The study carries out sediment yield estimation for the Shakkar catchment of the Narmada river in Madhya Pradesh and successfully implements a methodology for prioritization using Geographical Information Systems (GIS) and image processing on ERDAS and ILWIS software.
The catchment of Shakkar river is mainly a forest covered mountainous area and lies in humid climatic region. The land use and land cover map of the catchment is prepared using IRS LISS I digital data. The data is digitally processed by sequential clustering technique in PC ERDAS and themes identified through colour in GIS. Eighty-nine sub-watersheds are delineated from the report on watershed prioritization.
Erosion Intensity Mapping Unit (EIMU) is extracted using GIS operations on collateral data and maps produced from remote sensing data as well as GIS. Various operations of map overlay, classification, and reclassification are used and it is found that there are differences in EIMU extent. The GIS operation was useful in extracting eroded stream bank area in the northern plain region.
There are 3, 50, 36 sub-watersheds classified in very low, low and medium priority classes respectively. The values of sediment yield indices for these classes are 900-1000, 1000-1100 and 1100-1200 respectively.
Medium priority watersheds are located in alluvium, shale/ sandstone and basalt geology areas. In alluvium and shale/ sandstone areas of the northern plain, river bank erosion is the main grounds for medium priority class. Medium priority areas are also located in hilly and upland areas due to higher slopes and open land class. In areas of low priority efforts should be made to reduce soil loss from barren land, cultivated land and river banks.
The study estimates the sediment load from the Shakkar catchment at Gadarwara as 2121964 tonnes per year. The sediment yield from the catchment is 949 tonnes per year per sqkm.
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