A warning from an ancient oasis: intensive human activities are leading to potential ecological and social catastrophe

The Shiyang River Basin is an inland river basin in the Hexi Corridor, Gansu Province, northwest China. Shiyang is the largest basin in terms of human population density and has the highest exploitation of water resources in the northwest. Serious water shortages constrain social and economic development, and the area has some of the worst ecological and environmental deterioration in China. From historical data and recent observations, we have analysed changes in water systems in the Minqin oasis, at the end of the river basin, and assessed impacts and consequences of a changing climate and intensive human activity. Historically, climate change has been the main cause of changes in the oasis. In the last 50 years, however, a major influence has been intense human activity in the basin. With increasing population (159% in 50 years), the amount of cultivated land has been greatly expanded (by 51%). Many reservoirs have been built by damming rivers and large-scale irrigation has been introduced in the middle reaches of the basin. The introduction of leakage-free canals and more extensive exploitation of underground water have further expanded the irrigated area. Water use by humans has exceeded the carrying capacity of the water resources of the basin, which has led to a dramatic shift in water allocation between the upper and lower reaches and a rapid drop in the water table in the Minqin oasis (by as much as 14 m). The oasis is shrinking, natural vegetation that relies on underground water is disappearing, and desertification is accelerating. An ancient oasis that can be traced back 2000 years is disappearing and this must be a warning sign for future generations.     

Rehabilitating China's Largest Inland River

Abstract:  Wetlands are particularly important for conserving China's biodiversity but riparian wetlands in the Tarim River basin in western China have been reduced by 46% during the last 3 decades. The world's largest habitat for Populus euphratica , which is in the Tarim River basin, significantly shrank. To protect and restore the deteriorated ecosystems along the Tarim River and its associated wetlands, China's government initiated a multimillion dollar river restoration project to release water from upper dams to the dried-up lower reaches of the Tarim River starting in 2000. We monitored the responses of groundwater and vegetation to water recharge in the lower reaches of the river from 2000 to 2006 by establishing nine 1000-m-long transects perpendicular to the river at intervals of 20–45 km along the 320-km river course below the Daxihaizi Reservoir, the source of water conveyance, to Lake Taitema, the terminus of the Tarim River. Water recharges from the Daxihaizi Reservoir to the lower reaches of the Tarim River significantly increased groundwater levels and vegetation coverage at all monitoring sites along the river. The mean canopy size of the endangered plant species P. euphratica doubled after 6 years of water recharge. Some rare migrating birds returned to rest on the restored wetlands in summer along the lower reaches of the Tarim River. The biggest challenge facing decision makers, however, is to balance water allocation and water rights between agricultural and natural ecosystems in a sustainable way. A large number of inhabitants in the Tarim Basin depend on these limited water resources for a living. At the same time, the endangered ecosystems need to be protected. Given the ecological, socioeconomic, and sociopolitical realities in the Tarim Basin, adaptive water policies and strategies are needed for water allocation in these areas of limited water resources.     

Projected Climate‐Induced Habitat Loss for Salmonids in the John Day River Network,Oregon, U.S.A.

Abstract: Climate change will likely have profound effects on cold‐water species of freshwater fishes. As temperatures rise, cold‐water fish distributions may shift and contract in response. Predicting the effects of projected stream warming in stream networks is complicated by the generally poor correlation between water temperature and air temperature. Spatial dependencies in stream networks are complex because the geography of stream processes is governed by dimensions of flow direction and network structure. Therefore, forecasting climate‐driven range shifts of stream biota has lagged behind similar terrestrial modeling efforts. We predicted climate‐induced changes in summer thermal habitat for 3 cold‐water fish species—juvenile Chinook salmon, rainbow trout, and bull trout (Oncorhynchus tshawytscha, O. mykiss, and Salvelinus confluentus, respectively)—in the John Day River basin, northwestern United States. We used a spatially explicit statistical model designed to predict water temperature in stream networks on the basis of flow and spatial connectivity. The spatial distribution of stream temperature extremes during summers from 1993 through 2009 was largely governed by solar radiation and interannual extremes of air temperature. For a moderate climate change scenario, estimated declines by 2100 in the volume of habitat for Chinook salmon, rainbow trout, and bull trout were 69–95%, 51–87%, and 86–100%, respectively. Although some restoration strategies may be able to offset these projected effects, such forecasts point to how and where restoration and management efforts might focus.     

Perspectives on small watershed management in China: the case of Biliu

River basin management in China has focused on large rivers, such as the Yangtze and Yellow Rivers. However, there are also about 20,000 small river basins that deserve attention. The Biliu River basin in Liaoning Province, northeast China, which is 156 km in length, has many features common to small river basins, including divided jurisdiction among governments leading to vertical and horizontal fragmentation. In the Biliu basin, the key municipalities are Dalian with a population of almost 6 million people and Yingkou with about 2.28 million people. Each has different interests and needs, making coordination and collaboration difficult. The literature and practice suggest that effective integrated water resource management (IWRM) requires at least six features: (1) vision, policy and strategy; (2) a legislative or statutory basis to provide credibility and authority; (3) a river basin organization to coordinate development and management; (4) specification of functions and authority of the river basin organization; (5) public participation and community involvement; and (6) an IRWM strategy and plan. Water management in the Biliu River basin is assessed relative to these features of IWRM, with recommendations offered regarding changes to have water management in the Biliu River basin to reflect what is expected in an IWRM approach.     

荒漠河岸生态系统退化机理的定量分析

通过野外监测资料,采用聚类分析与主成分分析法,分析了荒漠河岸生态系统退化的内外因素与驱动力、植被退化的环境主导因子与生态退化程度,结果表明:(1)地质、地貌与气候条件等因素的影响,塔里木河下游生态系统存在脆弱和不稳定性是其退化的内因,外界干扰则是其退化的外在因素。人为干扰则是其退化发生的驱动力,起因于人口的增加、需求的增长。(2)在此过程中导致植被受损的环境主导因子是水,植被退化是人类干扰作用于植被赖以生存的环境主导因子所致。(3)其不同河段的生态退化可以归为三类:潜在沙漠化类(轻度退化),轻度沙漠化类(中度退化),中度或重度沙漠化类(重度退化),其中第三类型,土壤条件与其它两类差异较大,表现出土壤退化的滞后现象。     

荒漠河岸生态系统退化机理的定量分析

通过野外监测资料,采用聚类分析与主成分分析法,分析了荒漠河岸生态系统退化的内外因素与驱动力、植被退化的环境主导因子与生态退化程度,结果表明：（1）地质、地貌与气候条件等因素的影响,塔里木河下游生态系统存在脆弱和不稳定性是其退化的内因,外界干扰则是其退化的外在因素。人为干扰则是其退化发生的驱动力,起因于人口的增加、需求的增长。（2）在此过程中导致植被受损的环境主导因子是水,植被退化是人类干扰作用于植被赖以生存的环境主导因子所致。（3）其不同河段的生态退化可以归为三类：潜在沙漠化类（轻度退化）,轻度沙漠化类（中度退化）,中度或重度沙漠化类（重度退化）,其中第三类型,土壤条件与其它两类差异较大,表现出土壤退化的滞后现象。     

胡杨年轮记录的塔里木河下游54年来区域水环境历史变迁

通过胡杨（Populus euphratica Oliv．）树木年轮宽度的分析,建立了塔里木河下游大西海子（A）、阿克墩（B）、亚合甫马汗（c）、英苏（D）、阿布达勒（E）、喀尔达依（F）、吐格买莱（G）、阿拉干（H）、依干不及麻（I）和考干（J）10个采样区过去54a来的STD、RES和ARS年表,并借助RES年表,采用年代际变化分析和突变检验,反演了塔里木河下游54a年来区域水环境状况变迁时空格局。结果表明：①下游10个样区54a来区域水环境状况具有多样性和复杂性,并不完全表现为距离下游上段（大西海子水库）越近其水环境状况就越好,区域水环境状况总体变异程度由低到高排序为A、G、C、H、E、D、I、B、F、J,也反映了下游10个样区生态退化程度的差异;②下游54a来区域水环境状况最好时期出现在20世纪60年代和21世纪初,大部分区域最差时期主要集中在20世纪90年代,是下游地区长达30a断流水环境变干累积效应的体现;③下游10个样区区域水环境变化具有明显的突变时间,突变出现时间相对水文事件年代具有滞后性。胡杨年轮记录的塔里木河下游54a来区域水环境时空变迁格局对下游生态退化的历史认识具有重要意义。     

Emergence cues of a mayfly in a high-altitude stream ecosystem: potential response to climate change.

To understand the consequences of human accelerated environmental change, it is important to document the effects on natural populations of an increasing frequency of extreme climatic events. In stream ecosystems, recent climate change has resulted in extreme variation in both thermal and hydrological regimes. From 2001 to 2004, a severe drought in western United States corresponded with earlier emergence of the adult stage of the high-altitude stream mayfly, Baetis bicaudatus. Using a long-term database from a western Colorado stream, the peak emergence date of this mayfly population was predicted by both the magnitude and date of peak stream flow, and by the mean daily water temperature, suggesting that Baetis may respond to declining stream flow or increasing water temperature as proximate cues for early metamorphosis. However, in a one-year survey of multiple streams from the same drainage basin, only water temperature predicted spatial variation in the onset of emergence of this mayfly. To decouple the effects of temperature and flow, we separately manipulated these factors in flow-through microcosms and measured the timing of B. bicaudatus metamorphosis to the adult stage. Mayflies emerged sooner in a warmed-water treatment than an ambient-water treatment; but reducing flow did not accelerate the onset of mayfly emergence. Nonetheless, using warming temperatures to cue metamorphosis enables mayflies to time their emergence during the descending limb of the hydrograph when oviposition sites (protruding rocks) are becoming available. We speculate that large-scale climate changes involving warming and stream drying could cause significant shifts in the timing of mayfly metamorphosis, thereby having negative effects on populations that play an important role in stream ecosystems.     

Impact of drought on the ecological and chemical status of surface water and on the content of arsenic and fluoride pollutants of groundwater in the province of Salamanca (Western Spain)

The impact of drought on the ecological and chemical status of surface and groundwaters of the River Tormes (River Duero basin, northwestern Iberian Peninsula) was studied to evaluate the evolution of the quality of the river during its passage through the city of Salamanca (Spain). The Water Quality Index (WQI) of the river revealed that the drought period of 2005 did not significantly affect water chemical quality. However, during the study period differences were found in surface water ecological quality, using phytoplankton quality as AN indicator. These differences may be accentuated as a result of regulation of the River Tormes by the Santa Teresa reservoir. Arsenic and fluoride concentrations were measured in water wells, finding higher arsenic concentrations after the drought period and no correlation between the arsenic and fluoride contents. The results are useful for an overall understanding of potential impact of climate change on the ecological and chemical status of water in regional systems.     

电解锰产业集聚区河流锰污染演变趋势和时空分布特征

松桃河流域是我国锰产业最为集中的区域之一,资源开发和利用形成的污染严重.通过对松桃河电解锰产业集聚区流域2015-2019年的8个典型断面的总锰监测数据的分析,用秩相关系数法探究了河流锰污染总体变化趋势,并用系统聚类分析法分析了河流锰的时空分布特征,结合聚类结果对污染趋势做进一步分析.秩相关系数分析结果表明,近年来松桃...     

Multi-scale evaluation of river health in Liao River Basin, China

Previous studies on river health evaluation mainly focused on characterizations at a river-corridor scale and ignored the complex interactions between the river ecosystem and other components of the river basin. Based on the consideration of the interactions among rivers, associated river basin and habitats, an assessment framework with multi-scale indicators was developed. An index system divided among these three scales to characterize the health of river ecosystems in China’s Liao River Basin was established. Set pair analysis was applied to integrate the multi-scale indicators and determine the health classes. The evaluation results indicated that the rivers in the western and eastern zones of the Liao River were classified as sick, and rivers in the main stream of the Liao and Huntai rivers were classified as unhealthy. An excessive level of disturbances, such as large pollution loads and dense construction of water conservation projects within the river basin, were the main causes of the river health deterioration.     

Effects of climate change on surface water management of Seyhan basin,Turkey

The goal of this study was to set-up the basis for climate change adaptation of water resources management policies in Seyhan River basin. The first priority was to identify the balances between water resources and water users with respect to existing and planned projects. In this respect various aspects of Seyhan basin were evaluated, including evaluation of existing water resources, determination of water demand of existing and planned projects, and water resources supply-demand characteristics. The global climate change model was downscaled to the basin scale, the results were associated with hydrometeorological monitoring network and finally the impact of climate change on surface water resources and demands were determined for specific projection years. Water resources management scenarios were developed to evaluate adaptation alternatives to climate change scenarios at the basin level. It was determined that even though there was no water stress in Seyhan basin in 2010, many parts of the basin were expected to suffer significant shortages over the coming years.     

塔里木河下游生态输水过程中荒漠河岸林活力恢复监测

根据近5年来对塔里木河下游荒漠河岸林植被的监测数据,分析了生态输水后植物活力的恢复状况.结果显示:应急生态输水增加了塔里木河下游的生物多样性,使原本面临死亡的荒漠河岸植被重新复活,而且不同程度上促进了胡杨群落的自然更新;在近河道50 m的范围内均出现了少量的胡杨、柽柳实生苗,并且在离河道150 m的范围内已经有相当数量的胡杨次生苗,在离河道400 m范围内大约有25%的胡杨均有不同程度的基部新枝萌蘖.通过生态输水后地下水位的逐步抬升,河道两岸的低阶地发育着一定面积的草甸植被,形成了由胡杨、柽柳和草本植物所组成的干旱区非地带性河岸稀疏植被群落,说明应急生态输水对于胡杨为建群种的荒漠河岸林植被的恢复和自然更新产生了积极的影响.     

基于利益相关方意愿调查的东江流域生态补偿机制探讨

流域生态补偿已经成为解决流域生态环境保护问题、协调流域上下游利益冲突的重要手段之一。以东江流域为例,通过实地问卷调查和条件价值评估法评估流域上下游利益相关方生态补偿意愿,并探讨构建东江流域生态补偿机制。流域生态补偿意愿调查结果表明,流域内居民对东江流域生态环境保护有很高的积极性,对建立流域生态补偿机制有较高的认同度;下游地区城市居民平均支付意愿为332.7-364.5元/（年·户）,上游农民对于林地保护的平均受偿意愿为360.75元/（年·hm^2）;通过回归分析发现,受教育水平、收入、自来水水质对支付意愿影响显著,而受偿意愿受性别和受教育水平影响明显;充分考虑并协调好流域上下游利益相关方的诉求对东江流域生态环境保护和生态补偿机制的建立有着重要的现实意义。     

塔里木河下游植物群落结构特征分析

对塔里木河下游经30a断流后的应急输水河畔植被进行外业调查,分析了调查区植物群落的种类组成、垂直结构、密度结构以及优势种群的格局分布,旨在了解输水后研究区植物群落在结构特征方面恢复程度。结果表明:调查样地内有植物13种,其中胡杨(Populus euphratica)、柽柳(Tamarix)、黑果枸杞(Lycium ruthenicum)、花花柴(Karelinia caspica)和疏叶骆驼刺(Alhagi sparsifolia)为优势种。不同地下水条件物种的重要值不同,表现在不同离河距离具有不同的物种组成结构,随地下水埋深不同植物群落由以胡杨和胀果甘草为主到以柽柳、黑果枸杞、花花柴和疏叶骆驼刺等抗旱耐盐碱植物为主。乔木层密度随着离河距离加大而减小,灌木层和草本层密度随离河距离加大呈先增加后减小的趋势。群落垂直结构随离河距离加大由乔-灌-草3层逐渐转变为灌-草2层,随离河距离加大趋于简单。优势种群胡杨在离河300m以内呈聚集分布,聚集强度随离河距加大而增强;柽柳灌丛在离河50m呈均匀分布,离河150m以外呈聚集分布,但离河750m段有向随机分布发展趋势。植物群落结构特征在不同的离河距离具有差异,说明经过输水下游植物群落的恢复在结构特征方面有响应,为区域生态治理和保护提供科学依据。     

黄河下游断流研究进展

介绍了黄河下游断流的发生特点、断流成因及断流对三角洲人民生产生活及对生态环境的影响三个方面的研究成果和进展。这些研究表明:黄河下游断流是自然与人为因素叠加所致,但主要影响因素为人类活动,而气候变化、源区生态环境恶化也是导致黄河径流减少的重要因子,但由气候变化引起的黄河径流量改变的百分比还未确定;黄河下游断流对河口海域生态系统、三角洲演变、工农业生产及城乡人民生活等方面都会产生影响,严重断流时会导致三角洲土地利用格局发生变化,并产生一系列生态问题。今后一段时间,要研究保障区域生态安全的生态用水量,合理利用黄河水量的丰枯周期,从根本上解决黄河下游的断流问题。     

Integrated river basin management in rapidly urbanizing areas: a case of Shenzhen, China

The rapid urbanization of China is causing a burden on their water resources and hindering their sustainable development. This paper analyzes effective methods to integrated river basin management (IRBM) using Longgang River basin of Shenzhen as an example, which is the city with the fastest rate of urbanization in China and even the whole world. Over the past 20 years, China has undergone a population boom due to the increase of immigrant workers and rapid development of laborintensive industries, which led to the sharp increase of water consumption and sewage discharge. However, the construction of the water infrastructure is still lagging far behind the environmental and social development, with only 32.7% of sewage in the district being treated. Currently, every water quality indicator of the Longgang River basin was unable to meet the required corresponding environmental standards, which further aggravated the water shortages of the region. Thus, an analytical framework is proposed to address the IRBM of the study area. The problems with the current management system include the lack of decentralization in decision-making, lack of enforcement with redundant plans, weak management capacity, financial inadequacy, and a poor system of stakeholder participation. In light of the principles of IRBM and the situation of the region, corresponding measures are put forward, including an increase of power given to sub-district offices, fewer but more feasible plans, capacity building among stakeholders, a combination of planning and marketing for overcoming financial inadequacy, and profound reform in the public participation system. The framework and institutional suggestions could inform similar processes in other representative river basins.     

Water shortages and countermeasures for sustainable utilisation in the context of climate change in the Yellow River Delta region,China

With an increasing population and rapid development of the economy and society of the Yellow River Basin region, the Yellow River is at crisis point. The discrepancy between supply and demand of water resources is a key issue. In 2000–2006, the mean annual discharge of the Yellow River entering the delta was 13.2 billion m³, a reduction of 18.6 billion m³ compared with the 1980s, and 9 billion m³ less than in the 1990s. The water requirements of various sectors are increasing. Large amounts of water essential to maintain the health of the delta ecosystem have been diverted for other users. The lower river channel is shrinking and the threat of flooding is becoming severe. Moreover, water pollution is increasing to a serious level; the river mouth ecosystem is subject to degradation. Due to overall decreased flow into the delta, and almost no flow into the delta for much of the year except in wet periods, biodiversity is threatened and there has been degradation of the ecological environment. In view of the water scarcity and variation in water supply, particularly in the context of climate change, measures need to be taken to realise sustainable water use in the Yellow River Delta region. In view of the lack of a complete index system for sustainable utilisation of regional water resources in China, this paper examines the major countermeasures for sustainable water use in the region. A rational adjustment mechanism for water prices is needed. Adjustment of agricultural infrastructure and water saving need to be directed by water prices, and thus the reasonable exploitation of groundwater must also be directed by water prices. Participation of the public is to be encouraged, with the development of a water user association that will become involved in formulating water rights, water allocation and water prices. Decision-making, management and supervision of this association will be done in a democratic way to promote the social management of water saving.     

基于小流域尺度的目标抗生素排放量估算方法——以梅江流域为例

抗生素的大量使用和排放造成的环境污染和生态风险问题日益突出,抗生素排放量的估算是评价流域内抗生素污染程度的重要指标,但目前抗生素排放量估算方法尚不完善。本研究以梅江流域为例,建立了适合小流域尺度的典型抗生素排放量估算方法,计算了四环素类抗生素(TCs)向不同环境相的排放量并分析了其主要来源。结果表明:2016年梅江流域TCs排放量为8 558.1 kg,不同行政区抗生素排放量差异较大,其中梅江镇受人口密度及养殖密度影响,抗生素排放量最大,高达1 224.4 kg;同时流域内不同抗生素的排放量也有所不同,其大小顺序为强力霉素(DXC)土霉素(OTC)四环素(TC)金霉素(CTC);TCs受排放源、排放途径等因素影响,以进入环境水相及土壤相为主,其中进入水相中的抗生素主要来自人类及生猪粪便,进入土壤相中的抗生素主要来自生猪及三黄鸡粪便。梅江小流域抗生素具有潜在的生态风险,应加强抗生素使用管理。该研究为我国小尺度流域目标抗生素排放量的估算提供了十分有效的方法。     

Origins and scales of hypoxia on the Louisiana shelf: Importance of seasonal plankton dynamics and river nutrients and discharge

Management plans for the Mississippi River Basin call for reductions in nutrient concentrations up to 40% or more to reduce hypoxia in the Gulf of Mexico (GOM), while at the same time the government is considering new farm subsidies to promote development of biofuels from corn. Thus there are possibilities of both increasing and decreasing river nutrients depending on national priorities. River flow rates which also influence the extent of hypoxia on the shelf may be altered by global climate change. We have therefore developed a series of simulations to forecast ecosystem response to alterations in nutrient loading and river flow. We simulate ecosystem response and hypoxia events using a linked model consisting of multiple phytoplankton groups competing for nitrogen, phosphorus and light, zooplankton grazing that is influenced by prey edibility and stoichiometry, sub-pycnocline water-column metabolism that is influenced by sinking fecal pellets and algal cells, and multi-element sediment diagenesis. This model formulation depicts four areas of increasing salinity moving westward away from the Mississippi River point of discharge, where the surface mixed layer, four bottom layers and underlying sediments are represented in each area. The model supports the contention that a 40% decrease in river nutrient will substantially reduce the duration and areal extent of hypoxia on the shelf. But it also suggests that in low and middle salinity areas the hypoxia response is saturated with respect to nutrients, and that in high salinity regions small increases in nutrient and river flow will have disproportionally large effects on GOM hypoxia. The model simulations also suggest that river discharge is a stronger factor influencing hypoxia than river nutrients in the Mississippi River plume. Finally, the model simulations suggest that primary production in the low salinity regions is light limited while primary production in the higher salinity zones is phosphate limited during the May to October period when hypoxia is prevalent in the Mississippi River plume.