共查询到20条相似文献，搜索用时 15 毫秒
1.
Z. K. Ermakhanov I. S. Plotnikov N. V. Aladin P. Micklin 《Lakes & Reservoirs: Research and Management》2012,17(1):3-9
Aboriginal ichthyofauna of the Aral Sea consisted of 20 generative‐freshwater species from seven families. After acclimatization in 1927–1963, the number of species increased to 34. The regulation of Syr Dar’ya and Amu Dar’ya river water flows, and increasing water withdrawals, primarily for irrigation, resulted in a declining lake water level, increasing salinization and changing habitat conditions, especially for reproduction. As a result, the spawning areas were greatly reduced, and because of worsening conditions for natural reproduction, fish catches in 1961–1976 decreased more than 4‐fold. The first signs of the negative impacts of salinization on fishes appeared in the mid‐1960s. Natural reproduction ceased by the mid‐1970s, and indigenous commercial fish fauna were lost by the end of the 1970s. Flounder‐gloss was introduced from the Black Sea in 1979–1987 to preserve the fishery, and it was the only commercial fish left by 1991–2000. Because of the water level decline, the Aral Sea became divided in 1989 into the Large and Small Seas. By the end of the 1990s, flounder became extinct in the Large Aral because of high salinity, as did other fishes. Decreasing agriculture activity has resulted in stabilized run‐off of the Syr Dar’ya to the Small Aral since 1988, creating a freshened water zone where indigenous ichthyofauna returned from lacustrine systems and the river. The ecological state of the Small Aral is improving, with some aboriginal valuable commercial fishes having reached numbers making their commercial catch possible once again. 相似文献
2.
Igor S. Plotnikov Zaualkhan K. Ermakhanov Nikolai V. Aladin Philip Micklin 《Lakes & Reservoirs: Research and Management》2016,21(4):315-328
The Aral Sea is a terminal lake lying within the deserts of Central Asia in Kazakhstan and Uzbekistan, draining the Amu Darya and Syr Darya rivers. Before the 1960s, it was a large brackish water lake with an average salinity of 10.3 g L?1. The anthropogenic regression and salinization of the Aral Sea at that time resulted from increasing water withdrawals from the Amu Darya and Syr Darya for irrigation purposes. The salinization resulted in the disappearance of most of its invertebrates and all freshwater fish. As a result of the water level decrease, the Aral Sea divided into a northern Small Aral and a southern Large Aral at the end of the 1980s, with the two having different hydrological regimes. After construction the first Kokaral Dam in 1992, the water level of the Small Aral Sea increased by >1 m, with a gradual decline in the salinity beginning. To date, the Small Aral has again become brackish. Its average salinity reached 5.3 g L?1 by April–May 2013, with the highest salinity of 9.9 g L?1 in Butakov Bay, whereas the salinity was very low at 1.2–2.0 g L?1 in the estuary zone of the Syr Darya. There is an ongoing process of restoration of the former biodiversity, with many fresh water and brackish water invertebrate species reappearing due to the decreasing salinity. Freshwater fish species (bream, roach, carp, asp, zander, wels, etc.) returned into the Small Aral from the Syr Darya River and lakes in its lower reaches where they survived. Fisheries are recovering and catches are growing. Continuing salinity decreases, however, may cause decreases in the numbers, or even disappearance, of marine and halophilic invertebrate species. This study summarizes the results of studies of the Small Aral zooplankton, zoobenthos and ichthyofauna carried out in the spring of 2013. An historical review of changes in the Aral Sea and its fauna also is presented. 相似文献
3.
Abstract: The governments of the Aral Sea Basin countries, in cooperation with international organizations (UNESCO and World Bank) came up with a “water vision “for the region until 2025. The landlocked Aral Sea has been suffering from an imbalance in water evaporation, and, water inflow from its two main sources — Amu Darya and Syr Darya rivers, when the planners in the former Soviet Union from the 1960s diverted the river waters for irrigation. The irrigated area has increased from the 1960s by two‐thirds to 7 million hectares and the population by three‐fold to 50 million in the basin countries. Consequently the inflow to the Aral Sea from these two rivers decreased from 55 km3 in 1960 to a few km3 during the 1980s and 1990s. This has resulted in one of the worst man‐made ecological disasters of the century. In this paper, we examine different scenarios to achieve the vision goals and whether it is indeed feasible. Using IWMI basin‐oriented water accounting principles, we have shown that significant amount of water is being wasted in the region. Our analysis concludes that though not all the vision goals are likely to be met over the next 25 years, the inflow into the Aral Sea can be increased to over 20 km3 through better management and use of water resources. 相似文献
4.
Vadim I. Sokolov 《国际水》2013,38(2):104-115
Abstract The Uzbek socio-economic structure is characterized by the transition from a centrally-planned to a market-orientated economy, with a shifting from agricultural production to industrial development. However, the agricultural sector continues to play a significant role in a general economy of the country. The major water sector strategy is to decrease the dependence of agricultural production on climate by introducing advanced irrigation techniques and water saving methods to achieve future sustainable socio-economic development and environmental protection. Water management policy should be flexible enough to adapt to new demands. The regulation of consumption through demand management tools, such as appropriate pricing policies, has recently received greater attention in Uzbekistan. The main thesis of this paper is that allocation of water resources cannot be separated from ecological and economic considerations. The establishment of development objectives and the identification of constraints are also discussed. In the coming years, special attention will need to be paid to the control of water pollution and land salinization, water resources conservation, and acknowledging that actions to increase water productivity are as important as finding additional sources of water. 相似文献
5.
The construction of the Rogun Dam in the Amu Darya Basin to increase upstream energy generation creates potential trade-offs with existing downstream irrigation, due to the different timing of energy and irrigation water demands. The present analysis, based on a hydro-economic optimization model, shows that cooperative basin-wide maximization of benefits would lead to large increases in upstream hydropower production and only minor changes in downstream irrigation benefits. However, if upstream stations, including Rogun, are managed unilaterally to maximize energy production, hydropower benefits might more than double while irrigation benefits greatly decrease, thereby substantially reducing overall basin benefits. 相似文献
6.
Hussam Hussein 《国际水》2017,42(5):527-542
This article explores how the idea of a canal connecting the Dead Sea with either the Red Sea or the Mediterranean Sea has evolved. It analyzes the proposals, the official interests, and the undeclared reasons. It provides a critical understanding of the discourses behind the complex hydro-political dynamics in a changing and contested topography within the context of a wider geopolitical conflict. This study sheds lights on the relations between interests, discourses, and the canal project. This study contributes to the literature on water history by shedding light on the evolving relations between interests, discourses, and the canal project. 相似文献
7.
Aharon Oren 《Lakes & Reservoirs: Research and Management》2010,15(3):215-222
The Dead Sea, on the border between Israel and Jordan, currently contains around 348 g salt L?1. Divalent cations (Mg2+, Ca2+) dominate over monovalent cations (Na+, K+), while Cl? and Br? are the main anions. The pH of the Sea is about 6. The water balance of the lake is negative, having dropped over 1 m year?1 over the past decade. The water is supersaturated with Na+, with massive quantities of halite precipitating to the bottom of the lake. Biological monitoring since 1980 has indicated that blooms of the unicellular green alga Dunaliella and halophilic Archaea of the family Halobacteriaceae only develop following significant dilution of the upper water layers in the lake after very rainy winters. Such events occurred in 1980, and even more dramatically in 1992, when up to 3.5 × 107 Archaea mL?1 in the diluted upper 5–10 m of the water column coloured the lake red. Species isolated from the lake include Haloferax volcanii, Haloarcula marismortui, Halorubrum sodomense and Halobaculum gomorrense. Dunaliella was no longer observed in the lake after 1996, with prokaryote numbers remaining low. To characterize the residual microbial community in the lake, biomass was collected in February 2007 for environmental genomic analyses. The results were compared with the metagenome of microbial bloom material collected in 1992. The 16S rRNA archaeal phylotypes recovered from the 2007 sample were diverse, with phylotypes distantly related to the genera Halorhabdus, Haloplanus, Natronomonas and others. Halorhabdus sp. also was recovered in culture. The 1992 bloom sample was very homogeneous, however, with a single cluster remotely related to Halobacterium salinarum. These results illustrate that the microbial communities are dynamic, even in one of the most extreme environments on Earth, and exhibit strong shifts in species composition as conditions for life become increasingly adverse. 相似文献
8.
Nathan S. Bracken 《Journal of Contemporary Water Research & Education》2012,148(1):24-32
Most western states allow landowners to withdraw certain amounts of groundwater for specified purposes without obtaining a water right permit. As water demands increase in the West, some developers are using exempt wells to supply water to residential developments without acquiring the permits and water rights needed to build public water supply systems. This has led to concerns that the cumulative impact of these wells could impair senior water rights, create environmental problems, and threaten water quality in some areas. This article explores the considerations associated with mitigating exempt well impacts and argues that surgical approaches focused on specific issues and geographic areas (scalpels) are more politically and administratively feasible than broad efforts to repeal or reduce exemptions on a statewide basis (hammers). The views expressed in this article are those of the author alone and do not represent those of the Western States Water Council or its member states. 相似文献
9.
Philip Micklin 《Lakes & Reservoirs: Research and Management》2010,15(3):193-213
The Aral Sea, a once vast brackish terminal lake in the heart of Central Asia, has been rapidly drying since the 1960s. It had separated into four separate waterbodies by September 2009. The maximum water level decline was more than 26 m, whereas the lake surface area decreased 88% and the water volume 92%. The lake salinity increased by more than 20‐fold. Prior to the modern recession, the Aral Sea experienced a number of water level declines and subsequent recoveries over the last 10 millennia. The main causative factor until the 1960s was the periodic westward diversion of the Amu Dar’ya, the main influent river, towards the Caspian Sea by both natural and human forces. The post‐1960 recession, however, was overwhelmingly the result of unsustainable irrigation development. The lake’s modern recession has caused a broad range of severe negative ecological, economic and human welfare problems. To restore the Aral Sea to its 1960s’ size and ecological condition would be very difficult, if not impossible, in the foreseeable future. The plight of the Aral Sea, however, is far from hopeless. Partial restoration of portions of the lake is still feasible. A project to raise the Small (northern) Sea was completed in Fall 2005, raising its water level by 2 m, and lowering its salinity to a level not much higher than the early 1960 levels. Its ecological recovery has been dramatic, and a new project to improve further the Small Aral was recently announced. Improving the Large (southern) lake would be much more difficult and expensive. A project to save the deep Western Basin partially is technically feasible, however, and should be given careful evaluation. It is important to repair and preserve what is left of the deltas of the two tributary rivers, Syr Dar’ya and Amu Dar’ya, as these two rivers are of great ecological and economic value, and act as biological refugia for endemic species of the Aral Sea. 相似文献
10.
Jenna Tyler Rebecca M. Entress Pin Sun Douglas Noonan Abdul-Akeem Sadiq 《Journal of Flood Risk Management》2023,16(2):e12886
The United States Federal Emergency Management Agency (FEMA) provides funding to state and local governments as well as tribes and territories (SLTTs) through its Flood Mitigation Assistance (FMA) grant program to engage in flood risk management efforts. Although all communities are susceptible to flooding, flooding does not impact communities equally. This article contributes to FEMA's goal of addressing equity concerns by examining whether the FMA program is distributed equitably in counties located in eight coastal states in the United States. Using secondary data from OpenFEMA, the Centers for Disease Control and Prevention/Agency for Toxic Substances and Disease Registry, and parcel-level flood risk data from First Street Foundation from 2016 to 2020, results indicate that socially vulnerable counties are less likely to receive FMA funding, and counties with greater average flood risk are more likely to receive FMA funding. The findings suggest that there is an opportunity for FEMA to improve the FMA program so that funding can be more equitably distributed, such as providing grant writing and application training and support to socially vulnerable communities, educating socially vulnerable communities about the benefits of the FMA program, and extending the application deadline for socially vulnerable communities impacted by flood events. 相似文献
11.
《Journal of Flood Risk Management》2018,11(2):141-151
While a portfolio approach to flood mitigation that combines structural and non‐structural measures provides many benefits, in practice, the selection and implementation of flood mitigation measures is a complex process. This research examines the factors influencing the choice of flood mitigation measures by 27 rural municipalities in Western Massachusetts and the opportunities and constraints they face in implementing flood mitigation. The physical and institutional characteristics of these rural municipalities drive them to prioritise structural over non‐structural flood mitigation measures. Yet implementation of those measures is often hindered by state and federal regulations and by barriers to accessing state and federal assistance programmes. Consequently, the municipalities engage in reactionary and ancillary flood mitigation, and remain vulnerable to future flood events. These findings point to the importance of tailoring government policies and programmes to the specific context in which flood mitigation occurs, including the unique characteristics of rural municipalities. 相似文献
12.
Panagiotis Stefanidis Stefanos Stefanidis 《Lakes & Reservoirs: Research and Management》2012,17(2):113-117
The biggest threat to reservoirs after their construction, which can reduce their capacity, life cycle and water quality, is sediments carried inflowing streams. The sediment volumes in four reservoirs in Central Macedonia, Greece, were measured in this study. These measurements indicated the study reservoirs are under serious threat from sedimentation. Appropriate measures to protect these newly formed reservoirs from sedimentation also are proposed. 相似文献
13.
Laura Ziemer Sarah Bates Meg Casey Ada Montague 《Journal of Contemporary Water Research & Education》2012,148(1):33-43
Over the last decade, Montana's fastest growing basins have experienced a surge of reliance on a certain “permit‐exempt well loophole,” which enables small ground water diversions to avoid having to go through the regulatory process that determines whether the proposed use would adversely impact senior water users and ground water supply. This loophole has generated significant conflict with senior right owners in areas where exempt wells have provided water for large‐scale residential developments. As a partial solution, this article examines ground water mitigation exchanges designed to address similar issues in Washington and presents the 63rd Montana Legislature with recommendations for a Montana pilot project. 相似文献
14.
根据中国的经济发展状况和能源结构,大力发展水电势在必行.如何正确处理好水电开发与环境保护之间的关系,做到可持续发展,显得尤为重要.文章从生态环境、水土流失、水环境、移民安置、施工期的大气及声环境和人群健康等方面,论述了水电开发引发的主要环境问题及对策.在工程建设中重视环境保护,认真落实环保措施,就可以实现水电开发和环境保护双赢的目标. 相似文献
15.
This paper presents a study that aims to evaluate the impact of periurban development on the flood regime of a small river crossing a densely urbanised area, the city of Lyon (France). This research was conducted on the catchment of the Yzeron River in western Lyon. Statistical tests showed that both flood frequency and severity have increased in this catchment, between two distinct periods: the 1970s and the 1990s. Evaluation of the specific impact of urban development on the flood regimes requires the paying of attention to all possible contributing factors. For that purpose, we used a diachronic approach, with hydrologic and land‐use data from the two periods. We used these data to calibrate a distributed hydrologic model and then to simulate the urban, periurban, and rural hydrologic contributions in the past but also in the future. We also compare the floodable vulnerability amount with the flood hazard increase between the two periods to assess what components mainly affect the flood risk during this land‐use evolution. Finally, the basin scale efficiency of a generalised on‐site rainwater retention technique is evaluated to know how that technique could contribute to mitigate flood risk. 相似文献
16.
以节约能源,提高电厂汽轮机生产效率为目的,通过对电厂常用的300MW汽轮机的运行参数及能量转换过程等的分析,将汽轮机的损失分为两大类,一类是汽轮机的外部损失,一类是汽轮机的内部损失。重点总结出了汽轮机内部的七项主要级内损失:喷嘴损失、动叶损失、余速损失、鼓风摩擦损失、扇形损失、漏汽损失及湿汽损失,同时从不同角度分析了这七项级内损失产生的原因,并从汽轮机的结构设计与选择、增加相应的辅助装置或部件等方面阐述了减小各项级内能量损失的措施,以提高机组运行效率。 相似文献
17.
Roger J. Higgins 《河流研究与利用》1988,2(5):573-581
Subsequent to the selection of design capacity and the construction of a storage reservoir, water demands, valley land-use, and economic constraints may change and the reallocation of storage space in an existing reservoir may become desirable. The benefits of reallocating space to flood mitigation are the equivalent annual flood damages averted, while the costs arise from water shortages which would not have occurred if space had not been reallocated. These benefits and costs can be quantified for a particular region and the optimal airspace provision calculated. In a case study area, reallocation of part of the storage volume was justified, while excessive reallocation would result in significant net costs to the region. The optimum airspace allocation was not sensitive to the value assigned to water. The procedure used here could be applied to other river valleys, where the solution would be dependent on the intensity of land-use, as it influences both potential flood damages and the costs of water shortages. 相似文献
18.
针对跋山水库2004年度的库区淤积测量资料，分析了淤积量时间变化规律、空间变化规律，研究了库区淤积物淤积形态，掌握了库区淤积物颗粒组成规律，并提出了相应的水库减淤措施。 相似文献
19.
Robert L. Miller 《Journal of Flood Risk Management》2023,16(3):e12917
River diversions are a commonly used water management tool throughout the world. Low-gradient coastal rivers exhibit complex floodplain interactions and are subject to multiple uncertain drivers of future flood risk. The interacting factors make quantification of downstream diversion effects on ambient flood hazards in coastal riverine ecosystems challenging. This article analyzes the effects of a managed ecological diversion (MED) on downstream flood hazards in the flood-prone tidal freshwater Vermilion River system situated within the Atchafalaya Basin region of Louisiana, USA. A flexible and efficient hydraulic and hydrologic (H&H) modeling setup and counterfactual approach is utilized to develop and analyze 60 simulation scenarios aimed at quantifying the effects of an existing baseflow augmentation program on downstream flood hazards under uncertain future conditions. The analysis demonstrated the significance of preemptive diversion closure on the downstream flood levels in downstream rivers. The role of wetland topography and residual floodplain storage on MED-induced flood response was also highlighted. A variety of uncertain parameter/forcing scenarios were also evaluated to establish robustness of the findings and to extend the results to more general settings. The study provides insights on downstream flood response induced by MEDs, which are expected to become more prevalent in the future. 相似文献
20.
大地电磁法是一种天然源电磁测深方法,具有勘探深度较大,分辨能力强,观测效率高的特点,是探测岩溶及研究地质构造和寻找隐伏断层的 有效方法。尤其在大中型隧道的前期勘探中将会发挥重要的作用。该方法与常规的同类物探方法相比,在勘探深度和分辨率均有较大的提高。介绍了大地电磁法在沪蓉国道隧道比选勘 探中的应用效果,查明了两条测线的溶洞发育情况、断层分布及其特征,为今后在隧道、桥址地质勘察中快速探测溶洞及断层等地质构造,探索了一条新途径。 相似文献