不同土地覆被格局情景下多种生态系统服务的响应与权衡——以雅砻江二滩水利枢纽为例

在二滩水库集水区,按照当地生态政策发展以坡度为指标构建了10种未来土地覆被格局情景,研究生态系统减轻水库泥沙淤积、减轻水库面源污染、产水发电服务及价值对未来覆被格局的响应程度,并兼顾相关产业收益的变化,权衡各种情景格局的服务效益,优选利益相关方福祉提升幅度最大的情景格局。结果表明:1)现有土地覆被格局对减轻水库泥沙淤积功效的发挥不合理,而以退耕还林政策指导区域土地覆被格局变化,对集水区减轻河道和水库泥沙淤积具有较好功效。10种情景下,保沙价值的高低关系同入库泥沙量正好相反,遵循"随地表林地和草地面积比例的增加,保沙价值增加"的规律。随产沙总量的增加,高产沙强度像元呈现从水库周边逐渐向中上游蔓延的趋势。2)退耕还林政策单纯以坡度作为指标,指导土地覆被的转化,对集水区减轻水环境磷素非点源污染功效较差。除了全为未利用地覆被的情景10,余下9类情景模拟的入库磷素量及过滤磷素经济价值的高低关系完全一致,呈农田草地林地的规律。随入库磷素总量的增加,高强度磷素输出像元从雅砻江流域源区和大河湾区,逐渐蔓延扩散至集水区整个水网。3)随着集水区地表林地覆盖面积比例的减少,集水区生态系统总发电净利润值增加,且高净利润像元呈现从冕宁和喜德县的东部逐渐向整个集水区东南部乃至整个下游蔓延的趋势。4)从减轻对环境的负效应以及提升利益相关方福祉的角度,以坡度6°上下划分林地和耕地的情景5和以坡度15°和6°为阈值划分林草农的情景3为除极端的情景外,综合指标提升最高的两种情景。     

基于生态足迹的大型水电工程建设生态补偿标准评价模型——以三峡工程为例

生态足迹作为重要的生态环境指标,已被广泛应用于可持续性分析中,但在生态补偿领域应用的较少。运用生态足迹思想,构建了6类大型水电工程建设的生态供给足迹与生态需求足迹模型,以此为基础,确立了大型水电工程建设的生态补偿标准评价模型;并进行了三峡工程案例研究。结果表明:(1)三峡工程建设6项正面影响的生态供给足迹为949.96×104hm2/a,换算成总经济价值为619.18×108元/a;三峡工程建设9项负面影响的生态需求足迹为188.98×104hm2/a,换算成总经济损失为123.18×108元/a。(2)发电产品、调蓄洪水和发电环境效益是三峡工程的主要正面影响,三者经济价值占总经济价值的95.06%;水库泥沙淤积和水库淹没是三峡工程的主要负面影响,两者经济损失占总经济损失的85.56%。(3)三峡工程建设的生态补偿标准为123.18×108元/a,水电开发业主、中央政府和地方政府是主要的生态补偿主体,两者承担了95.06%的生态补偿标准额度;河流生态系统和移民是主要的生态补偿对象,两者获得了91.39%的生态补偿额度。通过对比分析发现,构建的模型在三峡工程案例中得到了很好的验证。     

Sedimentation of river-transported particles in the Öre estuary,northern Sweden

Sedimentation of river transported particles in the Öre Estuary was studied during spring flow (April–May, 1989). River input was calculated as the product of discharge and particle concentration in the river water. The concentration of suspended matter in the estuary water was determined with a light-scattering probe at 25 depth profiles throughout the estuary. The sedimentation was measured using sediment traps on 5 stations along a line from the river mouth to the mouth of the estuary. Sampling was carried out on four dates with different water discharge.The extension of the particle plume varied during the observation period mainly due to variation in river discharge. The maximum extension of the river plume occurred during the peak of the spring flow and covered approximately 70% of the estuary area. The sedimentation rates were generally high and the average retention time for a particle in the water column was less than 1 day which verifies that the river transported fine-grained particles are primary deposited within the estuary. The major part of the river input of suspended matter was deposited near the river mouth. There was a surplus of the total sedimentation compared to the river input which was due to wave-induced resuspension, especially in the eastern part of the estuary.     

Assessment of the eutrophication of Al Massira reservoir (Morocco) by means of a survey of the biogeochemical balance of phosphate

The biogeochemical balance of phosphate was studied in Al Massira reservoir (Morocco) from February 1991 to end January 1992. The study concerned P-supplies and losses by the Oum errbia river, sedimentation rate and water-sediment exchange.Supply and loss of phosphate were calculated from samples collected every 48 hours. Phosphate sedimentation rate was measured with sediment traps. The assessment of phosphate release at the water-sediment interface during either low oxic or anoxic conditions was made in situ with a benthic chamber.The results showed that phosphate input was higher than phosphate output resulting in a progressive increase of the internal phosphorus stock. The sedimentation flux ranged between 9 and 19 mg m^–2 d^–1 of P. Release of phosphate depended on the oxygen concentrations in the water.We suggest that a drastic control of phosphate input into the water must be achieved through a programme of dephosphorylation of the tributaries to avoid accumulation of calcium-bound phosphate which may become a source of upward release of bioavailable phosphate.Further investigations of this flux should be carried out to check the quantitative influence on phytoplankton community dynamics.     

Assessing the impacts of reservoir expansion using a population model for a threatened riverine fish

Increasing demand for water and a desire for greater human water security has facilitated the global expansion of dams, with river regulation acknowledged as the leading cause of biodiversity decline in rivers. Native biota within these stressed systems are also impacted by reductions in habitat availability, decreased hydraulic diversity, increased sedimentation, movement barriers, invasive species and altered flows that may profoundly change the character and functioning of rivers. Construction or enlargement of reservoirs is continuing, and whilst downstream impacts are often considered, upstream impacts receive far less attention. We develop a population model to examine the impacts of reservoir expansion on a threatened riverine species in South Eastern Australia: the two-spined blackfish. We examined two processes, loss of breeding habitat and increased predation, directly linked to reservoir expansion as well as a broader threat of recruitment failure due to sedimentation. These threatening processes were assessed using the expected minimum population size as an indicator of risk. As is often the case for threatened species, limited data were used to parameterise the model and sensitivity analysis performed to assess the appropriateness of the model parameterisation. The outcomes indicate that the two-spined blackfish population is vulnerable to the loss of breeding habitat particularly if two-spined blackfish are unable to spawn in the larger dam, although this vulnerability is ameliorated if the whole river is accounted for. Including possible impacts from the resident trout population for the whole river, indicates the two-spined blackfish to be vulnerable to low level predation particularly if the trout population have a high growth rate. Population modelling has rarely been used to predict the consequences of dam construction on aquatic species/communities. The example here shows it to be a powerful tool to visualise and quantify potential biodiversity outcomes.     

A large reservoir as a source of zooplankton for the river: structure of the populations and influence of fish predation

Within an extensive programme on the Seine river, including the large reservoirs in the upstream basin, zooplankton populations were investigated at the reservoir-river interface to find out their fate when released into the river. Zooplankton structure, abundance and biomass were analysed in the river upstream and downstream from the reservoir, in the release canal and in the reservoir. Whereas the river zooplankton are dominated by rotifers, microcrustaceans represent a large part of the population in the reservoir, because of the longer residence time (6 months). We have shown that the reservoir is a source of zooplankton; we calculated a biomass export of 30-60 tons C year^-1, which is, however, rapidly lost in the river. One of the main loss factors was found to be selective fish predation on larger zooplankton species developed in the reservoir.      

Riparian vegetation diversity along regulated rivers: contribution of novel and relict habitats

1. The creation and maintenance of spatial and temporal heterogeneity by rivers flowing through floodplain landscapes has been disrupted worldwide by dams and water diversions. Large reservoirs ( novel ecosystems ) now separate and isolate remnant floodplains ( relict ecosystems ). From above, these appear as a string of beads, with beads of different sizes and string connections of varying lengths.
2. Numerous studies have documented or forecast sharp declines in riparian biodiversity in relict ecosystems downstream from dams. Concurrently, novel ecosystems containing species and communities of the former predam ecosystems have arisen along all regulated rivers. These result from the creation of new environments caused by upper reservoir sedimentation, tributary sedimentation and the formation of reservoir shorelines.
3. The contribution of novel habitats to the overall biodiversity of regulated rivers has been poorly studied. Novel ecosystems may become relatively more important in supporting riverine biodiversity if relict ecosystems are not restored to predam levels. The Missouri River of the north-central U.S.A. is used to illustrate existing conditions on a large, regulated river system with a mixture of relict and novel ecosystems.     

Performance analysis of the Richland-Chambers treatment wetlands

The Tarrant Regional Water District (TRWD) is supplementing the flows to Richland-Chambers Reservoir, to meet future water supply needs of Dallas-Ft. Worth, TX. The Trinity River is the new source, but quality is not adequate. TRWD has constructed and investigated treatment wetland facilities located near the reservoir to upgrade river water quality, from an eight-year study at a 0.72 ha pilot site, and a five-year study at a 102 ha field-scale site. Both systems had a sedimentation basin followed by wetland cells in series. The pilot had two basins feeding three trains of three wetland cells each, while the field-scale system had one basin followed by four wetland cells in series. Water depths were about 30 cm for the pilot, and 40 cm for the field-scale. Design nominal detention times were roughly 5 and 9 days for pilot basins and wetland trains; and 1.5 and 8 days for the field-scale. The systems ran year-round, supplied with water pumped from the river, which at times was predominantly treated wastewater from the Dallas-Fort Worth metroplex. The primary target contaminants were suspended solids, nitrogen, and phosphorus. Nitrogen forms in pumped flows from the river were dominated by oxidized nitrogen, which was mostly nitrate nitrogen. Pilot nitrate removal from the river water was 92%, and 61% for phosphorus, while sediment removal was 97%. Field-scale nitrate removal from the river water was 77%, and 45% for phosphorus, while sediment removal was 96%. The field-scale project is located on land owned by the Texas Parks and Wildlife Department, and they participate in management of the wetlands for the secondary purpose of wildlife habitat.     

三峡库区不同水文类型支流大型底栖动物对蓄水的响应

为探究三峡水库修建对库区不同水文类型支流大型底栖动物的影响,于2015年7月和2016年1月对三峡水库四条支流的大型底栖动物进行调研,分别对周期性受蓄水影响支流的非回水区与回水区和长期受蓄水影响支流的非回水区与回水区大型底栖动物群落结构进行比较研究,结果表明:⑴7月份三峡水库145米低水位时期共采集到底栖动物655头计59种(属),在受蓄水影响河段采集到底栖动物4种共40头,优势种为日本沼虾(占受蓄水影响区域的57.5%); 1月份三峡水库175米蓄水时期共采集到底栖动物1123头计69种(属),在受蓄水影响河段采集到16种238头,优势种为锯齿新米虾(占受蓄水影响区域的14.2%)。⑵周期性受蓄水影响支流的非回水区与回水区底栖动物密度、生物量和多样性指数无显著差异(P0.05);长期受蓄水影响支流的非回水区与回水区之间底栖动物密度和Pielou均匀度指数无显著差异(P0.05),但非回水区底栖动物生物量显著高于回水区(P0.05),底栖动物多样性和丰富度极显著高于回水区(P0.01)。⑶7月份影响底栖动物分布的主要环境因子共6个,分别是水深、流速、硝态氮、溶解氧、水温和电导率; 1月份影响底栖动物分布的主要环境因子共7个,分别是水温、溶解氧、总磷、流速、深度、电导率和透明度。     

Longitudinal changes in zooplankton distribution below a reservoir outfall with reference to river planktivory

The fate and interactions with river organisms of zooplankton as they drift downriver from a reservoir on a fourth-order mountain stream (Hiji River, Japan) were investigated. Monthly samples were collected at the reservoir and six river sites, simultaneously, from May 2005 to May 2006. Aquatic macroinvertebrates and fish were colleted, and their stomach contents were analyzed in April and May, 2006, respectively. Drift from the reservoir was the primary source for the river plankton community; the abundance of zooplankton, particularly those of cladocerans and large rotifer, rapidly decreased within several kilometers of the dam. Analysis of the contents of fish stomachs showed that drifting zooplankton was the main food for fish, with strong food selectivity for cladocerans and large rotifers. However, fish and insect planktivores showed longitudinally different stomach contents, with progressively fewer zooplankton found in the stomachs at the downriver sites. The results suggest that the outflow of zooplankton from the reservoir is an important food source for the downstream predators, especially fish, but the drift of zooplankton and consequent food availability for the predators at lower sites are strongly limited by concentrated fish predation just below the reservoir dam.     

The influence of a deep-storage and an underground reservoir on the physicochemical limnology of a permanent central Texas river

This study was undertaken to determine the influence of a deep-storage reservoir and a downstream underground reservoir on the physicochemical limnology of a 98-km segment of a permanent river in central Texas. Seventeen parameters were studied. In general, impoundment in the deep-storage reservoir improved whereas inflow from the underground reservoir deteriorated water quality of the parent river. Overall combined effect of impoundment and inflow showed an improved water quality downstream from the study area from that found upstream of the study area.     

Water-borne seed transport and seed deposition during flooding in a small river-valley in Northern Germany

Water-borne seed transport and seed deposition during flooding were studied in the Upper Eider river (N-Germany) by direct sampling of the rivers seed content with aquatic seed traps and by analysing the number of deposited seeds on sedimentation mats which were exposed near the river on the soil surface during a flooding period of approx. three weeks.The number of seeds which were transported at the surface of the river Eider was continuously analysed by four aquatic seed traps for a period of 20 weeks (July–December 2000). To test the capture rate of these traps, a recapture experiment with colour marked seeds of Helianthus annuus L. was carried out. During the investigation period approx. 9000 seeds of 76 species were captured by the four aquatic seed traps. The number of trapped seeds varied both spatially (across the river profile) and temporally. Considering this variation and the capture rate of the traps, the water-borne seed transport was estimated to be 3139 seeds per week and meter of the river profile.The seed deposition during a flood in early spring 2002 was analysed by using 20 sedimentation mats. To distinguish effects of seed dispersal into patches from outside from seed rearrangement within patches, the water-borne seed transport was excluded from one half of the mats by fencing them with a woven fabric which was permeable for water but not for floating seeds. Outside of the exclosures 152 viable seeds of 26 species were deposited on the sedimentation mats while only one single seedling was found on mats from which water-borne seed transport was excluded.The results demonstrate that hydrochorous dispersal processes might play an important role in connecting otherwise fragmented populations in periodically flooded habitats along rivers.     

Integrated tank cultivation of salmonids and Gracilaria chilensis (Gracilariales,Rhodophyta)

In order to study the N and P balances in the Driss I reservoir, we measured concentrations in the water of these elements, their sedimentation rates, and their input by the river Inaouen and output through the dam. Supply and loss of N and P were calculated from samples collected every 48 hours and were for N 15 and 27. 5 mg m⁻² d⁻¹ and for P 33.6 and 1.1 mg m⁻² d⁻¹ respectively. The sedimentation rates, determined using sediment traps, were high, about 75 mg m⁻² d⁻¹ for N and 34 mg m⁻² d⁻¹ for P. Phosphate input came from point sources and was mainly in particulate form. A large fraction of the phosphate sedimented in the form of calcium bound phosphate, with some iron bound phosphate. Bioavailability was, however, low, as the particulate phosphate disappeared rapidly from the epilimnion because of the high sedimentation rate. The ratio Tot-N/Tot-P of the sedimented particulate matter varied between 0.05 and 7.74 and depended on primary production and watergate management.     

Effects of flow regulation, basin characteristics and land-use on macroinvertebrate communities in a large arid Patagonian river

Longitudinal distribution and abundance of macroinvertebrate communities were examined in relation to hydrochemical variables along the Chubut River in the Patagonian Precordillera and Plateau, Argentina. The Chubut River (>1000 km) is the largest river in the area and its basin is subject to multiple uses: agriculture, cattle raising, urbanization and the hydrological regime of the lower section is modified by a reservoir. Quantitative benthic samples were collected at 13 sites in the higher, middle and lower sections of the river basin. Sites were visited four times during 2004 and physicochemical parameters, chlorophyll a and particulate organic matter (POM) were assessed. Ninety-five taxa were collected in the study, with total species richness per site ranging from 5 to 51, and benthos density averaging 299–5024 ind m⁻². Altitude and turbidity were implicated as important factors determining macroinvertebrate assemblages along the river system, and an eutrophication gradient was documented in the regulated/urbanized section of the main river. High turbidity (TSS) and sedimentation limited algal productivity in the middle basin. Below the dam, TSS, total phosphorus (TP) and POM decreased, whereas soluble reactive phosphorus (SRP) and chlorophyll a increased. Macroinvertebrate density increased three fold in this area possibly due to habitat improvement and enhanced trophic resources. Mean species richness did not change below the impoundment; however the community was dominated by gastropods, chironomids and flatworms. The Chubut River is complex and its biotic community reflects the landscape attributes. While benthic composition and density was governed by turbidity and flood disturbance in some river segments, a greater environmental heterogeneity resulted in an unexpected high number of species at the main channel upper basin.     

The effects of impoundment and regulation upon the stomach contents of fish at Cow Green, Upper Teesdale

The stomach contents of 1003 brown trout, 1551 bullheads and 800 minnows taken from the reservoir basin and below the dam, before and after impoundment of the river Tees, were examined. Their composition reflected observations by other workers on river and reservoir benthos, except for the increase in numbers of Hydra and Nais below the dam, and Mollusca, Hirudinea and oligochaetes in the reservoir.
Trout below the dam ate more Ephemeroptera nymphs and Chironomidae larvae but fewer terrestrial casualties after river regulation, whereas bullheads ate more Mollusca but fewer Plecoptera nymphs. In both species Baetidae nymphs increased in numerical importance relative to Ecdyonuridae. Trout, but not bullheads, took zooplankton discharged from the reservoir.
Before impoundment, trout within the reservoir basin ate chiefly benthic organisms and terrestrial casualties. Inundated terrestrial material, mainly earthworms, formed the bulk of their food for at least three years after impoundment, whilst from the second year onwards Chironomidae and, in some years, Gammarus became increasingly important. Zooplankton was taken by all sizes of reservoir trout.
Bullheads within the reservoir basin ate chiefly river benthos before impoundment, with Ephemeroptera and Plecoptera nymphs predominant in older fish, and aquatic Diptera and Coleoptera also important in the fry. After impoundment, Chironomidae and Gammarus were the main items taken by older bullheads, and Chironomidae and micro-crustacea by the fry. Among all sizes of minnow, Chironomidae, micro-crustacea and detritus increased in numerical importance after impoundment.     

Chironomid (Diptera) larvae of the Butoniga reservoir,Istria, Croatia,and its feeder rivers

After the formation of a drinking water reservoir at Butoniga, Istria, research on the fauna of the Chironomidae larvae was undertaken in the feeder waters and the reservoir itself. Forty eight species were identified, belonging to the subfamilies Chironominae, Orthocladiinae, Diamesinae and Tanypodinae. Chironomidae colonized the reservoir waters relatively more quickly than other groups of macroscopic invertebrates. The similarity quotient (QS) of Chironomidae of the feeder waters and the reservoir is only 37.8%, which points to the formation of new communities in the reservoir. There were qualitative and quantitative changes in the composition of Chironomidae fauna in the river Mirna and in the river Butoniga downstream from the dam after water was released from the reservoir for the purpose of testing the dam. The Chironomid composition of the feeder waters places them in quality grade II. In the Butoniga reservoir the bottom water was assigned to grade II–III, because of the decomposition of the remains of surface fauna.     

Drawdown flushing in a chain of reservoirs—Effects on grayling populations and implications for sediment management

We used an information theoretic approach to assess the effects of an ecologically adjusted sediment management scheme on grayling (Thymallus thymallus L. 1758) populations. Additionally to reservoir operation, candidate models included a variety of parameters and processes that may influence grayling populations such as flow, temperature, density dependence, and bird predation. Population parameters analyzed included total densities, young of the year numbers, and larval densities. These analyses were supplemented by a characterization of sediments and sedimentation patterns in the reach. Investigations were carried out in six sites affected by flushing and in one control site. A total of thirteen flushing operations have been undertaken within the study period leading to considerable remobilization of fine sediments and gravel. Due to seasonal and hydrological restrictions, not every flood could be used for flushing. These limitations led to an interrupted management throughout the chain of reservoirs as well as to long time intervals between flushing events with possible effects on spawning habitat quality. None of the investigated population parameters was affected by flushing, and thus, the study generally supports the current reservoir management scheme. Our analyses revealed the magnitude and timing of high water events, temperature, and density‐dependent effects, that is, population densities the year before, as the most influential variables for grayling population dynamics in the investigated stretch. The siltation of reservoirs is a significant problem for reservoir storage, flood protection, river deltas, and coastal zones. Its management—which is inevitable to safeguard river deltas and secure flood protection—poses also the challenge to safeguard riverine ecosystems below reservoirs. Based on our experience, we propose a periodic flushing regime in concordance with the hydrograph thereby mimicking the timing, magnitude, frequency, and duration of natural SSC pulses and gravel transport. This flushing regime minimizes adverse downstream environmental impacts and maximizes benefits.     

减轻二滩水库泥沙淤积的生态系统服务价值评估

基于ArcGIS 9.2,构建了生态系统减轻水库泥沙淤积的评估模型,并结合泥沙输移比（SDR）和通用水土流失方程（USLE）,模拟了二滩水库集水区的产沙量和保沙量及其空间分布特征以及水库使用年限内其生态系统服务价值.结果表明：2000年,二滩水库集水区土壤保持量12.1×10⁸ t·a^-1,土壤保持量高值区主要分布于雅砻江干流和支流水网附近;泥沙输移比的高值主要分布在河道附近和水库周边,水库周边是最主要的产沙区和保沙区;研究区实际产沙量为629.3×10⁴ t·a^-1,占实际土壤侵蚀量的12.7%;农田是研究区最主要的产沙源,其产沙量占集水区总产沙量的62.9%;林地平均单位面积的保沙价值最高.在二滩水库使用年限内（100 a）,集水区对于减轻二滩水库泥沙淤积的总价值为27.53亿元.     

三峡水库初次蓄水后干流库区枝角类的空间分布与季节变化

为了阐明三峡水库初次蓄水后干流库区枝角类的时空分布规律, 2004年4月至2005年1月, 在600余公里干流库区设置10个样点, 定性和定量采集枝角类标本。本次调查共采到9种枝角类, 其中春季8种, 夏季5种, 秋季2种, 冬季3种。枝角类种类组成的空间分布差异明显, 河流状态的江段有4种, 水库状态的江段有7种, 水库状态的江段距大坝越近, 枝角类种类越丰富。枝角类的密度和生物量的空间分布和季节变化规律一致, 季节间差异极显著(P<0.01), 春季最高, 夏季次之, 秋季和冬季较低; 空间分布上表现为在干流库区的纵向分布上差异极显著(P<0.01), 河流状态样点远低于水库状态的样点, 水库上游江段又低于下游坝前段。结果显示三峡水库的枝角类具有明显的纵向分布和季节变化特征。     

Abundance and diversity of phytoplankton in the Paraná River (Argentina) 220 km downstream of the Yacyretá reservoir.

Patterns in the temporal composition, abundance and diversity of the phytoplankton community of the Paraná river prior to and after the initial filling phase of the Yacyretá reservoir are analyzed. The study site is located 220 km downstream from the Yacyretá reservoir and 30 km downstream from the confluence with the Paraguay river. Because both rivers remain separate and unmixed at the study site, we compared the possible effects of the impoundment on both river banks (left and right banks) in hydrological periods with similar duration and magnitude of the low and high water phases. Physical and chemical conditions measured on the right bank (water from the Paraguay river) were similar at both periods (pre and post-impoundment) whereas conductivity, pH and orthophosphate concentration increased on the left bank (water from the High Paraná river and Yacyretá reservoir) after the impoundment. Changes in phytoplankton density and diversity were observed only in samples collected from water flowing from the reservoir (left bank). The density of Chlorophyceae (Chloromonas acidophila, Chlamydomonas leptobasis, Choricystis minor, Chlorella vulgaris, Scenedesmus ecornis, Monoraphidium minutum, M. contortum and M. pusillum) and Cryptophyceae (Rhodomonas minuta, Cryptomonas marssonii and C. ovata) increased while Cyanophyceae (Cylindrospermopsis raciborskii, Raphidiopsis mediterranea and Planktolyngbya subtilis) and Bacillariophyceae (Aulacoseira granulata and its bioforms) decreased compared to previous studies conducted on the left bank of the Paraná river. Phytoplankton collected from the right bank of the river did not differ in pre and post- impoundment samples because they originate from the Paraguay river, which remains relatively unaffected by human activities.