One Dimensional Numerical Model For Storm Surge Prediction

Rolu P. Encarnacion

The Philippines, having the highest annual frequency of tropical cyclones in the world, is considered as a naturally surge-prone area. However, operational application of storm surge prediction schemes in the country are still in the formulative stages of development. This study is a modest contribution to these efforts. A one-dimensional numerical storm surge prediction model is formulated and developed in this paper.

The domain of the model is oriented perpendicular to the coast over a model basin in which the bottom slopes can be varied. The forcing function consists of surface wind generated by model typhoons. Experiments were performed with various formulations of the bottom stress. Several conceivable behaviors of the model typhoons were simulated in the experiments.

The results indicated that the model had performed well in simulating the observed storm surges in Baler, Aurora in 1981. This paper attempted to explain the prediction results with established theories and concepts regarding the behavior and movements of the sea under the actions of the driving and forcing effects of tropical cyclones particularly in the generation of the surges at the coast.

Some Experiments In The Objective Analysis Of The Wind-Field Over The Northwestern Pacific And Adjacent Regions

Jaime F. Bucoy

The present study is an initial attempt to apply objective analysis techniques in the interpolation of wind data from observation stations to equally spaced grid points for the purpose of assimilating data as input numerical prediction models using a variation of weighted average method. The programme was executed in the Nova mini-computer adapting a 17x23 grid points in a region from 20 degrees S to 44 degrees N and from 92 degrees E to the international dateline. The streamline and isotach patterns obtained by objective analysis of 4 cases are compared against conventional analyses. The result of comparison produced promising outputs. The average root mean square geographical distributions of errors are 5.42 mps and 4.84 mps for u and v wind components, respectively. The first guess wind pattern used in this study was the past 12-hr. ago analysis.

Improvement Of Typhoon Track Forecasting With A Barotropic Model

Ana B. De la Cruz

The study is an attempt to improve the performance of the operational barotropic model presently used in PAGASA. Three methodologies are considered together with the operational one. The main revisions consist of the improvement of the interpolation scheme and the computational scheme of the forecast position. Of these revisions, regression analysis was applied to the result of the method with the best forecast as shown from a verification. The forecast using the best method was correlated with the actual track to formulate a regression equation which is expected to give an improved forecast. This is done to improve further the forecast position if the deviation from the actual track is proven to be linearly correlated. Revision 2, the combination of improvement in the interpolation and computational scheme of the forecast position, shows to have improved the operational barotropic model though not significantly.

A Simple Lake Flood Simulation Model

Alan L. Pineda

Starting from the continuity equation and equation describing the behavior of the lake during floods is derived. The "quasi-linear storage type" was utilized as input to the model to accommodate the time of concentration. A computer program for HP-9845 was created for semi-automatic parameter calibration. The model went through a normal routine of application and parameter optimation in two lakes in Bicol River Basin namely: Lake Bato and Lake Buhi. The results are satisfactory according to the criteria for flood forecasting. The model then is integrated into an operation flood forecasting in Bicol River Basin.