Monsoon The Asian Monsoon is a great boon not only to humanity in this part of the world but also to the small medium and large rivers of this region to keep those systems actively discharging their functions. In fact the monsoon triggered flood/bank ful flows of water are the prime movers of sediment in the river systems and the net work of channels in the river basin. The hinterland or upland soil cover is eroded, altered and dismembered sheet rock is eroded and lithomarge exposed down below the soil profile is also eroded, transported and deposited in temporary sinks in the channels where ever there is a drop in the bed shear stress. Centre for Environment and Development 16 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala

The hydrograph, a two variable graph, i.e., stage vs. time graph, typically has a rising limb and a falling limb. In most rivers of Kerala the graph would not touch the X axis as there will be a base flow before the onset of monsoon and after peaking of flood flow, the stage falls and so does the curve that translates into falling limb, but would not touch the X axis again as a base flow will continue to exist.

As the river stage rises erosivity of water flow will be on the rise – sediment of all possible sizes eroded for downriver transport. But once the stage begins to drop sedimentation will restart and the eroded channel will be filled with sediment. In other words, in the absence of a less than normal monsoon for several consecutive number years will certainly jeopardize the sediment transport and consequently replacement of channel sediment removed by instream mining.

On the upstream of the Valapattanam bridge and Parassinikadavu minable sand volumes have been estimated for 2015, and stands at 203155 m3 , only 47236 m3 was lifted. Channel sediment storage in the form of bed sediment and sand bars rises proportionately with increasing stream order as well as cumulative channel length. Within channel sediment storage is also in the form of debris cones and fans, which is available for erosion and transport at times of bank full or flood discharges.

Empirical estimates by Richards (1982) suggest that sediment transport increases as a power function of flow i.e., as flow doubles there is more than a doubling of sediment transport and most sediment transport is associated with flood or bankfull flows.

Rate of denudation Rate of denudation or wearing down of earth‟s surface by the running water (or the rate of erosion), differs from one geologic and climatic setting to another. For example 0.01 mm/y is the estimate for the Appalachian region of USA (Leopold and Wolman, 1964), while central Sierra Nevada of California rate is .1 mm (Kandolff and mathews, 1993). The Alpine region of New Zealand the rate is 11.0 mm /y (Griffiths and Mac Saveny, 1983). The rise in rate of denudation is correlated to (a) regional climate (b) gradient of the channel as well as the grand gradient of the bare earth surface in the particular area and (c) soil and /or rock cover.

The monsoon climate (with alternating wet and dry spells) of Kerala is unique to the west coast of and much suited for deep chemical weathering of the surface or basement Centre for Environment and Development 17 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala rocks. The depth of chemical weathering of is unusually deep reaching depths of 30.0 m or occasionally even more. In general the midland of Kerala is covered with readily erodible lithogenic materials. The VRB (Valapattanam River Basin) is no exception.

In the west coast of India where rocks chemically transform to laterite, denudation rate can be as high as 10.00 mm annually. The VRB is no exception. The intersection of short run rivers, steep channel gradients and the very high rain fall jointly promote such denudation rates which prevails in parts of the world like the alpine New Zealand, or Taiwan. The rate of denudation in Himalayas is also high but the dissolved load conten in the ganbges is only 8% of the total load.

The VRB The river channel and VRB is no exception, is like a conveyor belt or transport zone receives the sediment and water from the production zone in the upstream and finally delivering to the sink zone. The large net work tributaries of different orders make the production zone. Out of the 1867 km2 basin area, relatively small area (~ < 5%) falls under the coastal land zone (<7.5 m amsl). Remainder of the basin area is dominantly shared dominantly by midland (7.5 - 75.0 m amsl) while a smaller share goes to the highland (>75.0 m amsl).

Chief sources of sediment to the stream net work are (a) river banks (b), debris cones/fans in the channel (c) sediment stored as channel fill and instream bars and (d) the hinterland. Sediment movement or transport to downstream, through channels takes place only during the phases of bankful and flood flows and in the context of VR, during the monsoon season.

In the VRB, the main channel is like a conveyor belt enabling transport of sediment and water,. Only the coarser bedload equivalent of fine aggregate moves at a lower velocity (in a stop, rest, roll and go fashion) whereas suspended load and dissolved load in the water column has the same velocity as the water. ------

Centre for Environment and Development 18 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala

Centre for Environment and Development 19 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala

Centre for Environment and Development 20 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala

5.0 RESULTS AND RECOMMENDATION OF THE STUDY OF JUNE 2015

Re-computation of the sand volume is assessed based on the study carried out during May- June 2015 and its report. The volume of sand allowed for mining during the period of 2014 and 2015 are also considered. Detailles of the study carried out during 2015 is described below.

 The survey works was carried out from the Parassinikadavu Bridge to Valappatanam bridge with a total length of 9km.

 Width of the river is varying from 66.00 m to 569.00 m. and the maximum depth recorded is 5.20 m at Thakuparamp Municipality 500 m from the Pazhasinikadave bridge.

 The river is passing through 5 panchayats (4 in left bank, 1 in right bank) and one municipality (Right bank).  The panchayats are Kolacheri, , Chirakkal and Valapattanam in left bank and Pappiniseri Panchayath and Thalipparambu Municipality in right bank.  Chirakkal Panchayat is in left bank.  The study area of Valluvan Kadave is in between the Valapattanam Bridge and

Centre for Environment and Development 21 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala

Pamthuruthy Bridge.

 Total 3 bridges are crossing this river (Pazhasinikadave bridge, Pampuruthy bridge and Valapattanam bridge.

 This stretch of the river is having 2 islands Pampuruthy Island and Bhagathsing Island.

 Total 46 profiles (cross sections) has been taken at an average distance of 250 M. The profiles are marked on the longitudinal section.

 Total 18 TBMs are marked on the permanent structures along the bank of the river on this stretch.

 TBM 16 is the nearest TBM of Valluvan Kadave

 The bench mark from the top of the Pazhasinikadave bridge has been transferred to the permanent structures available on the bank of the river for further reference.

 All the permanent structures such as bridges, kadavus, temple, panchayat well and islands are marked on the longitudinal section.

5.1 Results from GIS application: TABLE 1. PROJECTED UNIT-SEDIMENT-STORAGE IN TRIBUTARIES, VALAPATANAM RIVER BASIN Item Length, km Remark Tributaries + mainstem 625.0 ( 625x1000 m) Diva GIS data Channel fill thickness 0.01 (or 10cm) Reckoned Channel 1.00 (or 1.0 m) width Stored Sediment volume 62,500 m3

Scientific Basis

1. At any point in time the unit volume of sediment stored in the basin, reckoning only the major tributaries, is an eye opener of the sediment stored in channels. Assumption is idealistic, in that thickness of 0.10 m and channel width 1.00 m are assumed. It is a practice in hydrology to asses sediment and water discharge on the basis of such inputs. 2. Secondly and obviously the rivers or tributaries are not of uniform width from the source zone through the transport zone. Width can change and does to accommodate

Centre for Environment and Development 22 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala

the volume of sediment and water entering at different nodes from the sub water sheds. 3. However, this unit sediment discharge is a dependable floor figure in respect of sediment storage and hence the volume available for transport, provided the hydraulic regime exits. 4. As we go down stream in any river system the unit storage is less likely to change but total sediment volume transported will be a function of channel width. 5. The sediment storage estimate is ample proof for in ample in stream sediment storage to enable designed rates of sediment extraction. 6. Therefore ample scope exists for removal of instream sand at the rate of not exceeding say 200,000 m3 annually after monsoon – roughly a only third of in channel storage. The quantities can be verified after periodic surveys following the principle of restricting to two meter below the summer water level. 7. The rate of denudation of the upland and interfluves of the basin shall provide the sediment quanta estimated to reach the channels and replenish the channel storage. 8. If the instream sediment.is left untouched it will go to the ocean and stored there. 9. Hence instream mining of channel sediment within the prescribed limit is recommended.

Table 2. SEDIMENT VOLUME ESTIMATE: CHANNEL SEGMENT BETWEEN PARASSINIUKADAVU - VALAPATANAM BRIDGE

Channel Channel unit Channel fill, Sediment volume, m3 length, km width, m m 9.5 1.0 0.1 950 m3 For a channel width in the range of 550.0 m to 50.0 m or for an av. width of 300.0 m 9.5 300.0 0.10 9500 x 300 x 0.1 m3 or 285000 m3 For an av. channel width of 150.0 m 9.5 km 150 0.10 9500x150 x o.10 = 142500 m3

The projected sediment fill assumes a uniform thickness of 0.1M thick channel sediment fill and 2.0 m of summer water depth and an average channel width of 300.0 m. Even by allowing a lower average channel width of say 150.0 m between the points of reference, the projected sediment storage will be 1,42,500 m3).

If channel width is estimated through say transects of 500 m of river lengthy the projected volumes will be more precise. But the current estimate provides the ceiling figures. The

Centre for Environment and Development 23 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala earlier estimate of instream minable sand for 2015 of 203,155 m3 is not only well founded but it can be floor figure of the estimate.

We recommend that as only 47236 m3 was removed in 2015, there is ample ecologically justifiable scope for instream mining to the tune of the detailed estimate of 203155 m3 annually from this segment of 9.5 km.

Detractors might pose a question of sand availability in the VR main stem. I answer that aspect below.

1. The VR main channel through Aralampuzha over a river distance of several tens of km and other main tributaries function as a conveyor belt for sediment shed by the nearly 1800 km2 of land area of VR Basin, enjoying a monsoon climate driven deep chemical weathering for the last 65 My., and annual rain fall of 3300 mm or more. 2. The Barrage at Kuliyoor is not a dam and so allows through flow of sediment and water through the channels and the peak discharges are characteristics of monsoon season. The erosion of upland of the interfluves, derivation of sediment load and transport of the same to the channel net work as bedload is during the monsoon season only. 3. The rising limb of the hydrograph implies erosion and and the falling limb denotes deposition. Suppose a designed quantity of sediment is not removes that excess sediment will go to the ultimate sink or the ocean. The bedload transport does not follow the style of suspended oor dissolved load transport. Instead, bed load is transported downstream in several scores of instances of deposion in the channel and resuspension for transport downstream. 4. The base flow stage channel configuration with flowing water in between different types channel bars and over the sediment fill in the channel is a snap shot of the type sediment that is conveyed to the ultimate sink. 5. Foremost of all we have to reckon the huge volume sediment stored in the channels of the stream net work in the VRB. This is indicated in Table. 1.

Centre for Environment and Development 24 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala

Table 3. THE VALAPATANAM RIVER BASIN- VITAL METRICS (Primary Data source: Diva GIS; CWRDM Water Atlas and open domain literature)

Attribute Details Remark Basin area, km2 1867( includes 546 in Ka) .. Physiographic setting Lowland, <7.5 m:130 km2 Midland and highland Midland, 7.50-75.0 m: 666 supply sediment load km2 to stream net in Highland, >75.0 m: 541 km2 monsoon. Chief Tributaries Srikandapuram puzha .. Valia puzha, Veni puzha & puzha Stream length, km 1st order: 1597; 2nd order: 471; .. 3rd order:239; 4th order:102; 5th order:0.11; tributaries:625; Sum of all orders: 3036 Climate Monsoon with clear cut wet Av. rainfall: 3622 and dry spells mm/y Dominant weathering Chemical weathering, gruss or Good source of weathered basement very deep sediment of all grades Rate of denudation Very high, say 10 mm/y Value adopted from averaged over millennia regions of similar climatic, tectonic and physiographic frame work Water utilization Kuliyoor Barrage, 1979; Spill Allows through flow way capacity:3510 m3/sec. of sediment and water Operates only in bank full or in monsoon season. flood stages Site in mid midland Annual water discharge 4779.0 Mm3

Centre for Environment and Development 25 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala

6.0. SAND VOLUME BASED ON THE RESULT OF STUDY CARRIED OUT DURING MAY TO JUNE 2015 :

Parassinnikadavu Bridge to Valapattanam Bridge Sand Volume Calculation Sheet

Zone of Volume of Volume of Average Average Area of influence Volume of sand for sand for distance distance cross PF.No. L= sand (m3) RB LB before after section L1+L2 V Panchayat Panchayat (L1) (L2) (m2) /2 m V/2 m3 V/2 m3 1 250 250 250 20.82 5205 2602.5 2602.5 2 250 250 250 9.347 2336.75 1168.375 1168.375 3 250 250 250 10.032 12665.5 6332.75 6332.75 4 250 250 250 42.904 4964 2482 2482 5 250 250 250 48.496 12124 6062 6062 6 250 250 250 33.553 8388.25 4194.125 4194.125 7 250 250 250 45.411 11352.75 5676.375 5676.375 8 250 250 250 29.59 7397.5 3698.75 3698.75 9 250 250 250 44.575 11143.75 5571.875 5571.875 10 250 250 250 14.223 3555.75 1777.875 1777.875 11 250 250 250 37.599 9399.75 4699.875 4699.875 12 250 250 250 31.274 7818.5 3909.25 3909.25 13 250 250 250 30.069 7517.25 3758.625 3758.625 14 250 250 250 33.378 8344.5 4172.25 4172.25 15 250 250 250 68.175 17043.75 8521.875 8521.875 16 250 250 250 49.012 12253 6126.5 6126.5 17 250 250 250 20.764 5191 2595.5 2595.5 18 250 250 250 35.834 8958.5 4479.25 4479.25 19 250 250 250 9.104 2276 1138 1138 20 250 250 250 17.232 4308 2154 2154 21 250 250 250 19.349 4837.25 2418.625 2418.625 22 250 250 250 19.984 4996 2498 2498 23 250 250 250 28.245 7061.25 3530.625 3530.625 24 250 250 250 0 0 0 0 25 250 250 250 122.486 30621.5 15310.75 15310.75 26 250 250 250 12.445 3111.25 1555.625 1555.625 27 250 250 250 21.415 5353.75 2676.875 2676.875 28 250 250 250 21.291 5322.75 2661.375 2661.375 29 250 250 250 0 0 0 0 30 250 250 250 15.457 3864.25 1932.125 1932.125 31 250 250 250 59.412 14853 7426.5 7426.5 32 250 250 250 19.264 4816 2408 2408

Centre for Environment and Development 26 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala

33 250 250 250 25.166 6291.5 3145.75 3145.75 34 250 250 250 3.956 989 494.5 494.5 35 250 250 250 12.901 3225.25 1612.625 1612.625 36 250 250 250 4.434 1108.5 554.25 554.25 37 250 250 250 11.091 2772.75 1386.375 1386.375 38 250 250 250 29.578 7394.5 3697.25 3697.25 39 250 250 250 8.892 2223 1111.5 1111.5 40 250 250 250 18.724 4681 2340.5 2340.5 41 250 250 250 79.325 19831.25 9915.625 9915.625 42 250 250 250 50.662 12665.5 6332.75 6332.75 43 250 250 250 19.856 4964 2482 2482 44 250 250 250 0 0 0 0 45 250 250 250 10.193 2548.25 1274.125 1274.125 46 250 250 250 10.301 2575.25 1287.625 1287.625 Total 318350.25 159175.13 159175.125

Estimated Volume of sand in Chirakkal Panchayath PF. Volume of Volume of Total Remarks No. sand in LB sand in RB Volume 31 7426.5 0 7426.5 Near Kattampally Dam 32 2408 0 2408 Near Kattampally Dam 38 3697.25 0 3697.25 R.B of Island 39 1111.5 0 1111.5 R.B of Island 40 2340.5 0 2340.5 R.B of Island 41 9915.625 0 9915.625 Valluvan Kadave 42 6332.75 0 6332.75 Valluvan Kadave 43 2482 0 2482 Valluvan Kadave 44 0 0 0 Valapattanam Bridge

Total 35714.125

Deduct volume of sand in prohibited area 31 7426.5 0 7426.5 Near Kattampally Dam 32 2408 0 2408 Near Kattampally Dam 44 0 0 0 Valapattanam Bridge 38 0 3697.25 3697.25 R.B of Island 39 0 1111.5 1111.5 R.B of Island 40 0 2340.5 2340.5 R.B of Island Total 16983.75 deduction Net Volume of sand 18730.38 M3

Centre for Environment and Development 27 SAND AUDIT IN KANNUR DISTRICT - Re-computed Report Dept of Revenue & Disaster Management, Govt.of Kerala

Estimated Volume of Sand in Valluvan Kadave, Chirakkal Panchayath

PF. Volume of Volume of Total Volume Remarks No. sand in LB sand in RB 41 9915.625 0 9915.625 Valluvan Kadave 42 6332.75 0 6332.75 Valluvan Kadave 43 2482.00 0 2482.00 Valluvan Kadave Net Volume of sand 18730.38 M3 Quantity of sand in Valluvan Kadave 18730.00 M3 as per the statement Deduct volume of sand mined during Considered 1Tn. = 27 Cft. and 11768.00 M3 2015 as per record is 15255.00 Tn 35 Cft = 1 M3. Expected balance quantity of sand 6962.00 M3

Expected quantity of sand accumulated 142500 /9500 x 600 9000.00 M3 during the last monsoon 2016 (channel length of the kadave) Expected quantity of sand drained out 2700.00 M3 30% of 9000 to sea during the last monsoon 2016 Net expected quantity of sand 13262.00 M3 allowable for mining during 2016

Re-computed Volume of sand for mining in Valluvan Kadave, Chirakkl Panchayat for the period of 2016 based on the study carried out during May to June 2015 and sand mined during 2015 and GIS application for sand accumulation in the river for a stretch of Parassinnikadavu Bridge to Valapattanam Bridge of Valapattanam river 9.0 km. length, Kannur District, Kerala Volume of Volume of Expected Expected sand for sand volume of sand volume of Remarks Sl. mining mined accumulated sand for 75% of the Name of Local Body Kadave computed on during during the last mining volume is 2015 2015 monsoon 2016 during 2016 recommended M3 No. M3 M3 M3 M3 Valluvan 1 18730.00 11768.00 6300.00 13262.00 9947.00 Chirakkal Panchayath Kadave

Consider 1 m3 = 35 Cft and 27 Cft equal to 1 Tone

9947.00 M3 equal to 12894.00 Tone

Centre for Environment and Development 28