Analysis of hydrological changes in the Banas River: Analysing Bisalpur Dam impact and trends of the water scarcity

The construction of large-scale infrastructure projects like dams can substantially alter local hydrological systems,
prompting concerns about their impacts on river water levels and discharge. This study was undertaken in
response to the compelling need to investigate and analyze the potential implications of water scarcity, particularly
within the framework of the Bisalpur Dam located on the Banas River. This study uses non-parametric
trend analysis tests - Mann-Kendall (MK) and Modified Mann-Kendall (MMK) for river discharge and water
level trend analysis, and Sen’s Slope and Pettit’s test for detecting changes or trends. Significant shifts in these
parameters were identified post-construction. From 1960 to 2011, the Dam’s construction led to a marked
decrease in peak discharge (MK/MMK statistics Zc = 􀀀 3.24; Pc = 0.001), with a Sen’s slope of 􀀀 21.51 MCM/
year. Before the Dam’s construction, the peak discharge reached a maximum of 7680 MCM in 1981–82. The
gauge station’s water level significantly decreased (MK/MMK statistics Zc = 􀀀 3.46; Pc = 0.001) at an annual rate
of 􀀀 0.035 m/year. This level, peaking at 201.59 m in 1981–82, declined from an average of 196.04 m–194.5 m
post-construction. The findings underscore the extensive impact of dam construction on local hydrological parameters.
These results hold significant implications for future infrastructure projects, emphasizing the critical
need for comprehensive environmental impact assessments to be conducted before project implementation. This
understanding can aid in designing interventions with reduced environmental impacts, leading to more sustainable
infrastructure development.