Impact of fresh water inflow from a large river on aquatic environment and ecosystem in a large scale estuary

大河淡水流入对大范围河口水环境和生态系统的影响

• 批准号: 18560500
• 负责人: YANO Shinichiro
• 金额: $ 2.43万
• 依托单位: Kyushu University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2006
• 资助国家: 日本
• 起止时间: 2006 至 2007
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18560500/
• 关键词: estuary; Ariake Sea; coastal zone; semi-enclosed bay; material transport; tidal current; turbulent diffusion; micro-struwture of turbulence; 水質; 生態系; 乱流拡散係数

In order to investigate on movement of fresh water discharged into Ariake Sea from the Chikugo River, in-situ measurements of Lagrangian currents by using drifters with GPS were conducted. The measurements were carried out on June 7 and July 21, 2006 and July 17 and 28, 2007, under spring and middle tide conditions and with discharge of the Chikugo River from medium wcale flash (1,678m^3/s) to normal stage(approximately 50m^3/s). Position of fresh water body, velocity, salinity, water temperature, water quality (turbidity, Chlorophyll-a, pH), wind velocity and direction were continuously measured for one tidal period (approx. 13hrs) or a half period (approx. 8hrs). As a result of these measurements, the followings were clarified: (i) Under weak wind condition, pressure gradient force is a dominant factor for currents in NS direction, while Coriolis force for currents in EW directions. (ii)Under weak wind condition, riverine water from the Chikugo River is transported to the western area for one tidal period. The excursion depends on river flow rate. Especially, under flush condition, it can move into Isahaya Bay for only one tidal period. (iii) Under strong southern wind condition, riverine water stagnates in the eastern area In addition, to measure eddy diffusivity in horizontal and vertical directions, in-situ measurements by using drifters and the turbulent microstructure profiler were conducted. Horizontal eddy diffusivity varied from 1 to 10^2m^2/s, while vertical one changed from 10^<-7> to 10^<-3>m^2/s. The former depends on local condition of river inflow, and so on, but the latter was affected by density stratification, tide, and tidal hour. We expect that these results will contribute to development of high accurate numerical model of currents and material transport in Ariake Sea.

为了调查从Chikugo河中排入Ariake Sea的淡水运动，通过使用与GPS的漂流者对Lagrangian潮流的原位测量。测量是在2006年6月7日和7月21日以及2007年7月17日和28日进行的，在春季和中间潮汐条件下以及奇科戈河从中等wcale闪光灯（1,678m^3/s）释放到正常阶段（大约50m^3/s）。淡水体，速度，盐度，水温，水质（浊度，叶绿素-A，pH），风速和方向的位置连续测量一个潮汐周期（约13小时）或半个周期（约8小时） 。由于这些测量值，阐明了以下测量值：（i）在弱的风条件下，压力梯度力是沿NS方向的电流的主要因素，而Coriolis力是在EW方向上的电流。 （ii）在弱风条件下，奇库戈河的河流水被运送到西部地区一个潮汐时期。游览取决于河流流量。特别是，在潮流状态下，它只能在一个潮汐时期进入伊萨亚湾。 （iii）在强烈的南部风条件下，河流水还在东部地区停滞，以测量水平和垂直方向上的涡流扩散，使用漂流器和湍流微观结构探测器进行了原位测量。水平涡流扩散率从1到10^2m^2/s不等，而垂直的涡流扩散率从10^<-7>变为10^<-3> m^2/s。前者取决于河流流入的当地状况，依此类推，但后者受密度分层，潮汐和潮汐小时的影响。我们预计这些结果将有助于开发Ariake Sea的高准确的电流和材料运输的数值模型。

项目成果

Investigation on structure of currents in the mouth of Isahaya Bay by in-situ measurement using drifters

利用漂流器现场测量调查谏早湾口的水流结构

• 发表时间: 2008
• 作者: S.;Shigeta;et. al.
• 通讯作者: et. al.

外海を基準とした有明海のM2潮増幅率の変動特性と諫早湾潮受け堤防建設による影響

有明海M2潮汐放大系数相对于公海的变化特征及谏早湾防潮堤建设的影响

• 发表时间: 2008
• 期刊: 海の研究 17(in press)
• 作者: 田井 明;ら
• 通讯作者: ら

現地データに基づく島原半島沿岸域の流動に関する検討

基于实地数据的岛原半岛沿岸地区流量研究

• 发表时间: 2007
• 期刊: 平成18年度土木学会西部支部研究発表会講演概要集
• 作者: T. Matsushima;K. Maeda;T. Ishikawa;重田真一ら
• 通讯作者: 重田真一ら

諫早湾湾奥の締切りによる有明海のM2潮増幅率の時空間変動

谏早湾内部截断导致有明海M2潮汐放大系数时空变化

• 发表时间: 2007
• 作者: 田井 明;ら
• 通讯作者: ら

2007年冬季の水俣湾西側海域および八代海の流動特性に関する現地観測

2007年冬季水俣湾西部海域和八代海水流特征的实地观测

• 发表时间: 2008
• 作者: 宮良 幸秀;ら
• 通讯作者: ら