清江流域水布垭水库二氧化碳大气廓线空间分布及其水环境效应

为了研究水库水体二氧化碳源汇变化时空分布格局及其影响因素,选择清江流域水布垭水库为典型示范案例,在2010年5月8日到9日开展了二氧化碳观测实验,获取了水库上空大气二氧化碳浓度垂直变化以及沿水库中心线二氧化碳浓度的变化特征。然后基于地理信息系统空间分析技术对观测点二氧化碳浓度数据进行空间插值计算,得到整个水库水体的空间分布特征,并与水环境因子空间分布情况进行比较分析。研究结果表明：水布垭水库上空大气二氧化碳浓度在05 m高度以下最高,然后向上依次降低,其空间分布从水库上游到坝前呈现增加的趋势。同时水库水体二氧化碳浓度变化受到表层水温、叶绿素浓度等水环境重要因素的影响,与水温和气温呈负相关关系,而与叶绿素呈正相关关系     

门楼水库总氮环境容量计算及其总量控制方案研究

文中分析了门楼水库的总氮污染状况,提出了门楼水库总氮环境容量的计算原则、设计水文条件和水质保护目标,为改善市区居民的饮用水质量,保障市民的身体健康,制定合理的污染控制方案,提供了科学的参考依据。     

浅谈国内外江河湖库水体富营养化状况

随着人类对环境资源开发利用活动日益增加，特别是进入本世纪以来，工农业生产大规模地迅速发展，工业化带来了“城市化”现象，使得大量含有氮、磷营养物质的生活污水排入附近的湖泊，水库和河流，增加了这些水体的营养物质的负荷量，为了提高农作物产量，施用的化肥和牲畜粪便逐年增加，经雨水冲刷和渗透，进入水体的营养物质不断增多，以上这些人为因素的影响，极大地减少了水体由贫营养向富营养过渡所需要的时间，国内外的现状调查结果表明，在全球范围内30％－40％的湖泊和水库遭受不同程度富营养化影响，我国近年来湖泊富营养化呈发展趋势，从20世纪80年代后期的41％上升到90年代后期的77％，水库富营养化问题也较严重，处于富营养状态的水库个数和库容分别占所调查水库的30．8％和11．2％，总体而言，水体发生富营养化的程度和范围呈发展趋势，城市湖泊及邻近城镇的水库水体富营养化程度较高，湖泊和水库等相对静止的水体发生富营养化现象重于河流，但河流富营养化问题也不容轻视，富营养化已成为世界范围内水环境保护中的重大环境问题。     

用实测资料计算流域非点源污染负荷：以四川清平水库为例

把流域非点源污染负荷分成地面径流污染负荷、地下径流污染负荷和壤中流污染负荷。用水文学方法找出典型年河水中地下径流成分，然后分割出壤中流和地面径流。再根据实测的水质和流量资料计算出流域非点源污染负荷。方法简单可靠，具有典型性和代表性。     

Assessing the Eutrophication of Shengzhong Reservoir Based on Grey Clustering Method

Reservoir water environment is a grey system. The grey clustering method is applied to assessing the reservoir water enviromnent to establish a relatively complete model suitable for the reservoir eutrophication evaluation and appropriately evaluate the quality of reservoir water, providing evidence for reservoir management. According to China＇s lakes and reservoir eutrophication criteria and the characteristics of China＇s eutrophication, as well as certain evaluation indices, the degree of eutrophication is classified into six categories with the utilization of grey classified whitening weight function to represent the boundaries of classification, to determine the clustering weight and clustering coefficient of each index in grey classifications, and the classification of each clustering object. The comprehensive evaluation of reservoir eutrophication is established on such a foundation, with Sichuan Shengzhong Reservoir as the survey object and the analysis of the data attained by several typical monitoring points there in 2006. It is found that eutrophication of Tiebian Power Generation Station, Guoyuanchang and Dashiqiao Bridge is the heaviest, Tielusi and Qinggangya the second, and Lijiaba the least. The eutrophication of this reservoir is closely relevant to the irrational exploitation in its surrounding areas, especially to the aggravation of the non-point source pollution and the increase of net-culture fishing. Therefore, it is feasible to use grey clustering in environment quality evaluation, and the point lies in the correct division of grey whitening function     

湖北省主要大中型水库富营养状况及特征分析

水库在城市供水、工业用水、水产养殖、农业灌溉、水利防汛以及景观旅游等方面发挥着重要的作用,但随着社会经济的发展,部分水库的富营养化状况日益严重,成为影响社会经济发展的重大环境问题。通过在2010年的3、6、7、10月对湖北省30座主要大中型水库进行布点采样,对水体的水质状况分别进行了调查、监测,采用《地表水环境质量标准》湖库标准进行水质类别分析,采用湖库营养状态指数法对湖泊富营养化评价, 并运用因子聚类分析方法对这些水库进行了类型划分。结果表明：30座大、中型水库有14座水库水质类别为Ⅱ类~Ⅲ类, 占467%; 有8座水库水质类别为IV类,占267%;有8座水库水质类别为Ⅴ类或劣Ⅴ类,占267%;除白云湖水库为轻富营养化外,其余29座水库均属中营养状态;氨氮、磷作为营养物质是这些水库富营养化的主要影响因素,溶解氧对水体富营养化有重要影响,总氮、水温和有机物污染对水体富营养化产生较大影响;30座水库聚类分为城市工业废水污染源型、生活污水污染源型、农业非点源污染源型和养殖轻污染型4种水库类型。针对水库的污染类型,分别提出了减缓防治措施     

Scenario‐Based and Scenario‐Neutral Assessment of Climate Change Impacts on Operational Performance of a Multipurpose Reservoir

Scenario‐based and scenario‐neutral impacts assessment approaches provide complementary information about how climate change‐driven effects on streamflow may change the operational performance of multipurpose dams. Examining a case study of Cougar Dam in Oregon, United States, we simulated current reservoir operations under scenarios of plausible future hydrology. Streamflow projections from the CGCM3.1 general circulation model for the A1B emission scenario were used to generate stochastic reservoir inflows that were then further perturbed to simulate a potentially drier future. These were then used to drive a simple reservoir model. In the scenario‐based analysis, we found reservoir operations are vulnerable to climate change. Increases in fall and winter inflow could lead to more frequent flood storage, reducing flexibility to store incoming flood flows. Uncertainty in spring inflow volume complicates projection of future filling performance. The reservoir may fill more or less often, depending on whether springs are wetter or drier. In the summer, drawdown may occur earlier to meet conservation objectives. From the scenario‐neutral analysis, we identified thresholds of streamflow magnitude that can predict climate change impacts for a wide range of scenarios. Our results highlight projected operational challenges for Cougar Dam and provide an example of how scenario‐based and scenario‐neutral approaches may be applied concurrently to assess climate change impacts.     

Small farm ponds: overlooked features with important impacts on watershed sediment transport

Despite their size, small farm ponds are important features in many landscapes. Yet hydrographical databases often fail to capture these ponds, and their impacts on watershed processes remain unclear. For a 230‐km² portion of central Texas, United States (U.S.), we created a historical inventory of ponds and quantified the accuracy of automated detection methods under varying drought conditions. In addition, we documented pond dredging/enlargement events and identified sites that had been abandoned. We also analyzed sediment cores from downstream reservoirs to track changes in watershed sediment transport. Over 75 years, pond densities increased more than 350% — to among the highest documented in the U.S. — and the ability of automated methods to detect these ponds was highly dependent on drought severity (R² = 0.96). Approximately 5% of ponds present in the 1950s were no longer present in 2012, while 33% were dredged between 1937 and 2012. Downstream reservoir sedimentation has decreased by an average of 55% as ponds have increased in number. These findings suggest that small ponds and the maintenance of trapping efficiency have large‐scale impacts on sediment dynamics. Accurately accounting for these storage effects is vital to water resource planning efforts.     

Recycling Irrigation Reservoir Stratification and Implications for Crop Health and Production

Recycling irrigation reservoirs (RIRs) are an emerging aquatic ecosystem and water resource of global significance. This study investigated the vertical distribution of water temperature, dissolved oxygen (DO), and pH in eight RIRs at two nurseries each in Virginia and Maryland from 2011 to 2014. Monomictic thermal stratification was observed from April to October in all RIRs, despite their shallow depths (0.75‐3.89 m). The strongest stratification had a top‐bottom temperature difference of 21.53°C. The top‐bottom temperature difference was positively correlated with water column depth, air temperature, and daily light integral (p < 0.05). Wind speed did not impact the thermal stratification, likely due to their relatively small surface areas. Thermal stratification affected the vertical distribution of DO and pH. The top‐bottom differences in DO and pH were greater during stratification periods than nonstratification periods. Water pH in all RIRs was higher at the top than at the bottom with the greatest difference of 4.16 units. Discovery and characterization of thermal stratification in RIRs helps understand water quality dynamics in this novel ecosystem and promote safe and productive water reuse for irrigation. Specifically, water withdrawal depths should be adjusted according to variations in temperature, DO, and pH during the stratification and nonstratification periods to mitigate pathogen risk and improve water treatment efficacy and crop production.     

Synthesis of Common Management Concerns Associated with Dam Removal

Managers make decisions regarding if and how to remove dams in spite of uncertainty surrounding physical and ecological responses, and stakeholders often raise concerns about certain negative effects, regardless of whether these concerns are warranted at a particular site. We used a dam‐removal science database supplemented with other information sources to explore seven frequently raised concerns, herein Common Management Concerns (CMCs). We investigate the occurrence of these concerns and the contributing biophysical controls. The CMCs addressed are the following: degree and rate of reservoir sediment erosion, excessive channel incision upstream of reservoirs, downstream sediment aggradation, elevated downstream turbidity, drawdown impacts on local water infrastructure, colonization of reservoir sediments by nonnative plants, and expansion of invasive fish. Biophysical controls emerged for some of the concerns, providing managers with information to assess whether a given concern is likely to occur at a site. To fully assess CMC risk, managers should concurrently evaluate site conditions and identify the ecosystem or human uses that will be negatively affected if the biophysical phenomenon producing the CMC occurs. We show how many CMCs have one or more controls in common, facilitating the identification of multiple risks at a site, and demonstrate why CMC risks should be considered in the context of other factors such as natural watershed variability and disturbance history.