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171.
The lofty goals of the 1992 Earth Summit regarding sustainable development will not be achieved without major improvements in the management of transboundary water resources. This paper describes the serious nature of water-related conflicts and environmental damage associated with degradation of marine ecosystems, coastal zones, and shared surface/groundwater systems. Traditional approaches such as international conventions, watercourse agreements with basin organizations, and arbitration have generally fallen short of their objectives. This article suggests that a middle ground centered on multicountry institutional arrangements for joint fact finding, evaluation, and problem resolution may be a more productive approach over the short term to achieve sustainable development. The experience of the International Joint Commission (Canada and U.S.) is described as a way of providing a neutral ground for building trust among nations, for 'leveling the playing field' among small and large countries, and for providing mechanisms for countries to work jointly toward sustainable development of their shared resources without relinquishing their sovereignty. The Global Environment Facility (GEF) is playing a catalytic role in assisting countries to address transboundary water resources issues. The paper describes GEF's Operational Strategy and discusses the implications of joint institutional arrangements for the international waters focal area. Given that the environmental security of many nations rests on improved transboundary cooperation, the GEF provides a pragmatic opportunity for countries to cooperatively address these pressing problems.  相似文献   
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Count data on a lattice may arise in observational studies of ecological phenomena. In this paper a hierarchical spatial model is used to analyze weed counts. Anisotropy is introduced, and a bivariate extension of the model is presented.  相似文献   
179.
Hydrological processes and crop growth were simulated for the state of Brandenburg (Germany) using the hydrological/vegetation/water quality model SWIM, which can be applied for mesoscale river basins or regions. Hydrological validation was carried out for three mesoscale river basins in the area. The crop growth module was validated regionally for winter wheat, winter barley and maize. After that the analysis of climate change impacts on hydrology and crop growth was performed, using a transient 1.5 K scenario of climate change for Brandenburg and restricting the crop spectrum to the three above mentioned crops. According to the scenario, precipitation is expected to increase. The impact study was done comparing simulation results for two scenario periods 2022–2030 and 2042–2050 with those for a reference period 1981–1992. The atmospheric CO2 concentrations for the reference period and two scenario periods were set to 346, 406 and 436 ppm, respectively. Two different methods – an empirical one and a semi-mechanistic one – were used for adjustment of net photosynthesis to altered CO2. With warming, the model simulates an increase of evapotranspiration (+9.5%, +15.4%) and runoff (+7.0%, +17.2%). The crop yield was only slightly altered under the climate change only scenario (no CO2 fertilization effect) for barley and maize, and it was reduced for wheat (–6.2%, –10.3%). The impact of higher atmospheric CO2 compensated for climate-related wheat yield losses, and resulted in an increased yield both for barley and maize compared to the reference scenario. The simulated combined effect of climate change and elevated CO2 on crop yield was about 7% higher for the C3 crops when the CO2 and temperature interaction was ignored. The assumption that stomatal control of transpiration is taking place at the regional scale led to further increase in crop yield, which was larger for maize than for wheat and barley. The regional water balance was practically not affected by the partial stimulation of net photosynthesis due to higher CO2, while the introduction of stomatal control of regional transpiration reduced evapotranspiration and enlarged notably runoff and ground water recharge.  相似文献   
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Stock  Alfred 《Die Naturwissenschaften》1925,13(49):1000-1003
The Science of Nature -  相似文献   
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