Estimation of sediments produced in a subbasin using the Normalized Difference Vegetation Index

Estimativa dos sedimentos produzidos em uma sub-bacia usando o índice de vegetação por diferença normalizada

ABSTRACT

Among the parameters considered by the Revised Universal Soil Loss Equation (RUSLE), the soil cover and management factor (C) is the main human influenced factor affecting the estimation of water erosion, and one of the most sensitive to spatiotemporal variations. Consequently, this study aims to compare the efficiency of C factor estimates obtained from the literature for each land-use class (C_lit) and by calculation based on the Normalized Difference Vegetation Index (C_NDVI). We test the hypothesis that soil loss estimates based on C_NDVI approach are more accurate than those based on C_lit. Water erosion was estimated based on soil morphological, physical, and chemical properties in addition to climate, relief, management practices, and land use and cover. The modeling steps were realized with the help of the Geographic Information System. The results were validated using the data of total sediment transported with water discharge and daily runoff. RUSLE underestimated soil losses by 0.64 Mg ha^-1 year^-1 using C_lit and 0.45 Mg ha^-1 year^-1 with C_NDVI, which corresponds to errors of 21.05% and 14.80%, respectively. Therefore, the C_NDVI factor results are more accurate. Both methodologies identified areas with high erosion rates where the adoption of mitigation measures should be prioritized.

Index terms:
Soil conservation; water erosion; modeling; RUSLE