Estimating Runoff for Bamnidhi Watershed Using SCS Curve Number Approach and Geospatial Technique

Water is one of the most valuable natural resources and a vital component of the socioeconomic development of a nation. Water resources in India and throughout the world are under a lot of stress as a result of the limited supply and rising demand. Water availability of a region can be better estimated using rainfall runoff relationship. Runoff is mostly produced as a result of rainfall, which is a significant part of the hydrologic cycle. In this study, the rainfall-runoff relation of the Bamnidhi watershed in Chhattisgarh (India) is studied using SCS CN method. Various inputs such as HSG map and land use land cover were overlaid in ArcGIS platform for estimation of weighted curve number, based on which the runoff is estimated. The results of the study indicate that CN values range from 30 to 97. The lowest runoff potential is observed for forest regions having CN value of around 30, while highest runoff potential is observed for water bodies. The total runoff is found to be around 3.6 Million m3 for the period 2011 to 2020, which is about 10 to 25 percent of the total rainfall

Isolating the effects of land use land cover change and inter-decadal climate variations on the water and energy cycles over India, 1981–2010

Aim of this work is the assessment of the individual and combined impacts of land use land cover change (LULCC) and inter-decadal climate variations (CV) on the water and energy cycles over India, given extensive land use land cover change over the last decades. In this study, we quantify the contributions of LULC and CV on changes in the water and energy cycles over the Indian subcontinent through a scenario-based approach, with Community Land Model version 4.5 (CLM4.5) model runs from 1981 to 2010. The approach involves four simulation scenarios: (i) the first scenario considers no LULCC or CV (LULC is fixed and the atmospheric forcings for 1981–1990 are repeated in the decades afterwards); (ii) the second scenario considers only the impact of CV; (iii) the third scenario considers only the effect of LULCC by updating the LULC every 10 years; and (iv) the fourth scenario considers the combined impact of LULCC and CV. LULCC causes an overall decrease in the evapotranspiration (ET) and soil moisture (SM) by 0.3 % and 0.1 % respectively (comparing 1991–2010 with 1981–1990), while the net radiation changes < 1 %. On the other hand, CV caused an increase in the ET, SM and net radiation by + 5.4 %, +1.5 % and + 1.0 % respectively, in spite of decrease of precipitation of 6.6 %. The combined effect of LULCC and CV leads to an increase in the overall ET by 3.8 %. Among the LULC transitions, deforestation and urbanization are found to be the major causes for hydrological changes over the decades, but their impact is much smaller, since CV has a greater impact on the hydrological cycles over India than LULC. The in-depth understanding of the distinct contributions of LULCC and CV on the water and energy cycles in tropical and subtropical regions can be used for framing future water resources planning and management policies