Effects of an enhanced flood on riparian plants of the River Murray,South Australia

In October 2000, the flow of the River Murray entering South Australia was increased from 32 000 to 42 050 ML day^?1 by release of water from an offstream reservoir, and a downstream weir was raised by 500 mm to impound the flood and enhance local floodplain inundation. The flood was maintained for about two weeks, although the duration of inundation was longer at low elevations on the floodplain. Vegetation at three sites was surveyed before and after the flood to examine the impact of inundation on the growth and germination of flood‐tolerant, flood‐dependent and flood‐intolerant species. Among 32 recorded species, Atriplex vesicaria (bladder saltbush, Chenopodiaceae), Sporobolus mitchellii (rats tail couch, Graminae) and Sarcocornia quinqueflora (samphire, Chenopodiaceae) accounted for nearly 82% of the total cover/abundance. Flood‐tolerant and flood‐dependent species (e.g. S. mitchellii) grew and germinated and flood‐intolerant species (e.g. A. vesicaria) senesced. No aquatic plants germinated or established, despite favourable conditions, suggesting an impoverished seed bank or grazing. Based on the growth but lack of germination of flood‐tolerant and flood‐dependent species, the value of small, occasional interventions in environmental flow management may be to maintain existing communities rather than restore degraded ones. Copyright © 2004 John Wiley & Sons, Ltd.     

Water and Sediment Quality in Lakes along the Middle and Lower Reaches of the Yangtze River, China

Water and sediment samples were collected from 45 lakes along the middle-lower Yangtze River, China. Each lake was sampled seasonally, over a period of one year. Water quality variables and metals in sediments were measured. Lakes along the lowest part of the river, within the Yangtze River Delta, had highest nutrient concentrations and were eutrophic or hypereutrophic. Lakes displayed a gradient in many water chemistry variables, from the middle to the lower Yangtze River. Lakes of the Delta region had the highest conductivity, sulfate, turbidity, and Chl-a values, and the lowest dissolved oxygen concentrations. A number of lakes near urban areas in the study region also displayed similar conditions. Lakes polluted by heavy metals were found in the upper part of the lower Yangtze River and had high Cu, Cr, and Co concentrations in sediments. The mean I_geo (index of geoaccumulation) values for Cu, Cr, and Co classes ranged from 0 to 4, indicating moderate to heavy contamination, contributed mainly from untreated industrial waste water produced within the lake catchments. Lakes of the middle Yangtze River are generally in relatively better condition, except for those around urban zones, which experience higher nutrient and heavy metal loading. The spatial distribution of lake conditions in the area can be related to the policy of regional economic development. The Delta region in China is developed and includes such cities as Shanghai and Suzhou. Heavy industries have moved into the interior region of China too, and development of modern cities is now occurring under some level of environmental protection. Nevertheless, lakes in the central part are becoming seriously polluted with both heavy metals and nutrients because local authorities promote industrialization and urbanization to improve economic conditions, while often ignoring environmental protection. Pollution is increasingly occurring in upstream reaches, a tendency that will bring more environmental problems. Interior lakes of China require immediate attention to prevent further declines in water quality.     

Advection,growth and nutrient status of phytoplankton populations in the lower River Murray,South Australia

To investigate the link between river flow, nutrient availability and development of algal blooms, growth rates of the major phytoplankton species were examined in situ in the lower River Murray, South Australia over the 1994/1995 summer. Eight sites were selected over a 54 km reach between Lock 1 and Nildottie and growth rates estimated by monitoring mean cell density in time‐aligned parcels of water as they travelled downstream. Discharge at Lock 1 during the period of study (3000–5000 ML day⁻¹) typified summer entitlement flows to South Australia. A large, shallow floodplain lake (lagoon), with an hydraulic connection to the river, supported a large population of cyanobacteria in summer, but inputs to the main channel did not substantially affect the abundance and composition of river phytoplankton. Mean net growth rates of Anabaena circinalis and A. flos‐aquae f. flos‐aquae were 0.132 and 0.176 day⁻¹, respectively, although individual rates varied from positive to negative. In contrast, the mean growth rate of the filamentous diatom Aulacoseira granulata was −0.15 day⁻¹, reflecting a decrease in population size with advection downstream. Mean cell densities of the three species did not exceed 5000 cells mL⁻¹ throughout the study. Growth bioassays conducted in the laboratory indicated that nitrogen was often the nutrient limiting algal growth, although it was not established whether nitrogen was limiting in situ. A conceptual model is presented, linking these findings with those of other work on the lower River Murray, to summarize the physical and chemical environmental factors governing the abundance of cyanobacteria in this reach of the river. Copyright © 2000 John Wiley & Sons, Ltd.     

Riparian eucalypts and willows and their significance for aquatic invertebrates in the River Murray,South Australia

The exotic weeping willow Salix babylonica is compared to the native river redgum Eucalyptus camaldulensis as a modifier of invertebrate habitats in the littoral zone of the River Murray. Net samples indicated minor differences in the composition and diversity of invertebrate assemblages at three willow and three redgum sites. Packs of redgum and willow leaves in mesh bags were used to assess rates of leaf breakdown. Willow leaves (half-life 14–26 days) decomposed more quickly than redgum leaves (27–50 days), although they were affected more by physical abrasion than biological decomposition. Willow leaves in 2.5-cm mesh bags lost more weight than those in 300 μm bags, indicating that feeding by invertebrates was also a factor. Microbial activity was the main agent of weight loss in redgum leaves. After 8 weeks' incubation there were distinctive invertebrate assemblages associated with leaf packs at redgum and willow sites. At redgum sites, but not willow sites, there were different assemblages in willow and redgum packs. Feeding trials showed that the common atyid shrimp Paratya australiensis preferred microorganism-colonized redgum leaves over colonized willow leaves and fresh leaves, although this may reflect preferences for the associated biofilms. Leaf biofilms at redgum sites had relatively high density and diversity of diatoms; redgum leaves generally attracted greater densities of bacteria, and fungi were not prominent on either leaf type. © 1997 John Wiley & Sons, Ltd.     

入河污染物排放对湟水水质的影响分析

根据湟水污染物现状调查监测,湟水流域每年向黄河输送的主要污染物为75 193 t。依据《地表水资源质量评价技术规程》(SL395—2007),采用单指标评价法,由湟水2010—2011年水质监测资料,得出湟水流域水功能区水质达标率为42.9%;采用季节性Kendall检验方法,对近5 a湟水水质站水质进行趋势分析,表明湟水流域水质整体状况无趋向。随着污水管网建设、污水处理厂的投入运行和河道综合治理,湟水流域的水质将逐步好转,各水功能区水质目标将逐步实现。     

Human impacts on suspended sediment and turbidity in the River Murray,South Eastern Australia: Multiple lines of evidence

European settlement has led to increased loads of fine suspended sediment (SS) entering the River Murray, Australia's largest, and arguably, most important river. The River Murray's anthropogenic sediment history can be divided into four periods with varying source areas, sediment loads, and seasonal patterns. The Aboriginal period (before 1840) was characterized by clear water at summer low‐flows in the River Murray and its southern tributaries, with more sediment coming from the northern catchment than the southern, and the Darling River being turbid at all flows. There is little evidence that Aboriginal burning resulted in any measurable increase in SS. SS loads peaked in the 1870s and 1880s (the gold and gully period, 1850–1930) as valley floors were incised by gullies (mostly in northern tributaries), and gold sluicing flushed huge amounts of sludge into southern tributaries. Sedimentation in wetlands and on floodplains increased by 2–10 times in this period, and the biota in wetlands switched from clear water to turbid water communities. In the hiatus period (1930–1960) sediment supply from gullies and gold mining waned and low flow SS concentrations returned to low levels. Dam construction through the 1960s and 1970s (the regulation period, 1960 on) disconnected the River Murray from catchment derived sediment. Despite this, SS levels increased again: now largely derived from instream sources including bank erosion from long duration summer irrigation flows, the spread of bottom‐feeding carp (Cyprinus carpio), and wave erosion from boats. Erosion switched from winter to summer dominated. Significant investment in securing water for the environment in the Murray‐Darling Basin could be complemented by addressing in‐channel sediment sources in the River Murray itself to reduce turbidity. Overall, European era SS concentrations remain relatively low with small sediment delivery to the ocean (0.1 Mt per annum), despite high catchment erosion rates. This is due to poor sediment delivery efficiency through the low‐gradient landscape.     

Impact of Water Projects on River Flow Regimes and Water Quality in Huai River Basin

Research on the impact of water projects (dams or floodgates) on river hydrology and the surrounding environment is important in river basin management. However, it is a difficult scientific issue due to its complexity. Huai River Basin is a unique region in China with high densities in both population and water projects and is experiencing a serious pollution problem. Based on the extended SWAT model with consideration of dams & floodgates, this paper proposes a quantitative framework to assess the impact of dams & floodgates on the river flow regimes and water quality in the middle and upper reaches of Huai River Basin. The results show that: (1) The dams & floodgates reduced the basin’s annual average flow by 2%, in comparison with the scenario of no water projects in the whole basin during 1991–2000, because of the regulation and storage of dams & floodgates. The flow in the non-flood season reduced 5% while the change of flow in the flood season was not acute. The impact of dams & floodgates on the annual flow are different in wet and dry years. In the wet year (1991), the impact of dams & floodgates is not obvious because the gates were opened to control the floods and their main functions are to change the temporal distribution in a year. In the dry year (1999), the flow reduced remarkably in comparison with the flow without dams & floodgates in the basin because the gates were closed in order to meet the water demand. The flow in the flood season increased by 8% whiles the flow in the non-flood season reduced by 12%. (2) There was a certain impact of dams & floodgates on water quality but they were quite different in the different area. It would be changed from the positive effect to the negative effect from the upriver to downstream. The dams & floodgates in the upper reaches played a positive role to improve water quality. But the ones in the middle and lower reaches played a negative role with contribution from 0 to 0.4. However, the contribution of exceeding pollutant discharge was more than 0.6. (3) The joint operation of dams & floodgates to control water quantity and quality will improve the water environment in Huai River Basin, but the key to improve the basin’s water environment is pollution control. This research will guide the anti-pollution and the united water quantity and quality assessment of dams & floodgates in Huai River Basin. Moreover it will provide a foundation to achieve the integrated basin management and sustainability of Huai River Basin.     

Hydrologic and Water Quality Modeling of Lower Nestos River Basin

Modeling efforts on Nestos river are presented. First, the Soil and Water Assessment Tool (SWAT), within a GIS interface (version AVSWATX), was applied to the lower Nestos River basin in Northern Greece. The model was calibrated and verified with the use of field data collected at four monitoring sites along the river course for a period of 3?years (October 2006?COctober 2009). The performance of the model was evaluated with the use of numerous statistical parameters, which showed a good agreement between the predicted and the observed values. The validated model was then used to test the impact of various management scenarios on the river flow and nutrient loadings. Second, a fuzzy logic model approach was used for the short-term prediction of water depth and chlorophyll-a (Chl-a) in the river according to measured values. The study showed that both the SWAT model and the fuzzy logic technique, if properly calibrated, could be useful and reliable tools in water resources management.     

Seasonal Forecasts of Unregulated Inflows into the Murray River, Australia

Water users along the Murray River, Australia, have traditionally used climatology forecasts of river flows for intra-annual planning of water use and trading. In this paper, we develop and assess the performance of statistical models for forecasting three-month inflow totals for the Murray River. Predictors are selected to represent the influence of initial catchment conditions and future climate on streamflows. These predictors vary with season and location, but are dominated by antecedent streamflows and indices describing the El Nino–Southern Oscillation. For all seasons, the forecasts are skilful with respect to climatology forecasts, and the forecast probability distributions appear to be reliable. Forecast skill is highest for forecasts made between September and December. The forecasts appear to be robust with respect to event size and time, except for the austral autumn seasons for which none of the predictors can forecast the decline in seasonal rainfall over the most recent decade.     

Impact of ENSO on River Flows in Guyana

The El Niño Southern Oscillation (ENSO) phenomenon is a natural part of the global climate system resulting from the interactions between large-scale ocean atmospheric circulation processes in the equatorial Pacific and Indian Oceans. In Guyana, for all the adverse weather and extreme hydrological events, the blame goes to El Niño or La Niña. This paper investigates the relationship between ENSO and three Guyanese river flows; the Demarara, Essequibo and Mazaruni. This work sheds some light on the effects of this phenomenon on these river flows which may be useful for the adaptation policies dealing with the impacts of ENSO.     

拉萨河下游水温变化特征及其影响因子分析

以拉萨河下游1956—1982年水温、气温及流量资料为基础,利用累计距平和滑动平均法分析了水温变化特性及变化趋势,并分析了水温对气温及流量变化的响应关系。结果表明:1拉萨河下游河段水温沿程升温率为1.0~2.8℃/100 km,研究河段的下游段因气温升高,且多为分汊型河道,故水温显著升高,研究站点间春季水温温差较大,冬季水温温差较小;2研究河段年均水温为7.3~8.4℃,夏季水温变幅大于冬季的;320世纪50年代中期到60年代中期水温降温率为-0.74℃/10 a,60年代中期到70年代初期水温升温率为0.47℃/10 a,70年代初期到80年代初期水温倾向率为0.005℃/10 a;4多年平均水温高于多年平均气温,同时期内水温的变化趋势与气温的相同,与流量的相反。     

剑潭水利枢纽对东江惠州段水质影响分析

通过对剑潭水利枢纽工程建成前后东江惠州段水质变化情况进行分析评价,并对剑潭水利枢纽建成后库区水质及坝址下游水质的影响原因进行初步分析,通过分析评价认为剑潭水利枢纽建成后,库区及坝址下游水质均有所改善,且坝址下游水质状况趋于稳定。     

Impact of Dam Construction on Water Quality and Water Self-Purification Capacity of the Lancang River, China

Along with the sequent completion of Manwan and Dachaoshan Dam, the river continuum of the middle and lower reaches of the Lancang River was separated into three types of segments: reservoir, below-dam segment and downstream flowing segment. The long-term series of water quality and river flow data over 20 years were analyzed in order to study the impact of dam construction and operation on water quality and water self-purification capacity of these different river segments. From pre-dam period to the first 7 years after Manwan Dam had been accomplished, the water quality of Manwan Reservoir became worse due to the accumulation of pollutants, and then to the next 5 years the water quality became better in virtue of the water self-purification of the reservoir. The cooperative operation of Manwan and Dachaoshan Dam had cumulatively positive impacts on water quality of their below-dam segment but no impacts on that of downstream flowing segment. From pre-dam period to the first 7 years after the closure of Manwan Dam, the water self-purification capacity of Xiaowan–Manwan segment for BOD₅, COD_Mn and NH₃–N decreased. Also, the water self-purification capacity of Manwan–Dachaoshan segment for BOD₅ and COD_Mn decreased but for NH₃–N increased. However, the water self-purification capacity of Jinghong–Ganlanba segment changed contrary to Manwan–Dachaoshan segment. In general, the construction of Manwan Dam negatively affected the water self-purification capacity of reservoir and below-dam segment but impose little impact on that of downstream flowing segment. This study suggested that it is necessary to pay attention to the effect of complicated temporal and spatial characteristics of dam on aquatic ecosystem.     

Environmental flow enhances native fish spawning and recruitment in the Murray River,Australia

Environmental flows aim to mimic components of a river's natural flow variability, including the magnitude, frequency, timing, duration, rate of change and the predictability of flow events. Aspects of the natural flow regime are thought to be linked to critical components of the life history strategies of many riverine fishes, including spawning and recruitment. In the Murray River, Australia, environmental flows are increasingly being used as a restoration tool; however, there is little information about the response of fish to these managed flow events. This study reports on the results from a 3‐year study on the effects of water management on the spawning and recruitment of four native fish species in the mid‐Murray River system. Two of these years were hydrologically similar, while the third year encompassed an extensive period of floodplain inundation, including the use of the largest environmental flow allocation to date in Australia. Drift nets were used to collect the drifting eggs and larvae of four iconic native species throughout their spawning season each year. Young‐of‐year were collected in the following autumn. Although golden perch and silver perch eggs were collected in all 3 years, both species increased their spawning activity during the major flood period compared to the previous two seasons. Murray cod and trout cod appeared not to increase their spawning activity in the flood year, but their recruitment may be increased when floodplain inundation occurs at times when their larvae and juveniles are present, most likely through the generation of abundant food resources. Whilst further study is required to confirm the role and mechanism of flooding in the spawning and recruitment of these species; this study provides important evidence of a link between the provision of an environmental flood and fish spawning and recruitment, and has significant implications for managing flows in regulated rivers. Copyright © 2008 John Wiley & Sons, Ltd.     

Flow management strategies to control blooms of the cyanobacterium,Anabaena circinalis,in the River Murray at Morgan,South Australia

The Murray–Darling river system is highly regulated and is Australia's major surface water resource. It is subject to blooms of the toxic cyanobacterium Anabaena circinalis, which present significant water quality problems. As a result of these blooms, an algal management strategy has been developed for the Murray–Darling basin. One of the major objectives of the strategy is the development of flow management strategies for key reaches of the river system. Intensive studies in the Murrumbidgee River, Australia, have indicated that persistent thermal stratification is a requirement for blooms of this cyanobacterium to occur. In the lower Murray, mean wind speed was found to be the major factor affecting the degree of thermal stratification under low flow conditions, which generally exist during the months of December to March. In this paper, the effect of various flow management scenarios on the likelihood of the occurrence of blooms in the River Murray at Morgan, South Australia, are assessed. A frequency analysis is carried out on 30 years of wind speed data to determine the probability of occurrence of persistent thermal stratification under a number of flow regimes. The scenarios evaluated include existing base flow conditions, altered base flow regimes, temporary releases from an upstream storage (Lake Victoria) and the temporary reduction of weir pool levels. The results obtained indicate that the dispersal of existing blooms by simultaneously reducing the weir pool levels at Locks 1–3 is the most effective and economical strategy for combating bloom formation by A. circinalis in the River Murray at Morgan. Copyright © 2001 John Wiley & Sons, Ltd.     

南水北调中线工程调水后对汉江中下游河势的影响

利用不平衡输沙原理,对汉江中下游河道进行不同调水方案的冲淤计算及河势变化分析.计算成果表明:河道冲刷量调水145亿m3方案小于调水15亿m3方案;水位下降值调水145亿m3方案也较调水15亿m3方案的小.调水145亿m3后,下游水量减少,给汉江中下游河势、防洪、引水和航运带来一定的影响,须开辟其它水源或修建工程满足汉江中下游工农业生产及航运用水的需要.     

黄河调水调沙试验对下游河道行洪规律的影响

山东省东明县高村河段在黄河下游河道具有一定的代表性.20世纪90年代,由于黄河下游持续小水高沙,低水期延长,主槽发生严重的淤积,河道行洪能力明显下降.2002年以来,黄河水利委员会通过小浪底水库进行了三次调水调沙试验,使该河段主河槽泥沙得到有效的冲刷,仅2003年5月至12月,山东河道(高村至汊2)主槽冲刷就达11756万m3,冲刷厚度0.23m,行洪能力得到大大提高.     

万家寨引黄工程供水水质分析与预测

万家寨引黄工程供水水质的好坏直接关系到整个工程的成败。本文通过对影响南干线未来供水水质的主要因素-万家寨水库水质状况，汾河水库上游河段及汾河水库水质状况的监测评价以及对未来供水水质进行的初步预测，定性地指出了未来的供水水质状况，影响供水水质的主要因素和水污染治理的重点。     

引黄用水发展概况及其对黄河下游冲淤与防洪的影响

黄河下游的洪水和泥沙淤积问题尚未得有效的控制，黄河流域水资源供需矛盾日益突出。近年来黄河下游河道主槽淤积抬升较多，中等洪水淹没范围增大；汛前河道断流是时间拉长，断流河段不段上延。本针对上述问题分析了引黄用水发展情况、引水引沙特点以及引黄用水对黄河下游径商、河道冲淤和防洪的影响。     

Modeling of Po River Water Quality in Torino (Italy)

The aim of this paper is to examine the Po river quality in a small stretch between two stations in Piedmont in the north of Italy. In this stretch a large pollution load is introduced and diluted in the fluent water of the river. The load has been quantified and about it we performed mass balances and modeling in order to understand the entity, the origin and the final fate of the immitted pollutants. In particular the objective of the work is to highlight the entity and the impact of Torino metropolitan area discharge on the quality of the same river. The obtained results show in particular, as well as the great impact of the Torino metropolitan area (the calculated pollution from Torino to the station downstream increases, for example for the COD of the 38%), the large contribute to the pollution from the Po river affluents (the pollution, for the COD, from Torino to the station downstream increases, considering the affluents too, of the 49%). The other fundamental point of investigation is the analysis of the impact produced by the Metropolitan Wastewater Treatment Plant (SMAT, Società Metropolitana Acque Torino) on the quality of the water. The obtained results show that the SMAT Plant determines the environmental state of the Po river in the station downstream of the same treatment plant. At the end we have evaluated the general pollution state in order to highlight which interventions are necessary in order to respect what is prescribed from the Italian laws.