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Water resourse planning of patan branch canal command area through RS & GIS
Methodology: Necessary Data and Equipment Used: Following data was procured and used to get the different thematic maps of Bargi command area. Topographical and Satellite Data: To collect the information regarding topographical details and other land characteristic, toposheet at the scale of 1:50000, which were prepared by Survey of India (SOI), in 1976, were consulted. Satellite data for Rabi and Kharif seasons of the year 2000 were obtained from National Data Centre, National Remote Sensing Agency, Hyderabad.  Fig 1 Index map of the Study area Remote Sensing Data Used:
Hardware and Software: The hardware used are namely Personal computer, H.P. scanner, Color scanner, Plotter (HP 5400 C), DeskJet printer (HP 840 C), CD Writer and ILWIS 2.2 (Integrated Land and Water Information system version 2.0), Microsoft Office, Microsoft Word 6.0, Microsoft Excel, Adobe Photoshop software¢s which were used for the preparation of thematic maps of the command area. Generation of Thematic map: Initially base maps were prepared from SOI toposheets at 1:50000 scales. Command area boundaries, slope map, settlements/transport network, soil map, hydrogeomorphological map, drainage network, land use/land cover, ground water potential, canal water availability are the theme maps prepared for study. Features on a paper map or other analog documents were scanned. They were imported and, georeferenced then digitized by ‘on screen digitization’ in ILWIS. Command area boundaries, Contour, Soil, Drainage, hydrogeomorphological, canal water availability and ground water potential maps were prepared by digitization. Digital elevation model (DEM) was generated through contour interpolation. The output of the contour interpolation was a raster map, using shortest distance towards the two nearest isoclines. The DEM was converted into slope percentage map. The digitized thematic maps are the vector map, which were also converted in the raster form for further interpretation. The land use / land cover map of the command area was prepared through the data obtained from NDC, NRSA, Hyderabad. IRS – IC LISS III data of 18th Jan. 2000 was used for this purpose. The false colour composite (FCC) of 4 band data in the ratio of 3,2,1 i.e. red, green & blue colour assigned to infrared band, red visible band and green visible band prepared from the satellite imagery. To differentiate different land covers, Normalized Difference Vegetation Index (NDVI) was calculated. In NDVI map Values are ranging from – 0.5 to + 1.0. They are classified by slicing operation for three basic land uses, as per the requirement of study, namely water bodies, wasteland & cultivated area. Integration of Maps through GIS: Intersections of various thematic maps were performed by overlaying one theme map over the other, through cross operation of raster maps in ILWIS software. The cross operation performs an overlay of two raster maps by comparing pixels at the same position in both maps and keeping track of all the combinations that occurred between the values or classes in both maps. The georeference of input raster maps was kept the same. During the cross operation, combinations of class names, identifiers or values of pixels in both maps were listed and the number of pixels occurring in this combination was computed through histogram. The results were stored in an output cross map and in a cross table. The output cross table obtains an identifier domain, with the same name as the output map. This domain contains items, which were combinations of the class names, IDs, groups, name or values of the first input map. Water Resource Action Plan: Preparation of water resource planning involves study of different thematic maps and quick visit to the study area for verification. A number of spot observations were made by covering almost all types of landforms, soil, slope, ground water potential and quality, rainfall and climate, present land use etc. The land characteristics as mapped in the respective theme maps were recorded along with the present land use. The existing irrigation practices and cropping pattern were also noted. Few possible options were discussed with an aim to achieve, optimally within the overall framework of sustainability of production. Unless and otherwise the present land use was found beyond the threshold limit of some land parameters, a drastically different option was not recommended since such a change would not meet the high level of acceptability. The threshold limit of a parameter vis-à-vis its consideration for a particular recommended land use practice varies from area to area. While making alternate recommendations for land use practice, futuristic consideration such as exploitation of ground water, if presently not exploited, possibility of adopting more efficient system of irrigation and water management and other site improvements through soil and water conservation were also kept in view. Availability of improved varieties of crops, trees, shrubs and grasses and advantages of interdependency of agriculture, livestock, and other practices as in case of integrated farming system that had been made available through contemporary research were also taken into consideration. Current trends on land use management and sustainable farming systems were adopted from Guidelines of IMSD (IMSD, 1996). Thus, with these considerations, finally land use practice is recommended for the site as per its recorded parameters. For a particular recommendation or combinations of recommended land use practices various types of combinations of land parameters were developed which serve as the decision rules for integration of thematic maps and preparation of action plan. On preparation of the decision rules, the same was discussed with experts / specialists in land management and farming system research. Views of the selected farmers and local line departmental officials of the study area were suitably considered to finalize the decision rules. The decision rules for water resource planning were finalized and presented in Table 1. |