Mapping of Crop Management Factor (C) for Sylhet Sadar using Remote Sensing and GIS

Sylhet Sadar suffers from excessive rainfall causing the enormous soil loss in this area. C-factor is one of the most important parameter of the Universal Soil Loss Equation (USLE) and revised version of USLE for estimating soil loss. The current study was conducted for determining the crop management factor (C) using remote sensing (RS) and geographical information system (GIS) tools. Satellite images (Landsat 7 ETM+ of 2000, 2010 and Landsat 8 OLI-TIRS of 2020) of the study area were analyzed using ArcGIS 10.5 and ENVI 5.1 software to generate maps for land use and land cover (LULC), normalized differential vegetative index (NDVI) and crop management factor (C). Results showed that the percentage of each LULC classes from 2000 to 2020 was changed over time. There was rapid growth in crop land, water bodies and settlement areas between 2000 and 2020 while the same period observed lessening in vegetation coverage. The relationship between C-factor and vegetation indices such as NDVI was identified. As NDVI and C-factor values are correlated, both lowest and highest NDVI (-0.506–0.629) and C-factor value (0.185–0.753) was found at the same year (2000). By the next 20 years in 2020, the highest NDVI value reduced to 0.373 and lowest C-factor value increased to 0.314 indicates that vegetation coverage of the study area is decreasing. To ensure proper soil management it is therefore imperative to encourage forest regeneration activities, tree planting exercises, crop rotation, conservation tillage practices and shrub growth schemes.