Water Resources Projects

Following severe disruption to civil life and infrastructure after the 2016 May floods in the Kelani River Basin, the Government of Sri Lanka (GOSL) decided to implement Flood Risk Mitigation Interventions in the Kelani basin as a priority. Climate Resilience Improvement Project (CRIP) supported this objective of the Government by undertaking to fund prefeasibility/feasibility studies of the proposed development interventions to mitigate flood risk in the Kelani Basin. These primary interventions include; I. Construction of earthen embankments, concrete floodwalls, riverbank erosion control structures and river training works along both banks to a distance of 35km between Hanwella and the sea outfall. II. Construction of gate structures and pumping facilities at the confluence of tributaries of the main river along this river reach. III. Construction of embankments upstream of Hanwella, a distance of 12km from Hanwella to prevent inundation of land due to interventions along the river reach from Hanwella to the sea outfall. IV. Construction of two multi-purpose reservoirs in the upper basin of Kelani River. The recent numerical modelling studies undertaken by CRIP for investigating feasible solutions for flood and drought mitigation in Kelani River Basin including constructing river embankments (flood protection dikes) have found that the existing salinity barrier / weir will cause a measurable increase in the water levels up to several kilometres upstream (up to Kaduwela) during extreme river flow regimes. This resulted in the GOSL deciding to replace the existing structure with a permanent gated salinity barrier for salinity exclusion without affecting the channel flood conveyance capacity and flood level. As a result, the project of “Preparation of Detailed Design for Proposed Salinity Barrier at Ambathale in Kelani River” (Contract No: CRIP/CS/COS/41) has been formulated and awarded to Lanka Hydraulic Institute Ltd and Ceywater Consultants Pvt Ltd, in August 2019. The project objective of the consultancy assignment is to prepare Detailed Designs, Drawings, Cost estimates and Bidding documents for the proposed Gated Salinity Barrier at Ambatale in Kelani River. In summary, the scopes of work are: • Task A _ Inception: Define Approach, Formulation of data need and availability, Prepare Inception Report indicating final staffing and final work plan to complete the work to schedule. • Task B_ Literature Review: Carry out a comprehensive review of all studies undertaken regarding the proposed Salinity Barrier • Task C_ Geotechnical Investigations: Plan Geotechnical investigations based on previous studies and undertake Geotechnical investigation. • Task D_Hydrological / Hydraulic / Structural Designs • Task E_ Geotechnical Design Studies • Task F_ Mechanical &Operational Design of gates • Task G_Reporting: Preparation of Design Report including construction drawings • Task H_ Prepare Cost Estimates • Task I_ Prepare Bidding Documents