Aquatic weed problems in a hydroelectric river: The R. Otra,Norway

Excessive abundance of submerged macrophytes is a less well-known but highly undesirable effect resulting from hydropower development. An example is the acidic River Otra, which is an extensively exploited hydroelectric river located in a region of infertile soils in southern Norway. The operating schemes annually generate some 4·1 TWh of hydropower. Many stretches of the River Otra support massive infestations of a submerged phenotype of Juncus bulbosus L. Evidence from a multidisciplinary study demonstrates that proliferation of J. bulbosus is achieved under an altered flow regime typical of Norwegian hydrorivers. The main features are augmented winter flows, concomitant lack of ice-cover, and intermediate ranges and frequencies of water-level fluctuation. These hydrological conditions prevail in tailwaters and intermediate-type hydrolakes on the Otra. By contrast with the Otra River, an adjacent water-course, the acidified Tovdal River, supported only scattered J. bulbosus in its upper, non-regulated sections, whereas a hydrolake on the lower Tovdal River had locally abundant growth of J. bulbosus. Acidification per se is an unlikely determinant of profuse growth for this species: non-natural habitats created by hydropower operation provide vacant space for an opportunistic species such as J. bulbosus.     

Water quality and non-point sources of risk: the Jiulong River Watershed, P. R. of China

Retrospective water quality assessment plays an essential role in identifying trends and causal associations between exposures and risks, thus it can be a guide for water resources management. We have developed empirical relationships between several time-varying social and economic factors of economic development, water quality variables such as nitrate-nitrogen, COD(Mn), BOD(5), and DO, in the Jiulong River Watershed and its main tributary, the West River. Our analyses used alternative statistical methods to reduce the dimensionality of the analysis first and then strengthen the study's causal associations. The statistical methods included: factor analysis (FA), trend analysis, Monte Carlo/bootstrap simulations, robust regressions and a coupled equations model, integrated into a framework that allows an investigation and resolution of the issues that may affect the estimated results. After resolving these, we found that the concentrations of nitrogen compounds increased over time in the West River region, and that fertilizer used in agricultural fruit crops was the main risk with regard to nitrogen pollution. The relationships we developed can identify hazards and explain the impact of sources of different types of pollution, such as urbanization, and agriculture.     

老挝电气化建设

1 概述 老挝人民民主共和国是位于东南亚的一个内陆国家。北邻中国,东接越南,西边紧靠泰国和缅甸,南部与柬埔寨接壤。老挝人民民主共和国拥有550万人口,其首都万象位于中部。国土面积236,800km2,其中2/3为山地。根据地形特征,全国可分为3个主要地形区:1)北部地区由坡地和山地组成,海拔在500m-2000m之间;2)东部地区也由坡地和山地组成,海拔在500m-2000m之间;3)西部地区的海拔一般在100m-300m之间。