A novel approach to analyze the impact of groundwater drought on the perennial environment and hyporheic zone of surface water bodies

Abstract

Surface water bodies provide essential sources of fresh water for drinking, agriculture and industrial purposes. The hyporheic zone beneath and around surface water bodies plays a crucial role in maintaining the health and functionality of aquatic ecosystems. In recent times, surface water bodies have been observed to dry up rapidly in many parts of the globe due to groundwater drought. Hence, examining the sustenance of the surface water bodies over time is essential, which includes examining whether they are in a gaining or losing state and acting as perennial or non-perennial. In this context, this research aimed to analyze the behavioural changes in surface water bodies due to groundwater drought and stream-aquifer interaction in the Godavari Basin, India. This study proposes a new index called the Potential Stream-Aquifer Interaction Index (PSAII) or the Potential River Perenniality Index (PRPI) to define the nature of surface water bodies. This study employs satellite-derived bathymetry to determine water depth in ungauged lakes and Standardized Ground Water Table Index (SGWTI) to ascertain the magnitude of groundwater drought. The influence of groundwater drought on surface water bodies is determined based on the correlation of the head difference between groundwater table (GWT) and water surface elevation, as well as the SGWTI. The analysis reveals that PRPI for the upper Godavari River ranges from 0 to −0.4, and the lower Godavari River lies between 2.03 and 2.04 from 2009 to 2018, validated by the flow duration curves. The correlation between head difference and SGWTI lies between 0.8 and 0.9 for the upper Godavari and 0.08 to 0.48 for the lower Godavari River. The results imply that the upper Godavari river basin has become non-perennial due to groundwater drought. Based on the correlation analysis, it is also found that several ungauged lakes in the vicinity of the upper Godavari River are highly influenced by groundwater drought.