Remote Sensing based rapid watershed health appraisal - a case study for Rajasthan
D. Dutta, S. Narasimhan and J. R. Sharma RRSSC/DOS (ISRO), CAZRI Campus Jodhpur - 342 003 Eight watersheds, distributed uniformly throughout the agroclimatic zones of Rajasthan were studied for their performance in terms of biomass gain, landuse change and drainage line stabilization. The study of satellite data prior to treatment (1988) were compared with post treated watersheds after 8 years i.e. in 1996 to reveal the noticeable changes over the years. Surface manifestation of various treatments given, were recorded in terms of increase in number and extent of water bodies, forest/horticultural plantation, agroforestry and cropping intensity. For comparing the performance of the watersheds located at different agroclimatic set up a comprehensive rating procedure was adopted for quantification of the changes, which considers all the visible impacts derived from the data. The ratio of performance of watershed in the year 1996 over base year i.e. 1988 gives the performance index, which was named as watershed health index (WHI). Positive biomass change was found in only 3 watersheds, whereas five of the watersheds revealed negative biomass change. However in terms of landuse change only one watershed had negative change, 4 had slow but steady change and 3 were almost unchanged. Overall ranking of in terms of biomass, landuse and drainage line performance envisages that Ambali performed the best even if it is in semi arid to arid environment but Bawliya pada showed least performance. As the parameters required for descriptive health analysis is difficult to get, laborious and time consuming, this method of appraisal was found quite suitable especially when comparing a large number of treated watersheds. If the ground based information like sediment yield, crop productivity, changes in intensity and cropping pattern is integrated with socio-economic information like employment generation, number of working days for daily wage labourers, labour migration etc. along with the satellite derived health index, it will augment to provide a detailed insight into the impact of watershed treatment for decision alternatives and cost benefit analysis. | ||
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