For numerical simulation on behaviors of groundwater level in the Yellow River Basin, China, the authors estimated spatial distribution of groundwater resource demand (1996) in pixel base with high resolution. Annual agricultural use reached around 150, 000 to 290, 000 t (1120 m)^-2 in half region of the Northchina Plain, especially surroundings of major cities, and both of annual industrial and annual domestic use reached around 60, 000 to 270, 000 t (1120 m)^-2 at major cities in the Northchina Plain, Zhengzhou, Luoyang, Xi'an etc. Spatial data of groundwater use of China with high resolution is not accessible and this study shows a new approach to clarify this distribution through comparison of simulated groundwater level based on the authors' results and the actual data.

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Utilization of biomass resources has become of interest in recent years. Under this circumstances, especially the bio-fuel production systems based on the energy crops are paid attention. On the other hand, to avoid the competition with food production, the energy crop production in abandoned agricultural field is desirable, which potentially make some another environmental impact. To design the desirable energy crop utilization system, its sustainability should be estimated from various points of view including the environmental impact. In this study, a methodology for designing the energy crop utilization system was developed based on the simultaneous estimation of impact on water environment and energy balance of the system. Bioethanol production from rice cultivated in the abandoned agricultural field was focused as a bio-fuel production system. To estimate the relationship among the methods of fertilization, crop yields, and environmental impacts, a numerical model which can describe the growth of rice, water and nitrogen flow in the paddy field was developed. And using this model, the biomass growth and nitrogen loading into the water environment when a high-yielding variety of rice was cultivated in the abandoned paddy field under a certain environmental condition were calculated. Furthermore, the energy consumption in the rice production and in the process to produce the bio-ethanol from the rice was estimated. Finally, a method to estimate the effects of fertilization procedure and purity of produced ethanol on the nitrogen loading into water environment and energy gain simultaneously was proposed. This set of methodology is useful to design the rational energy crop utilization system.

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In the search for ways to encourage more participation in voluntary activities, more attention is being given to what motivates people to participate. Participation in voluntary activity is usually explained by rational choice theory, but theoretical predictions have not always concurred with empirical outcomes. We proposed a theory of volunteer opportunity and verified the theory by using a web survey. Our central hypothesis was that having access to opportunities leads to higher participation rates in voluntary activity. Our analysis of the factors involved in participation in voluntary activity supported the hypotheses based on this theory. For example, number of interests, some sources of information related to the area and specific activities, and other factors connected with participation opportunities had significant positive effects on participation. Factors related to egoistic motives, however, were either not significant or had significant negative effects, and economic models were thus not supported. It was clear that participation in voluntary activity is related to number of participation opportunities, and we suggest further development of the theory of volunteer opportunity.

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Damping of waves propagating through a macrophyte zone was experimentally investigated under two conditions : on a flat bottom and on a mildly sloping bottom. On the flat bottom, wave height slightly decreased by floating-leaved and submerged macrophytes. On the sloping bottom, in contrast, both the macrophytes exerted significant influence on the variation in wave height. This suggests that floating-leaved and submerged macrophytes play an important role in damping of wind-induced or boat induced waves, in combination with emergent macrophyte, on the bank-slopes of lakes and ponds.

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