Site Suitability Analysis For Artificial Recharge And Water Harvesting Structures In Hard Rock Terrain P.Sreedhar Reddy Assistant Professor National Institute of Technology Warangal Ph: + 91 9848893804 papakarisreedhar@yahoo.com Deva Pratap National Institute of Technology Warangal In many parts of the world rapid growth in population, agriculture sector and industrialization have increased the demand for water. With the increasing use of water for various activities, ground water declines at an accelerated rate. In order to prevent the fast depletion of ground water levels, artificial recharge is required. Various artificial recharge and water harvesting structures are required to allow the movement of rainwater from the catchment surface into the under ground formations. Selection of suitable sites for artificial recharge and water harvesting structures needs a large volume of multidisciplinary data from various sources. Remote sensing is of immense use for natural resources mapping and generating necessary spatial database required as input for GIS analysis. GIS is an ideal tool for collecting, storing and analyzing spatial and non - spatial data, and developing a model based on existing factors to arrive at a suitable natural resources development and management action plans. Both these techniques in conjunction with each other are the most efficient tools for selecting suitable sites for artificial recharge structures and water harvesting structures. In the present study, an integrated remote sensing and GIS based methodology is adopted for identifying the suitable sites for artificial recharge structures and water harvesting structures in the chosen study area located in the Jangaon and the Lingala Ghanpur mandals of Warangal District, Andhra Pradesh, India. IRS P6 (Resourcesat. I) - LISS III precision geocoded FCC data on 1:50,000 scale and field observation data were used for extracting thematic information such as geomorphology, geological structures, soil, landuse landcover, well locations, drainage pattern etc. of the area. Slope map and flow accumulation maps were prepared using Survey of India toposheets on 1:50,000 scale. Soil erosion map of the study area was prepared using universal soil loss equation (USLE). The various thematic layers and field observation data were integrated into GIS and various spatial and non spatial queries were performed. The suitable sites for installation of artificial recharge structures and water harvesting structures were identified. Introduction: Water, one of the most essential resources in our day-to-day life, is becoming scarce in urban as well as rural areas mainly due to reduction in infiltration rate as a result of large scale paving of the surface and deforestation respectively. In India, though a huge quantity of surface water is available, the topography and other factors limit the storage of this water. Where the surface water is scarce, the alternative source of ground water assumes importance in the context of water supply. Due to over exploitation of ground water, the ground water levels in many areas show a declining trend, which in turn tends to increase both the investment cost and the operational cost. This problem can be alleviated to some extent by artificially recharging the potential aquifer and efficient harvesting of the rainwater. Remote sensing and Geographic Information System (GIS) methods permit rapid and cost effective natural resources survey and management. Moreover remote sensing and GIS are playing a rapidly increasing role in the field of hydrology and water resources development. Jothiprakash et. al (2003) have delineated the potential zones for artificial recharge of ground water in Agniar – Ambuliar-Southvellar river basins located in Tamilnadu, India through integration of various thematic maps using ArcView GIS. The study area covers an area of 4566 Km2. Thematic maps pertaining to geology, permeability, effective soil depth, drainage depth, soil texture, water holding capacity and physiography were prepared on 1:2,50,000 scale using conventional methods. Pankaj and Amit (2000) have delineated various ground water potential zones for the assessment of groundwater availability in a hard rock terrain with the help of hydrogeological parameters using IRS – 1B, LISS II digital data. Area selected for this study is a part of Bargarh district, Orissa, India covering an area of about 680 km2. Sreenivasan et.al (2000) had under taken a study in the Ramganj Mandi tehsil of Kota district for geomorphology, geology, structure, soil, landuse and landcover, etc., of the area. Slope developing methodology for use of GIS in identifying sites for water harvesting and ground water harvesting structures. IRS LISS II geocoded FCC’s on 1:50,000 scale and other collateral data were used in this study for extracting thematic information such as map was prepared using SOI topographic maps on 1:50,000 scale. Ashok Kumar (1997) carried the study to determine watershed wise detailed sub-surface aquifer geometry. Also, evaluated geo-morphology and terrain modeling and identified the groundwater recharge sites, check dam / water harvesting sites on the basis of geo-hydrological, hydro-geophysical and digital basement terrain model (DBTM) data analysis of existing Land-use. Also identified the land degradation, integration of natural resources & sustainable land-use planning for efficient use of available water resource, computerization of natural resources themes through GIS software application for the area located in the upper reaches of Siwane basin, part of Hazaribagh Upper Plateau. Northern & western limit are scarp zone of Hazaribagh Upper Plateau and Hazaribagh Lower Plateau. Study area: The study area (Fig.1) is situated in Jangoan and Lingalaganpur mandals, Warangal district, Andhra Pradesh, India and bounded by a latitudes 17 o 40 / to 17 o 50 / N and longitudes 79 o 5 / to 79 o 15 / E . The total area of watershed is about 35.8 km2. Topography of the area varies from almost flat terrain to moderate hills. The altitude varies from 345 to 480 meters above the mean sea level and the slope varies from 0 to 20 degrees. Mean annual rain fall of the study area is 859 mm.  Fig1: Study area Data used: Satellite data A standard False Colour Composite (FCC) of IRS P6 (Resourcesat-I) LISS III data acquired on 16th October 2004 has been used for the preparation of landuse land cover map. Collateral data Survey of India toposheet No’s 56 O/1 and 56 O/2 on 1:50000 scale used for preparation of base map, drainage map, water bodies map and preparation of digital elevation model. Hydrogeomorphological map prepared by the RSI under the guidance of the National Remote sensing Agency used Field data Two dimensional position of the each well point in the field is located using GPS, and this positional data is integrated in to the GIS for the preparation of well location map and the soil profile data is used to prepare the soil map of the study area. Software’s used ArcGIS 8.3, Arc View 3.2a, Arc Info 7.2.1, ERDAS Imagine 8.6 and AutoCad Map 2000. Methodology: Various analog maps, which were in different scales obtained from different organizations such as Survey of India and NRSA, were converted into vector format by digitizing in AutoCad Map software. All the digitized data is export in to the ArcGIS software to build the spatial data. Digital image processing of the satellite data were carried out for extraction of pertinent information. The Resourcesat LISS III data was classified using supervised classification technique for the preparation of the land use – land cover map. Soil map of the area have been prepared by using soil profile data collected in the field. Well positions in the field were taken using GPS and well inventory data is attached to the corresponding wells for the preparation of well location map. Soil erosion map of the area have been prepared based on universal soil loss equation. All the above themes were brought into GIS software for the preparation of various thematic maps, further processing and analysis to identify the suitable sites for the installation of artificial recharge and water harvesting structures. RESULTS AND DISCUSSIONS: Preparation of thematic maps: Various thematic maps (Fig 2) of the area such as base map, drainage map, and water bodies map were prepared from the Survey of India topographic maps. Drainage pattern of the study area indicates the dendritic nature. Schreve’s stream ordering method is used to prepare the stream ordering map, it consists the 1st to 12th order of the stream. Generally ground water recharge structures like check dams are constructed on low order streams and where the stream is influent. Water bodies present in the area are almost distributed evenly over the study area. Surroundings of some of the water bodies and some of the dries water bodies contains the fine soils like clay and loamy, these are suitable for constructing the farm ponds to store the water for life saving irrigation and to provide the water for live stack and human beings in arid areas.  Fig. 2: Base map, Drainage, Water bodies The soil map is prepared from the field surveys by observing the soil samples in the field. Boundaries of the various soil types are marked on the corresponding toposheet of the study area, after wards these boundaries are traced and digitized for the preparation of the soil map (Fig. 3). Soils are grouped into three classes depending on soil properties, i.e. red soil, clay and loamy. The predominant soil type, red soil was found around 87% of the study area. Various water harvesting structures like farm ponds, percolation tanks, ground water recharge areas are provided based on the soil type. Land use and land cover map prepared using the digital data of Resourcesat – 1 LISS - III image. Multispectral supervised classification technique in ERDAS is used to classify the image for the preparation of land use and land cover map. The imagery was classified into several classes’ i.e. barren land, irrigated land and settlements as shown in Fig 3. The classified data exported into GIS environment for further analysis. Land use and land cover map is having crucial role in identifying the various ground water recharge sites like check dams, farm ponds and groundwater recharge areas e.t.c. Slope and flow accumulation of the area were derived from the digital elevation model (Fig.3) of the study area is prepared from the contour data available on the SOI topographic map of scale 1: 50,000.  Fig 3: Soil, Landuse Landcover, Digital Elevation model, Slope Geomorphological map (Fig. 4) and geological structures map (Fig. 4) of the study area were prepared by the visual interpretation of the Resourcesat – 1 LISS - III image. Based on the geomorphological map and geological structures map it is concluded that 55% of the study area is pediplane with shallow weathered and 32% of the area is pediplane with moderately weathered and also it is concluded that lineaments (fractures, joints, faults etc) are evenly spread over the study area. In the hard rock terrain ground water recharge occurs where the secondary structural disturbance i.e., lineaments (fractures, joints, faults etc.) are found in confined aquifer. Hence the hydrogeomorphological map is having a key role in identifying the groundwater recharges sites. Well positions in the field are determined using GPS instrument and the positions are integrated into the GIS environment for the preparation of the well location map (Fig. 4). Well profile information, well details and condition of the water table is obtained by observing the wells in the field survey. Well cross section details and well information details are attached to the corresponding well in the well location map. Soil erosion map (Fig 4) of the study area is prepared based on the Universal Soil Loss Equation (USLE). Universal soil loss equation is given by Soil loss = R 3 K 3 LS 3 C3 P, where R, K, Ls, C, P are the rainfall runoff, soil errodibility, slope length gradient, crop/vegetation and management and support practice factors respectively.  Fig 4: Geomorphology, Geological Structures, Well inventory, Soil erosion Artificial Recharge and Water Harvesting: Artificial recharge is the process of augmenting the natural movement of surface water into underground formations by some artificial methods. This is accomplished by constructing infiltration facilities or by inducing recharge from surface water bodies. In hard rock areas, the underlying lithological units do not have sufficient porosity and permeability. Hence in these areas, groundwater recharge is less than the water that is being drawn out from the aquifers. Hence, groundwater cannot suffice the requirement for agriculture or drinking water. Thus, additional recharge by artificial methods becomes necessary to meet the water deficit. In India, artificial recharge measures are taken in the vast hard rock terrains, mostly in Maharashtra and other Southern States. The performance of these efforts can be immensely increased if they are performed through proper scientific planning. Water harvesting is the collecting and using precipitation from the catchment surface. Structures for rain water harvesting mainly for storage purpose were selected on impervious base. Criteria for Selecting the Sites for Various Water Harvesting and Recharge Structures Various site conditions considered for the selection of Sites for the water harvesting and recharge structures are tabulated below (table 1).  Location Map of the Water Harvesting Structures and Artificial Recharge Structures: Location map of the water harvesting structures and artificial recharge structures (Fig.5) is prepared by integrating various maps such as soil map, geological structures map, hydro morphological map, soil erosion map, slope map, Flow accumulation map, drainage map, base map, land use and land cover map, water bodies map and the non spatial data base including well profile and well conditions. By applying the various spatial and non spatial queries on the above maps as per guide lines has mentioned above in the section criteria for selecting the sites for various water harvesting and recharge structures, the suitable locations for artificial recharge structures and water harvesting structures were identified  Fig. 5 Suitable sites for the artificial recharge and water harvesting structures Conclusions: Geologically the area comprises of granite and granitic gneiss with small fractures and intrusive. Geomorphology of the area consists 55% of the study area is pediplain with shallow weathered, 32% of the area is pediplane with moderately weathered and 13% of the area consists rocky pediment and residual hills.Land use and land cover map of the area is prepared using IRS - P6 (Resourcesat -I) LISS III precision geocoded data acquired on 16th October 2004. Study area is classified into three classes i.e., irrigated land covering 65 % of the area, barren land covering 19 % of the area and settlements covering the 16 % of the area. The study area consists three types of soils namely red soil, clayey soil and loamy soil and 87% of the area covering with the red soil.Spatial impact of the various factors such as soil structure, hydrogeomorphology, geological structures, soil erosion, slope of the area etc. on the artificial recharge was identified. The study shows that 30% of the study area is suitable for the artificial recharge i.e., suitable for construction of artificial recharge pits and check dams. 2.5 % of the study area is suitable for the construction of farm ponds to store the rain water. Sites for soil conservation structures like contour bunds are identified where the soil erosion and slope of the area is high. References:
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