Since the early years of 1970s, Research Group for Water Balance had pursued a study of the hydrogeological systems in the Kumamoto groundwater basin as a basic research for the planning and an effective water resources management. I have summarized those hydrogeological studies on Kumamoto Area and basic concepts of permissive limit or capacity of the environment is being settled among the concerned persons in the field of groundwater pollution. It is necessary for the evaluation of groundwater resources based on socio-engineering and evironmental geology in each groundwater basin to build a groundwater model.; Groundwater basin, Hydrogeology, Simulation, Management, Environmental capacity, sustained yield

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The hydrological problem of Saga area is governed by the fact that almost the area is below the Ariake sea level with the highest tide in Japan. Another problem is difficulty of supplying huge quantity of water for agriculture because of less water resources in Saga area. Therefore, open channel network system, Saga creeks, have been developed in this area. In this paper, an old system of water management on Saga creeks is described. The water management was a kind of integrated system by making use of function of Saga creeks such as drainage, storage. On the other hand, the main objective of modern and general water management is to protect flood damage caused by main river. The paper describes that, according to the modern concept, there has been many problems on drainage system in lowland especially in Saga area. Also, it is described that many factors to be cleared such as the drainage characteristic, time constant of design rainfall and the storage effect of channel network are examined. Finally, it is pointed out that the integrated water management system should be developed especially in lowland such as Saga area.

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In many rural areas, such as Saga, there have been many effective community activities for improving the water environment. The activities in cooperation with the administration, such as dredging, weeding etc. have been continuing for the last 12 years. It is important to enhance and support the community activities especially for the water environment in Saga. A questionaire survey was made on the inhabitant's consciousness concerning water quality and the various activities. As a result, it is clear that the inhabitants still require good water quality suitable for swimming. Their consciousness to participate in the activities is very strong, although they feel a kind of tiredness. Also the degree of water quality improvement, was investigated by examining the organic carbon content in dredged mud. From the results, the improvement has been considerable. Therefore these community activities are very necessary, socially, for the environment of the Saga channel network.

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We are paying attention to a function that a river holds as precious amenityresources or the natural resources.
Therefore, it will be decided for value of water quality that the evaluation for river scenery, recreational use and the ecosystem. We must control a quality of water from the point of view that desirable for the ecosystem or expecting what quality of water when a person do some recreations.
We took 20 adults and 10 infants to 9 rivers in Kanto District by a bus andmade quationnaires and site investigations.
We discuss the structure of consciousness that they feel comforatable when doing some activities (walk, play with water, swim).

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Lake Izunuma is a famous place for the coming of migrating flying swans. But, the leftovers of foods which were fed to the waterbirds and their droppings are one of the causes of water pollution.
In order to prevent water pollution of Lake Izunuma, a feeding pond was constructed near the lake. Last winter, a total number of about 160, 000 waterbirds entered into this pond anda build-up of pollutants of 12kg T-N, 1.5kg T-P and 120kg COD were found. This means that the pollutants going to Lake Izunuma were reduced.
After this, the polluted water in the feeding pond will be introduced into a plant field and purification by the plant, Zizania latifolia, which is a food for the swans, will be attempted.

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Kojima Lake, Okayama prefecture, is an artificial lake which was separated from Kojima Bay for the purpose of agricultural water use. Since the separation, the water quality has deteriorated. Therefore, much money has been spent on coutermeasures against the water pollution. By the way, Kojima Lake was needed to feed water for irrigation because rice paddy fields around Kojima lake had been reclamated without preparing enough water for irrigation since 18th century. We investigated the impacts of the reclamation and separation on the water environment and the community around the lake based on the historical data. The reclamation and separation greatly influenced on the water environment and fishery. Most of the short term purposes of the works were attained. But new problems occurred after the completion of the works or some of the purposes became meaningless because of the change of social background.

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This article aims to present how to develop a comprehensive water quality index. Proposed indexing method consists of water quality parameters, weighting, value functions and aggregation process. Choice of parameters are based on a Delphi questionair tecnique. Result index WQI is applied to the Matsushima Bay in order to assess annual trend of water quality and to compare it's value with COD. It is concluded that a Delphi tecnique is useful to summarize the knowledge and experience of experts in water quality manegement and a developed water quality index WQI is an appropriate tool for evaluating overall water quality.

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Numerical simulation was conducted for coral reef conservation in port area from the hydraulic point of view. Naha Port in south western part of Japan was selected as an example. Coral reef is said sensitive to turbidity of fine silt, water salinity and temperature, activity of predators and so on. For the maintenance of the ecological activity and the reef-zoning, larvae support from mother reef is important. Coastal hydraulics mainly affect a).diffusion and settling of the turbidity load from the land area, and b).drifting route of the released eggs/larvae from mother coral reefs.
Calculations on coastal flow, water exchange, drifting path of larvae and diffusion of turbidity were tried by numerical simulation models. For the calculation of drifting, larva markers are released from the main active reef area and drifting paths traced. For the calculation of turbidity diffusion, particle load and diameter fractions were estimated, using the observation data during a strong rain fall.
The critical values of turbidity nor settling rate are not yet established officially for coastal reef conservation. Comparing a damaged reef of another island, river mouth area in this port is relatively not suitable for coral transplantation. Outside fringes of the existing reefs, protected by breakwater from the inflow turbidity load, are expected to have the high potential as mother coral to north and south neighbor reefs. These results give useful information for the comprehensive planning of coastal water surface zoning at coral sea.

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