A capstone project report submitted in partial fulfillment of the requirements for the degree of Bachelor of Science in Engineering Civil and Infrastructure Engineering, School of Engineering and Technology

Capstone Project (B.Sc.)-Asian Institute of Technology, 2017

Climate change is affecting various sectors. It also affects hydrologic systems, which in turn alters streamflow in rivers. The project focus on the impact assessment of current and projected future climate on streamflow of the Kelani River Basin, Sri Lanka. The Hydrologic Engineering Centers Hydrologic Modeling System version 4.1 (HEC-HMS 4.1) was used to develop hydrological model of the study area. All the Simulations were evaluated on daily time-scale basis. The model was calibrated (2000-2005) and validated (2006-2011) at two stations. Visual inspection of hydrograph as well as evaluation of model performance statistics suggested that model performance is satisfactory. Results from the calibrated and validated model showed that the streamflow in the study basin is lower during March-July and higher during January-February. Average annual rainfall, runoff and evapotranspiration is estimated as 3087, 1842, and 1310 mm, respectively. The model was then used to assess changes in streamflow under projected future rainfall and temperature. Results showed that dry season streamflow is projected to change by 33 percent and 34 percent for mid-future (2041-2071) under RCP 4.5 and RCP 8.5 scenarios, respectively. Whereas, wet reason (July September) streamflow is projected to increase in 14 percent and 12 percent for RCP4.5 and RCP8.5 scenarios, respectively.