The effect of changing climate and land use/land cover on water resources in hard rock region of maharashtra state

Abstract

The climate, land use and land cover show the changing behaviour over a period of time. These factors influence the water resources. However, it is necessary to know their impact on the quantification of surface water and groundwater resources to enable to plan and manage these resources appropriately. Therefore, it is necessary to build the water resource models for the catchment area. Water resource modelling of an entire catchment is a complex phenomenon but of a great importance for obtaining a better quantitative understanding of water uses and arriving at important water management decisions. Therefore, the use of water resource models such as MIKE SHE in conjunction with remote sensing and GIS techniques is helpful in planning and management of land and water resources and managing water resources. In this study, it is proposed to use the surface water-groundwater resource model MIKE SHE for the estimation of groundwater resources, and the methodology was developed for this purpose. The MIKE SHE model was calibrated for a small catchment using remote sensing data and GIS. Mapping of the study area was carried out with the help of Geocoded (1:50000) IRS-1C/1D LISS-III and PAN images. The input data that was used for preprocessing and set-up preparation of the MIKE SHE model were catchment boundary map, topography, land use/land cover map, soil distribution map, climatological data and crop characteristic (LAI, root depth) and hydraulic properties of soils in the catchment. Roughness coefficient of overland and channel flow, initial water depth, maximum profile water balance error and storing time steps were considered as calibration parameters. The roughness coefficient was varied in the range of 5 to 15, initial water depth in 0 to 0.1mm, maximum profile water balance error in 0.0001 to 0.02 and storing time steps in 120 to 720h, respectively. The groundwater fluctuations were simulated for 31 well locations for each combination of calibration parameters. The RMSE between the simulated and actual groundwater fluctuations was calculated, and the set of calibration parameters that yielded the lowest values of RMSE (3.83) was selected for the calibrated MIKE SHE model. These were 10, 0.01mm, 0.0001 and 360h for roughness coefficient, initial water depth, maximum profile water balance error and storing time steps, respectively. Dhor-nani catchment which is a small part of the upper Godavari river basin in Ahmednagar district of Maharashtra state (upstream of Jaikwadi dam) was used to evaluate the effect of changes in land use/land cover and climate on surface water and groundwater resources. Two model set-ups of calibrated MIKE SHE were prepared for the years 1998 and 2005, respectively. The remote sensing images of IRS 1-D (Wifs) for the year 1998 (January) and IRS 1-D (A-Wifs) for the year 2005 (November), climate and other data on various aspects of the catchment – namely, topography, soil distribution and cropping pattern of the respective years, i.e. 1998 and 2005 – were used. The results of Dhor-nani catchment for the years 1998 and 2005 for influence of change in land use/land cover and climate on water resources indicate that groundwater levels and overland water depths were influenced by change in land use/land cover and climate. The groundwater levels were shallower in the year 1998 compared to 2005, and the depth of overland water increased in 2005 as compared in the year 1998. This may be due to increased values of rainfall (climate) and the changes in land use/land cover between 2years.