Hazard Mapping for Storm Surge and Factorial Analysis of Environmental Variables over Ariake and Yatsusiro -Sea

(1)发展了潮滩及其沟谷形态的数值分析方法。建立了基于风暴潮、巨浪和潮汐相互作用的风暴潮危险性图及其最大发生次数预测。将准三维海洋环流模式POM(普林斯顿海洋模型)应用于具有复杂海底地形的湾内水流和物质输运的数值模拟。将POM平流计算的数值格式由中心差分格式改为TVD格式，以提高其可移植性。试验模拟表明，改进后的方案m平流项是有效的。考虑到风暴潮最大发生次数的预测，提出了减少风暴潮灾害的对策。(2)在绘制海面风暴潮危险性图时，利用中尺度气象模式(PSU/NCAR MM5)计算了海面风速。这项模拟进行了一年多，…并将计算得到的风场与实测值进行了比较。模拟成功地再现了受周围复杂地形影响的近地表风场。预计利用模式模拟的风场进行暴雨预报是可能的。提出了一个白浪耗散应力的数学模型，作为大气与沿海海洋之间的能量传递界面。利用TINS界面模型，建立了风-浪-流数值体系(WWC体系)，其中集成了风应力(风场)、白盖型破碎器应力(波浪场)和底应力(流场)之间的关系。系统中还考虑了波浪浅化对白潮消散应力的增强作用。(3)为了阐明地形变化与季节平均海平面变化之间的关系，本文对潮间带滩涂的海底剖面变化进行了实地调查和数值分析。实地调查发现，6-10月平均潮位上涨约40厘米。此外，为了评价滩涂地形响应的主要原因，提出了用二次多项式逼近近岸剖面的方法。研究了多项式的三个参数与外力之间的关系。因此，潮汐运动在具有凸起向上剖面的潮滩中占主导地位。在比目前的观测间隔更短的时间尺度上，风浪和河流流量的控制可能变得重要。TINS为今后在风暴和台风前后的观测提供了依据。(4)积累了有明海区的水质数据和微生物信息，以评价有明海区的富营养化状况。米多里河入海口表层海水中Chl-a浓度高于近岸。地表水细菌数量夏季高于其他季节。此外，还分析了海水中悬浮固体颗粒的变化规律，大部分样品在0.4~0.5μm范围内和10μm左右出现两个优势峰，Chl-a浓度与颗粒变化模式的关系不明显，但Chl-a浓度与其它浓度的关系不同。较少

(1)Numerical methods for analyzing the form of tidelands and their gullies were developed. Hazard Mapping for Storm Surge based on Interaction between Storm Surges, High Waves and Tide, and Their Maximum Occurrence Prediction were developed. Quasi-three dimensional ocean circulation model POM (Princeton Ocean Model) was applied to the simulation of current and material transport in the bay, which has complex bottom topography. Numerical scheme for advection computation in POM was changed from the central difference to TVD scheme to improve its transportability. Test simulation made clear the effectiveness of the modified scheme m advection term. Considering the Maximum Occurrence Prediction of Storm Surge, the Countermeasure for decrease the disaster of Storm Surge were performed.(2)Toward the drawing of storm serge hazard map along the Ariake-Shiranui coast, sea surface wind was computed using a meso-scale eteorological model (PSU/NCAR MM5). The simulation was conducted over one year, … More 1999, and the computed wind are compared with observation. The simulation successfully reproduced the near surface wind affected by the surrounding complex topography. It is expected that the accurate storm serge prediction is possible by the use of model simulated wind field. A mathematical model of whitecaps dissipation stress was proposed as an energy transfer interface between atmosphere and coastal ocean. Using tins interface model, numerical Wind-Wave-Current System (WWC System) was established, in which the relation between wind stresses (wind field), whitecap breaker stresses (wave field) and bottom stresses (current field) were integrated. Enhancing effects of whitecap dissipation stress due to wave shoaling was also taken into consideration in the system.(3)In order to clarify the relationship between the morphological changes and the seasonal mean sea level changes, the present study obvious the results of field survey and numerical analysis about bottom profile changes of the intertidal flats. In the field survey, it is found that the average tide level rose about 40 cm from June to October. Also, in order to evaluate the dominating causes of morphological response on the tidal flats, quadratic polynomial approach has been proposed for approximation of cross-shore profiles. A relationship between three parameters of the polynomial and external forces has been examined. Consequently, tidal motions are dominant for tidal flats, which have convex-upwards profiles. A domination of wind waves and river discharges can become important at a time scale that is shorter than the present observation intervals. Tins warrants future observations at before and after both storm and typhoon conditions.(4)The water quality data and the information on microorganisms in Ariake Sea were accumulated, in order to evaluate the eutrophication in Ariake Sea. The chlorophyll-a (Chl-a) concentration in surface seawater at the estuary of Midori River was higher than it offshore. The bacterial number in surface water was higher in summer than in the other season. Additionally, the granular variation of suspended solids in seawater was analyzed, and two dominant peaks were shown in most of samples ; one is at the range of 0.4 to 0.5 μm and the other is around 10μm. The relationship between the Chl-a concentration and the granular variation pattern was not observed, but those between Chl-a concentration and the others were observed in various. Less