Estimation of Runoff from Small Agricultural Watersheds Using Remote Sensing and GIS

摘要

Water is the most critical resource and constraint in the semi-arid tropics (SAT). To minimize the land degradation and sustain crop productivity in the SAT, management and efficient utilization of rain water is important. Watershed based resource utilization involves the optimum use of area's precipitation for the improvement and stabilization of agriculture on the watershed through better water, soil, and crop management. More effective utilization of water for the production of crops can be facilitated by (ⅰ) in situ conversation of moisture, of rainwater. (ⅱ) proper drainage, collection, storage, and reutilization of runoff. (ⅲ) ground water recovery from wells. Water can be managed if watershed is taken as a unit. Runoff and consequent soil erosion are inevitable under a tropical monsoon. These need quantification for the design and adaptation of control measures, these can be done by monitoring the soil and runoff losses on watershed basis. Runoff is the important hydrological factor in the watershed management. Any rainfall based planning and design activity require quantification of water yield in the form of runoff resulting from the interaction between rainfall and the land features. By making models, we can see what would occur in a system if we changed certain characteristics of it, without actually making the changes. The type of the soil present in Lalatora (Milli) and Guna watersheds Vertisols and Bundi watershed Consists of silt clay/sandy clay. With the help of SCS model, in conjunction with Remote Sensing and GIS it is possible to make management plans for usage and development of a watershed. The present study aimed at "Estimation of Runoff using Remote Sensing and GIS". The study falls in the Semi-Arid Tropics and comparatively away from the urban civilization of Madhya Pradesh and Rajasthan states. Spatial and non spatial data was generated availing SOI (Survey Of India) Top sheets and satellite imagery as well. Thematic layers like base map, drainage map, slope map, land use/land cover were generated with the help of visual image interpretation elements. Runoff of the area is computed through Soil Conversation Service Curve Number technique .The runoff values were computed considering four precipitation events occurred during August 2004 duely giving to consideration to the wetting process time. The estimation reveals that during the third event high runoff is recorded in -spite of low rainfall compared to the consecutive events. The reason may be ample wetting process during antecedent high rainfall event. The estimated values are comparatively low with that of ICRISAT computed values following different technique. It is observed that the computations of ICRISAT have not considered the natural drainage divine. The procedure followed for runoff computations following the natural drainage divine can be applied else where under similar environs.