山东省海河流域水土流失防治存在问题及对策

山东海河流域涉及黄泛平原风沙国家级水土流失重点预防区和省级水土流失重点预防区，文章基于流域水土流失特点，在调查流域水土保持生态建设、水土流失综合治理现状的基础上分析存在的问题，提出水土流失多领域综合治理措施、强化水土保持预防监督监管、优化监测站点布局、现代化升级改造现有监测网络等方面的对策建议。     

金华市水土流失状况及防治对策

通过对金华市水土流失的现状及其成因的综合分析，提出预防和治理水土流失的措施。     

线路工程建设对水土保持敏感评估及防治策略成效分析

广州至连州高速公路建设线路长，现状该区域水土流失情况较轻，对工程建设中线路所经过的生态保护区，河流区，村庄耕地区的水土流失敏感度进行分析，发现工程建设对沿线区域的水土保持情况产生了不利影响，分区采取防治措施预防水土流失，并对沿线区域的水土敏感进行了评估，分析了水土流失防治措施的治理成效。     

浅析三门县水土流失综合治理的技术体系

三门县属于南方红壤丘陵区和省级水土流失重点监督区。根据三门县第1次水土保持措施普查,目前县域内各乡镇均有水土保持措施分布,已基本形成了以工程措施体系、植物措施体系、生态修复措施体系为主,预防监督管理贯穿其中的水土流失综合治理技术体系,并在全县水土流失防治工作中取得了显著成效。未来全县水土保持工作的重点是在完善和巩固现有措施体系的基础上,加强预防监督管理体系建设,进一步治理现有水土流失和控制新增水土流失发生,为全县可持续发展提供生态保障。     

巴润河水库建设过程中的水土流失防治措施的研究

文章通过对巴润河水库开发建设过程的水土流失特点、危害的分析和水土流失预测,针对各区的水土流失特点,进行水土流失防治措施设计,预防水土流失和保护生态环境,保障水库工程的安全运营。     

谈加强城市水土流失防治措施

文章分析了城市水土保持的含义及造成城市水土流失的具体原因,探讨了防治城市水土流失的措施与建议,为城市水土流失预防和治理工作提供借鉴。     

北三农场黑土区水土流失防治措施

黑龙江省农垦总局绥化分局北部农场地处丘陵漫岗地带,是全局黑土区水土流失较严重地区,文章通过对水土流失现状和成因分析认为,采用非工程措施和工程措施相结合,是治理和预防这三场黑土区水土流失最有效途径。     

某工程水土流失防治目标及防治措施布设实例分析

水利工程建设项目在建设过程中扰动原地表植被和地下岩土层以及产生大量的堆置废弃物,极易造成水土流失。水土保持是指对自然因素和人为活动造成水土流失所采取的预防和治理措施。文中以石阡县獐子沟水利工程水土流失防治布设为例,并结合笔者积累经验,阐述了水利工程水土流失的防治目标和水土流失具体防治措施。     

水利部将分区防治水土流失

第二次全国水土流失遥感调查成果新闻发布会于１月２１日在北京召开．从会上得知，“十五”期间，水利部将以这次调查成果为基础，划定重点预防保护区、重点监督区和重点治理区，对水土流失实行分区防治．水利部下一步防治水土流失的对策是：对水土流失轻微、植被覆盖度较高、存在潜在水土流失危险的重点预防保护区，要建立健全管护机构，制定法规制度，切实保护好现有植被．同时要大力推行封山禁牧、舍饲养畜、草场封育轮牧，实施大面积保护等措施．对开发建设项目比较集中的区域，要按照《水土保持法》的规定，实施重点监督管理，加强执法…     

兰溪市开发建设中的水土流失与治理

兰溪市针对开发建设中所形成的水土流失危害，采取有效措施，加强预防监督和水土保持综合治理，避免走先破坏后治理的老路，取得了积极的成效。     

A DEM‐based parallel computing hydrodynamic and transport model

The sudden and accidental water pollution response system (SAWPRS) for Yangtze River in central China required to develop a hydrodynamic and transport model, which is readily available and capable of simulating a large river system within GIS environment. This study facilitates such effort by developing a parallel computing method based on digital elevation model (DEM) using overlapping domain decomposition approach (ODDA) and message passing interface (MPI) protocol. The hydrodynamic and transport model was redesigned using finite volume method for hydrodynamic and transport model dispersion, the SIMPLEC method for solving the flow field, and the pressure weighted interpolating method for the flow field modification. This modelling approach was verified in two experiments using different sets of computer clusters. The model output was evaluated against the measured data collected for the year 1998 for Wanzhou, an upstream river segment of Yangtze River. The relative error was found to be less than 10%. The performance of parallel computation was found excellent as evident from the cost efficiency values greater than 0.81 in both experiments and increased computation speed while increasing the number of computer clusters. Overall, the parallel computing modelling system developed here was found to meet all requirements of SAWPRS. Copyright © 2010 John Wiley & Sons, Ltd.     

Eutrophication as a ‘wicked’ problem

Eutrophication, or the enrichment of lakes and reservoirs with plant nutrients such as nitrogen and phosphorus, is an ongoing concern facing human societies around the world. Once thought to have been resolved using engineering approaches such as municipal wastewater treatment and storm water management, the problem of nutrient enrichment not only persists, but even continues to increase, being manifested in harmful algal blooms, limitations on access to safe drinking water supplies, and related concerns associated with fresh water in lakes and reservoirs. The continuing concern surrounding eutrophication fulfils the many attributes of a ‘wicked’ or complex problem facing society. This report reviews seriatim the ten attributes of a wicked problem, and the implications of these attributes for lake and reservoir management are discussed. Recognition of eutrophication as a wicked problem requires site‐specific approaches, based on specific knowledge of individual water bodies, as well as an ongoing commitment to lake and reservoir management to respond to new manifestations of the problems of nutrient enrichment as they continue to be revealed over time.     

Body size,experience, and sex do matter: Multiyear study shows improved passage rates for alewife (Alosa pseudoharengus) through small‐scale Denil and pool‐and‐weir fishways

Alewife (Alosa pseudoharengus) passage through 3 fishways was assessed during the 2013–2016 spawning runs in 3 rivers of the Isthmus of Chignecto, Canada. From April 24 to June 10, 5,423 alewife with a mean ± SD fork length of 227 ± 18 mm were tagged with passive integrated transponders. During their tagging year, approximately half of individuals (40% to 64%) went undetected whereas those detected used fishways from April 16 to July 8. Detected alewife were significantly longer than those undetected. Attraction rates to fishway entrances in 2015 and 2016 ranged from 85% to 98%. Annual fishway passage rates for pooled fish tagged that year and returnees, varied from 64% to 97% for 2 Denil style fishways. A pool‐and‐weir fishway that was dysfunctional (2013), repaired (2014), and replaced (2015–2016) yielded 0.5%, 25%, 60%, and 73% annual pooled passage rates, respectively. Larger individuals, previously tagged returnees, and males compared to females of a similar size had higher passage success suggesting some fishways may apply population‐level selective pressures. Alewife passage rates related to fishway style, design, and proper function, with greater passage for the 2 Denils than the pool‐and‐weir fishway in our study. Regular structural maintenance and fish passage reviews are essential management considerations to ensure fishway functioning and river connectivity. Replacement of a fishway with poor fish passage may be the best option to improve passage rates. Future research should address the effects of multiple anthropogenic instream obstructions, environmental variables, negative sublethal post‐tagging effects, and the importance of returnees on fish passage rates in fishways.     

Water quality management: A regional perspective— The severn-trent area

The management of water quality in U.K. rivers is going through a period of major change due to the proposed reorganization of the water industry and to the increasing demands on river resources and the imposition of stricter environmental standards. Changes to the river classification scheme and effluent consent conditions are discussed. A brief summary is given of some of the quality problems that are of particular concern in the Severn-Trent area. The impact on quality of river regulation including in-river purification lakes is described. Catchment models have been developed to assist with the management of river resources. These and other river quality modelling techniques are reviewed.     

Limnological aspects of humic substances in Chubut River (Patagonia‐Argentina)

Humic Substances (HSs) of the Chubut River (Patagonia‐Argentina) have been investigated, during two consecutive years and different climatic seasons, in order to obtain a first approach at their spatial and temporal distribution, as well as their origin and relation with environmental characteristics. Absorbance at 250 nm and limnological variables were measured and the data processed by different statistical tools. We found that the processes developed in the lower sections of Chubut River are dominated by those produced in the Florentino Ameghino Reservoir. The riverine HSs are present in very low concentrations, have mainly autochthonous origin, exhibit spatial homogeneity and temporal variability similar to nutrients (nitrates and soluble reactive phosphorus). Copyright © 2010 John Wiley & Sons, Ltd.     

VEGETATION–LANDFORM ASSEMBLAGES ALONG SELECTED RIVERS IN THE CZECH REPUBLIC,A DECADE AFTER A 500‐YEAR FLOOD EVENT

Rivers with a natural flow regime strongly influence the dynamics of riparian plant communities through hydrological and geomorphological processes. In this study, associations between fluvial landforms and vegetation are investigated on three near‐natural rivers in the Czech Republic a decade after a 500‐year return period flood in July 1997. This extreme disturbance destroyed the anthropogenically modified river channels and created suitable conditions for a range of ecosystems with high diversity and ecological stability. Field surveys were conducted on fluvial landforms (bars, islands, banks, floodplains and terraces) along three ‘renaturalized’ rivers, where no technical modifications had subsequently been made to their channels outside urban areas and the floodplains had been left in a post‐flood state. Vegetation species abundance and 13 environmental variables (topographical, hydrological and soil) were investigated in summer 2007, 10 years after the extreme flood disturbance. The results suggest that the recently created fluvial geomorphic forms are key environmental determinants of riparian vegetation distribution patterns. A range of statistical analyses illustrate that some plant species show predictable patterns of occurrence that correspond with the fluvial forms, supporting a fourfold grouping of herbaceous and woody species and the identification of typical plant communities associated with gravel bars, islands, banks, floodplains and terraces. An investigation of the species richness found on different fluvial landforms showed that the highest number of species occurred on the floodplain and decreased gradually towards the channel bed and towards terraces. Investigation of existing conditions in reaches of rivers with natural dynamics of fluvial processes provides valuable information that can be used as an effective tool for planning restoration strategies and precise management. However, the most important finding of this study is the remarkable establishment of complex river corridor vegetation–landform associations within 10 years of a 500‐year flood that removed the heavily cultivated landscape that had existed before the event. Copyright © 2011 John Wiley & Sons, Ltd.     

Sediment in Mosul Dam reservoir using the HEC‐RAS model

Mosul Dam, located on the Tigris River north of Iraq, is experiencing sedimentation problems, especially near the Al‐Jazeera pumping station that supplies the irrigation water for the Al‐Jazeera project. The sources of the sediment accumulated within the reservoir are from the Tigris River, as well as ten side valleys on both sides of the reservoir. The sediment inflow rate into the reservoir and the released values are considered on the basis of the operation schedule of the dam for the considered period from 1986 to 2011. The sediment loads were estimated on the basis of available measurements and estimated literature values. The HEC‐RAS 4.1 model was used for flows and sediments in the main river and reservoir. The model was calibrated for flow simulations (coefficient of determination r² = 0.87) and sediment routing based on bed level, (with resultant r² = 0.98 and Mean Absolute Deviation of 0.95). The Ackers–White equation was used in the HEC‐RAS model for sediment routing because of the wide range of sediment sizes in the study case. The resultant total accumulated sediment load volume was 1.13 km³, a value that is very close to the measured values (1.143 km³) obtained from a previous bathymetric survey. Furthermore, the model indicated most of the sediment (80.7%) was deposited during the first five of the dam operation.     

Hydrological Effects on Relationships Between δ15N of River Nitrate and Land Use in a Rural River Basin,Western Japan

This study aimed to examine how the relationship between δ¹⁵N of nitrate (δ¹⁵N_NO3) in rivers and land use within a river basin changes with varying hydrological conditions. This information would aid in identifying the dominant source contributing to increased nitrate concentrations in rural rivers. For this, δ¹⁵N_NO3 in river water was investigated monthly in the five subbasins of the Hii River basin (area: 911 km²), western Japan, for 1 year and 3 months. There were significant correlations (p < 0.05) between δ¹⁵N_NO3 and the land‐use ratio (i.e. ratios of forested, agricultural and residential areas in a subbasin) for the majority of the observation days, indicating that δ¹⁵N_NO3 reflected land use within the basin. δ¹⁵N_NO3 ranged from +1.4‰ to +8.5‰ and was lower in a subbasin with a higher forested area ratio. We found that the absolute value of the regression slope of the relationship between δ¹⁵N_NO3 and the land‐use ratio decreased with increasing river discharge. This finding demonstrates that differences in δ¹⁵N_NO3 among subbasins with different land‐use compositions became smaller under higher flow conditions. Because δ¹⁵N_NO3 decreased with increasing river discharge, the small absolute value of the regression slope under high flow conditions indicates that forested areas could be the dominant source of river nitrate during high flows in all subbasins investigated regardless of land‐use composition. The results suggest that forested areas make a large contribution to the increase in nitrate concentration in downstream rivers during high flows, because the nitrate concentration increased with increasing river discharge. Copyright © 2014 John Wiley & Sons, Ltd.     

Variations in fish assemblages in a tributary of the upper Paraná River,Brazil: A comparison between pre and post‐closure phases of dams

This paper purposed to evaluate alterations in fish assemblage (structure and species richness) and variations in the abundance of the most abundant species captured in the Piquiri River, due to the closure of Porto Primavera (in 1998; located upstream the Piquiri River mouth) and the Itaipu (in 1982; located downstream) dams in the upper Paraná River. The effects of selected environmental variables were also determined. Fishes were sampled during four distinct periods. Six samplings were conducted in each period, at two different sites (Campina and Apertado). For sampling, gill and trammel nets were used. Species abundances were indexed by catch per unit of effort. Spatial and temporal changes in environmental variables were summarized by a principal components analysis (PCA). To summarize structure of the assemblage, a nonmetric multidimensional scaling (NMS) was used. To test the significance of between‐group differences at each periods and sites we used a multiresponse permutation procedure (MRPP). To test the association between fish assemblage and the environmental variables matrices, we used procrustean superimposition approach. A total of 2693 individuals were caught, belonging to 69 species, 4 orders and 19 families. Species richness differed spatially; the Campina site had greater mean richness (13) per sampling than the Apertado site (10). The structure of the fish assemblages showed significant temporal and spatial variations, which were more evident in the last period at the Apertado site (after the closure of Porto Primavera Dam). Spatial and temporal changes in structure of fish assemblages were not associated to environmental variables. Temporal changes in abundance, both in number and in weight, of the most abundant species were verified in both sites. The lack of migratory species was highlighted, which sharply decreased in the last studied period, when they were replaced by sedentary species. These findings appear to be related to regional factors, such as the decrease of floods registered in the upper Paraná basin, exacerbated by the control prompted by dams. Copyright © 2009 John Wiley & Sons, Ltd.     

A Multi‐scale,Hierarchical Model to Map Riparian Zones

Riparian zones are important for their contribution to biodiversity and ecosystem services, especially in the western USA where riparian zones occupy a small proportion of the landscape but support a majority of the biodiversity. However, few accurate datasets of riparian zone locations are available over broad spatial extents, and cost efficient methods to map riparian zones at fine spatial resolutions do not currently exist. We created a multi‐scale, hierarchical, and process‐guided method to map the location of riparian zones using readily available, national datasets. We demonstrate the applicably of this straightforward method in the Southern Rockies Ecoregion, where we mapped both current riparian zones (the riparian zone that is not strongly modified by human land uses and is assumed to support natural riparian vegetation) and potential riparian zones (the area that would likely support natural riparian vegetation in the absence of human activity). The overall accuracy of our method for potential and current riparian zones was 92%. The Southern Rockies Ecoregion is composed of 3.1% (±0.3%) potential and 2.5 (±0.2%) current riparian zones, indicating that roughly 21.0% (±0.5%) of riparian zones have been removed by human activities. This modelling approach can be used to create detailed maps of riparian zones to inform regional conservation and management decision‐making, and the methods can be applied to different regions at multiple scales from small watersheds to a national analysis. Copyright © 2016 John Wiley & Sons, Ltd.