Geo-environmental Assessment for Determining Suitability of Buildable Land in Context of a Hill Town

Pushplata* and R. Anbalagan*

Abstract

Inappropriateness of the building and construction activities tai

Introduction Problems and Issues of Urban Development in Hill Towns Increased construction activities are natural outcome of urbanization in an area. However, Various problems faced by hill towns are these activities, though at much smaller consequent upon unplanned growth and/or scale and pace than that in plains, have the inappropriate planned efforts in some cases. potential to adversely affect and have already These problems range from those related to affected in some cases the sensitive instability of hill slopes and ecological environmental context in which they are disturbances to those related to accessibility located. Building and construction activity of residential areas from work centers and taking place in most of the popular hill are community facilities, traffic and often considered to be a cause of transportation, infrastructure development environmental degradation. Therefore, a and visual incompatibility of builtforms. In proper understanding of various problems, addition, towns that is centres of tourist their causative factors and issues related to attraction face problems consequent upon rapid urbanization and consequent unplanned/excessive tourism. More instances construction activities is essential for evolving of landslides/subsidence of hill slopes/roads, the methodology for geo-environmental failure/cracks in buildings are observed in assessment for determining suitability of areas with increased construction activities. buildable land. Quantitative and qualitative changes in

‘ Associate Professor, Department of Architecture and Planning •'Professor, Department, of Earth Sciences. Indian Institute of Technology, Roorkee hydrology have also taken place, besides of hill slopes/roads and failures/ cracks in loss of vegetation cover and increased soil buildings. In some cases natural drainage erosion. Micro-climatic changes are also courses are also disturbed leading to further reported in some areas (Anbalagan, 1992); instability. In addition, buildings with greater B.I.S., 1998; Pushplata, 2000; Sinaj. 2007 bulk are built on steeper slopes requiring and Venkatesh, 2007). extensive cutting of slopes/ development of large terraces for functional and economic High land values due to shortage of suitable reasons, which result not only in land for building purposes in proximity to disturbances to slope stability and ecology existing centre of development and low of the areas, but in these buildings looking affordability of the majority of inhabitants in out of place as well. Provision of roads, hill towns has resulted in building of houses parking and other infrastructure required for in areas that are located away from centres these buildings/ uses further aggravates the and/ or building on slopes that are climatically problems. All these not only disturb the slope unsuitable or unstable( with lower land values). stability but also disturb the vegetation cover Expansion of residential areas in far off and natural drainage patterns leading to locations necessitates longer walking environmental problems as shown in Fig.1 distances and time to reach work centers and below. community facilities and inadequate infrastructure on account of its high cost. Thus, it is primarily the lack of proper Whereas, building on relatively unstable understanding of the natural environment and slopes obviously aggravates and sometime their affect on the built environment and its causes problems of instability- resulting in incorporation in planning and design of urban frequent instances of landslides, subsidence settlements that has led to a multitude of

Absence/ Inappropriate Unsuitable Location and Building Building Site development planning / landuse pattern B u lk w .r.t design Terracing insensitive Existing Natural Slope to slope Restoration of T Vegetation Drains Gradient gradient soil cover Location of

Residential W ork V isual areas centres Incompatibility

Cutting o f trees Extensive Terracing / w Cutting of Slopes i Natural factors — Unstable Shaded Far o ff Weak geologic strata Steep terrain T Heavy Rainfall Climatic Discomfort Debris generation

1 L a n d ­ Subsid­ Building Accessibility Water supply. slid e s ence Sewerage failure Instability Inadequate Infrastructure \f \f \f

Microclimatic Loss of Soil Disturbance changes Vegetation Erosion of Natural cover Drainage Environmental Degradation

Fig. 1: Inter-relationship between Planning of Built Environment and Various Problems in Hill Towns problems in hill towns as discussed above. identifying main criteria, their sub-criterion In order to address the above problems and and indicators/parameters, and assigning issues of a hill settlement it is essential to them weightages on the basis of literature develop a methodology for determination of review and study of hill towns of the region. suitability of land for development/building purposes. Thereafter, a rating scheme on the lines of Landslide Hazard Evaluation Factor (LHEF) Need for a comprehensive technique for rating scheme has been formulated. Finally site appraisal a suitability index has been worked out. Though techniques of geo-technical The suitability analysis has been done taking assessment like [1] Landslide Hazard into account five major criteria, namely, hill Zonation [2], guidelines for selection and stability, ecological sensitivity, location, development of sites in Hill Areas [3] and micro-climate and aesthetic characteristics. slope analysis are available, their application The sub criteria for hill stability are those is at regional level and site level respectively adopted for landslide hazard zonation, that and do not address the issues at settlement/ is lithology, geologic structure, relative relief, area level. Some methodologies and slope morphometry, landuse and landcover techniques of townscape analysis and and hydro-geological conditions [1]. Likewise, environment appraisal are available, most of the sub criteria of second criteria of ecological which are very descriptive and/or largely sensitivity are water sources, natural drainage subjective statements of townscape and/or pattern, vegetation, topography and soil landscape quality. The townscape analysis erosion. The third criterion of micro-climate concentrates on visual qualities of the locality is constituted of sub criteria of solar access, and the environmental appraisals primarily exposure to winds, rainfall and humidity, concentrate on natural systems in the snowfall and skylight/daylight factors. The environment. Whereas, site planning fourth criterion of location is constituted of techniques are generally used for individual proximity to existing development, buildings/site level and have not been adapted accessibility, infrastructure and quality of at larger scale/used as a basis for preparing place. The indicators/parameters of each of landuse plans and development controls: these have been identified. Thereafter ratings Since broader and more complex have been assigned to different categories in environment, planning and built form issues each of these. The suitability of areas from are involved in a hill town context, none of these criteria is determined after multiplying these techniques are applicable as such. the sum total of ratings of all the sub criteria with the weightages assigned to them. This A comprehensive assessment of hilly methodology has been demonstrated in terrains, taking into consideration the key context of Almora- a hill town in Uttarakhand, concerns of natural and built environment is which is witnessing rapid urban growth. essential, as not only both are interdependent: the physiographic (landform, Almora - the study context topography), ecological, climatic, locational The hill town of Almora, situated at 29° 30' N (socio-functional) and visual contexts in a latitude and 79° 40’E longitude at a height of place are also interdependent. Thus, the 1646m above msl, is the administrative immediate need is to develop assessment headquarter of in the state of technique that are comprehensive, analytical, Uttarakhand (Fig. 2). The town is located on objedive(and not very desaiptive)and easy to apply. a saddle shaped ridge and its elevation varies from about 1500 m to 1800 m above mean Methodology for Geo-environmental sea level in the lesser Himalayan Assessment physiographic belt. River Kosi on the West The proposed methodology consists of and river Suyal on the East flows from NE to pattern caused due to construction on unsafe •«GnAh.sr*K and shaded area as discussed earlier causes inconvenience to people.

General Geological Setting and Lithology Almora is located in the central part of the synclinal Almora Nappe of Kumaun Lesser Himalaya on a ridge which is delimited by the North Almora Thrust and South Almora Thrust. The lithology exposed in the north western slopes of the town , as observed in the areas along the lower mall road,is schist Fig. 2 ; Geographic location of Almora which is inter- bedded with quartzite, granite and phyllite which are covered by soil (fig 4). SW and from E to SW of the town, Quartzite occurs interbedded with schist in respectively. this area and are highly micaceous in nature. Almora was the capital of Kumaun region for Being fine to medium grained in grain size, three centuries (since its establishment in quartzite are bedded and compacted but 1564), and remained the most important town slightly weathered on the surface and along of the region till 1884. The town started the joint planes. There are two to three sets growing after independence with setting up of joints and well developed foliation planes of number of departmental offices and in quartzites. Whereas schists are institutions and has grown considerably again interbedded with quartzite and are over the last two decades, stimulated by micaceous. These are fine grained rocks and setting up of the large institutions like characterised by well developed schistosity. Kumaun University campus, BASE hospital, Being moderately to highly weathered, research institutes. Construction of Dhara schists along with quartzites cover almost naula road and lower Mall road facilitated the the major part of the area. At places phyllite development in areas far off from the existing are interbedded with quartzite. Phyllites are town. The permanent population of the town also fine to medium grained and having has increased from 13,094 in 1951 to 30,613 relatively less mica content as compared to in 2001. This along with increase in tourist the schist. Foliations are well developed in population has resulted in expansion of town phyllites but are rough in nature. Phyllites in almost all the directions. cover minor part of the area. The southern part of the town area consists of massive Whereas, most of the growth of town has granite. These Granites are fractured at taken place on sfopes along the main access places and are moderately to highly roads of the town (the upper and the lower weathered along the fractures resulting in Mall roads, Dharanaula road), some formation of gauges. In the area, granites are development has taken place in far off areas, rich in microcline and are medium to coarse from Khatyari on the south-west to Narain grained [3]. Tewari Dewal (NTD) ,Heera Dhungari and Ranidhara on the north-north west and Pande The lithology exposed in the area on the khola on the slopes opposite the main town opposite south-eastern slopes is phyllites as shown in the Fig. 3 above. This spread and schists which are interbedded with out pattern of growth of the town, particularly micaceous quartzites of Almora group (Fig. the residential development and the location 5). Intrusion of granite and granodiorite are of work centres in far off areas along with the also observed at places as shown in fig.4 Fig. 3: View of Almora showing extent of develop- nnent and detailed study area below. The quartzites in the area mainly occur as interbedded with schists. The quartzites are highly micaceous in nature, at places where they show well developed foliation planes. They are fine to medium grained and are thickly bedded. They are slightly Fig. 4: Salient lithological features weathered on the surface and along the joint Fig. 6 : Landslide Hazard Zonation map planes which are two to three sets in number. in the formation of gauges. They are rich in The schists are interbedded with quartzite microcline and are medium to coarse grained. and are also micaceous in nature. These are They lack well developed joint sets [3]. fine grained rocl

map of the area in and around the town has been prepared (Fig 6). Thereafter one of the potential areas for urbanisation located in the low hazard zone has been selected for geo- environmental assessment. The study area lies between the Toll at Syali Dhar and Matela village at a distance of 10 km from Almora along the Bareilly- Bageshwar road. The area is delineated by the ridges on south and east side, Khankal ka Ghadehra on the north and the road on the west. Kosi river flows on the west close by below the study area. Part of the area consists of agricultural fields with sparse vegetation and scattered houses, and the remaining is covered by Sitoli reserve forest (Fig. 7 ) The area has been subdivided into 31 facets for the purpose of detailed analysis (Fig 8a). The area is covered with well compacted debris. Foliation is the major geological discontinuity of the area. On the basis of Fig. 7: Detailed study area examination of rock types in the vicinity of the area, two sets of joints are observed. One of the LHZ map of the area. In order to dipping towards S,SE and the other dipping evaluate the status of causative factors, a number of thematic maps pertaining to each towards N,NW as compared to the slope which is inclined towards south west, hence of the causative factors were prepared namely the slope is stable from the structural point lithological map, structural map, land use and land cover map, slope morphometry map, of view. The relative relief in the areas varies from low /medium in areas under agriculture relative map and hydro -geological map to high in area under the forest and some covering all the slope facets of study area. pocket below the road. The slope gradient in These maps depict the nature and distribution most of the area is less than 15° whereas it of corresponding causative factors over the area. Ratings for the various parameters of is between 16° to 25° in few areas. Thus the area has been classified as low to medium various facets have been awarded according hazard zone on the basis of LHEF rating to IS 14496 (part 2) [2], Ratings for 3 facets scheme (Fig 8b). Based on this the suitability with distinct characterstics are given in table of the low hazard zone has been taken as 7 (1). and that of moderate hazard zone as 5, on a 10 point scale. Fig. a : Facet map

scorn 0 500m ikm

INVIRUNMNrAL SUtTAMiT Fig. c: Ecological Suitability Map Fig d: Climatic Suitability Map

Fig. e: Locational Suitability Map Fig. f: Integrated Suitability Map Fig. 8 (a - f): Locational Suitability Map

Further the ecological sensitivity of the area been awarded on the basis of presence / have been w/orked out on the basis of sub proximity of springs their importance, criteria as mentioned earlier in the potential of recharging and venerability of methodology. Rating for vegetation having a pollution. Rating for natural drainage pattern weightage of 3, has been aw/arded on the with a weightage of 1, is awarded on basis of basis of extent of vegetation cover, quality presence/proximity to major/minor drains and and scarcity of vegetation. Ratings for their gradients. Whereas rating for erosion topography having a weightage 3 is based (weightage 1) is determined by susceptibility on the slope gradient. Likew/ise, rating for of the area to erosion. Ecological sensitivity water sources having a weightage of 2, has of the area is shown in fig 8c below. Like wise the suitability of the study area from problems to the people and effects the microclimatic considerations is determined environment adversely. A methodology for on the basis of solar access,which intern is determining suitability of areas in an around dependent on the slope aspect (weightage hill towns, integrating the key issues of 5) and the extent of shading (weightage 2); natural and built environment as proposed, and exposure of wind (weightage3) (fig 8d). is essential for ensuring safe and sustainable The suitability of locational criteria is worked growth of hill towns that is socially out on the basis of proximity of existing acceptable. Suitability of areas thus development (weightage 3), accessibility determined should become the basis of (weightage 3) infrastructure (weightage 2.5) landuse planning as well as development and quality of place (weightage 1.5) (fig 8e) controls for identifying building locations and Whereas, the visual criteria for suitability bulk, thereby ensuring contextually include the visibility (weightage 4),visual appropriate development of hill towns. exposure (weightage 3) and aesthetic value of the area (weightage 3). The overall References suitability of the area for development is Anbalagan, R. (1992). Terrain Evaluation and determined according to weightages assigned Landslide Hazard Zonation for to these criteria, which can vary depending Environmental Regeneration and Landuse upon the particular context. In this case the Planning in Mountain Terrain, Proc. of VI hill stability,locational and microclimatic Int. Symp. on Landslides, Christchurch, pp criteria has been assigned a weightage of 861-868. 25 each and ecological sensitivity has been assigned a weightage of 20 and aesthetic Bureau of Indian Standards, (1998). I.S. 14496 considerations have been given a weightage Part 2): Indian Standard- Preparation of of 5 only. An integrated suitability rating has Landslide Hazard Zonation Maps in thus been obtained by adding the rating of Mountainous Terrains- Guidelines, Part 2: all the criteria and shown in fig 8f below. Macro-zonation, B.I.S., New Delhi. (2000), I.S. 14804:,Guidelines for Siting Design Accordingly, the facets with relatively with and Selection of Materials for Residential gentle slope, sparse vegetation, facing South/ Buildings in Hilly Areas. south west and located near the vehicular road are found to have higher rating as Pushplata (2000). Urban Design Matrix for Hill compared to the facets with steeper Towns , University of Roorkee, Roorkee (unpublished Phd thesis) gradients, forest and facing north/northeast/ north west, demonstrating the validity of Sinaj. S (2007). Landslide Hazard Zonation methodology proposed Mapping of Almora Upper Mall Road, Kumaun Himalayan, Uttarakhand, NT The same methodology can be applied to the Roorkee (unpublished M.Sc Applied rest of the areas for determining their Geology Dissertation) suiatability for buildabie land. Venkatesh, P., (2007). Landslide Hazard Conclusions Zonation of slopes around Almora by pass road, Kumaun Himalaya Uttarakhand The existing pattern of expansion of hill towns (unpublished M.Sc Applied Geology in far off, unstable areas and areas without Dissertation). adequate solar exposure causes numerous