Towards Sustainable Water Management: A Holistic Approach for Hydrological Modelling and Flood Frequency Analysis for Upper Sabarmati River Basin

Rainfall affects India's economy and agricultural activities, which largely rely on it. From Rajasthan's arid deserts to the northeast's heavy rainfall, India's rainfall patterns vary. India receives 1170 mm of rainfall annually, distributed unevenly, especially in northern India. Climate change, urbanization, and water demand affect rainfall patterns and river flow of the Upper Sabarmati River Basin due to unevenly distributed rainfall, which supplies 8208 sq. km. of water to the region. Water management requires understanding the basin's hydrological processes and flood characteristics. Using rainfall, streamflow, and land use data, the study creates a basin hydrological model. ArcGIS and Hydrological Engineering Center-Hydrological Model System (HEC-HMS) simulate water movement through the basin and allow for scenario analysis of land use and climate changes. Hydrological modelling shows that changing land use, such as converting forests and farms to cities, can increase peak flow rates and decrease base flow rates. Different climate scenarios show that climate change can increase precipitation and streamflow variability, which can increase basin flood risks. This study also used Log-Pearson Type III distribution to analyse flood frequency in the basin for Jotasan and Kheroj stations. This analysis helps assess flood risk and plan flood management infrastructure and recurrence flood interval. The SCS CN technique demonstrated a strong correspondence between the measured and modelled peak discharge values. The calibrated model had a Nash-Sutcliffe value (NSE), R2, and RMSE standard deviation value of 0.829, 0.937, and 0.4, respectively, while the validated model had values of 0.736, 0.935, and 0.5 respectively. The R2 value for flood frequency analysis was 0.961 and 0.781 Jotasan and Kheroj, respectively. This research work can help create sustainable water management policies that account for the basin's hydrological processes and floods.