Temporal variations in runoff and soil loss in relation to soil conservation practices in catchments in Shiwaliks of lower Himalayas

The soil conservation strategies adopted in the catchments of Shiwaliks, the most fragile region in the Himalayan ecosystem, failed to serve their purpose after a few years of their execution. A study was carried out in four differentially-treated catchments to monitor the variation in runoff and soil loss. The treatments imposed during 1988 included fencing,planting native vegetation and engineering structures in catchment I ; planting native vegetation and fencing in catchment II ; fencing alone in catchment III in addition to an untreated catchment IV. The soil loss during the initial years (1989 – 1995) of imposition of the treatments was lowest (25. 2 t ha- 1) in catchment I, treated to the maximum extent and highest (43. 3 t ha - 1) in untreated catchment IV. During the later period (1996 – 2006) the trends reversed, i. e., catchment IV recorded the lowest (14. 1 t ha- 1) soil loss whereas catchment I recorded the highest (23. 4 t ha- 1) soil loss despite the fact that there was no change in the status of soil conservation or the characteristics of the catchments. The runoff was 71 % higher in untreated catchment than in treated catchments initially and this difference decreased to 27% during the later period.