Dynamic conservation mechanism of temporal water area and its roles in preservation of riparian ecosystem

(1)“万多”回水的形成过程我们在基索河一系列峡谷的“万多”回水进行了实地调查，“万多”回水是通往主干道的一个海湾。以下游地区的潮汐效应为例。通过实地调查、文献研究和数值模拟，将万多主河道冲刷分为大尺度和小尺度的淤积区子河道两个尺度，解释了湾岛主要洼地是在洪水作用下形成的，受植被扩张影响的推移质输运，子河道是由沙质淤积区泥沙的日潮汐运动形成的。此外，这些渠道在退潮期向湾岛地区提供来自沙质基质的不同水质起着重要作用。(2)回水水质和回水周围的地下水运动，即湾岛、池塘，对水质形成机制具有重要意义。野外研究和数值模拟表明，回水的存在改变了地下水的流动，加速了地下水的流动；沙洲地下水的水质，特别是氮的水质，既受反硝化作用的影响，又受表层补给的影响，表层补给中含有有机质。(3)藻类的生长和剥离当考虑回水水质时，藻类产生的影响是很重要的。对藻类的产生、丝状藻与非丝状藻的竞争以及藻类的脱落进行了野外实验和室内实验。此外，还建立了藻类竞争的数值模拟模型。

(1)Formation process of "Wando" backwaterWe conducted field research at "Wando" backwater, which is an embayment opening to main river channel, at Kiso river's a series of grolyns. as the example case with tidal effect in downstream area. Two scale geography, one is large scale including main Wando's scouring and the other is sub channel in deposition area in smaller scale by field research, literature research, and numerical simulations.It is explained main depression at Wando is formed under flood, by bed load transport affected by of vegetation area's expansionsAnd subchannels are formed by daily tidal motion of sediment on deposition area of sand. Additionally, these channels take an important role to supply different water quality to Wando area from sand substrate during ebb-tide stage.(2)Water quality in backwater and subsurface waterWater movement in subsurfacewater surrounding backwater, i.e. Wando, pond, are significant for mechanisms of water quality formation. Field research and numerical simulation shows that subsurface flow is change by the existence of backwater and accelerated.In sandbar, water quality, especially in Nitrogen, of subsurface water is changed by both by denitrification and supply from surface layer, which include organic matter.(3)Growth and detachment of algaeWhen we consider water quality in backwater, the effects by argae production is important. We conducts field experiment and laboratory experiment on algae's production, competition between filamentous and non-filamentous periphyton, and debouchments. Additionaly, we made numerical simulation model on algae competition