Geomorphic character and dynamics of gully morphology, erosion and management in laterite Terrain: few observations from Dwarka – Brahmani Interfluve, Eastern India

Abstract

The most intensified form of soil erosion is the gully which is an extreme figure of land degradation in India, and alongside gully erosion signifies instability in the fragile landscape. The present study encompasses the lateritic interfluve and badlands of Dwarka – Brahmani River Basin (eastern India). The geomorphic research reveals a variable range of annual erosion rates (8.12–24.01 kg m−2 y−1) at watershed scale (i.e., three catchments of permanent gullies) using models and field measured data. It is found that the main cause of gully formation is too much runoff water at a certain location of slope – a threshold condition that may be brought about by external factors (land cover) or internal factors (slope). It is found that in the event-based rainfall range of 42 mm to 137.2 mm the gullies can yield runoff of 40.02 mm to 118.0 mm in excess moisture condition of monsoon. Intense rainfall is the primary trigger, but the local conditions such as slope morphometry, land use, barren soil cover and soil-plant characteristics control the triggering of gully erosion. The potential erosion map of area depicts annual erosion rate beyond the soil tolerance limit (T-value – 1.0 kg m−2 y−1). Finally it is suggested that reduction of runoff discharge, channel grade, vegetative measures and structural control of gully headcut erosion and sedimentation are the key procedures of erosion protection in the laterite terrain.

Keywords

• gully morphometry
• geomorphic threshold
• soil conservation service curve number (scs-cn)
• revised universal soil loss equation (rsule)
• erosion management