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Rain Water Harvesting & Water Resource Planning in and Around Pilani using GIS

Rajiv Gupta
Educational Hardware Division
Birla Institute of Technology and Science,
Pilani India
Email: [email protected]

S R Nandha Kumar , S Sudharson

Surface water is inadequate to meet our demands and we have to depend on ground water and rain water. Due to rapid urbanization, infiltration of rain water into the sub-soil has decreased. Due to exponential population growth and industrialization the rate of drawing water from the water table is completely in excess to the rate at which the water table gets recharged by natural means. As a result of this the water table is decreasing drastically. Rain Water Harvesting, is merely “putting back rain water into the soil, where it will be stored in underground reservoirs and rivers, so that we can draw it whenever we need it”. This is a real time project which aims at developing a rain water harvesting system which should be sustainable, replicable, scalable and economically viable. In the year 2002 Rajasthan faced a severe drought, so Rajasthani Association of North America (RANA) decided to fund a project to develop a rain water harvesting scheme. A scalable four phase scheme has been proposed by BITS and case study was done for the village Raila which is around 5 Km from BITS campus. Manual surveying was done and the map of the village was created using AUTOCAD. After creation of the map GIS (Geographical Information System) software’s ARC GIS 8.3 and ARC VIEW 3.1 were used for the analysis. GIS can handle complex network problems, such as stream network analysis. There are, of course, other types of network analysis, involving road networks. GIS could be used to model the flow of water through a river system, to plan a flood warning system.

Some applications of GIS are obvious, for example water supply companies use GIS as a spatial database of pipes and manholes; local governments can use GIS to manage and update property boundaries, emergency operations and environmental resources. Buffers are zones of specified distance around features. Buffers are used for proximity analysis. Finding what features are within a set distance identifies an area and the features inside that area that are affected by an event or activity. For example, a forester would monitor logging to make sure it doesn’t occur within a 100-meter buffer along streams. Distance is one way of defining and measuring how close something is. You can also measure what’s nearby using cost. Time is one of the most common costs—it takes longer, for example, for customers to get to a store through heavy traffic. Arc Map lets you buffer features in a layer or graphics you draw on top of your map. You can buffer features at a specific distance or use an attribute value to create variable width buffers. Use multiple ring buffers to show features within distinct bands of distance—for example, 50, 100, and 150 meters.

Till now the application of GIS is limited to such networks. The present paper aims to extend the use of GIS to model pipe networks integrated with drawing tools such as AUTOCAD. The AUTOCAD image of the village was georeferenced to match with the real world coordinates and necessarily digitized. Potential locations for construction of tanks were identified. The catchment area was decided according to the place available and buffers were created accordingly. Lengths of the pipes required were calculated from the results obtained from Shortest Path Analysis (SPA) and cost was worked out. The use of GIS technologies helps to do the work easily. Future aspects could be use of GPS data to find out topography and hence flow direction and enhance the model.