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Ground Water Assessment Water Quality >>Watershed Management Surface Water Management Integrated approach for comprehensive planning of watershed development through artificial recharge and rainwater harvesting - A case study S D Tripathi, N C Gautam, C Bhanu Prakash, Dinesh Kar Speck SpatialTech Limited, Hyderabad, India ABSTRACT Groundwater is a precious resource with limited extent. Indiscriminate use of groundwater for various activities results in fast decline of the resource. Integration of remotely sensed data and field survey data on a GIS platform provides convergent analysis of diverse data sets for decision making in groundwater management and planning through artificial recharge of groundwater and rainwater harvesting. Speck SpatialTech Limited (SST) adopted a multi-disciplinary approach for developing a comprehensive tool for planning watershed development through artificial recharge of ground water and rainwater harvesting in 2500 sq km area spanning across 3 districts in Chhattisgarh state of India. In total thirty two (32) watersheds of various sizes (ranging from 16 sq km to 248 sq km) falling in Mahanadi basin were delineated. The study involved detailed surveys on natural resources, understanding hydrology of aquifers, evaluation of quality and quantity of ground water, analysis of socio-economic fabric, water demand assessment and its impact on ground water reserves. An integrated analysis on a GIS platform was carried out to identify sites suitable for artificial recharge and rainwater harvesting. Water resource development plan was generated for each identified site, describing type of recharge structure, detailed engineering design, cost benefit analysis and monitoring guidelines. Complete survey details, analysis and results were presented in the form of Watershed-wise Detailed Project Reports (DPRs). Rampur watershed (code 4G2C1r1) is discussed under the present case study to explain the methodology and results. Introduction Water is an indispensable constituent of every day life and it is widely distributed in nature so that it may be available quickly and easily. However, with increasing population and rapid urbanization along with advent of modern technologies, water use has increased tremendously. Hence, there is a need for an early rational and practical policy for development of water resources, water use and its conservation i.e. optimal use of available water resources is essential for development of the country. Remote sensing and GIS plays an important role in the study of natural resources and helps in planning water resources development. One of the greatest advantages of using remote sensing data for hydrological investigations and monitoring is its ability to generate information in spatial and temporal domain, which is very crucial for successful analysis, prediction and validation (Saraf, 1999). Remote sensing provides multi-spectral, multi-temporal and multi-sensor data of the earth's surface (Choudhury, 1999). However, the use of remote sensing technology involves large amount of spatial data management and requires an efficient system to handle such data. Thematic layers generated using remote sensing data like geology, geomorphology, land use/land cover, soils etc can be integrated in a Geographic Information System (GIS) framework and analysed with logical condition to generate ground water potential zone maps. An integrated study covering the aspect of groundwater recharge is a crucial requirement of the present day (Choudhury, 1999). The present work is an attempt in this direction. Apart from the natural resources, geological and geo-physical surveys and hydro-chemical investigations, the study also takes an account of the social-economic fabric and water demand for the watershed area, and use remote sensing and GIS based analysis for identification of suitable sites for rainwater harvesting, artificial recharge. The study concludes with suggestion of suitable recharge structures with detailed engineering plans, maintenance and monitoring guidelines, cost estimates and cost-benefit analysis. Objectives The study was carried out to generate Detailed Project Report (DPR) on artificial recharge of groundwater and rainwater harvesting for Rampur watershed. The study includes;
Study Area Physiographically Chhattisgarh state is divided into three distinct zones as Bastar zone, Chhattisgarh plains and Northern Hill region. The entire study area (32 watersheds) covers parts of the districts of Bilaspur, Korba and Korea, this falls in the Northern Hill region. The main river flowing in the state is Mahanadi and its tributaries are Seonath, Hasdeo, Mand, Arpa etc. The Rampur watershed of Korba district falls in Mahanadi river basin. In this region the climate is predominantly sub-tropical with summer temperatures of around 29oC and winter temperatures of 21oC. The bulk of the precipitation is in July - September period [800 to over 1200 mm] with January - February precipitation of less than 50 mm. The river is one of the most active silt-depositing streams in the Indian subcontinent. The district forms a part of central Indian Peninsular shield. Geologically the district comprises the rock formation of Archaean, Chattisgarh supergroup, Gondwana supergroup and Basaltic formations of Deccan traps. Rampur watershed (Code 4G2C1r1) covers an area of 157 Sq km and is situated in the south-eastern corner of Korba district, Chhattisgarh state. The watershed is covered in Survey of India toposheet No.s 64 J/15 and 64 J/16 (1:50,000 Scale). The watershed lies between 82° 51' to 83° 00' longitudes and 22° 10' to 22° 20' latitudes  Fig. 1: Location map Geology of the watershed Geologically the area consists of Archaeans, upper proterozoic formations and Gondwanas. Archaeans are represented by granites and gneisses found in the SW corner of the watershed. South of granites, upper proterozoic formations are found. The upper proterozoic formations are represented by Chhattisgarh super group consisting of shaly sandstones, shaly limestones and limestones. The Gondwanas are represented by both lower and upper Gondwanas. The lower Gondwanas are represented by Talchir formations and Barakar formations, while the upper Gondwanas are represented by Kampti sandstones. The Kampti bed belongs to Ranigunj series of upper Gondwanas. These Kampti beds comprise red and grey argillaceous sandstones and conglomerates with inter stratified shales. The beds contain patches and nodular of ferruginous material. Data Used Satellite data: LISS - III sensor data of Indian Remote Sensing Satellite IRS-P6 (RESOURCESAT) were acquired. Image data in multispectral bands as green (0.52 - 0.59 µm), red (0.62-0.68 µm), near infrared (0.77 - 0.86 µm) and having spatial resolution of 23.8 m were used. Two season images were procured from National Remote Sensing Agency Data Centre. Kharif season data acquired on 25th November, 2003 and Rabi season data of 29th February, 2004 were procured. Ancillary data: A number of published maps and reports were used for the purpose of thematic layer generation as input. These are topographical maps at 1:50000 scale from Survey of India (SOI), geological maps at 1: 50,000/63,360 scale from Geological Survey of India (GSI), soil maps at 1:500,000 scale from National Bureau of soil survey (NBSS), maps from National geophysical research institute (NGRI) and reports from Public health engineering department (PHED), Central ground water board (CGWB), state ground water boards (SGB) were also used. Meteorological data like rainfall, temperature, number of rainy days etc. were collected from Indian Meteorological department (IMD). Field observation data: Field data were collected for land use / land cover, socio-economic fabric and water demand. Demographic data related to the revenue villages of the watershed, Geophysical data for aquifer parameters and water level details were also collected through field surveys. Methodology 1. Procurement of data Satellite images for rabi and kharif season, existing geology maps, SOI topographical maps, soil maps, census reports and climatic details were procured from respective sources. 2. Delineation of watersheds The drainage divides have been located by analyzing contour lines. From contour lines, attempt has been made to identify downside direction, and an array has been plotted to note down the direction. A divide line has been drawn where arrows show opposite direction. A stream is a line, where two arrows converge. This divide line has been drawn from the gauge location and the process continues until the whole watershed has been demarcated. 3. Preparation of base map Base map for each watershed was generated using survey of India toposheet giving all required base information e.g. roads (metalled and un-metalled), cart tracks, railway lines, drainage, canals, ponds, important locations (Revenue Villages). 4. Geo-referencing and processing of data Satellite imagery procured was rectified with reference to the SOI topographical maps. Image enhancement techniques were employed to make the satellite data more interpretable. Further the rectified image was subset based on the area of interest for each watershed. 5. Pre-field interpretation Satellite data were interpreted for land use and land cover into different classes of agriculture, forestry, wastelands, built-up lands and water bodies. The minimum mappable unit at 1:50000 scale were kept as 3mm X 3mm. This layer is then exported into ArcInfo platform to check for dangle errors and label errors if any. 6. Ground truth collection 6.1 Field work for land use Satellite imageries of both the seasons and the pre-field interpretation results were used for field verification. Location information was collected using GPS during the field visit. Tonal and textural differences were correlated with the terrain features. The units marked were modified according to the existing features on the ground. 6.2 Geo-physical survey Geological/geophysical surveys were carried out in the field to understand aquifer geometry and groundwater status. Adequate number of geophysical soundings and pump tests were carried out for the watershed to generate maps for "depth to water table", groundwater contours, fence diagram etc. Available rock types in each watershed including structural and lithological details were studied as well. 7. Socio-economic survey The study also focussed on the analysis of social profile, water quality, water supply, water consumption, awareness and participation in Water Harvesting Schemes. Such study necessitates the collection of the both primary and secondary data. The primary data was generated through questionnaire surveys in all the villages. The questionnaire was structured so as to derive the information related to the objectives set forth. The questionnaire was divided into five modules through which information is extracted pertaining to
Based on the existing percapita and standard percapita consumption (@55 litres per person), water deficit or water surplus analysis was done for the year 2001. Based on the percapita deficit of water, four water supply priority zones are identified as given in the table below. 
8. Water demand Analysis Based on the 1991 - 2001 population growth rate, population for the years 2011 and 2021 was projected and water demand was forecasted for the same period taking per capita consumption at the existing rate for the rural areas. 9. Sample Collection & Analysis 9.1 Water quality analysis Hydro-chemical analysis was undertaken by collecting representative water samples from each village in respective watersheds. A litre of water was collected from each village from available drinking water source with a special preference to groundwater source. The sample was subjected to analysis for standard physical and chemical parameters. The analysis helped in understanding the quality of drinking water in each watershed. 9.2 Soil sample analysis Soil samples collected during the field visit were analysed for the infiltration rate and other chemical parameters. 10. Thematic maps generation Physiography map & Slope maps were generated from the contours and spot heights taken from SOI topographical maps. Geological features like rock types were extracted from the existing GSI maps at 1:63,360 scale. The structures like lineaments were incorporated by extracting from the satellite images and SOI topographical maps. Geomorphologic maps were prepared using SOI toposheets, IRS P6 LISS III satellite imageries (FCC), and available literatures on geomorphology, geology of the area. Soil maps were generated from the existing maps from NBSS. The outputs were at 1:50000 scale. Based on the field observations the pre-field interpreted land use layer was modified and finalised. All drainages details were taken out from toposheets and further modified by satellite data. The units were checked for any errors of labelling. Groundwater prospects map was prepared using IRS LISS III FCC satellite imagery supplemented by ground data. Geomorphic, structural as well as lithological parameters of the watershed were taken into consideration. The groundwater prospects of the delineated geomorphic units were evaluated using available hydrologic characterise and aquifer parameters. Unit wise statistics for Land Use / Land Cover and Geomorphology were generated using Arc/Info platform and were reported. 11. Integrated Analysis and Site identification Suitable Artificial Recharge sites were identified by an integrated analysis of various inputs from slope, geomorphology, soil, land use, geology of the terrain, aquifer characteristics and socio-economic study for water demand. Preference was given to the sites which were proximal to habitations with local precipitation. The various types of structures suggested were Masonry/Boulder check dams and spreading ponds based on the site suitability and recharge potential. 12. Feasibility Study of the Proposed Site Detailed engineering surveys were conducted to verify the proposed sites and type of structures. The gully section of the stream at the proposed site and catchment area for the sties were verified to study the feasibility the proposed site and structure. 13. Cost estimates The cost estimates for various elements designed were prepared for different phases of construction and post-construction periods, which are essential for financial planning required during the construction work. 14. Cost benefit analysis The recharge to ground water or effectiveness of water harvesting structures varies from 35 to 75%. The location of water harvesting structure in suitable sites and proper design plays an important role in effectiveness and efficiency of water harvesting structures. The evaporation losses are generally within 15% of the total storage. Direct benefit due to any water harvesting structure may be attributed to additional recharge to ground water enabling additional area brought under cultivation, enhanced domestic and industrial water supplies.  Fig. 2: Methodology flow chart Conclusion
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 Fig. 3: Satellite data and thematic |