Modeling and assessing land-use and hydrological regimes to future land-use scenario for sustainable watershed management in a semi-arid region of southern India

Abstract

The present study investigates impact of land use land cover (LULC) change and water harvesting interventions in Kanva watershed, a rural catchment in Kaveri basin, located in semi arid region of southern India. Remote sensing data and Soil and Water assessment Tool hydrological model was used to assess changes in total water yield, groundwater recharge, percolation and evapotranspiration. Post classification change detection technique was used for LULC change analysis in 1992, 2001, 2008 and 2014. Modelling was also performed to assess potential impact of LULC using predicted land use scenario of 2022. A comparison between 1995–2003 (pre-watershed management) and 2004–2016 (post-watershed management) simulations indicated an increase of 1.01%, 4.65% and 1.74% in average runoff coefficient, groundwater recharge coefficient and percolation coefficient respectively, and decrease in evaporation coefficient by 0.51%. The results showed that LULC changes and water harvesting accounted for a difference in hydrological components between these two periods. Scenario analyses were performed for different adoption rates of rain water harvesting (RWH) interventions in sub-watersheds of Kanva watershed and its impact on hydrological parameters, especially on total water yield was identified. The analysis indicated that average runoff coefficient was 9.16% during pre-watershed period and 9.25% during post-watershed period. Further up-scaling of RWH would reduce the flow and runoff coefficient may decrease to 6.07% if RWH is adopted in whole of Kanva watershed. The results suggested that if extensive RWH is carried out in the Kanva watershed, it would result in unsustainable water management due to reduced flow downstream. The study found that the sustainability of watersheds in arid and semi-arid regions is very important given the uncertainties in future hydrologic regimes due to changes in land cover and changes in extreme rainfall patterns thus requiring suitable management interventions.