Soil Erosion in South and Southeast Asia: A Review.

Soil Erosion in South and Southeast Asia: A Review

Dhanuska Wijesinghe¹ and Dara M. Park^1*

¹Department of Agriculture and Environmental Sciences, Clemson University, Clemson, SC, 29634

*Contact: darap@clemson.edu

Knowledge of soil erosion is a key requirement for land use planning and the assessment of sediment related environmental impacts of agricultural management. South and Southeast Asia covers a large land area with diverse ecoregions, land uses and management practices. Dramatic changes in climate, edaphic and more importantly land use factors during the last decade increase the vulnerability of the soils to erosion in the South and Southeast Asian region. Runoff and soil erosion have been studied extensively in the region throughout the few last decades in natural ecosystems and farmlands. Various land management strategies during the have increased land degradation posing severe limitations on the sustainable use of agricultural lands. The region has a tropical humid climate with tropical rainforest as the major form of natural vegetation. More than 94 % of the area suitable for agriculture in South Asia has already been cultivated, leaving little provision for agricultural expansion. Heavy rainfall combined with agriculture on hillsides often has led to erosion reducing agricultural productivity of upland farming systems; however, deposition of sediments in the lowland has created large areas of alluvial soils adequate for farming. Water erosion which covers 21 % of the total land area (46% of the total degraded area) has become the most severe problem in the region. Loss of top soil was the most common subtype of water erosion in the region followed by terrain deformation (gullying, landslides etc.). This review synthesizes the research activities that were conducted in the field of soil erosion in the South and Southeast Asian region during the last fifteen years. Research activities focused an extensive range of methodologies at different spatial and temporal scales. The effectiveness of improved conservation practices on managing soil erosion and sediment yield at catchment scale are also discussed.

Key Words: Soil erosion, South and Southeast Asia, Runoff