Flood warning and effective radial gate operations of Deduru Oya reservoir are important in flash flood controlling and reducing the impact of flash floods. Future rainfall forecast is essential to obtain runoff forecast into the reservoir and for the hydrological modelling. A limited number of studies have been conducted on weather forecasting in Sri Lanka. This study proposes a weather forecasting model for the basin using Weather Research and Forecast (WRF) model. WRF model was optimized by doing a series of simulations with multiple microphysics and cumulus physics parametrization schemes. Optimum physics combinations were identified considering two extreme rainfall events on 2 November 2015 and 16 May 2016, and the results were validated for the extreme rainfall event on 1 September 2017. WSM3 and Betts-Miller-Janjic cumulus schemes were found to be the optimum parameterization schemes for microphysics and cloud microphysics, respectively. The developed model can be used for weather forecasting in the region.

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Abstract:The present knowledge on the behaviour of hydraulic jump is only for smooth, horizontal channel beds and very limited studies have been reported in literature on the performance of hydraulic jumps on rough beds. This research attempts to investigate the characteristics of hydraulic jumps formed on rough, horizontal channel beds under different flow conditions using laboratory investigations. A series of experiments were carried out in a rectangular flume which consists of artificially roughened beds formed by placing rectangular wooden strips in specific intervals. The hydraulic parameters such as, initial water depth, sequent water depth, and flow rate were measured for different bed roughnesses. The analysis of experimental data showed that the rough bed reduces the distance to the jump from the gate and the sequent depth ratio than those on smooth beds while creating a high energy loss. With the availability of a large number of experimental data on hydraulic jumps over rough channel beds, mathematical formulations were developed to express the hydraulic jump characteristics relating roughness parameters such as; roughness density and roughness height.

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