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

(1)建立了分析潮滩及其沟壑形态的数值方法。建立了基于风暴潮、高波、潮汐相互作用的风暴潮灾害制图及其最大发生概率预测方法。采用准三维海洋环流模式POM （Princeton ocean model）模拟了海底地形复杂的海湾内的洋流和物质输运。为了提高平流计算的可移植性，将平流计算的数值格式由中心差分格式改为TVD格式。试验模拟验证了改进方案m平流项的有效性。结合风暴潮最大发生预测，提出了减少风暴潮灾害的对策。(2)为绘制有良-白海岸风暴日线图，采用中尺度气象模式（PSU/NCAR MM5）计算海面风。在1999年前后进行了1年的模拟，并与实际观测结果进行了比较。模拟成功地再现了受周围复杂地形影响的近地面风。利用模式模拟的风场，可以实现对风暴哔哔线的准确预报。提出了白浪耗散应力作为大气与沿海海洋能量传递界面的数学模型。利用tin界面模型，建立了综合风应力（风场）、白浪破浪应力（波场）和底应力（流场）三者之间关系的数值风波流系统。系统还考虑了浪涌对白头耗散应力的增强作用。(3)为了阐明潮间带形态变化与季节平均海平面变化之间的关系，本研究对潮间带底部剖面变化进行了野外调查和数值分析。野外调查发现，6 ~ 10月平均涨潮约40 cm。此外，为了评估潮滩形态响应的主要原因，还提出了二次多项式方法来近似滨岸剖面。考察了多项式的三个参数与外力之间的关系。因此，潮汐运动在潮滩中占主导地位，潮滩具有向上凸起的剖面。在比目前观测间隔更短的时间尺度上，对风浪和河流流量的控制可能变得很重要。这保证了未来在风暴和台风条件前后的观测。(4)收集有明海水质资料和微生物信息，对有明海富营养化进行评价。米多里河河口表层海水中叶绿素-a （Chl-a）浓度高于近海。夏季地表水细菌数量高于其他季节。此外，还分析了海水中悬浮固体颗粒的变化规律，大多数样品都出现了两个主导峰；一个在0.4 ~ 0.5 μm范围内，另一个在10μm左右。Chl-a浓度与颗粒变化模式之间没有关系，但Chl-a浓度与其他颗粒变化模式之间存在不同程度的关系。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