Runoff Concentrations Research Articles

Fifty years of recorded hillslope runoff on seasonally frozen ground: the Swift Current, Saskatchewan, Canada, dataset

Abstract. Long records of hillslope runoff and nutrient concentrations are rare – on seasonally frozen ground they are almost non-existent. The Swift Current hillslopes at the Swift Current Research and Development Centre on the Canadian Prairies provide such a long-term hydrological record. Runoff, runoff nutrient concentration, snowpack depth, density and water equivalent, soil moisture, and soil nutrient concentration were monitored on the three 5 ha hillslopes over a 50-year period (1962–2011). Digital elevation data are available for the three hillslopes at a 2 m horizontal resolution, and, for one of the hillslopes (Hillslope 2), at a 0.25 m horizontal resolution. Runoff from the hillslopes was generated episodically during snowmelt and occasional rainfall events. Hillslope runoff was measured with a 0.61 m H-flume. Daily runoff nutrient concentration data are available for nitrate–N (March 1971–April 2011), ammoniacal–N (February 1996–April 2011), and phosphate-P (March–April 1971; June 1991–April 2011). Snowpack data (snowpack depth, density, and water equivalent) were determined via manual snow surveys carried out several times each winter, between January and March, between 1965 and 2011. Gravimetric soil moisture content was measured in October and April each year between 1971 and 2011 at five depth intervals (0–15, 15–30, 30–60, 60–90, and 90–120 cm) at nine points on each hillslope. We provide these hillslope data in two publicly available repositories: (1) 1962–2011 data on runoff, runoff nutrients, snowpack, soil moisture, soil nutrients, and crop and tillage practices at https://doi.org/10.23684/hhn5-rz52 (McConkey and Thiagarajan, 2018); and (2) digital elevation data at https://doi.org/10.20383/101.0117 (Coles et al., 2018). Complete climate data recorded at a Environment and Climate Change Canada meteorological station located 390 m from the three hillslopes are publicly available at http://climate.weather.gc.ca/ (last access: 30 August 2019).

First flush analysis using a rainfall simulator on a micro catchment in an arid climate

Urban runoff water from simulated rainfall for three different land uses (residential, industrial, commercial) at six different locations of Doha, Qatar was analysed for physico-chemical parameters such as, trace metals, pH, total suspended solids (TSS), total organic carbon (TOC), total phosphorus (TP), total kjeldahl nitrogen (TKN) and polyaromatic hydrocarbons (PAHs). Rainfall events with two different intensities (40 mm/h and 20 mm/h) were simulated in a micro catchment area (4.55 × 4.55 m2) using a specially designed portable rainfall simulator. Out of six sites, runoff samples were collected from five sites with paved surfaces. The study results demonstrated significant concentration of TSS, Cu, Fe, Mn and Zn in the urban runoff exceeding the Qatar Ministry of Municipality and Environment (MME) and Tropical Australian Standards. The first flush effect was also investigated during the experiment which exhibited first flush effect of selected pollutants (TSS, TKN, TP, TOC and heavy metals) at five study sites with impervious surfaces. The magnitude of the first flush varies across the study sites and was found to be affected by the surface texture of the sites. Analysis of variance revealed that, rainfall intensity has limited effect on the first flush in the studied scenarios, however, first flush effects showed relation with the event mean runoff concentration. Furthermore, strong positive correlations were observed between analysed water quality parameters, particularly between TSS, TOC and metals. This study is the first study investigating first flush in Qatar's capital, Doha which will provide a ground for future researcher to design appropriate stormwater treatment devices that will capture and treat the first flush for significant reduction of urban stormwater pollution.

Long-term Variation in Agricultural Edge-of-Field Phosphorus Transport during Snowmelt, Rain, and Mixed Runoff Events.

Runoff of nutrients and erosion of soil from agricultural lands affect soil fertility and are important nonpoint contributors of P and N to surface and ground waters, yet studies of edge-of-field nutrient transport from snowmelt or rainfall runoff on frozen ground are limited. The objective of this study was to quantify the temporal and spatial variation in edge-of-field snowmelt, rain, and mixed (rain on snow) runoff events for sediment and P loadings in five agricultural subwatersheds over a 12-yr period. Edge-of-field runoff events from five subwatersheds at Pioneer Farm near Platteville, WI, ranging in size from approximately 4 to 30 ha were sampled using automated samplers from 2002 through 2014 to determine sediment and P yields (mass loads). Mean dissolved reactive P (DRP) runoff concentrations for each event type (rain = 1.24 mg L, snow = 1.90 mg L, mix = 2.23 mg L) were above total P (TP) water quality guidelines for surface waters. The percentages of TP that was DRP for snow, mixed, and rain events were 74, 84, and 39%, respectively. Although variation in total annual P yield in edge-of-field runoff was noted between years and among sites within a given year, when aggregated over the study period, the subwatersheds showed similar transport characteristics with respect to DRP and TP yield. This study highlights the importance of examining long-term datasets in quantifying annual yields and understanding the timing of DRP and TP transport for developing best management practices and improving model accuracy in cold weather agricultural systems.

Estimation of depression-focussed groundwater recharge using chloride mass balance: problems and solutions across scales

This study evaluates the applicability of the chloride mass balance (CMB) method for groundwater recharge estimation in a semi-arid region in Canada, where recharge largely occurs under topographic depressions. The CMB applicability was tested at three scales: point-scale recharge rates at different topographical positions; average recharge rates incorporating multiple topographical positions on a local scale; and an identification of spatial trends of recharge on a regional scale. Agricultural chloride inputs were shown to be a major factor affecting chloride concentrations at all three scales, where elevated chloride concentrations in the shallow subsurface affected by agricultural inputs surpassed background concentrations by an order of magnitude. The propagation depth of elevated concentrations varied among study sites from being largely confined to the unsaturated zone to extending well into the saturated zone. Lateral chloride redistribution further affected the CMB applicability for point-scale recharge rates. Specific solutions enabling the CMB application in these conditions are presented, including runoff concentration measurements for point-scale estimates, using groundwater age tracers on a local scale, and using the harmonic mean concentration of a large number of samples on a regional scale.

Evaluating the Variation of Dissolved Metals on a Highway Roadside Using a Generalized Additive Mixed Model (GAMM)

Assessing metal concentrations in roadside soils requires a better understanding of the extent to which they are affected by different environmental factors such as soil texture, depth, pH, runoff concentration, and precipitation. Monthly data of dissolved Cd, Ni, Cr, Pb, Cu, and Zn concentrations in three different roadside soils (sandy loam, gravel (0–32 mm) and a mixture of sandy loam and gravel) were measured during a 2-year lysimeter field study at different depths. The data was used to assess the variation of trace elements and how they were affected by environmental factors. For data interpretation, generalized additive mixed models (GAMMs) were used to explore the complex behavior of metals in heterogeneous soils by detecting linear and nonlinear trends of metal concentrations in the soil solution. As a result, the modeling approach showed that Cd, Ni, Cr, Pb, Cu, and Zn concentrations are functions of different environmental variables, which have either linear or nonlinear behavior. All investigated metals showed that pH could explain their variation. With exception of precipitation, Ni and Cr variations can nearly be explained by the same environmental factors used in this study (time, pH, infiltration volume, roadside soil type, runoff concentrations, and depth). During the study period, we found that Zn variation can be explained by its nonlinear relationship with all the significant studied environmental factors. As the depth increases from the surface to 30 cm of depth, the metal concentration of Cd, Ni, Cr, Pb, and Zn increases. Surprisingly, the roadside soil consisting of gravel has the lowest organic carbon and showed the lowest median concentration of Cd, Ni, Pb, Cu, and Zn at 30 cm. Moreover, the model showed that the surface runoff volume has no effect on the metal variation in the soil solution.

Remediation of Stormwater Pollutants by Porous Asphalt Pavement

Porous Asphalt (PA) pavements are an increasingly adopted tool in the green stormwater infrastructure toolbox to manage stormwater in urbanized watersheds across the United States. This technology has seen particular interest in western Washington State, where permeable pavements are recognized as an approved best management practice per the National Pollutant Discharge Elimination System (NPDES) municipal stormwater permit. Stormwater effluent concentrations from six PA cells were compared with runoff concentrations from three standard impervious asphalt cells to quantify pollutant removal efficiencies by porous asphalt systems. Additionally, the effects of maintenance and pavement age on pollutant removal efficiencies were examined. Twelve natural and artificial storms were examined over a five-year period. Street dirt and pollutant spikes were added to the pavements prior to some storm events to simulate high loading conditions. Results from this work show that porous asphalt pavements are highly efficient at removing particulate pollutants, specifically coarse sediments (98.7%), total Pb ( 98.4%), total Zn (97.8%), and total suspended solids (93.4%). Dissolved metals and Polycyclic Aromatic Hydrocarbons (PAH) were not significantly removed. Removal efficiencies for total Pb, total Zn, motor oil, and diesel H. improved with the age of the system. Annual maintenance of the pavements with a regenerative air street sweeper did not yield significant pollutant removal efficiency differences between maintained and unmaintained PA cells.

Evaluation of contaminant retention in the soil of sustainable drainage systems: methodological reflections on the determination of sorption isotherms

Abstract Runoff infiltration in Sustainable Drainage Systems enables the interception of a part of urban contaminant fluxes owing to several processes. The soil's ability to retain dissolved pollutants is generally assessed via sorption isotherms obtained from batch studies; however, the experimental points are not always in the same range as runoff concentrations. The present work (i) explores the consequences of modelling runoff–soil interactions from out-of-range equilibrium concentrations and (ii) proposes an improved method to ensure that experimental points fall within the desired range. Uncertainty analysis demonstrates that for a non-linear isotherm, using an extrapolated relationship may introduce significant biases in the ensuing estimations. Therefore, the proposed method consists of anticipating the equilibrium state of batch tests to accurately set the experimental conditions and reach appropriate concentrations. It is successfully applied to the determination of the sorption properties of copper and zinc onto three soils with different electrolyte solutions, as well as those of bisphenol A and three alkylphenols onto one soil. The contrasting affinities between the studied species and the soil materials could be related to their intrinsic properties and the soils' pedological parameters, as well as the presence of salt or dissolved organic ligands which partially inhibited metal sorption.

Managing runoff and soil loss in asparagus production systems

On slightly sloping land, current asparagus cultivation practices (including prolonged periods of bare soil, surface capping and compaction of wheelings) can lead to runoff and soil loss. This can result in on-site impacts to crops and field operations and offsite impacts on the wider environment. Research into soil and water management in green asparagus production has been undertaken in the UK since 2010. This paper details two separate runoff and erosion trials conducted in 2012 and 2013 on commercial asparagus fields. Each trial has tested the efficacy of a range of treatments applied to inter-row wheelings including green waste compost (of PAS:100 quality protocol standard) and wheat straw mulch at different application rates, both with and without shallow soil disturbance. It was realised early on that compost was ineffective in runoff and soil loss management where application quantity was restricted by nitrogen regulations in Nitrate Vulnerable Zones. Straw mulch alone has consistently reduced soil loss across both trials by 72 to 87% as compared to the bare soil control. Shallow soil disturbance alone reduced soil loss by 4 to 13%, with no significant differences observed between various tillage implements tested. Despite the reductions observed in soil loss, runoff sediment concentration still exceeds that stipulated by EU Directive for surface water quality; risking pollution of any receiving water bodies. The knowledge gained from these studies should be used to develop more effective runoff and soil loss control in order to ensure the future sustainability of asparagus production.

Variations of Water Runoff and Suspended Sediment Yield in the Kamchatsky Krai, Russia

This study investigates the spatial and temporal variability of water runoff and suspended sediment yield in rivers in the Kamchatsky Krai territory (in the Far East of the Russian Federation). It is based on data from 269 monitoring stations for the period of hydrometeorological observations (1930–2015). The representativeness and the homogeneity of data on water runoff and suspended sediment yield was examined. Regions with prescribed limits of specific water discharge (L·s−1·km−2) and suspended sediment concentration (mg·L−1) variability were selected in the Kamchatsky Krai territory. Most rivers in this region are characterized by two relatively long trends in these characteristics that increased from the late 1970s to the early 1980s, followed by a subsequent decline (until 2015). Kamchatsky Krai includes 9 specific water discharge and 18 suspended sediment concentration regions. Hydrometeorological data of three zonal types of water runoff and corresponding suspended sediment concentration distribution were described, and five azonal types of water regime were characterized. One of these types was characterized by a nearly uniform distribution of water runoff within the year, due to the predominance of groundwater feeding source, while the rest of them had mixed feeding. The present study is the first study to describe the water regime of rivers on volcanic flanks in the Kamchatsky Krai.

A numerical model for the simulation of snowpack solute dynamics to capture runoff ionic pulses during snowmelt: The PULSE model

Early ionic pulse during spring snowmelt can account for a significant portion of the total annual nutrient load in seasonally snow-covered areas. Ionic pulses are a consequence of snow grain core to surface ion segregation during metamorphism, a process commonly referred to as ion exclusion. While numerous studies have provided quantitative measurements of this phenomenon, very few process-based mathematical models have been proposed for diagnostic and prognostic investigations. A few early modelling attempts have been successful in capturing this process assuming transport through porous media with variable porosity. However, this process is represented in models in ways that misalign with the mechanistic view of the process described in the literature. In this research, a process-based model is proposed that can simulated ionic pulses in runoff by emulating solute leaching from snow grains during melt and the subsequent vertical solute transport by meltwater through the snowpack. To facilitate its use without the need for snow-physics’ models, simplified alternative methods are proposed to estimate some of the variables required by the model. The model was applied to two regions, and a total of 4 study sites, that are subject to significantly different winter climatic and hydrological conditions. Comparison between observations and simulation results suggest that the model can capture well the overall snow melt runoff concentration pattern, including both the timing and magnitude of the early melt ionic pulse. The model enables the prediction of concentration profiles of the dry (snow) and liquid (wet) fractions within the snow matrix for the first time. Although there is a computational cost associated with the proposed modelling framework, this study demonstrates that it can provide more detailed information about the reallocation and transport of ions through snowpacks, which can ultimately be used to improve nutrient transport predictions during snowmelt.

Assessing Roadway Contributions to Stormwater Flows, Concentrations, and Loads with the StreamStats Application

The Oregon Department of Transportation (ODOT) and other state departments of transportation need quantitative information about the percentages of different land cover categories above any given stream crossing in the state to assess and address roadway contributions to water-quality impairments and resulting total maximum daily loads. The U.S. Geological Survey, in cooperation with ODOT and the FHWA, added roadway and land cover information to the online StreamStats application to facilitate analysis of stormwater runoff contributions from different land covers. Analysis of 25 delineated basins with drainage areas of about 100 mi2 indicates the diversity of land covers in the Willamette Valley, Oregon. On average, agricultural, developed, and undeveloped land covers comprise 15%, 2.3%, and 82% of these basin areas. On average, these basins contained about 10 mi of state highways and 222 mi of non-state roads. The Stochastic Empirical Loading and Dilution Model was used with available water-quality data to simulate long-term yields of total phosphorus from highways, non-highway roadways, and agricultural, developed, and undeveloped areas. These yields were applied to land cover areas obtained from StreamStats for the Willamette River above Wilsonville, Oregon. This analysis indicated that highway yields were larger than yields from other land covers because highway runoff concentrations were higher than other land covers and the highway is fully impervious. However, the total highway area was a fraction of the other land covers. Accordingly, highway runoff mitigation measures can be effective for managing water quality locally, they may have limited effect on achieving basin-wide stormwater reduction goals.

Metals in Soil and Runoff from a Piedmont Hay Field Amended with Broiler Litter and Flue Gas Desulfurization Gypsum

Flue gas desulfurization gypsum (FGDG) from coal-fired power plants is readily available for agricultural use in many US regions. Broiler litter (BL) provides plant available N, P, and K but can be a source of unwanted As, Cu, and Zn. As a source of Ca and S, FGDG can reduce losses of P and other elements in runoff from BL-amended areas. Rainfall simulation plots (2.0 m) were established on a Piedmont Cecil soil growing 'Coastal' bermudagrass ( L.) for hay. Accumulation and transport of As, Cu, Cd, Cr, Hg, Pb, and Zn were evaluated after annual BL applications (13.5 Mg ha) with four FGDG rates (0, 2.2, 4.5, 9.0 Mg ha) and two FGDG treatments (0 and 9 Mg ha) without BL. Runoff As concentrations were sixfold greater with BL than without ( ≤ 0.01) and were similar to BL with FGDG at 2.2, 4.5 or 9.0 Mg ha ( ≤ 0.10). Runoff concentrations of target elements did not increase where FGDG was applied alone. After three annual applications of FGDG and BL, soil concentrations of As, Cr, Pb, Hg, and Cu were well below levels of environmental concern. Our findings indicate that runoff losses of As from BL application are not reduced with FGDG but support other research indicating no identifiable environmental risks from FGDG beneficial use in agricultural systems.

An empirical approach for computing surface runoff concentration time

Abstract This article examines data from the Shihuiyao, Nierji, Tongmeng, Jiangqiao, and Dalai hydrological stations in the Nen River basin to understand the hydrological processes occurring in the catchments. Daily precipitation and runoff data from 1955 to 1973 were combined using the smoothed minima trial method to determine the surface runoff concentration time. Then, a genetic algorithm was used to optimize the parameters and obtain an optimal empirical formula. An improved empirical formula was implemented with the genetic algorithm and optimized parameters then incorporated variable average rainfall intensity, correlation between basin area, surface runoff average concentration time, and average rainfall intensity. Finally, an optimized empirical formula (using genetic algorithm to optimize the parameters) and improved empirical formula (incorporating variable average rainfall intensity) were tested by using the daily precipitation and runoff data from the Baishan and Hongshi hydrological stations of the Second Songhua River. The results show that an optimized and improved formula can be used to more accurately estimate hydrologic conditions in the Nen River. Therefore, the improved formula is an efficient method for calculating surface runoff concentration time. Surface runoff concentration time is an important basis for differentiating source waters, which include surface runoff and underground runoff.

水利工程对坝下径流的影响——以葛洲坝、三峡水利枢纽为例

PDF HTML阅读 XML下载 导出引用 引用提醒 水利工程对坝下径流的影响——以葛洲坝、三峡水利枢纽为例 DOI: 10.5846/stxb201704070596 作者: 作者单位: 中国生态环境研究中心城市与区域生态国家重点实验室,中国生态环境研究中心城市与区域生态国家重点实验室,中国生态环境研究中心城市与区域生态国家重点实验室,中国生态环境研究中心城市与区域生态国家重点实验室 作者简介: 通讯作者: 中图分类号: 基金项目: 中国科学院科技服务网络计划项目（KFJ-STS-ZDTP-03）；国家重点研发计划项目（2016YFC0503401） Effects of dams on runoff in the lower reaches: A case study of the Gezhouba hydro-project and the Three Gorges project Author: Affiliation: State Key Laboratory of Urban and Regional Ecology,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,State Key Laboratory of Urban and Regional Ecology,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,State Key Laboratory of Urban and Regional Ecology,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,State Key Laboratory of Urban and Regional Ecology,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:水利工程建设在给人类带来抗旱防洪效益、发电效益、航运效益、养殖等效益的同时，也对河流水文动态产生了一系列的影响，主要表现为对径流的调节。基于宜昌站1890-2014年径流数据，综合采用径流集中度、集中期和相位差分析等多种方法，分析了水利工程建设对径流年内分配以及枯水期的影响。结果表明：宜昌站径流集中度呈现缓慢下降趋势并在2004年发生突变，2003年以后径流集中度相对于2003年以前下降0.06（下降幅度为12.98%），说明葛洲坝水利枢纽、三峡工程建成以后宜昌站径流在年内分配变得平缓，洪峰被有效削弱，且三峡工程对宜昌站径流集中度减少的贡献率大于葛洲坝水利枢纽（贡献率分别为92.03%和7.97%）；葛洲坝和三峡水利枢纽建成后，宜昌站径流重心提前8d（集中期从8月9日提前至7月31日）；宜昌站进入枯水期的时间提前约20d（三峡大坝建设以前，宜昌站在12月7-11日进入枯水期，建设以后在11月底进入枯水期），水利工程对水文过程的影响可能导致下游枯水期污染加剧和湿地生境提前缩小，进而影响下游水环境和湿地生物多样性。上述结果定量揭示了水利工程对水文过程的影响及其潜在生态效应，可为认识水利工程的生态影响以及流域生态环境变化的驱动因素提供科学依据。 Abstract:The Yangtze basin is rich in water and biological resources, providing essential natural conditions for economic development in the southern region of China. Various water conservation facilities have been constructed in the basin to perform water resource scheduling and electrical energy conversion. By 2009, there were 46000 reservoirs built in the basin, with a total irrigation capacity of more than 120 billion m3. These projects were associated with benefits in terms of drought flood control, power generation, shipping, breeding, and so on, but also had both positive and negative effects on runoff. Therefore, watershed water security not only affects economic development and ecological security in the southern region of China, but also is an inevitable requirement for sustainable development. We participated in an academic conference on soil and water conservation and disaster prevention and mitigation in the Yangtze River economic belt, during which several scholars and experts extensively discussed the current problems in the Yangtze River basin. Some experts pointed out that the construction of the Three Gorges project and other water conservancies would lead to an advance in the timing of the dry season in the middle and lower reaches of the Yangtze River, resulting in increased water pollution, changes in the habitats of migratory birds, and a series of ecological problems. Although low water levels and floods are classified into the extreme hydrology category, early drought has no significant impact on human activity, and is not as well studied as floods. With the growth of the social economy and population explosion, the gap between the supply and demand of water resources is increasing. Especially in the dry season, several ecological problems are experienced, including increased water pollution caused by the reduction in runoff and river blanking caused by excessive use of low water resources. Thus, it is necessary to study the effects of water conservancy projects on the dry season. After the conference, we conducted a field visit and a survey along the Yangtze River area, with a view to use the data to effectively assess the impact of water conservancy construction during the dry season. Since the construction of the Three Gorges project has attracted greater attention, its water security and ecological benefits have always been the focus of discussions. Therefore, we selected Yichang station as the study area and analyzed the impacts of the Gezhouba hydro-project and the Three Gorges project on hydrological dynamics. Based on the runoff data of Yichang station from 1890 to 2014, the effects of water conservancy construction on the distribution of runoff and the dry season were analyzed using runoff concentration degree and period and phase difference analysis. The results showed that the runoff concentration of Yichang station tended to decrease, with a mutation occurrence in 2004. After 2003, the runoff concentration decreased by 0.06 (a decrease of 12.98%) from that before 2003. This indicated that after the completion of the Gezhouba water conservancy project and the Three Gorges project, the runoff distribution in Yichang station over the year became gentle and the peak floods were effectively weakened. The rate of contribution of the Three Gorges project toward decreasing the runoff concentration degree in Yichang station (92.03%) was greater than that of the Gezhouba water conservancy project (7.97%). After the Gezhouba and Three Gorges projects were completed, the runoff concentration period and beginning of the dry season in Yichang station have advanced (with advances of 8 and 20 days, respectively). Following completion of the water conservation projects, changes to the water-carrying capacity of the environment and wetlands in the lower reaches will take place earlier than previously, resulting in increased water pollution, changes in wetland biodiversity, and several ecological problems. Our results revealed the influence of the water conservation projects on hydrological processes and their potential ecological efficiency, providing a scientific basis to better understand the influence of water conservation projects on runoff. 参考文献 相似文献 引证文献

The influence of Three Gorges Reservoir high water level on the rainfall runoff

After Three Gorges Reservoir building up, the natural river course and the near hillside inside the backwater region are inundated to form a fairly wide man-made lake which affects the hydrological characteristics and floodwater transmission to different degrees. When the reservoir impound to high water level, the conflux time is obviously shortened, the flood-peak discharge increase, and the peak type became sharper. The change of runoff yield and concentration makes the forecast scheme unable to be applied well. Based on the practice of Three Gorges Reservoir operation, the rainfall-runoff characteristics of the backwater region under the condition of high water level are analysed and summarized, then a set of unit hydrographs suitable for rainfall-runoff calculation are recalibrated, which has great reference value for hydrological forecasting of Three Gorges region.

Construction and Application of Snow-melting Runoff Model Based on MODIS Satellite Data

It is very complicated to accurately describe the process of watershed runoff yield and concentration, which is comprehensive influenced by snow covering, temperature, precipitation, the wetland areas and other factors in the basin of Kaidu River upstream of Chahanwusu Reservoir. It is that real-time updating MODIS satellite snow cover products MOD10A2 and 30 meters by 30 meters of DEM data are applied to calculate elevation~ basin area ~ snow covering area curve, virtual free reservoir is put forward to simulate the wetlands concentration of upstream Bayinbuluke and sahentuohai hydrological gauge stations and mixed melting snow and runoff yield under saturated storage concentration model is constructed in this article. The model behaved good to simulate the Inflow process of Chahanwusu Reservoir, and the relative error between simulated and measured processes reached 83.79%, the deterministic coefficient reaches about 0.8, which is better supporting Chahanwusu Reservoir’s operation scheduling and dispatch decision.

Effect of Sodic Irrigation Water on Organic Carbon and Nitrogen Concentrations, Fluxes and Exports from Newly Installed St. Augustine Grass Sod in South-Central Texas

Population growth in towns and cities requires new construction of homes and conversion of native land use to urban and suburban landscapes. Municipal tap water is generally used for irrigating these urban and suburban landscapes and its water quality can differ globally dependent on whether it is sourced from ground or surface waters. We examined runoff dissolved organic carbon (DOC) and organic nitrogen (DON) concentrations, fluxes and exports from newly installed, fertilized and unfertilized St. Augustine (Stenotaphrum secundatum (Walt.) Kuntze ‘Raleigh’) sod irrigated with a sodic municipal tap water during two 5-week establishment periods (August and September). In unfertilized plots, concentrations of DOC in runoff significantly increased from 20.5 to 73.7 mg L-1 and from 29.6 to 113.3 mg L-1 Runoff concentrations of DOC in fertilized plots significantly increased from 27.3 to 72.0 mg L-1 and from 30.0 to 120.3 mg L-1. Concentrations of DON in runoff did not increase in either unfertilized or fertilized plots. Total DOC exports were 2036 ± 803 kg km-2 and 3341 ± 227 kg km-2 and DON exports were 99 ± 43 kg km-2 and 134 ± 15 kg km-2 respectively for the two turfgrass installation dates for the unfertilized plots. Fertilization had no significant effect on DOC and DON exports (p = 0.29 and 0.18). Na+, K+, Mg2+ and Ca2+ were implicated in both DOC and DON fluxes suggesting that as resources for irrigation water for urban landscapes decline and alternative irrigation water supplies such as grey and black water are utilized we would expect, due to their higher Na+ content that DOC and DON fluxes to urban watersheds will increase.

The success of recent land management efforts to reduce soil erosion in northern France

Soil erosion is an important problem in open-field agricultural landscapes. With almost no permanent vegetation in small headwater catchments, and with few physical obstacles to reduce runoff velocities, runoff concentration along linear landscape elements (plot boundaries) or thalwegs frequently causes ephemeral gullies to form — the latter reflecting the poor hydrogeomorphic condition of the land- and soilscape. To address this problem, and to remediate negative on- and off-site effects, land management efforts have multiplied over the past decades in many regions. This includes, amongst other measures, the implementation of vegetation barriers called ‘fascines’. In the loess-dominated Aa River basin of northern France, where cropland accounts for 67% of the cover, we investigated the effect of fascines on ephemeral gully erosion dynamics, together with rainfall characteristics and cropland management. This was accomplished through a spatially explicit study of 269 sites prone to ephemeral gullying using a diachronic analysis of historical aerial photographs. Between 1947 and 2012, ephemeral gully densities at the scale of the Aa River basin (643km2) varied between 0.39 and 1.31mha−1 (long-term average of 0.68mha−1 (with local maxima up to 9.35mha−1). Densities are, however, much higher when only considering the most erosion-vulnerable municipalities (long-term average of 2.23–4.30mha−1); those values should be used when comparing results from this study to other reports of ephemeral gully erosion. Fascines were introduced in 2001 and were present in ~30% of the gully erosion sites by 2012. Although the presence of fascines has an effect on gully length reduction, spatial and temporal variations in gully length were mainly driven by cumulative precipitation. Measurement of sediment deposition at 29 fascines in 2016 showed that only 47% of the fascines functioned as sediment sinks. They stored on average 1.7Mg of sediment per winter half-year, corresponding to 0.009Mgha−1. The results suggest that fascines positively impact the landscape's resilience and reduce ephemeral gully erosion rates. The use of vegetation barriers such as fascines are increasingly implemented for erosion control in western Europe, but pose problems for the management of open-field landscapes.

Direct-seeded rice increases nitrogen runoff losses in southeastern China

recent years, alternative rice cultivation methods have been widely developed in Asia, and the environmental consequences of these practices on nitrogen (N) runoff losses from intensively cultivated rice fields deserve attention. A two-year field experiment (2013–2014) was conducted in a rice field in southeastern China to evaluate the N losses in runoff resulting from four rice cultivationmethods: (1) conventional, manually transplanted seedling rice (CTSR); (2) mechanically transplanted seedling rice (MTSR); (3) dry direct-seeded rice (DDSR); and (4) wet direct-seeded rice (WDSR). Runoff volumes; runoff concentrations of NH4+-N, NO3−-N, and total N (TN); N uptake; and grain yield were measured. The seasonal runoff volumes varied from 775 to 2397m3ha−1 in 2013 and 2014. Compared with CTSR, WDSR and DDSR significantly increased the total runoff volumes by 76% and 30%in 2013, and by 46% and 26% in 2014, respectively. The seasonal TN losses in runoff from the rice fields ranged from 1.99 to 10.18kgNha−1, accounting for 0.74–3.77% of the seasonal N input during the two years. In contrast with CTSR, WDSR increased TN losses by 169% in 2013 and by 143% in 2014, while DDSR increased TN losses by 31% in 2013 and by 84% in 2014. Direct-seeded rice significantly increased runoff N losses during the early growth period largely by increasing runoff volumes and/or the N concentrations in runoff water. The main forms of N lost in runoff were NH4+-N for CTSR, MTSR and WDSR and NO3−-N for DDSR. The grain yield, N uptake at mid-tillering and panicle initiation stages were similar in WDSR and DDSR and significantly lower than those under CTSR and MTSR. The results show that direct-seeded rice increased N runoff losses from intensively cultivated rice fields in southeastern China.

A Pulse of Mercury and Major Ions in Snowmelt Runoff from a Small Arctic Alaska Watershed.

Atmospheric mercury (Hg) is deposited to Polar Regions during springtime atmospheric mercury depletion events (AMDEs) that require halogens and snow or ice surfaces. The fate of this Hg during and following snowmelt is largely unknown. We measured Hg, major ions, and stable water isotopes from the snowpack through the entire spring melt runoff period for two years. Our small (2.5 ha) watershed is near Barrow (now Utqiaġvik), Alaska. We measured discharge, made 10 000 snow depths, and collected over 100 samples of snow and meltwater for chemical analysis in 2008 and 2009 from the watershed snowpack and ephemeral stream channel. Results show an "ionic pulse" of mercury and major ions in runoff during both snowmelt seasons, but major ion and Hg runoff concentrations were roughly 50% higher in 2008 than in 2009. Though total discharge as a percent of total watershed snowpack water equivalent prior to the melt was similar in both years (36% in 2008 melt runoff and 34% in 2009), it is possible that record low precipitation in the summer of 2007 led to the higher major ion and Hg concentrations in 2008 melt runoff. Total dissolved Hg meltwater runoff of 14.3 (± 0.7) mg/ha in 2008 and 8.1 (± 0.4) mg/ha in 2009 is five to seven times higher than that reported from other arctic watersheds. We calculate 78% of snowpack Hg was exported with snowmelt runoff in 2008 and 41% in 2009. Our results suggest AMDE Hg complexed with Cl- or Br- may be less likely to be photochemically reduced and re-emitted to the atmosphere prior to snowmelt, and we estimate that roughly 25% of the Hg in snowmelt is attributable to AMDEs. Projected Arctic warming, with more open sea ice leads providing halogen sources that promote AMDEs, may provide enhanced Hg deposition, reduced Hg emission and, ultimately, an increase in snowpack and snowmelt runoff Hg concentrations.