Water, sediment and nutrient movement in forested and non-forested catchments in Kumaun Himalaya

Abstract

Overland flow, and soil and nutrient loss were assessed for four sites under original forest cover, and for four sites affected by soil deposition, landslide or cultivation in the Kumaun Himalaya during the 1981 and 1982 monsoon seasons. Overland flow was positively related with rainfall quantity and intensity and was reduced by the growth of ground vegetation during the later months of the monsoon season. Average overland flow was only 0.50% of the total incident rainfall indicating that these catchments are subsurface flow systems. Soil loss was positively related with overland flow, both being greater for non-forested compared to forested sites. Rainfall added a significant amount of nutrients. This extra system input was greater than loss through overland flow and runoff soil. The forested sites lost less nutrients compared to non-forested sites. The loss of nutrients was in the order: Ca > K > P > N. The forests of the catchments in Himalaya should be protected to avoid the impairment of hydrologic processes.