Stormwater drainage in expressway design analysis of Colombo Katunayake expressway at Kalu Oya

Abstract

Flooding hasI been identified as the most costly and damaging natural hazards when lth magnitude and frequency is considered, assessment of stormwater drainage systems is very important to manage flooding. Most of the new infrastructure development projects such as (Instruction of expressways obstruct natural drainage paths. Therefore, when designing such projects, lie attention should be paid to identify potential impacts. Field assessment, hydrologic analysis, and hydrodynamic modelling play key roles in identifying the flow dynamics in case of engineering infrastructure developments such as roads, bridges or causeways. The present work describes the hiydrologic and hydrodynamic modelling case study of Colombo Katunayake Expressway (CKE) at Ill' intersection of Kalu Oya. A systematic field assessment, hydrologic analysis and a hydrodynamic modelling exercise was carried out. Data were collected through field work, agency visits, and illlitarature surveys. Hydrologic analysis was carried out to estimate the design discharge for different 'durn periods for both existing and future conditions incorporating rapid variation in land use mttern due to development activities. A hydrodynamic model was developed, calibrated, and irified. Design alternatives were considered through various possible scenarios modeled with a satisfactory hydrodynamic modelling having model calibration and verification errors of 55 % and 46 % respectively.