Urban Water Projects

In recent years at times severe flooding has taken place in the Greater Colombo basin caused by heavy rainfall and limited storage, conveyance and outfall capacities. The drainage system needs to be improved, extra storages to be created and conveyance and outfall capacities to be enlarged and a World Bank loan of estimated USD 100million is intended to be made available to the Government of Sri Lanka. The proposed interventions are to be re-evaluated and a priority ranking of projects will be required. To arrive at an optimal set of interventions the activities will be carried in three phases: • Phase I: Surveys, Definition and Feasibility; • Phase II: Detailed Designs, Works Packaging and Bidding Documents; • Phase III: Construction of Designed Interventions The Phase I project has been awarded to COWI A/S in association with LHI. The project covers a basin area of 85km2 The main objectives of the study are as follows: • Topographic, bathymetric and hydrographic survey • Land use maps • Digitization of urban drainage system • Review of short interval design rainfall for urban drainage and canal system • Development, calibration, validation and application of urban drainage model • Review of design and cost estimate of proposed micro-drainage projects • Upgrading, calibration, validation and application of hydraulic model • Statistical analysis of boundary conditions • Assessment of effectiveness, preliminary design and cost estimation of interventions • Cost-benefit analysis and environmental assessment • Real-time operational management • TOR for detailed design