Gross channel changes along the Durance River,Southern France,over the last 100 years using cartographic data

Gross channel changes for the Durance were determined using topographic maps from the 1890s and 1980s. Various width parameters were measured at 1 km intervals over 189 km from the Rhône junction at Avignon to La Saulce, some 31 km downstream of the dam at Serre Ponc¸on. During this period channel size has been considerably reduced. This can be attributed to four factors, two natural and two human induced. Firstly, there was a reduction in effective runoff at the end of the Little Ice Age (late 19th century). Secondly, runoff was further reduced with lower precipitation after about 1940. Thirdly, channel widths have been reduced by bank protection and by flood mitigation works. Finally, large‐scale river regulation by EDF (Electricité de France), completed in the early 1960s, includes large dams to store alpine runoff, concrete canals to convey released water through some 20 power stations, and barrages to intercept tributary runoff and divert flows into the canals. In the lower Mediterranean part of the river, some of the diverted waters are discharged into irrigation and urban water canals (about 114 m³ s⁻¹) and the rest into the Etang de Berre. Only about 1% of the mean discharge now reaches the Rhône. Discussion of available research provides insight into the four impacts, including additional comparative post‐regulatory evidence from the Syndicat Mixte, a group concerned with environmental problems in the lower river. Evidence for channel change in lower parts of tributaries and for bed incision was found to be less conclusive. Such impacts may have been reduced by the interruptions of long‐profile continuity by barrages and dams, and by lower discharges. Such discontinuities have adversely affected the ecology, low environmental flows and treated sewage dispersion. With some exceptions, environmental sustainability has not been a major issue because the Durance is such an important economic resource in terms of power, urban and irrigation waters, and building materials. Copyright © 2000 John Wiley & Sons, Ltd.     

The relationship between geomorphic river adjustment and management actions over the last 50 years in the Upper Hunter Catchment,NSW, Australia

The installation of 517 river works in the upper Hunter catchment, New South Wales over the last 50 years is linked to geomorphic river adjustment and flood history at catchment and reach scales. Nineteen types of works are classified into three categories consisting of engineering, heavy machinery and vegetation works. Since 1952, a transition in techniques has been detected from engineering‐based approaches, to river training/maintenance, to more ecosystem‐based approaches. From the 1950s to the mid‐1980s extensive river engineering was undertaken. Projects were concentrated along laterally unconfined rivers and were generally implemented after major phases of geomorphic river adjustment. Neither the type of river nor the type of river adjustment guided the implementation of differing management techniques or their distribution in the catchment. A blanket approach was adopted, applying the same types of works across all types of river. Emphasis was placed upon concerns for bank instability rather than bed instability. Hence in many cases, river works addressed the symptoms (i.e. bank erosion) rather than the underlying causes of river change (i.e. bed incision). Since the mid 1980s, techniques have evolved towards vegetation‐based procedures. The development of more effective river rehabilitation programmes requires that greater consideration is given to proactive strategies which build upon an understanding of geomorphic river adjustments at the catchment scale. Copyright © 2008 John Wiley & Sons, Ltd.     

近千年淮河流域河湖水系连通演变特征

分析了近千年淮河流域河湖水系的自然演变以及人类活动的扰动,深入探讨了其成因。研究表明:目前淮河流域河湖水系连通格局是人类在抵御黄河洪水和泥沙入侵的抗争中,遵循自然规律的同时兼顾漕运、灌溉等社会发展所需而构建的防洪、排涝、冲沙、灌溉、供水等的工程体系。流域主要干支流和湖泊连通基本受人工所控,自然-人工河网交织,河流-湖泊水量交换频繁,入江入海水道基本畅通,并与黄河、长江、海河等各大水系连通,基本解决了河水出海无路,洪涝灾害频发的问题。河湖水系连通在一定时期内对稳定淮河流域社会安定团结、推动经济发展起着积极作用,但也不可避免地对流域生态环境产生了一定的负面影响。水系连通下流域水资源演变规律、环境生态效应以及对社会经济布局的影响等研究是亟待解决的关键科学问题。     

Distribution,abundance and development of trichoptera larvae in the river north tyne following the commencement of hydroelectric power generation

Following turbine installation at the Kielder dam, the River North Tyne downstream is now characterized by large daily fluctuations in flow. A survey of trichopteran populations (Hydropsychidae, Rhyacophilidae and Polycentropodidae) was carried out to assess the impact of hydroelectric power generation (Phase III), and to compare the results with similar pre-impoundment (Phase I) and post-impoundment (Phase II) surveys. Benthic samples were collected quarterly upstream from the reservoir and at four stations downstream. Although the same three species (Hydropsyche siltalai, Hydropsyche pellucidula and Rhyacophila dorsalis) continue to dominate, there were some notable differences found between sampling sites. Species diversity was drastically reduced at the station nearest the dam, where 99% of all larvae collected were R. dorsalis. At the next station 5 km downstream, where previously H. siltalai had been dominant, R. dorsalis now constitutes 65% of collections. At the two stations farthest away from the dam the former prevalence of H. siltalai was re-established. It is suggested that the unstable, high flows at the reservoir outlet are likely to favour the predatory R. dorsalis rather than the filter feeding hydropsychids whose nets may be susceptible to damage. Upstream from Kielder Water, R. dorsalis was prominent in benthic samples, whereas numbers of H. siltalai were 10 times lower than in Phase II and 60 times lower than in Phase I. The extent to which such upstream changes may be related to altered patterns of community structure below the dam is not known, but these observations may warrant a more cautious approach when considering upstream areas as unaffected ‘reference sites’. Instar analyses suggested that winter-warm, summer-cool discharges were continuing to modify larval growth rates, as noted in Phase II. The results of this study are discussed in relation to present trends in water resource development in Britain, especially with regard to future needs in monitoring and research.     

Serial discontinuities in a Rocky mountain river. II. Distribution and abundance of trichoptera

River regulation in the headwaters and middle reaches of the Gunnison River, Colorado, significantly altered distributions and abundances of Trichoptera fauna. Twenty-five species were collected from mainstream samples, with the greatest species richness occurring at an unregulated, rhithron segment above the central reach dams. At sites immediately below the three hypolimnial-release dams and a reregulation dam, species richness was reduced 35–90 per cent and abundance > 95 per cent. Net-spinning caddisflies were the dominant trichopterans at unregulated sites; Arctopsyche grandis in the upper reaches (218 organisms, 586 mg dry mass m^?2) and Hydropsyche cockerelli, H. occidentalis and Cheumatopsyche pettiti in the lower river (9041 total organisms, 6621 mg m^?2), downstream from the last dam. The observed distributional pattern of low trichopteran densities in dam tailwaters and high hydropsychid densities at sites 60–80 km below the central reach dams is a classic expression of continuum resets and adjustments in response to stream regulation as predicted by the Serial Discontinuity Concept.     

过去500年海河流域旱涝变化规律

研究历史旱涝变化规律对于区域综合防灾减灾具有重要的现实意义。以海河流域的旱涝灾害文献记录和旱涝等级资料为基础,重建过去500a区域综合旱涝指数序列,探讨海河流域1470年-2000年旱涝变化的规律。研究发现海河流域旱涝灾害的频发期具有明显的时段性,呈现出"旱-涝-旱"波动。从16世纪初期开始由洪涝转向干旱,并于17世纪初期达到顶点;从17世纪中后期开始海河再次进入相对易受洪涝灾害影响的时期,其中19世纪初期处在最低值,到20世纪20年代左右,流域再次进入相对干旱的时期,且干旱的严重程度逐年增加。同时,研究区存在2.5a、9.8a、18.6a、31.3a、83.50a、125.3a和167.0a等旱涝周期性过程。     

Reconstruction of lake-level and climate changes in Lake Qarun,Egypt, during the last 7000 years

Sediment cores from Lake Qarun provide a record of mid-late Holocene climatic changes in Northern and Eastern Africa as well as environmental changes due to the activities of ancient Egyptians. We used sedimentological, mineralogical, and geochemical analyses of the cores to investigate long-term variations in lake level due to changing hydrologic inputs. An age model based on three paired ¹⁴C and paleomagnetic measurements suggests that the base of the sediment cores is as old as ∼ 5000 B.C.E. Geochemical analyses indicated that lake sediments were derived from Nile floods with an admixture of Saharan sand. Laminated endogenic carbonate-rich clayey silt lithofacies with benthic diatoms are indicative of relatively low lake levels, saline waters and dry conditions; massive lithofacies with planktonic diatom species are indicative of relatively high lake levels, fresh waters and humid conditions. Faintly laminated clayey silt lithofacies suggest intermediate conditions. Variations in lithology as well as diatom composition suggest that the lake level has varied from relatively high levels in its early history to lower levels in later years although there have been numerous cycles in water level over the past 7000 years. A combination of climate changes in the source area of the Nile River as a result of monsoon dynamics; climatic changes in the setting area of the Lake Qarun; and human activities through the dynasties in Egypt produced these variations in lake level.     

近500年黄淮海地区洪旱事件时空变化特征

依据近500年洪旱等级数据,采用滑动平均、累积距平、频率统计、小波分析和Mann-Kendall突变检验和空间分析方法,评估了研究区近500年洪旱灾害时空变化特征。结果表明:黄淮海地区洪旱灾害具有明显的年际和年代际变化,近年来趋向干旱发展。各子区域的年际变化存在一定的差异,突变时段差别较大。洪旱灾害发生周期的空间分布差异性显著,19世纪后半叶以来洪旱灾害频繁。研究结果对于防灾减灾、灾害预测、工程建设以及相关研究等有重要的价值。     

The Sanaga discharge at the Edea Catchment outlet (Cameroon): An example of hydrologic responses of a tropical rain‐fed river system to changes in precipitation and groundwater inputs and to flow regulation

The Sanaga River is one of Sub‐Saharan Africa's largest and greatly regulated rivers. Available flow data for this hydrosystem largely cover the pre‐ and post‐regulation periods. From comparisons between unregulated (hypothetical) and observed scenarios, it has been possible to separate and to quantify hydro‐climatic (groundwater + rainfall) change effects from anthropogenic impacts (especially dam‐related alterations). To appreciate shifts in the river regime, discontinuity detection tests and the IHA model were applied to discharge data series reflecting average and extreme flow conditions, respectively. Results obtained principally from the Hubert segmentation method reveal that a major discontinuity occurred in 1970–1971 separating a surplus phase between 1945–1946 and 1969–1970, and a deficient and much contrasted one, from 1971/1972. This implies that the Sanaga catchment is dominantly affected by hydro‐climatic changes. However, wide land cover/land use changes experienced here since 1988 have resulted in an increase in surface runoff. Additional quickflows linked to these changes may have partly compensated for the substantial decline in the dry season rainfall and groundwater inputs observed from this date. Although at the monthly scale, dam‐related impacts on average flows increase with stage of regulation, the seasonal variability of the river regime remains generally unaffected. A comparison of the IHA statistics, calculated from unregulated and observed streamflow data, show that hydrologic shifts occurring in maximum and minimum discharges are mostly significant from 1971/1972 and are mainly due to the action of dams. Minimum flows appear, however, widely impacted, thus reflecting the prime objective assigned to the existing reservoirs, constructed to supplement flows for hydroelectricity production during the dry season. Copyright © 2010 John Wiley & Sons, Ltd.     

小浪底水库下游浮游生物及细菌群落对水沙调控的响应规律

浮游动物、浮游植物和细菌群落广泛分布于河流生态系统,发挥着初级生产者、初级消费者和分解者的重要作用,对于环境条件的波动较为敏感。本文于2018—2019年黄河小浪底水库调水调沙前、中、后期对下游河流进行了调查采样,得出水环境因子、浮游生物与细菌群落的定量结果,以明确在不同调水调沙阶段下游河流水环境因子,浮游生物和细菌群落的演变规律及相互作用。通过结构方程模型(SEM)和基于距离的冗余分析(dbRDA)、分别明确了调水调沙影响下浮游生物以及细菌群落对水环境因子的响应规律。结果表明,调水调沙不同阶段下,浮游植物、浮游动物和细菌对于环境因子的响应方式具有较大的差异,溶解氧(在调水调沙前影响系数最大,为0.86)、温度(在调水调沙期间影响系数最大,为0.76),以及电导率(调水调沙后影响系数最大,为0.82)等环境因子对浮游生物的生物量影响最明显,而溶解氧(在调水调沙前)和叶绿素a(调水调沙期间至调水调沙后)对于细菌群落的影响最大。此外,调水调沙过程改变了浮游生物群落内部关系,削弱了浮游动物对浮游植物的捕食,同时也使得悬浮和沉积状态的细菌群落在样点之间的差异性增大。本研究明确了浮游生物及细菌群...     

赣江外洲站近50年水沙变化规律

基于赣江外洲站年径流量时间序列(1957-2008年)和年输沙量时间序列(1966-2008年),采用肯德尔秩次相关检验法、有序聚类分析和秩和检验法、小波分析法对赣江水沙变化规律进行分析.结果表明:年径流量时间序列趋势变化不明显,不存在显著跳跃点,当时间尺度为17时,存在以10～12a为周期的丰枯变化.年输沙量时间序列下降趋势明显,在1984年和1998年附近发生跳跃,周期性变化可分为两段,1966-1986年间,在时间尺度为6时平均变化周期约为4a,1986年后,在时间尺度为1时平均变化周期约为3.7a.水土保持、人工采砂、万安水库拦沙等是影响赣江输沙量显著变化的主要因素.     

Influence of regulation on environmental conditions and the macroinvertebrate community in the upper Colorado river

The influence of stream regulation on environmental conditions and concomitant alterations of macroinvertebrate community structure was determined from field studies conducted from September 1981-June 1983 at three sites on the upper Colorado River. Site 1 (reference site) was located above Granby and Shadow Mountain Reservoirs, a deep-release storage impoundment, whereas sites 2 (regulated site) and 3 (recovery site) were located 0·4 and 4·0 km, respectively, below the dam. Although macroinvertebrate diversity was reduced at the regulated site compared to both the reference and recovery sites, the number of taxa (43) was considerably higher than values reported from studies of other regulated streams in the Rocky Mountains. Macroinvertebrate mean annual density in the regulated site was twenty times higher than at the reference site and slightly higher than the recovery site. The regulated site was characterized by the absence of heptageniid mayflies, reductions in stoneflies, caddisflies, shredders, and predators, and high densities of Baetis spp., Ephemerella infrequens, chironomids, and non-insect taxa. Many of these faunal changes are attributed to alterations in the temperature regime induced by regulation and to changes in the source and temporal sequencing of organic detritus. Although the number of annual degree days was actually greater below the dam than above the reservoir, other components of the thermal regime was severely altered by regulation. At the regulated site the primary source of coarse organic detritus was autochthonous (decaying algae) with a vernal pulse, in contrast to the typical autumnal pulse of allochthonous leaf litter. There was no evidence that the greater substrate permeability and flow predictability below the dam directly influenced the reduction of species.     

黄河干流水生态系统结构特征沿程变化及健康评价

根据2008年在黄河干流刘家峡以下河段水生态调查资料，分析了黄河干流水生态系统理化性状和生物群落结构的沿程变化；参照20世纪50和80年代水生态调查资料，对比分析了黄河干流水生态系统几十年来的变化情况，并分析了变化的原因；建立黄河水生态系统健康评价指标，对黄河干流各河段的水生态系统健康状况进行了评价，揭示了黄河水生态系的真实状况。研究结果表明：（1）由于自然和人类活动影响的差异，黄河干流水生态系统结构特征沿程分布差异比较大；（2）2008年黄河干流水生态状况与20世纪50、80年代相比，除底栖动物外，其它生物种类和数量均下降明显。（3）黄河水生态系统健康状况不容乐观，干流大部分河段生态系统的结构和功能发生了较大的变化，部分生态功能丧失。     

海河流域60年降水量的变化及未来情景分析

降水量是水文循环的重要因素。利用Mann-Kendall趋势检验方法,分析了1951—2010年海河流域降水量的历史演变规律;并根据大气环流数据分析了降水变化的原因;利用全球气候模式数据预测了未来降水量的可能变化情景。主要结论为:(1)1951—2010年,海河流域的年降水量呈显著减少趋势,达到了5%的显著性水平,其中夏季降水减少的幅度最大。(2)南方涛动指数(SOI)和海河流域降水具有较好的正相关,而太平洋年代波动(PDO)和太平洋年代内的波动(IPO)与海河流域降水具有较好的负相关。(3)在未来气候变化背景下,海河流域的年降水量和月降水量都将呈现出增加趋势;在A1B情景下,总体上流域东部降水量的增加幅度要大于流域西部。相关研究成果对于保障流域的水资源安全,支撑区域经济社会可持续发展,具有重要的科学价值和实际意义。     

Flooding frequency and invertebrate emergence from dry floodplain sediments of the river murray,Australia

Regulation of lowland rivers often alienates large areas of the floodplain, altering the natural regime of flooding frequency, duration, and magnitude. The extent to which such changes alter the productivity of river-floodplain ecosystems and the contribution of aquatic invertebrates emerging from dry floodplain sediments is unknown. To examine this in a section of the River Murray in South Australia, fourteen replicate sods of dry sediment collected from four areas of the floodplain that had experienced different average flood recurrence frequencies (annually, 1 in 7, 1 in 11, and 1 in 22 years) were inundated in the laboratory, simulating flooding. Invertebrates emerging from the dry sediments were sampled with replacement 1, 2, 3, 7, 10, 14, 21, and 28 days after inundation, enabling comparisons of temporal changes in faunal composition and biomass. The greatest biomass and numbers of invertebrates emerged from annually-flooded sods whereas sediments usually flooded once in 22 years yielded only protozoans. Large numbers of cladocerans and rotifers were recorded within two days of inundation whereas ostracods were not numerous until two weeks later. Heterogeneity in faunal composition and biomass among replicates probably reflected patchiness in microtopography and resting stage settlement, and variable hatching ‘strategies’. Although experimental conditions rapidly diverged from the natural situation over time because of the unrealistic constraints of enclosure, results suggest a potentially significant contribution by emergent invertebrates to the newly-inundated floodplain foodweb. Reducing floodplain inundation frequency through regulation and flood mitigation probably severely reduces this reserve, removing a food resource for young fish and other predators.     

抚远江段江道演变分析及整治必要性

黑龙江干流抚远江段是交错汉道河型，俄侧汊道有发展条件但由于植被好树木茂密。坍岸树木沉入堆积。自我防护发展很慢，我国一侧汊道已成为主流且其趋势不可逆转，所以这段江道防护工程的兴建是十分紧迫必要的。     

塔里木河下游应急输水前后生态变化遥感监测分析

本文介绍了塔里木河的水资源和生态恶化现状，分析了向塔河应急输水的必要性和可行性。根据3个时相的遥感影像，从图像解译、分类以及植被指数、植被覆盖度两个主要方面对塔河下游输水前后3年来的生态变化作了定性和定量分析，对输水效果进行了评价并提出了建议。结果表明：5次应急输水对塔河下游生态恢复起到了巨大的推动作用，有效地遏制了生态的继续恶化，为我国综合治理塔河赢得了宝贵的时间。     

Long‐term changes in flow regime and fish assemblage composition in the guadalupe and san marcos rivers of texas

Riverine flow regimes are naturally dynamic, but become increasingly homogenized following anthropogenic flow alteration. Loss of dynamism disrupts naturally occurring structuring mechanisms within the associated biotic communities, at times causing shifts in composition. Here we considered how stream fish assemblages in two Central Texas rivers changed after alteration of flow regime by either construction of a mainstem, deep storage reservoir or flood‐retaining structures. Following impoundment, number of large and small floods increased from 0.81 to 1.07 floods per year (FPY) in the upper Guadalupe River, decreased from 0.84 to 0.42 FPY in the lower Guadalupe River and decreased from 0.87 to 0.7 FPY in the San Marcos River. Historical ichthyofauna data ranging from 1938 to 2006 were used to assess changes in assemblage composition and species abundance. Assemblages did not differ in the upper Guadalupe River (Bray–Curtis index = 37.4%; ANOSIM global R = 0.079, p = 0.08), but did differ in the lower Guadalupe River (25%; global R = 0.409, p < 0.01) and San Marcos River (27%; global R = 0.19, p < 0.01). In general, habitat generalist species dominated assemblages during periods of reduced flood frequencies (i.e. drought of record; following impoundment), whereas regionally endemic species (N = 3) and substrate and broadcast spawning species (N = 5) declined (b₁ < 0; α = 0.05). Based on the results from this study, managing flows in the lower Guadalupe River to mimic historical timing of flood pulses might attenuate contemporary disruption of natural assemblage composition. Copyright © 2010 John Wiley & Sons, Ltd.     

黄河口近十年变化遥感监测及水沙条件分析

黄河流域自1999年实行流域水资源统一配置以来,有效遏制了下游断流的发生,2002年至2006年间又连续进行了调水调沙,这两项重要举措使黄河口的水沙环境在人力作用下发生了较明显的变化,而水沙条件是控制黄河三角洲湿地发育的主导因素,那么水沙环境的改变必然引起黄河口发生变化。本文中先利用多期多源遥感影像对比监测了1996年至2006年间黄河口在造陆、岸线、植被覆盖度及总体生态环境质量方面的变化,然后分析了在此期间黄河下游利津站来水来沙特征。通过对黄河口的变化与水沙条件相应关系分析,表明从2003年开始,黄河口明显出现淤积大于蚀退及植被覆盖有所增加是对水沙条件得以改善的响应。     

河道调整研究现状及其对黄河下游游荡型河道调整的启示

系统梳理了河道调整研究现状,全面论述了与冲积河流调整相关的河相关系、不同边界下河道调整过程、冲积河流线性理论的研究现状及发展动态.新形势下黄河下游游荡型河道调整应重点研究水沙变化与有限控制边界对河道调整的耦合效应、河道断面自调整数理分析中断面形态假定、有限控制边界条件下游荡型河流主槽摆动幅度和频率等问题,这不仅有助于加...