Design Flood Estimation of Swarnamukhi Barrage in Nellore District, Andhra Pradesh, India

This study focuses on the re-estimation of the design flood value for the Swarna Mukhi Barrage-cum-Bridge, located near Vakadu in the SPSR Nellore district (Latitude 14° 0' 25" N, Longitude 80° 4' 11" E). The reassessment aims to enhance structural resilience and inform effective water management and flood preparedness strategies. Design storm analysis was conducted using the Hydrologic Engineering Center’s Statistical Software Package (HEC-SSP). Estimated flood discharge for 100 years return period were compared with the existing design flood capacity to evaluate its adequacy. Design storm value of 100 years T was 35.97cm. Base width of the flood hydrograph was 45 hours. Peak value of flood hydrograph obtained as 100 years T was 7451 cumecs. Based on IS specification (11223-1985), structure qualifies for 100 Year T. The estimated flood value 100 Year T was 7451 m3/sec whereas designed flood value of Swarna Mukhi barrage was 6450 m3/sec with a difference of 1001 m3/sec suggesting the provision of additional spillway for the structure to contain the flood and to ensure safety of the barrage.