Assessment of natural environment and maintenance of infrastructure for co-existence with environment in Ariake and Yatsusiro Coastal region

(1)对有莱克海以及白川河和南川河两个河口的潮流和海浪进行了数值分析。研究了潮位和入河流量对这些区域的速度场特征和悬浮物浓度分布的影响。此外，还发展了分析潮滩及其沟谷形态的数值方法。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，改进方案在对流条件下是有效的。(2)对底土进行了…分类对7种碎屑进行了MAD含量、硫化物、COD/I损失和COD/MAD含量四个变量的Claster分析，发现主要物种的Claster分析结果不同。此外，作者还提出了一个丰富度指数IR，它定量地反映了潮滩底栖动物的丰富度。该指数由公式IR=H‘x WWU定义，其中H’是Shannon函数的多样性指数，WWU是单位面积底栖生物的湿重。该指数在一定程度上反映了潮滩碎屑的特征，但没有发现簇间指数有明显的差异。今年考察了一些可能影响该指数的因素，发现潮滩上适宜的干燥期长度可能是底栖生物丰富度的理想选择。(3)估算了有宅内海和中越内海滩涂的反硝化能力，确定了影响反硝化作用的因素。研究发现，底泥中的粉粒和粘粒含量对反硝化效果有很大影响。因此，泥沙和粘土含量较高的萨加地区滩涂的反硝化速率高于所考察的其他滩涂。夏季雨季降雨量大，氮源和碳源丰富，反硝化细菌活跃，反硝化能力最强。本研究的目的是评价白川江潮滩反硝化活动中的潮汐作用和底栖生物等底栖动物的作用。采用充填近岸海洋沉积物的管子，分别在有无污水的情况下，进行了反硝化速率与沉积物性质的关系试验。根据硝态氮浓度随潮汐变化的变化规律，计算了反硝化率。结果表明，生物扰动对反硝化速率的影响受沉积物COD水平和氧化还原电位的影响。(4)在沉积相、硅藻和底栖有孔虫组合以及熊本附近4个水深21~44m的活塞柱状样的14&gt；C年龄的基础上，研究了近10,000年来有赖克海中部的环境变化。结果表明，海水侵入该地区的海平面约低于50米，目前的海平面约为9500年，熊本岛附近的整个地区被淹没在中央海湾环境中，与目前的约7,400年前相同。此外，海洋环境持续向内陆扩展，覆盖了目前熊本平原约5400年的整个区域。(5)本研究的目的是使用双界二分选择(DB-DC)方法对条件估值方法(CVM)进行检验。由于云服务器使用声明偏好(SP)数据，因此它可以衡量非市场商品的存在价值。然而，评价的可靠性不如显示偏好(RP)方法。CVM在评估非市场商品的价值时，需要根据SP数据进行偏差检验。本文的研究对象有两个。一种是云服务器通过不同的支付类型进行评估的测试。二是检验和消除DB-DC方法中的起点偏差和说是偏差。在本研究中，采用了两种支付方式。一种是基于新的税收，另一种是基于税收重新分配。将两种支付方式的评估结果与理论结果进行了比较，并检验了CVM评估的可靠性。较少

(1)Numerical analysis of tidal flows and ocean waves were performed for all of Ariake-sea and the both estuary of Sirakawa and Midorikawa rivers. Velocity field characteristics and concentration distributions of suspended solids in those areas were evaluated as a function of tidal levels and river inflow rates. Also, 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 in advection term.(2) Bottom soils ware classifi … More ed to seven clasters by claster analysis with four variables, mad content, sulfieds, COD/I gnission loss and COD/mad content, and it was found that major species are different by claster. Also, authors proposed a richness index, IR, which quantitatively shows richness in benthos in tidal flats. The index is defined by the equation, IR = H' x WWU, where H' is diversity index by Shannon function and WWU is the wet weight of benthoses in unit area. The feature of the clasters of tidal flats was presented by the index in some degree but the clear difference in the index between clusters was not found, hi this year, some factors supposed to influence on the index were examined, and it was found that the appropriate length of dried period on the tidal flat may be desirable for the richness of benthoses.(3) Denitrification capability of the tidal flats in Ariake Inland Sea and Yatsushiro Inland Sea was estimated and factors that affect denitrification were determined. It was found mat denitrification capability was largely influenced by die silt and clay content of mud. Therefore the denitrification rate of tidal flats in Saga area where the silt and clay content of mud was much high was higher than the other tidal flatsexamined. And the denitrification capability is highest in summer when the source of nitrogen and carbon was rich because of heavy rainfall in the rainy season and Denitrifying bacteria was active. The objectives of this study is to evaluate the tidal action and benthic animals such asseawom in denitirification activities of the tidal flat in Shirakawa river. Experimental were conducted to determine the dependence of denitirification rate on sediment character using tubes filled with costal marine sediment both with and without sewaorm. Based on the tidalaction-dependent decrease of NO3-N concentrations, denitirification rate were calculated. The result indicate that the effect of bioturbation on denitirification rate ware influenced by sediment COD levels and redox potential.(4) On the basis on sedimentary facies, diatom and benthic foraminiferal assemblages, and ^<14> C ages of 4 piston cores, 21 to 44 meters in water depth, off Kumamoto, environmental changes in the central part of the Ariake Sea were examined during the last 10,000 years. As a results, it is clarified that marine water invaded into the area around 50 meters below a present sea level about 9,500 yrBP, and the whole area off Kumamoto became to be underlain in the central bay environment same as a present about 7,400 yrBP. Further, the marine environment spread to inland continuously and covered entirely all over the present Kumamoto Plain area about 5,400 yrBP.(5) The aim of this study is to check the Contingent Valuation Method (CVM) using double-bounded dichotomous choice (DB-DC) method. Since CVM uses Stated Preference (SP) data, it can measure existence value of non-market goods. However, reliability of the evaluation is inferior to Revealed Preference (RP) Method. It is necessary to check the bias based on SP data when value of non-market goods is evaluated by CVM. There are two targets in this paper. One is a test of evaluations by CVM through different payment types. Another is to check and to get rid of a starting point bias and a yea-saying bias in DB-DC method. In this study, two types of payment way were applied. One was based on new taxation, and another was based on tax reallocation. The evaluations through two payment types were compared with theoretical results, and reliability of the evaluations by CVM was tested. Less