Hydrologic responses to variations in storm direction provide useful information for the analysis and prediction of floods and the development of watershed management strategies. However, the prediction of hydrologic responses to changes in storm direction is a difficult task that requires meteorological simulations and extensive computation. It is also difficult to identify the center of rotation of a storm affecting a basin of interest. Therefore, we propose a simple approach of rotating the basin position relative to the storm within the rainfall-runoff simulation model instead of changing the pathway of the storm, which we term the Basin Rotation Method (BRM). The proposed BRM was tested on four major typhoon events in South Korea. The results illustrated that the original basin orientation (i.e., before it was rotated) exhibits earlier and higher peak discharge and earlier recession compared to the basin after rotation. We conclude that the proposed method (BRM) is a viable alternative for use in assessing the directional influence of moving storms on floods caused by historical rather than hypothetical storm events.

The probability distribution of wind speeds is a mathematical function describing the range and relative frequency of wind speeds at a particular location . In other word , the behavior of wind velocity at a given site can be specified as a probability distribution function. The accuracy of design wind estimation depends on the choice of an appropriate probability distribution model (PDM) and parameter estimation techniques. Generally, parameters for PDMs are estimated with the method of moments(MOM), probability weighted moments(PWM), and maximum likelihood (ML). In this work , we tried to estimate the parameters of PDMs for wind speed data using a recently developed meta-heuristic approach known as a harmony search (HS) that is a phenomenon-mimicking algorithm. The performance of the HS is compared to the genetic algorithm (GA) and conventional method (i.e.,ML) via simulation and case study.