Rainfall forecast in the Upper Mahaweli basin in Sri Lanka using RegCM model

15th Asian Congress of Fluid Mechanics

物理学;力学

Muhammadh, K.M.^1 ; Mafas, M.M.M.^1 ; Weerakoon, S.B.^1

Faculty of Engineering, University of Peradeniya, Peradeniya, Sri Lanka^1

关键词: Absolute error;    Gauging stations;    Global climate model;    Model calibration and validation;    Rainfall and runoffs;    Rainfall forecasts;    Regional climate modeling;    Reservoir operation;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/822/1/012075/pdf
DOI  :  10.1088/1742-6596/822/1/012075

学科分类：力学，机械学

来源: IOP

【 摘 要 】

The Upper Mahaweli basin is the upper most sub basin of 788 km2 in size above Polgolla barrage in the Mahaweli River, the longest river in Sri Lanka which starts from the central hills of the island and drains to the sea at the North-east coast. Rainfall forecast in the Upper Mahaweli basin is important for issuing flood warning in the river downstream of the reservoirs, landslide warning in the settlements in hilly areas. Anticipatory water management in the basin including reservoir operations, barrage gate operation for releasing water for irrigation and flood control also require reliable rainfall and runoff prediction in the sub basin. In this study, the Regional Climate Model (RegCM V4.4.5.11) is calibrated for the basin to dynamically downscale reanalysis weather data of Global Climate Model (GCM) to forecast the rainfall in the basin. Observed rainfalls at gauging stations within the basin were used for model calibration and validation. The observed rainfall data was analysed using ARC GIS and the output of RegCM was analysed using GrADS tool. The output of the model and the observed precipitation were obtained on grids of size 0.1 degrees and the accuracy of the predictions were analysed using RMSE and Mean Model Absolute Error percentage (MAME %). The predictions by the calibrated RegCM model for the basin is shown to be satisfactory. The model is a useful tool for rainfall forecast in the Upper Mahaweli River basin.