Lag Time and Time of Concentration evaluation for flood risk estimation using GIS modelling techniques – A case study of Lidder Watershed, J&K, India

This research focuses on evaluating lag time (TL) and time of concentration (TC) using GIS modeling techniques in the Lidder Watershed, Jammu and Kashmir, India, to improve flood risk estimation. Lag time and time of concentration are critical hydrological parameters that reflect a watershed's response to rainfall events, influencing flood dynamics and watershed management strategies. The study employs the Soil Conservation Service formula and GIS tools to calculate TL and TC based on factors such as hydraulic length, average slope, and curve number. The computed lag time of approximately 457.10 minutes and time of concentration of 761 minutes provide essential insights into watershed hydrology, particularly in data-scarce mountainous regions. Additionally, the weighted curve number (CNaw) of 73.63 signifies the surface runoff potential within the basin, aiding flood risk assessment. These findings highlight the significance of integrating spatial data and advanced modeling techniques for accurate hydrological assessments, essential for flood forecasting, infrastructure design, and land use planning. The study underscores the vulnerability of the Lidder Watershed to flash floods due to its circular shape coefficient, varying elevations, and significant slopes. Proposed measures for improving flood risk assessment and watershed management include implementing flood early warning systems, optimizing land use planning, designing resilient infrastructure, raising community awareness, and fostering integrated watershed management practices. By adopting these strategies and continuing research efforts, the Lidder River basin and similar regions can enhance flood resilience, protect lives and property, and promote sustainable development amidst climate change and urbanization challenges.