In this paper, a comparison of two methods for the calculation of the height of atmospheric boundary layer (ABL), using balloon-borne GPS radiosonde data is presented. ABL has been characterized using vertical profiles of meteorological parameter. The gradient of virtual potential temperature (𝜃_v) profile for the determination of mixed layer heights (MLH) and the mean value of turbulent flow depth (TFD) obtained from the vertical profile of Bulk Richardson Number ($R_{iB}$) have been used in this study. Oneyear data have been used for the study. There is large seasonal variability in MLH with a peak in the summer and winter whereas the TFD remained steady throughout the year. Results from the present study indicate that the magnitudes of TFD are often larger than the MLH.

This study focuses on examination of variability in the depth to water below ground level (bgl) from 1996 to 2016 in Ahmednagar district of Maharashtra, India in changing climate. Spatial variability of groundwater depth was mapped and classified as shallow, normal, deep and moderate using GIS modeling. Groundwater decline rates during successive decades were examined and critical areas with a significant fall in groundwater levels (GWL) were detected. Present study also focuses on examination of block-wise variability of GWL. Ground water level shows significant variability during 1996–2016 at confidence level 95%. The long term ground water level fluctuation indicates that water levels in major parts of the study area have declined drastically. The depth to ground water in major parts of the study area ranges between 6 and 15 m bgl except in Parner and Shrirampur blocks. Furthermore, depth to water level is >15 mbgl over Sangamner block during the drought year 2004. Present study reports a significant decadal increase of about 0.7 m in water leval decline over the study area. Groundwater depletion over the study area has been observed with decrease in groundwater recharge and increase in temperature and urbanization. Groundwater depletion shows coherent variability with temperature. Our results report a significant decrease of about 0.61 cm/year in ground water recharge as a result of decrease in precipitation and a decadal increase of about 0.1$^{\circ}$ C in temperature over the study area. Evapotranspiration (ET) shows yearly increasing trend of about 9.6 mm over the study area. Results reported in this study highlight the importance of sustainable groundwater resource management over the study area.