梯级水电开发对水生境累积影响的

我国当前大多数流域梯级水电开发已引起比较严重的水生境问题，而以往水电工程对水生境的影响一般只对单个工程来考虑，迫切需要进行梯级水电开发对水生境的累积影响的研究。本文对国内外累积影响的研究方法进行对比分析，同时，提出水生境研究的特点，提出对梯级水电开发对水生境的累积影响研究的方法框架，为水生境累积影响的分析提供参考。     

基于分解协调法的梯级泵站优化模型局部敏感性分析

为了提高梯级泵站的运行效率,对其进行优化调度研究十分必要。以济南市玉符河卧虎山水库梯级泵站为例,基于分解协调法建立了能耗优化模型和日运行电费优化模型,利用修正的Morris筛选法对模型进行了局部敏感性分析。结果表明:对于能耗优化模型,能耗和单位流量(扬程)能耗随着瞬时流量、后池水位的增加和前池水位的降低而增加,参数的敏感性排序为瞬时流量、前池水位、后池水位;对于日运行电费模型,参数的敏感性排序为日调水量、高峰时段最小流量、低谷时段最大流量。在不超过机组承受能力和满足各种运行条件的情况下,高峰时段最小流量越小和低谷时段最大流量越大,日运行电费相对来说越小。研究为梯级泵站的优化调度提供了一定的参考和指导意义。     

渠道梯级电站群优化调度方法

针对渠道梯级电站群的运行特点,建立了这类梯级电站群最优调度的双目标、多维、动态数学模型。对于这种复杂模型的求解,采用了目前较为成功的大系统分解协调方法。其中,站内运行采用模拟模型,全系统调度采用动态规划模型。经过模型求解,提出了一种控制站前水位变幅的简单调控方法。     

Community-level impacts induced by introduced largemouth bass and bluegill in farm ponds in Japan

Largemouth bass Micropterus salmoides and bluegill Lepomis macrochirus have been introduced into many countries and have become cosmopolitan exotic species. However, only a few studies show their impact on introduced communities. To investigate their impact, we performed natural snapshot experiments in 15 farm ponds in Saitama prefecture, eastern Japan. We selected 10 and 5 small ponds in similar environmental conditions, but with and without exotics, respectively. The numbers of fish, crustaceans, and nymphal odonates were smaller in ponds where exotics were found and some species were considered to be locally extinct in several ponds. On the other hand, the numbers of benthic organisms, i.e. tadpoles, chironomids, chaoborids, and Oligochaeta were more abundant in ponds with exotics. These two groups of organisms were separated clearly on the first axis of DCA, which indicats that this difference was mainly induced by bass predation. This result suggests a trophic cascade in which top-down effects induced by exotics propagated to fish, crustaceans, and nymphal odonates directly and to some benthic organisms indirectly. Therefore, when one is to conserve native organisms, attention should be paid not only to direct negative effects, but also to indirect effects propagating to various trophic levels. Because farm ponds are typical Japanese small lentic systems having rich biodiversities and bass and bluegill have been shown to change farm pond communities widely, conservational treatments including eradication of exotic fish should be conducted immediately.     

Large Dams,Restructuring and Regional Integration in Southeast Asia

Large dams are a dramatic intervention affecting ecosystems, livelihoods and resource use, notably in upland areas. Dams are significant, both in terms of their scale of impact and due to their role in appropriating part of the upland resource base for mainly lowland and urban beneficiaries. Whereas in the past the tensions associated with impact of dams in Southeast Asia have been played out within national borders, mainly in Thailand, the new impetus for dam construction reflects an internationalised agenda — namely integration of the mainland Southeast Asian regional resource economy. This paper examines the background to large dam construction in mainland Southeast Asia, current and projected developments, and their implications in a number of arenas. Case studies from Lao PDR, Thailand and Vietnam illustrate the main points. It is shown that political­economic restructuring associated with the changing geopolitics of the region is a major influence on the revived agenda for large dam construction, and that such restructuring modulates the direct and indirect impacts of dams at local, national and regional levels.     

Effects of a suspended shade cloth cover on water quality of an agricultural reservoir for irrigation

Water availability and quality are two fundamental factors for agriculture in arid and semi-arid regions. This study evaluates the effects of a water-permeable, Suspended Shade Cloth Cover (SSCC), on the quality of water stored in an on-farm Agricultural Water Reservoir (AWR). Water quality (water temperature, electrical conductivity, chlorophyll-a concentration, dissolved oxygen concentration and water turbidity) and environmental (evaporation, rainfall, wind speed and solar radiation) parameters were measured over a 2-year period in a typical AWR located in south-eastern Spain. In the first year, the AWR remained uncovered and the behaviour was quasi-isothermal. In the second year, installing a SSCC induced a thermal gradient in the water that reached a maximum temperature difference of 12 °C during summer. The lack of turbulence under the cover and the reduction in photosynthesis (95% reduction of chlorophyll-a) reduced the concentration of dissolved oxygen to 1.5 mg L⁻¹, and turbidity from 40 NTU at installation to less than 1 NTU. The positive balance between rainfall and evaporation during the second year reduced the electrical conductivity of the water by 8.2%. The improvement in water quality associated with the installation of a SSCC increases the efficiency of drip irrigation systems by reducing the water filtering requirements, the likelihood of emitter clogging, and the risk of irrigation-induced salinity.     

农村饮水安全工程阶梯水价优化设计

合理的水价是保障供水工程健康发展,实现可持续的农村饮水安全的必要条件.提出由生存水量和生活水量构成的2级阶梯水价是适合农村现状的水价模式;分析了农村供水工程的成本回收、用水户的用水需求、生存水量的核定,以及水价承受能力问题,在此基础上建立了阶梯水价优化模型;以山东临清某农村水厂为例进行了实例测算,结果表明该方案有积极的实施价值.     

The impacts of invasive rodents on island invertebrates

The widespread invasive rodents Rattus norvegicus, R. rattus, R. exulans and Mus musculus have been implicated in the decline and extinction of hundreds of island endemic vertebrates, but their effects on island invertebrates are less well-known. Here I present the first global review of the subject, which confirms that large-bodied invertebrates are most at risk from these rodents, and that although a disproportionate number of studies (69%) are from New Zealand, rodent-invertebrate impacts are geographically widespread. Mechanisms of impact are both direct (mediated by predation) and indirect (involving intermediary species). Some studies also suggest knock-on effects on ecosystem properties, and given the diverse ecological functions of invertebrates (as detritivores, primary consumers, predators, prey and pollinators), I suggest that an understanding of the interactions between invasive rodents and invertebrates in island ecosystems is essential for effective conservation management. Currently many reported impacts are unquantified, come from uncontrolled and unreplicated designs, or rely on time-series with inadequate baseline data. In addition to basic improvements in study design, this review highlights a need for studies which investigate mechanisms of impact, or impacts across trophic levels.     

Economic Feasibility of Saving Water Through Controlling Outflow of Ghanats

The purpose of this study was toinvestigate the economic feasibility ofimplementing a scheme to control theoutflow of ghanats in Iran. The schemesaves an average of 34,000 m3 of waterper ghanat each year during the months whenthere is no agricultural activity. Thewater saved will later be used forirrigation purposes. The cost of theimplementation of the scheme is compared tothose of two other alternatives: theconstruction of new ghanats and the diggingof new wells to provide the same amount ofwater saved by the scheme. The resultsindicate that obtaining the amount of watersaved by executing the scheme costs 877 and26 times less than those required forproducing a new ghanat or a new well,respectively. On the basis of theseresults, application of the scheme to 25%of the existing ghanats in Iran that aretechnically suitable is stronglyrecommended.