Variability in trends of streamflow and precipitation in the Narmada River Basin over the past four decades

Abstract

Hydrological climate variables such as precipitation, temperature, humidity, evapotranspiration, infiltration, and streamflow provide useful information for the effective planning, design, and management of water resources. In the present study, monthly precipitation and streamflow data were analyzed to assess the variability in trends of precipitation over the Upper Narmada Basin (UNB), Middle Narmada Basin (MNB), and Lower Narmada Basin (LNB) for 41 years (1981–2021) using the widely accepted Mann–Kendall Test (MKT), Innovative Trend Analysis (ITA), and magnitude by Sen's Slope estimator, thereby extending further by a decade, the last study by Thomas et al. (2015). The inclusion of more factors affecting the streamflow in response to the rainfall often makes the model very complex and unreliable. In the present study, to overcome this limitation, a simple yet most definite correlation was established between rainfall and streamflow, which can serve as a meaningful indicator of basin behavior. Poor correlation was observed for the UNB and the MNB compared to the LNB, which may be attributed to the presence of tributaries. The result of this study will be helpful to policymakers and water resource managers to plan and adopt suitable schemes of water conservation and management in the Narmada basin.