To elucidate the water balance in the Hetao Irrigation District of the Yellow River Basin, the evapotranspiration (ET) from an irrigated field of wheat, which is one of the main crops of this district, was estimated by the Bowen ratio energy balance method. As the observation results, the ET was measured as 456 mm during the observation period from 5 May to 27 July. In the same period, the rainfall was measured as 24 mm, the irrigated water was measured as 289 mm. Thus not only the water which was irrigated from the ditch to the wheat field, but also the water which infiltrated from the ditch to the deep soil layers were evapotranspired from the wheat field. Furthermore, to predict the evapotranspiration in different condition of solar radiation and vapor pressure deficit, the parameter of canopy resistance was modeled by the Penman Monteith method and the Bulk method respectively. Modeled ET by both two methods could reproduce actual ET successfully, whereas the Bulk method could reproduce ET more appropriately.

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In order to find the changes in rainfall characteristics and to examine the affect on rice production under rainfed conditions, a statistical analysis was carried out for 50 years daily rainfall record at Vientiane Municipal, Laos Meteorological Observatory. The rainfall recode was divided into two periods for each 25 years. Although total annual rainfalls have no trend, annual maximum daily rainfalls fluctuate and increase at the same probability year. Frequency of drought is increasing in the second period and more severe drought on September is increasing. On the contrary, in the first period heavy rainfalls causing flood such as over 100 mm/day are distributed intensively on August and September, although in the second period such rainfalls are also found from May to July.

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The expansion and concentration of urban areas cause the urban environment degradation, e.g. revealed as heat island phenomena. Many researchers have reported on the anthropogenic heat impact to the atmosphere, while not so many researchers have reported on the impact to the hydrosphere. To obtain the water and heat balance in artificial sewage system, we carried out the sewage temperature observation in wastewater treatment plants. By analyzing the observed data and other statistical data from Tokyo metropolitan, we got the following major results. 1. The leaching water from soil into sewage pipe dominates 22% of the whole sewage. 2. The heat added by water use in the urban area during one year amounts to 9% of whole energy use. 3. The process of heat flow in the sewage system is revealed in each season. In summer, the sewage loses its heat by conduction from the sewage out of the pipe and gains heat at WWTP. Totally, the sewage system reduces sewage heat and discharges it to hydrosphere. 4. In winter, both the conducted heat and the heat added in WWTP are small. Thus the sewage system doesn't change the heat.

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The purpose of this paper is to consider what modern open levee brought the upper basin inhabitants simultaneously pursuing environmental conservation and flood control by a case study approach. It deals with Kasumitei upstream of Kitakawa River in Miyazaki Prefecture, and focuses on farmers in the upper basin regarded as reservoir in the management strategy. They utilize Kitakawa River for agricultural use, and suffer from flood almost every year because of the open levees. The levees were re-constructed in modern management strategy by a national government. The following findings of hearing investigation and literature searching are obtained: the open levees in the area had brought people a new sense of distinction of upper basin (reservoir) and lower basin (beneficiary), and the consciousness of unfairness was understood by the people in another context of declining agriculture versus other remunerative industries. It must be noted that the context has brought people to claim compensation not only for their flood damage but also for their continuing agriculture in the upper basin. It remains to be solved how to build consensus including upper basin area, and how to further strengthen the collaboration with relevant ministries in watershed management toward a consecutive implementation of an effective policy.

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This research addresses the problem of growing shortage of water resources from the world-wide viewpoints by modeling of the socio-environmental changes. There are two main objects; namely (i) to simulate and predict trends in the development of human civilization in different continents taking into account the effects of limited water resources through feedback links between water availability and the human actions, and (ii) to identify the important roles and effects of water resources that have on the growth of the world so as to aid in the planning of scenarios and policies for sustainable development. A model exploring water needs in the various continents is developed using System Dynamics. Identification of continents with acute water shortage and development limitations will also be possible with this model.

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