Variable Streamflow Contributions in Nested Subwatersheds of a US Midwestern Urban Watershed

Quantification of runoff is critical to estimate and control water pollution in urban regions, but variation in impervious area and land-use type can complicate the quantification of runoff. We quantified the streamflow contributions of subwatersheds and the historical changes in streamflow in a flood prone urbanizing watershed in US Midwest to guide the establishment of a future pollution-control plan. Streamflow data from five nested hydrological stations enabled accurate estimations of streamflow contribution from five subwatersheds with variable impervious areas (from 0.5% to 26.6%). We corrected the impact of Missouri river backwatering at the most downstream station by comparing its streamflow with an upstream station using double-mass analysis combined with Bernaola-Galvan Heuristic Segmentation approach. We also compared the streamflow of the urbanizing watershed with seven surrounding rural watersheds to estimate the cumulative impact of urbanization on the streamflow regime. The two most urbanized subwatersheds contributed >365 mm streamflow in 2012 with 657 mm precipitation, which was more than fourfold greater than the two least urbanized subwatersheds. Runoff occurred almost exclusively over the most urbanized subwatersheds during the dry period. The frequent floods occurred and the same amount of precipitation produced ~100 mm more streamflow in 2008–2014 than 1967–1980 in the urbanizing watershed; such phenomena did not occur in surrounding rural watersheds. Our approaches provide comprehensive information for planning on runoff control and pollutant reduction in urban watersheds.     

Watershed Protection Challenges in Rapidly Urbanizing Regions: The Case of Tegucigalpa,Honduras

Abstract

Rapidly urbanizing regions present watershed managers with a range of challenges, especially when drinking water sources and their watersheds are located within the margins of urban and suburban expansion. These challenges can be acute in those developing countries where land-use regulations and environmental protection laws are inadequate or poorly applied, the latter often a result of the lack of defined institutional responsibilities and coordination. The Los Laureles reservoir and Guacerique watershed that supply 30 percent of Tegucigalpa's drinking water provide a powerful case study of the kinds of natural resource pressures that may lead to water quality and reliability deterioration as urban growth continues. Sedimentation, high turbidity, and high pathogen counts have accompanied decisions to locate projects such as the construction of a major ring-road/highway expansion, military bases and hospitals, and a 10,000 unit public worker housing complex in the watershed. These problems have been exacerbated by the development of private housing and poultry plants, and widespread firewood extraction from the remaining forest cover around the margins and upstream of the reservoir. For a variety of reasons, geographical and economic, watersheds like Gaucerique may frequently become neglected components of the water supply system and their protection receive much lower priority than efforts to expand and improve water supply coverage to consumers. In particular, by contributing little to revenue generation in the short term, watershed spending may be cut back from already low levels during water sector privatization as managers are forced to pay greater attention to balancing their budgets.     

Landscape-scale modeling of water quality in Lake Superior and Lake Michigan watersheds: How useful are forest-based indicators?

The Great Lakes watersheds have an important influence on the water quality of the nearshore environment, therefore, watershed characteristics can be used to predict what will be observed in the streams. We used novel landscape information describing the forest cover change, along with forest census data and established land cover data to predict total phosphorus and turbidity in Great Lakes streams. In Lake Superior, we modeled increased phosphorus as a function of the increase in the proportion of persisting forest, forest disturbed during 2000–2009, and agricultural land, and we modeled increased turbidity as a function of the increase in the proportion of persisting forest, forest disturbed during 2000–2009, agricultural land, and urban land. In Lake Michigan, we modeled increased phosphorus as a function of ecoregion, decrease in the proportion of forest disturbed during 1984–1999 and watershed storage, and increase in the proportion of urban land, and we modeled increased turbidity as a function of ecoregion, increase in the proportion of forest disturbed during 2000–2009, and decrease in the proportion softwood forest. We used these relationships to identify priority areas for restoration in the Lake Superior basin in the southwestern watersheds, and in west central and southwest watersheds of the Lake Michigan basin. We then used the models to estimate water quality in watersheds without observed instream data to prioritize those areas for management. Prioritizing watersheds will aid effective management of the Great Lakes watershed and result in efficient use of restoration funds, which will lead to improved nearshore water quality.     

Hydrologic alterations in the Wabash River watershed,USA

Flow alteration of streams from anthropogenic impacts is ubiquitous worldwide. In this paper, we examine flow alteration in a single watershed, the Wabash River and suggest potential impacts on aquatic assemblages. The Indicators of Hydrologic Alteration (IHA) software was used to evaluate hydrological variables generated from daily discharge data of 80 USGS gauging stations, during the past several decades. We used the approach of regressions of hydrological variables against time to identify hydrologic change. An average of 6.9 hydrologic variables (of 33 variables) were significantly altered at each station, and stations with larger watersheds had an increased number of altered variables. A principal components (PC) analysis of altered hydrologic variables resulted in three of four PC axes that were correlated with watershed area. Significant results were: (1) larger streams were more likely to have hydrologic alteration than smaller streams; (2) streams with upstream dams had increased minimum flows for 1‐, 3‐, 7‐ and 30‐day intervals, decreased maximum flows for 1‐, 3‐, 7‐ and 30‐day intervals, increased fall rates, decreased summer monthly flows and decreased high pulse counts; (3) the presence of agriculture in upstream watersheds resulted in an increased number of zero flow days, increased low pulse counts and decreased high flows during October and April. No significant differences were detected in hydrologic alteration based on urban land‐use of upstream watersheds. Hydrologic alterations in the Wabash River watershed have undoubtedly resulted in ecological degradation. We suggest that changes in assemblages during the past century are linked to these hydrologic alterations. Copyright © 2008 John Wiley & Sons, Ltd.     

近30年内蒙古入湖流域干旱特征时空变化分析

黄河中上游地区入湖流域干旱特征时空变化对下游淡水湖泊水量调控及生态环境改善具有重要作用。基于乌梁素海东部流域23个水文气象站1986-2015年的逐日降水资料,经预白化处理后,选取基于标准化降水指数(SPI)的干旱历时和干旱严重度作为评价指标,应用Mann-Kendall法分析30 a来乌梁素海东部流域的干旱特征及变化趋势。研究结果表明:乌梁素海东部流域山区降水量多于平原地区降水量;干旱历时及干旱严重度随时间变化均不显著,流域北部和东南部地区干旱呈持续发展趋势;短时间尺度气象干旱集中发生在流域中部及东南部,中长时间尺度的农业和水文干旱共同发生在流域北部。在乌梁素海降水量微幅减少的趋势下,由于东部流域受水利工程建设等人类活动的影响,流域径流补给量呈明显降低趋势,而为改善湖泊水质、抑制黄藻,必然需相应增加凌汛期及灌溉间隙期引黄水量,二者关系的有效平衡及合理调控,可为区域从量质综合角度改善湖泊环境提供新思路。     

Comparison of the interannual and interdecadal variability of heavy flood characteristics upstream and downstream from dams in inversed hydrologic regime: Case study of Matawin River (Québec,Canada)

Erected in 1930, the Matawin Dam caused an inversion of the hydrologic regime of the Matawin River: snow‐melt water in spring (April to June) is stored in the reservoir and then released in winter (January to March) to feed the hydroelectric generating stations built downstream on the Saint‐Maurice River. Thus, heavy floods occur upstream from the dam in spring but downstream in winter. We compared the interannual and interdecadal variability of the heavy flood characteristics (magnitude, duration, frequency and variability) both upstream (spring floods) and downstream (winter floods) from the dam during the 1934–1994 period. This comparison revealed that the principal change observed downstream from the dam translates into a strong increase in the duration (in days) of heavy floods. The average duration of these floods quintupled. This change in duration occurred around the mid‐1960s and thus led to a significant decrease in the magnitude, frequency and variability of heavy floods. It also altered the relationship between the climate indices and these fundamental characteristics (magnitude, frequency and duration). Downstream from the dam, the magnitude and frequency are positively correlated to the Atlantic multidecadal oscillation (AMO), whereas upstream they are negatively correlated to the same index. However, the AMO index is negatively correlated to the duration downstream from the dam, whereas upstream this characteristic is no longer significantly correlated to any climatic index. Two factors have been invoked to explain this change observed downstream from the dam.

• The cooling observed since the 1960s at the station located at the dam. However, this cooling was not observed on the scale of the entire watershed. This reduces its plausibility.
• The increase in hydroelectric power production in the watershed after nationalization of hydroelectric power in 1962. This increase would be explained by the expansion of the market for hydroelectric power (national and international markets). Before nationalization, the hydroelectric power produced in the watershed was intended only for regional industries.

Copyright © 2010 John Wiley & Sons, Ltd.     

Assessment of water conflict in Mae Chaem River Basin,Northern Thailand

For this study, we conducted a quantitative water resources assessment of the Mae Chaem River Basin, Thailand, an area with dry season water scarcity and water use conflicts between upstream and downstream inhabitants. The block-wise TOPMODEL with the Muskingum–Cunge flow routing method (BTOPMC) was used to predict run-off in 21 sub-basins and Geographic Information System (GIS) was employed to collect information for crop water demand evaluation. Four sub-basins exhibited critical water conditions in 2000. The conversion of forestlands into agricultural lands during the past decade has engendered water scarcity in the dry season and flooding in the wet season.     

太湖流域河道内用水控制指标分析计算

河道内用水控制指标是反映水资源供需平衡状况、协调河道内外用水、统筹上下游用水关系及流域和区域水资源配置优化程度的重要指标。文中根据太湖流域特点,选取了太湖及平原河网区13个代表站的水位资料,通过频率分析法和Tennant法,提出在满足生活、生产和生态用水条件下,太湖和流域平原河网区代表站允许的最低旬平均水位控制指标,及黄浦江松浦大桥断面允许的最小月净泄量控制指标。     

雅砻江和金沙江中下游梯级水库联合优化调度建模及应用Ⅱ——联合优化调度规则分析

为提升长江上游水资源利用效率,在“雅砻江和金沙江中下游梯级水库联合优化调度建模及应用Ⅰ—联合优化调度潜力分析”的基础上,进一步探究了雅砻江和金沙江中下游梯级上下游水库间和不同梯级间的运行规律,绘制了联合优化调度图,并分析了相关电站的蓄放水次序。研究表明:汛前金中、雅砻江梯级水库与金下梯级各水库消落开始次序宜为两河口—龙盘—锦屏一级—二滩—向家坝—白鹤滩—溪洛渡—乌东德,总体消落思路为上游水库优先消落,尽可能的保持下游溪洛渡、乌东德等电站高水位运行,提高流域整体发电效益;汛末各水库蓄水开始次序宜为锦屏一级—龙盘/二滩—两河口—乌东德—白鹤滩/溪洛渡—向家坝,总体蓄水思路为上游水库优先释放防洪库容开始蓄水,减轻下游防洪压力,且来水偏丰年份的蓄水时间相应有所推迟。     

A Fast Semi Distributed Rainfall Runoff Model for Engineering Applications in Arid and Semi-Arid Regions

A new GIS based rainfall runoff model is developed for engineering applications, achieving a highly automated watershed analysis process starting from watershed delineation and up to the runoff hydrograph calculation. The model can be classified as a semi-distributed time area model that adopts an improved grid based approach for calculation of watershed response. The model deals with each grid cell in the digital elevation model as an independent hydrologic unit. Travel time through each grid cell is estimated using Manning’s formula and a stream power formula that relates the hydraulic radius at the cell to the characteristics of its upstream watershed area and excess rainfall depth. The watershed response at its outlet is estimated by routing the response of each grid cell using a flow path response function that is defined for that cell. The routed responses of all watershed cells are then convoluted to produce the outflow hydrograph. Model advantages include accuracy improvements due to the incorporation of grid-based routing calculations (both translation and attenuation), fully automated model structure, and fast ability to model many watersheds simultaneously. The combination of these advantages constitutes the novelty of the model that makes it very suitable for engineering design as well as for real-time applications. The model was tested using the data of the experimental watershed, Walnut Gulch, Arizona, USA, gauged by 88 rainfall stations and several discharge recording flumes. The results show that the model can accurately predict the runoff hydrograph where suitable input is available.     

基于分形和R/S分析的渭河干流径流变化特征研究

变化环境下日益突出的水资源供需矛盾对流域水资源管理提出更高要求。通过分析流域径流量变化特征,揭示流域水资源演变趋势,为流域水资源合理开发利用提供依据。以渭河流域为研究区域,采用Mann-Kendall非参数检验、分形理论和R/S等方法分析渭河干流6个典型水文站1956—2015年径流时空变化特征、持续性及两者之间的关系。结果表明:渭河干流各站点的月径流量均呈减少趋势,从上游到下游,月径流量减少趋势的显著性越来越弱,呈显著性减少趋势的月份越来越少。渭河干流各站点的月径流深Hurst指数均大于0.5,即未来与历史变化情况呈正相关性,各站点未来月径流量将呈持续减少趋势。汛期分维数大于非汛期,上游月径流分维数小于下游,中游月径流分维数最大。分维数越大,径流过程变化越复杂,河流调节能力越差,表明渭河干流在汛期和中游径流量调节能力相对较差。Hurst指数与分形维数之间有着显著负相关性,即径流量越复杂,分维数越大,Hurst指数越小。研究结果可为流域水资源科学调度提供依据,有利于促进流域内水资源严格管理。     

Identification of the SCS-CN Parameter Spatial Distribution Using Rainfall-Runoff Data in Heterogeneous Watersheds

The Soil Conservation Service Curve Number (SCS-CN) method is widely used for predicting direct runoff volume for a given rainfall event. However, previous results indicated that when the CN value is determined from measured rainfall-runoff data in a natural watershed it is not possible to attribute a single CN value to the watershed, but actually the calculated CN values vary systematically with the rainfall depth. In a previous study, the authors investigated the hypothesis that the observed correlation between the calculated CN value and the rainfall depth in a watershed reflects the effect of the inevitable presence of soil-cover complex spatial variability along watersheds. In this study, a method to determine SCS-CN parameter values from rainfall-runoff data in heterogeneous watersheds is proposed. This method exploits the observed correlation between the calculated CN values and the rainfall depths in order to identify the spatial distribution of CN values along the watershed taking in to account the specific characteristics of the watershed. The proposed method utilizes the available rainfall-runoff data, remote sensing data and GIS techniques in order to provide information on spatial watershed characteristics that drive hydrological behavior. Furthermore, it allows the estimation of CN values for specific soil-land cover complexes in more complex watersheds. The proposed method was tested in a small experimental watershed in Greece. The watershed is equipped with a dense hydro-meteorological network, which together with a detailed land cover and soil survey using remote sensing and GIS techniques provided the detailed data required for this analysis.     

Occurrence of Lawn Care and Agricultural Pesticides in the Don River and Humber River Watersheds (1998–2002)

Between 1998 and 2002, surface water samples were collected from several sites in the Don River and Humber River watersheds, both tributaries to Lake Ontario, and analyzed for a variety of pesticides, including those used for urban lawn care. Analyses included 152 pesticide active ingredients and eight metabolites. Samples were collected during base flow periods (i.e., dry events) and rainfall events (i.e., wet events). The objectives of the study were to determine which pesticides were detectable, whether there was a difference in the detection frequency between the two watersheds and between upstream and downstream in each river, and whether precipitation influenced the frequency of detection. Eleven pesticides and one metabolite were detected in surface waters of the Don and Humber rivers or their tributaries, with approximately 72% of samples containing at least one pesticide attributable to lawn care use. The pesticides and pesticide metabolite detected in this study included 2,4-D, atrazine, bromacil, carbofuran, chlorpyrifos, cypermethrin, diazinon, dicamba, MECOPROP, metolachlor, metribuzin, and an atrazine metabolite (des-ethyl atrazine). Four pesticides exceeded federal or provincial water quality guidelines/objectives. Diazinon exceeded the provincial water quality objective in 28% of the samples taken. For the three other pesticides (atrazine, carbofuran and chlorpyrifos) exceedance of a water quality criteria occurred in less than 1% of the samples.     

三峡库区龙河流域降雨侵蚀力的时空分布特征

为详细研究三峡库区龙河流域降雨侵蚀力的时空分布特征,根据流域及其周边共12个雨量站连续41 a(1970—2010年)的日降雨资料,按照降雨侵蚀力简易模型,对龙河流域降雨侵蚀力年内分配和年际变化规律进行了计算和分析。研究表明龙河流域多年侵蚀力变化范围为2 031.47~10 927.57 MJ·mm/(hm²·h),多年均值为4 662.00 MJ·mm/(hm²·h);流域年降雨侵蚀力总体趋势为由东北向西南递减,侵蚀力高值区在黄水和悦来场一带,低值区位于廖家坝站附近。流域年降雨和年降雨侵蚀力年内分布较集中,汛期降雨、汛期降雨侵蚀力分别占全年比重的78.43%和78.56%;流域侵蚀力分布最集中时段为5—7月份。龙河流域4站M-K统计值Z值均>0,其降雨侵蚀力为增加趋势;其余3站Z值均<0,其降雨侵蚀力为减小趋势;但所有站点的Z值都没有通过α=0.05的显著性水平检验。1970—2010年间,对整个流域而言,降雨侵蚀力减小趋势不显著,降雨量增加趋势不显著。     

Land‐use effects on water quality of a first‐order stream in the Ozark Highlands,mid‐southern United States

Urban and agricultural land uses can alter the natural hydrologic conditions of streams and rivers and often degrade water quality. In the Ozark Highlands of the mid‐southern United States, the climate, topography, soil properties, karst limestone geology, agricultural practices and rapid urbanization make water quality of particular concern due to the increased potential for water quality degradation by contaminant leaching to groundwater and runoff to surface waters. The objective of this study was to evaluate the effects of season (i.e. dry/cool and wet/warm) and riparian land use (i.e. urban, grazed pasture, ungrazed pasture, wetland, cultivated agriculture and grassland) on surface water quality in a first‐order stream within a diverse agricultural watershed in the Ozark Highlands. Water samples were collected twice a month within each land use during base‐flow conditions from October 2006 through October 2007. Samples were also collected periodically during storm‐flow conditions from October 2006 through December 2007. The greatest in‐stream pH was adjacent to the grazed pasture. In‐stream NO₃‐N concentrations were greatest adjacent to the cultivated agriculture and grassland during the dry/cool season (i.e. October 2006 to March 2007) and averaged 2.67 mg L^?1. In‐stream soluble reactive P (SRP) concentrations were greatest adjacent to the grassland during the wet/warm season (i.e. April 2007 to October 2007) and averaged 0.81 mg L^?1. Concentrations of SRP, K, Mg and Zn were greater during storm‐ than base‐flow conditions and in‐stream As concentrations frequently exceeded 0.01 mg L^?1. Discharge and in‐stream NH₄‐N concentrations were unaffected by land use or season and averaged 0.003 m³ s^?1 and 0.10 mg L^?1, respectively, across all land uses and seasons. Results of this study clearly demonstrate the significant effect of adjacent land use on in‐stream water quality of a first‐order stream in a diverse agricultural watershed and highlight the importance of managing upstream land use in order to regulate downstream water quality. Copyright © 2010 John Wiley & Sons, Ltd.     

El Niño–Southern Oscillation Link to South Florida Hydrology and Water Management Applications

This study evaluates the relationships between El Niño–Southern Oscillation (ENSO) indices and South Florida hydrology and proposes applications to water management decision making. ENSO relations to the Upper Kissimmee Basin rainfall, watershed for Lake Okeechobee, and cumulative sea surface temperature (SST) anomalies at Niño 3.4 were evaluated. Additionally, relationship between ENSO and Lake Okeechobee inflows, Arbuckle Creek and Josephine Creek flows were analyzed. Hydrology of the northern watersheds of the South Florida water management system is linked to ENSO events. Dry season (November–May) rainfall and flows are higher than average during El Niño years and lower during La Niña years, at the 90% confidence level or higher. The relationship is strongest when the ENSO event is strong as shown with analysis of correlation. ENSO prediction has more certainty than hydrologic prediction for a region. Identifying ENSO and hydrologic relationships can aid water management decision making by providing a lead-time of months to mitigate drought or flood impacts. The ENSO tracking method, which was published in a previous study, is presented to track ENSO strength and event type to provide supplemental outlook on dry season rainfall for Lake Okeechobee operations. Lake Okeechobee, which is the main storage in the South Florida water management system, is regulated by a schedule with a limited band of stage fluctuation because of susceptibility of the Herbert Hoover Dike to wave erosion and seepage at high stages. An early decision making approach to storage management with respect to ENSO related hydrology, is presented based on tracking the strength of ENSO events.     

三峡水库蓄水后坝下游干流枯水期水位变化研究

三峡工程建成运行以来,水库清水下泄对坝下游河道造成了明显冲刷,同时枯水期水库向下游补水,提高了坝下游沿程水位与平均流量,改善了下游供水形势。根据坝下游干流沿程宜昌、枝城、沙市、螺山、汉口、大通等水文站的水位、流量、大断面等资料以及三峡水库优化调度方案,分析了三峡水库建成运行以来沿程各站枯水期水位流量关系变化,旨在定量研究三峡水库枯季补水和清水下泄对河道的冲刷作用及对三峡坝址下游沿程水位的影响。研究表明:三峡水库蓄水以来,宜昌-汉口河段各控制站在不同流量条件下,水位均有不同程度的降低;枯水期综合考虑补水和冲刷作用后,不同月份沿程各站水位有升有降。     

Hydrologic Response of Streams Restored with Check Dams in the Chiricahua Mountains,Arizona

In this study, hydrological processes are evaluated to determine impacts of stream restoration in the West Turkey Creek, Chiricahua Mountains, southeast Arizona, during a summer‐monsoon season (June–October of 2013). A paired‐watershed approach was used to analyze the effectiveness of check dams to mitigate high flows and impact long‐term maintenance of hydrologic function. One watershed had been extensively altered by the installation of numerous small check dams over the past 30 years, and the other was untreated (control). We modified and installed a new stream‐gauging mechanism developed for remote areas, to compare the water balance and calculate rainfall–runoff ratios. Results show that even 30 years after installation, most of the check dams were still functional. The watershed treated with check dams has a lower runoff response to precipitation compared with the untreated, most notably in measurements of peak flow. Concerns that downstream flows would be reduced in the treated watershed, due to storage of water behind upstream check dams, were not realized; instead, flow volumes were actually higher overall in the treated stream, even though peak flows were dampened. We surmise that check dams are a useful management tool for reducing flow velocities associated with erosion and degradation and posit they can increase baseflow in aridlands. © 2015 The Authors. River Research and Applications published by John Wiley & Sons, Ltd.     

溪洛渡向家坝梯级水电站联合蓄放水规律分析

传统的梯级水电站联合运行蓄放水是下游梯级水库"先蓄后放",保持高水头运用的方式,但由于没有充分考虑汛期水库发电水头受阻、水头重叠等情况,其结果不一定符合实际。针对溪洛渡和向家坝梯级组合具有上游梯级库容大、水头变幅大、受阻更多、梯级水头重叠较多的特点,并考虑梯级电站的发电特性,采用溪洛渡-向家坝联合优化调度模型,对两电站的蓄放水规律进行了研究。结果表明,上游溪洛渡电站先蓄水后放水可减少汛期梯级电站发电受阻程度,提高总预想出力,有利于提高梯级电站的发电量。     

Temporal changes in the hydrology and nutrient concentrations of a large tropical river: Anthropogenic influence in the Lower Grijalva River,Mexico

Dam construction and nutrient loading are among the greatest threats to freshwater ecosystems, altering ecological processes and the provisioning of ecosystem services. Temporal change in hydrology and ambient nitrogen and phosphorus concentrations was studied on the Grijalva, a large tropical river in southern Mexico, where four hydroelectric dams operate and where land conversion has impacted the freshwater environment. Temporal changes in discharge and in river chemistry were examined by analysing long‐term discharge and nutrient data using the software Indicators of Hydrologic Alteration and Mann–Kendall tests. Furthermore, additional water chemistry samples were collected to examine seasonal nutrient dynamics in the lower Grijalva. Long‐term discharge data indicated dam construction has severely altered temporal patterns in discharge and other hydrological characteristics. The lower Grijalva has also experienced increase in nitrate concentrations through time, which may be attributed to the expansion of agricultural and urban areas in the watershed. In contrast, total phosphorus appeared to decline at the sites influenced by dam construction. Lower nutrient concentrations were recorded upstream from the city of Villahermosa, suggesting that inputs from urban areas may have contributed to nutrient loading. Additionally, higher nitrate and total phosphorus concentrations were detected in tributaries draining intensive agricultural and suburban areas. Collectively, the results from the study suggest that dam construction and land conversion in large, tropical watersheds can produce chemical and hydrological changes, which may negatively impact important ecosystem services—such as fisheries and the provisioning of sources of drinking water—and may compromise the integrity of coastal zones.