Revised Universal Soil Loss Equation(RUSLE) model coupled with transport limited sediment delivery(TLSD) function was used to predict the longtime average annual soil loss, and to identify the critical erosion-/deposi...Revised Universal Soil Loss Equation(RUSLE) model coupled with transport limited sediment delivery(TLSD) function was used to predict the longtime average annual soil loss, and to identify the critical erosion-/deposition-prone areas in a tropical mountain river basin, viz., Muthirapuzha River Basin(MRB; area=271.75 km^2), in the southern Western Ghats, India. Mean gross soil erosion in MRB is 14.36 t ha^(-1) yr^(-1), whereas mean net soil erosion(i.e., gross erosion-deposition) is only 3.60 t ha^(-1) yr^(-1)(i.e., roughly 25% of the gross erosion). Majority of the basin area(~86%) experiences only slight erosion(<5 t ha^(-1) yr^(-1)), and nearly 3% of the area functions as depositional environment for the eroded sediments(e.g., the terraces of stream reaches, the gentle plains as well as the foot slopes of the plateau scarps and the terrain with concordant summits). Although mean gross soil erosion rates in the natural vegetation belts are relatively higher, compared to agriculture, settlement/built-up areas and tea plantation, the sediment transport efficiency in agricultural areas and tea plantation is significantly high,reflecting the role of human activities on accelerated soil erosion. In MRB, on a mean basis, 0.42 t of soil organic carbon(SOC) content is being eroded per hectare annually, and SOC loss from the 4th order subbasins shows considerable differences, mainly due to the spatial variability in the gross soil erosion rates among the sub-basins. The quantitative results, on soil erosion and deposition, modelled using RUSLE and TLSD, are expected to be beneficial while formulating comprehensive land management strategies for reducing the extent of soil degradation in tropical mountain river basins.展开更多
The Muthirapuzha watershed(MW)is one among the major tributaries of Periyarthe longest west flowing river in Kerala,India.A morphometric analysis was carried out to determine the spatial variations in the drainage ch...The Muthirapuzha watershed(MW)is one among the major tributaries of Periyarthe longest west flowing river in Kerala,India.A morphometric analysis was carried out to determine the spatial variations in the drainage characteristics of MW and its 14 fourth order sub-watersheds(SW1SW14)using Survey of India topographic maps and Landsat ETMimagery.The study revealed that the watershed includes a sixth order stream and lower order streams dominate the basin.Results did indicate that rainfall has a significant role in the drainage development whereas structure and relief of rocks dictate the drainage pattern.The asymmetry in the drainage distribution is correlated with the tectonic history of the Munnar plateau in the late Paleocene age.The watershed is moderate to well-drained and exhibited a geomorphic maturity in its physiographic development.The shape parameters revealed the elongated nature of MW and drainage network development in the watershed.Further,the analysis provided significant insight into the terrain characteristics.This study strongly brings to light,(a)the tendency of the watershed to soil loss and(b)the hydrological makeup of the subwatersheds,which combined helped to formulate a comprehensive watershed management plan.展开更多
基金Financial support from Kerala State Council for Science, Technology, and Environment (004/FSHP/05KSCSTE)
文摘Revised Universal Soil Loss Equation(RUSLE) model coupled with transport limited sediment delivery(TLSD) function was used to predict the longtime average annual soil loss, and to identify the critical erosion-/deposition-prone areas in a tropical mountain river basin, viz., Muthirapuzha River Basin(MRB; area=271.75 km^2), in the southern Western Ghats, India. Mean gross soil erosion in MRB is 14.36 t ha^(-1) yr^(-1), whereas mean net soil erosion(i.e., gross erosion-deposition) is only 3.60 t ha^(-1) yr^(-1)(i.e., roughly 25% of the gross erosion). Majority of the basin area(~86%) experiences only slight erosion(<5 t ha^(-1) yr^(-1)), and nearly 3% of the area functions as depositional environment for the eroded sediments(e.g., the terraces of stream reaches, the gentle plains as well as the foot slopes of the plateau scarps and the terrain with concordant summits). Although mean gross soil erosion rates in the natural vegetation belts are relatively higher, compared to agriculture, settlement/built-up areas and tea plantation, the sediment transport efficiency in agricultural areas and tea plantation is significantly high,reflecting the role of human activities on accelerated soil erosion. In MRB, on a mean basis, 0.42 t of soil organic carbon(SOC) content is being eroded per hectare annually, and SOC loss from the 4th order subbasins shows considerable differences, mainly due to the spatial variability in the gross soil erosion rates among the sub-basins. The quantitative results, on soil erosion and deposition, modelled using RUSLE and TLSD, are expected to be beneficial while formulating comprehensive land management strategies for reducing the extent of soil degradation in tropical mountain river basins.
文摘The Muthirapuzha watershed(MW)is one among the major tributaries of Periyarthe longest west flowing river in Kerala,India.A morphometric analysis was carried out to determine the spatial variations in the drainage characteristics of MW and its 14 fourth order sub-watersheds(SW1SW14)using Survey of India topographic maps and Landsat ETMimagery.The study revealed that the watershed includes a sixth order stream and lower order streams dominate the basin.Results did indicate that rainfall has a significant role in the drainage development whereas structure and relief of rocks dictate the drainage pattern.The asymmetry in the drainage distribution is correlated with the tectonic history of the Munnar plateau in the late Paleocene age.The watershed is moderate to well-drained and exhibited a geomorphic maturity in its physiographic development.The shape parameters revealed the elongated nature of MW and drainage network development in the watershed.Further,the analysis provided significant insight into the terrain characteristics.This study strongly brings to light,(a)the tendency of the watershed to soil loss and(b)the hydrological makeup of the subwatersheds,which combined helped to formulate a comprehensive watershed management plan.
