Temporal Variability and Potential Predictability of the Streamflow Regimes in the North‐Eastern Iberian Peninsula

This paper investigates the temporal variability and potential predictability of streamflow regimes in the north‐eastern Spain for the 1970–2010 period. Two different regimes are found, those characterized for having peak flows in the winter and those where this maximum appears in the spring. The main characteristic time scales of streamflows in each area are studied by singular spectral analysis (SSA). While winter streamflow regime only shows interannual variability (quasi‐oscillatory modes around 5.5 and 2.3 years), spring streamflow (2.6 and 6.6 years) also presents a decadal variability component. Based on this result, a modelling process is conducted using autoregressive moving average (ARMA) models, for interannual variability modelling, and stable teleconnections between global oceanic sea surface temperature (SST) anomalies and river flow, for decadal variability modelling. Finally, a one‐step‐ahead prediction experiment is computed to obtain forecasted streamflows. The results for winter streamflow regime modelling show a phase concordance between the raw and the forecasted streamflow time series of around 70% and a correlation around 0.7, for the validation period (2001–2010). For spring streamflow, additionally to the ARMA modelling for the interannual component, a model based on the SST has been established that involves some oceanic regions from previous seasons located, fundamentally, not only in the North Atlantic but also in the Indian Ocean. The combined model (SST + ARMA) significantly improves the prediction based on the ARMA model alone, showing a phase concordance and a correlation around 90% and 0.7 respectively. This modelling scheme provides predictability skills of the rivers from the Inland Catalan Basins at different time scales, representing an added value for water planning. Copyright © 2014 John Wiley & Sons, Ltd.     

Differences in Spatial Patterns of Drought on Different Time Scales: An Analysis of the Iberian Peninsula

The differences in spatial patterns of drought over a range of time scales were analysed by the Standardized Precipitation Index (SPI). In a climatic area with a wide range of precipitation characteristics (the Iberian Peninsula), Pearson III distribution is flexible enough to calculate the drought index on different time scales. The Pearson III distribution was adapted to precipitation frequencies at time scales of 1, 3, 6, 12, 24 and 36 months. Spatial patterns of drought were analysed by Principal Component Analysis. The number of components found increased as the time scale did, which indicates great spatial complexity in drought analysis and uncertainty in drought classification, mainly at scales of 24 or 36 months, since the relationships between SPI series of observatories becomes more distant as the time scale increases. We concluded that there were no homogeneous regions with similar drought patterns that could be used for effective drought management or early warning.     

乌鲁木齐市经济社会用水结构变化及未来趋势分析

分析城市用水结构的变化并科学预测未来需水结构,是编制水资源利用规划的前提和基础,对区域水资源的合理配置具有重要意义。在分析乌鲁木齐市社会经济各业用结构变化及其规律的基础上,探讨了其变化的主要原因,并预测了未来用水结构的发展趋势及其对未来水资源供需形势的影响,对协调未来可能利用水资源与社会经济发展的关系、制定合理的水资源配置方案、促进经济社会可持续发展提供参考。     

Trend Analysis of Maximum Hydrologic Drought Variables Using Mann–Kendall and Şen's Innovative Trend Method

Droughts as destructive climatic extreme events affect natural environment of an area. Identifying droughts has a vital importance in the planning and management of water resource systems of a river basin. This study investigates the trends of maximum hydrologic drought variables, annual maximum duration (AMD), and annual maximum severity (AMS), by using Mann–Kendall, modified Mann–Kendall, and recently developed ?en's innovative trend analysis (ITA) methods. These methods are applied to the AMD and AMS of nine different stations located in Coruh River Basin, Turkey, in which numerous highly critical power plants have recently been constructed, under construction, or planned. Basic Mann–Kendall test indicated no trend in the investigated stations while the modified Mann–Kendall gave significantly decreasing trend for AMS series of station 2304 and for AMD series of station 2321 at 10% significance level. Modified Mann–Kendall and ITA approaches indicate that the AMS of station 2304 show significantly decreasing trend. According to the ITA method, the peak AMS values of the stations 2315 and 2322 have also significantly decreasing trend after 1986. Both modified MK and ITA methods provide increasing trends in drought severities of the stations 2316 and 2323. It should be noted that some droughts or water stress may be occurred in these stations in the future. Modified Mann–Kendall test provides no significant trend for the seven stations while ITA results indicated some positive or negative trends at these stations. The primary points of interest of ?en's ITA method are that it is not subject to any assumption such as serial relationship, non‐normality, sample size, and trends of low, medium, and high data can be seen by this method easily. The study indicates that the ITA method could be simply and successfully used by hydrologist or water resources decision makers or in identifying droughts to prepare efficient management plans. Copyright © 2016 John Wiley & Sons, Ltd.     

Trends in low flows of German rivers since 1950: Comparability of different low‐flow indicators and their spatial patterns

Climate change, land‐use shifts, reservoir storage, and water withdrawals impact low flows in rivers, creating challenges for ecological integrity and human uses. A systematic investigation of river discharges was carried out for 79 stream gauges in Germany. Available time series between 1950 and 2013 were analysed for trends in annual minimum low flows, discharge deficits, and low‐flow durations. The application of different low‐flow indicators led to similar spatial patterns, although each metric is used for different purposes in water management applications. Statistical tests identified significant discharge trends at more than half of the stations investigated. Low‐flow trends since 1950 tended to be catchment specific, suggesting that climate change has not been the dominant driver. Most of the gauges investigated showed statistically significant increases in low flows. This can be mainly attributed to reservoir management. For rivers showing snow‐ and icemelt‐dominated flow regimes, such trends are probably overlain by climate‐driven changes (increasing amounts of rainfall, earlier snowmelt in spring). In contrast, stations showing statistically significant decreases in low flows were correlated with areas of decreasing mining activity. Hydrologic impacts of climate change are widespread and significant, but the results here suggest that human river management remains the dominant hydrologic driver on many rivers.     

Status and Trends in Biotic Integrity in a Sub‐Tropical River Drainage: Analysis of the Fish Assemblage Over a Three Decade Period

We characterized the biotic integrity of the sub‐tropical Duero River, Mexico, comparing current and past index of biotic integrity (IBI) scores with results of an environmental quality index (EQI), inventorying abiotic characteristics and human impacts, and documenting ecosystem changes over the last three decades. We sampled the fish community and measured environmental variables during the dry season of 2009 at 19 sites. We compared 2009 findings with fish data obtained in 1986 and 1991 at nine of the sites. The correlation between the IBI and EQI was high (r² = 0.79, p = 0.0002), indicating that the IBI accurately characterized environmental condition. Thirteen sites were degraded (68%) based on IBI scores, three were fair (16%) and three had good conditions (16%). Based on the EQI, 12 sites were classified as poor (63%), two as fair (11%) and five as good (19%). A cluster analysis of nine abiotic variables and the IBI values yielded three groups: six sites with good integrity and environmental quality, eight with high chemical oxygen demand and four with high total dissolved solids. A discriminant analysis (square canonical correlation: 0.922, and Wilks' lambda significance: 0.001) identified biochemical oxygen demand, distance to vegetation and total dissolved solids as the main predictors. Compared to 1986 and 1991, 2009 IBI values and ratings had declined significantly (multiple response permutation procedure A = 0.16, p = 0.0005), indicating a trend of environmental deterioration, with scores and ratings at 7 of 9 sites lower in 2009. One site had declined from good to fair, one from good to poor, five from fair to poor, one had remained fair and one had remained good. Degradation was related to excessive human water use, reduced river flows, increased wastewater discharge, deforestation, erosion, and invasive species, and mismanagement of preserved sites (springs), all of which highlight an urgent need to reverse declining environmental conditions. Copyright © 2014 John Wiley & Sons, Ltd.     

南水北调中线冬期输水气温研究

南水北调中线线路较长,从暖温带的长江流域流向半寒带的海河流域,沿途水工建筑物多,冬季冰情问题是关乎冬季生产和生活安全的重大问题.本研究根据南水北调沿途新乡及新乡以北地区50年的气象资料,分析了新乡、安阳、邢台、石家庄50年气温变化及四个气象站气温之间关系.重点分析最北端的石家庄站气温、气候特点及稳定转负日期,根椐暖冬、冷冬不同标准为冬季气候进行分类.为南水北调中线工程冬期输水提供可靠科学依据.     

Assessing the Efficiency of an Elver Ladder Using a Multi‐State Mark–Recapture Model

The decline of the European eel (Anguilla anguilla) stock has led the European Commission to enforce a regulation (Council Regulation N° 1100/2007), in which each member state was required to establish an eel management plan. Various measures in the French plan aim at restoring river connectivity by mitigating the impact of obstacles on the colonization of continental water by eels. Consequently, many obstacles are going to be equipped with elver ladder in the near future. In this context, a method to assess the passability of an obstacle seems essential. In this study, we developed a tag–recapture method, appropriate to glass eels and elvers, and an associated multi‐state mark–recapture model (i) to assess the passability of a ladder and (ii) to quantify the effect of various environmental factors on this passability. An application to a specific obstacle is applied as an illustrative example that demonstrates the relevance of the assessment method, and how the results can be used to propose technical solution to improve the efficiency of the ladder. Nine tag–recapture campaigns were carried on this obstacle, and about 4400 young eels were tagged. The model demonstrates that the efficiency of the ladder was rather low, especially during low river flow periods, mainly because of accessibility problems. The model also demonstrates the major influence of the river flow on the probability for an eel to pass the ladder; consequently, managing river flow during the migration period can be a relevant measure to improve river connectivity and facilitate colonization of the watershed. Copyright © 2014 John Wiley & Sons, Ltd.     

南水北调受水区工业需水量的多方法组合预测

以南水北调东线江苏段受水区为对象,2020年为现状年,在趋势法、多元线性回归和BP神经网络的基础上,利用相对误差-反距离权重法构建了一种组合模型。采用该组合模型预测江苏段受水区2030年工业需水量。结果表明：基于趋势法、多元线性回归和BP神经网络所得的工业需水量预测值之间的偏差均小于10%,各单一方法与真实值之间的平均误差均小于10%;组合预测模型所得工业需水量的决定系数（R²）比单一需水预测模型高0.02~0.09;江苏段受水区2030年工业需水总量预测值为14.68×10⁸ m³,相比现状年工业需水总量增加了70.3%。研究成果不仅可为南水北调东线江苏段受水区提供可靠的工业需水量预测数据,也可为其他南水北调受水区工业需水量预测提供方法借鉴。     

The Dragonfly Association Index (Insecta: Odonata)—a Tool for the Type‐Specific Assessment of Lowland Rivers

Species traits of 57 Odonata species occurring in the Austrian bioregion Eastern Ridges and Lowlands (ecoregion Hungarian Lowlands; Illies, 1978 ) were defined by factor loadings of 12 habitat parameters: stream sections crenon, rhithron and potamon; flow velocity; standing water; temporary water; size of water body; open water; open banks; submerged macrophytes; reed; and riparian trees. On the basis of the species‐specific configurations of these habitat parameters, cluster analysis revealed seven dragonfly associations with different habitat needs: association of open waters, association of sparsely vegetated banks, association of reed and riparian trees, association of reed and submerged macrophytes, association of temporary waters, rhithron association and potamon association. Correlations between the associations' habitat requirements and the habitat parameters of the seven (near‐)natural river types, which are present in this bioregion were performed to define river type‐specific association compositions. From these results, a dragonfly association index was created to assess the ecological status of these rivers within the five‐tiered system of the European Union Water Framework Directive, emphasizing hydro‐morphological aspects by comparing the type‐specific reference situation with the actual status quo of dragonfly colonization. The method was applied at different rivers, particularly for the purpose of evaluating restoration measures. Copyright © 2014 John Wiley & Sons, Ltd.     

用成组生物毒性测试方法评价北方某市饮用水安全性

生物毒性测试方法可作为化学分析有效的补充手段。应用一组可检测类二恶英物质、类雌激素物质和遗传毒性物质的生物毒性测试方法,对北方某城市水源水、水厂工艺出水以及水龙头出水的潜在慢性毒性进行评价。结果表明地下水源水质,无论从类二恶英效应、类雌激素效应还是遗传毒性效应分析,都明显要好于地表水源水质;现有运行工艺尤其是加氯消毒工艺,对类雌激素物质的去除作用比较明显,对类二恶英效应的去除不明显并有上升趋势,对遗传毒性类物质(包括直接的和间接的)由于消毒副产物的产生,甚至有可能升高原水中的毒性效应;成组生物毒性测试方法可有效地评价水体的安全性。     

基于灰色预测模型的区域水资源承载力预测分析

水资源承载力研究集综合评价和预测分析为一体。以宜昌市为例,在2005—2015年宜昌市“水资源-社会经济-生态环境”复合系统承载力综合评价基础上,采用GM(1,1)灰色预测模型预测2020年、2025年、2030年水资源承载力;在分析未来水平年预测结果不确定性的基础上,结合最严格水资源管理制度和河长制,探讨4种情景假设下宜昌市社会经济发展模式的可持续性。研究结果表明,未来水平年宜昌市水资源承载力状态良好(2025年左右达到Ⅰ级),建议宜昌市社会经济与生态环境协调可持续发展。     

Patterns of species richness and introduced species in native freshwater fish faunas of a Mediterranean‐type basin: the Guadiana River (southwest Iberian Peninsula)

In this study, we analysed the factors affecting species richness and introduced species component patterns in native fish faunas of 30 streams of the Middle Basin of the Guadiana River. From a principal component analysis and a stepwise multiple regression analysis performed on a data matrix composed of ten hydrological and biotic variables, we showed that: (1) fish species richness increased with stream length and watershed area, (2) the number of native species in a stream declined as channelizations and river regulation (constructions of dams) are higher, whereas introduced species increased in the same way, (3) the two main negative factors affecting native ichthyofaunas affected dissimilar ecological areas: channelizations, which depend on land‐use intensity of floodplain, mainly occurred in lower reaches of streams, but construction of dams mainly took place in upper sections of rivers, (4) the length of the remaining well‐preserved reaches in a stream appeared to be the only factor accurately predicting native fish species richness, and (5) native fish faunas of small isolated streams are more vulnerable to habitat alteration than those of large streams. Both isolation and fragmentation of populations were recorded, so the conservation status of native and highly endemic fish fauna of the study area is extreme. Protection of the few still extant, well‐preserved small streams and upper reaches, habitat restoration of channeled areas, and inclusion of the need for native fish fauna conservation in long‐term public planning of water use become a priority. Fish communities appear to be a sensitive indicator of biological monitoring to assess environmental degradation. Copyright © 2001 John Wiley & Sons, Ltd.     

嫩江下游段水质现状及变化趋势分析

本文对嫩江下游吉林省境内江段水质现状开展评论,指出了年均及年内不同水期水质变化情况,并根据多年水质监测资料对历年水质变化趋势进行了分析评价。     

Economic analysis of water temperature reduction practices in a large river floodplain: an exploratory study of the Willamette River,Oregon

This paper examines ecosystem restoration practices that focus on water temperature reductions in the upper mainstem Willamette River, Oregon, for the benefit of endangered salmonids and other native cold‐water species. The analysis integrates hydrologic, natural science and economic models to determine the cost‐effectiveness of alternative water temperature reduction strategies. A temperature model is used to simulate the effects of combinations of upstream riparian shading and flow augmentations on downstream water temperatures. Costs associated with these strategies are estimated and consist of the opportunity costs of lost agricultural production and recreation opportunities due to flow releases from an up‐stream reservoir. Temperature reductions from another strategy, hyporheic flow enhancement, are also examined. Restoration strategies associated with enhanced hyporheic cooling consist of removal/reconnection of current obstacles to the creation of dynamic river channel complexity. The observed reduction of summer water temperatures associated with enhanced channel complexity indicates that restoring hyporheic flow processes is more likely to achieve cost‐effective temperature reductions and meet the total maximum daily load (TMDL) target than conventional approaches that rely on increased riparian shading or/and combinations of flow augmentation. Although the costs associated with the hyporheic flow enhancement approach are substantial, the effects of such a long‐term ecological improvement of the floodplain are expected to assist the recovery of salmonid populations and provide ancillary benefits to society. Copyright © 2008 John Wiley & Sons, Ltd.     

Using wavelet analysis to detect changes in water temperature regimes at multiple scales: effects of multi‐purpose dams in the Willamette River basin

Maintaining the natural complexity of water temperature regimes is a key to maintaining diverse biological communities. Insect communities, food webs, and fish respond to the magnitude and duration of water temperature fluctuations. Disruption of these natural patterns has the potential to alter physiological processes, behavioural adaptations, and community structure and dynamics. We analysed multiple >300‐day time series of water temperature from the Willamette River basin, Oregon, to assess the impact of large multi‐purpose dams on water temperature variability at temporal scales ranging from 1 to 32 days, short temporal scales that are commonly ignored. We applied wavelet analysis to quantify the variability of water temperature at multiple temporal scales simultaneously. We compared water temperature regimes above and below dams and before and after dam construction. The advantages of wavelet analysis are the ability to examine all temporal scales simultaneously and independently as well as the ability to preserve the temporal context of the wavelet coefficients. We were able to detect significant (p < 0.0001) reductions in water temperature variability, defined as the variability of the wavelet coefficients, as a result of dams at the 1‐, 2‐, 4‐, and 8‐day scales. There were no significant differences in water temperature variability between managed and natural flows at the 16‐ and 32‐day scale (p = 0.80). In addition to the well‐documented effects of dams on seasonal patterns in water temperature or on water temperature extremes, our results demonstrate that dams have significantly muted the small temporal scale variance in water temperature patterns to which many organisms may have been adapted. Conserving or restoring natural temperature patterns in rivers will require attention to these small‐scale complexities. Published in 2007 by John Wiley & Sons, Ltd.     

Evaporation modelling using neural networks for assessing the self‐sustainability of a water body

Studies addressing the self‐sustainability of water bodies are crucial from the perspective of sustainable water resources management. An artificial water body is vulnerable to drastic water level changes resulting from various hydroclimatical and geological factors. It is incumbent therefore to rigorously investigate the effects of these factors in order to assess the response of the water body, consequent to a wide range of scenarios. This study focuses on the self‐sustainability of a water body, based on the water budget approach, and taking into account various hydroclimatical and geological factors in the study area. As the available evaporation data shared a very short (~2 years) common time frame with the other variables, evaporation was modelled using regression and artificial neural network models. The study results indicated the water body would be self‐sustainable under the extreme climatical and hydrological conditions considered. While seepage exhibited substantial impacts on the storage of the water body, evaporation was found to have only marginal impacts.     

运城市地表水水环境质量现状分析

运用单元河段单项评价和综合评价方法,对运城市水环境污染源状况、主要河流水质现状、污染物变化趋势进行分析评价,提出了水环境保护对策建议。     

Water temperatures in the headwaters of the Volga River: Trend analyses,possible future changes,and implications for a pan‐European perspective

Water temperature is a physical property influencing abiotic and biotic parameters in an aquatic ecosystem. In different Central European rivers and lakes, a general trend of water temperatures in the range of +0.05 to +0.8 °C per decade was identified. Our case study analyses whether similar patterns apply to the headwaters of the Volga River, in the East European plain. Based on a dataset of water temperatures for 2008–2015, we investigated the spatial and temporal distribution of water temperature along the Tudovka River and estimated backward as well as predicted future changes from development scenarios throughout the 21st century. Stochastic models were applied to track trends and variations in water temperature. Furthermore, the correlation between water temperature and air temperatures was used to model historical water temperatures and to predict possible changes in the future, under the effects of climate change. Based on climate change scenarios, an increase of the mean water temperatures as well as changes regarding the ice cover can be expected until the end of this century. The conditions described for the headwaters of the Volga River system represent a valuable dataset for medium and large rivers in the East European plain and serve as a basis for future management.