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1.
AbstractThe aim of this study was to understand seasonal variations in the vertical structure of the water column, and to quantify the importance of the physical forces (solar radiation, wind and hydraulic retention time) that control mixing processes in a reservoir bordering the Pantanal floodplain. Samples were taken every three months in the reservoir centre, at four depths, for the measurement of nine physical and chemical water quality parameters. The reservoir presented a long stratification period with complete mixing in winter. The vertical structure showed that, during the stratification period, the upper layers of the reservoir are homogeneous and the physical and chemical composition only changes at greater depths. The wind acting over an extended period is the only factor that significantly influences the vertical structure in the reservoir, giving rise to mixing processes. Moreover, the position of the draw-off point in the upper layer of the reservoir, together with the reservoir depth, enhances vertical stability. 相似文献
2.
热分层对水库水质的季节性影响——以西安黑河水库为例 总被引：3，自引：1，他引：2
深水水库作为城市的重要供水水源,通常由于热量在垂向水体上的不均匀分配形成热分层.热分层会阻碍垂向上水体交换引发水质分层现象,在冬季水库发生“翻库”之后,水体混合导致水库的整体水质下降.结合热分层指数可以客观、直接地表达水库热分层的稳定程度.综合水库的气温、水体更新率和水质参数(溶解氧、pH、总磷、氨氮)的年度变化,对陕西黑河水库2008-2010年的热分层状况进行研究.研究表明:水库的热分层形成会直接恶化底部水质尤其会加速底部水体中溶解氧的消耗;热分层的年度变化主要受气温控制,但在特定时期较大的水体更新率可以在一定程度上弱化水体热分层,减缓底部水质恶化.该结果可使水库管理者在水库分层最稳定、水质恶化最严重时期以人工调节水体更新率的方式弱化热分层,为保证水质安全提供参考. 相似文献
3.
西南峡谷型水库的季节性分层与水质的突发性恶化 总被引：40，自引：3，他引：37
选择西南云贵高原乌江流域的百花湖水库进行了气象、水温度和水化学(DO、FeⅡ和MnⅡ)的连续监测(13个月).结果表明,由于气候等原因,百花湖水库的水体在夏季形成分层,但是没有典型分层湖泊的温跃层变化,这种水体温度结构可以在4-10月保持稳定;这种"不显著的"温度分层结构,有效限制了上下水团的混合,形成显著的水体溶解氧分层,氧化/还原界面可达到水深8m左右.20世纪90年代初以来,贵州多座水库频繁出现的季节性水质恶化现象,与水库水体混合期(多为夏末初秋),水体分层结构失稳有关.上下层水体的垂直交替,使下层水体中的还原性物质带入上层湖水,造成表层水体缺氧和表观浑浊,鱼类窒息死亡.在百花湖水库的研究表明,西南地区深水水库,可以在夏季出现一定的水体温度分层结构,并导致显著的水体水化学(如溶解氧)分层,进而影响水库水环境质量. 相似文献
4.
V. N. Zyryanov 《Water Resources》2009,36(4):396-405
The effect of the formation of reverse slope of water level in stratified reservoirs and the appearance of current velocity peak within the water body are described. Velocity profiles with a peak within the flow have been recorded in experiments at relatively small vertical density gradients; therefore, the stratification alone is not enough to cause such effect. The wind as a cause of this effect is also ruled out. An important part in this problem is shown to belong to the effect of reservoir morphometry on the interrelated behavior of the free surface and the interfaces between layers. It is shown that, at a constant transit flow, the free surface in a stratified reservoir may be a nonmonotonic function decreasing in the general direction of transit flow and inversions in the level curve can appear, i.e., an inverse level course with an inverse slope of the free surface may form. Velocity profiles with an inflection point and a peak in underlying layers form in such cases. 相似文献
5.
Solute exchange between the interstitial waters and overlying waters on the Washington continental shelf was investigated based on measurements of the pore-water sulfate distribution and sulfate reduction rates as well as through models describing the distribution of sulfate in anaerobic pore waters. The depth-integrated sulfate reduction rate greatly exceeded the influx of sulfate attributable to molecular diffusion and sediment accumulation acting on the measured vertical sulfate gradients, and indicated that additional transport mechanisms must have been operating. Sediment mixing was probably not the primary mechanism since high eddy diffusivities would be required to depths of 30 cm to maintain the observed sulfate distribution, whereas previously measured210Pb distributions indicated sediment mixing is primarily restricted to depths <7 cm. Irrigation of bottom water through animal burrows was the most likely mechanism. To describe this process, a general diffusive irrigation coefficient, B, was formulated. Vertical profiles of B showed the main irrigation zone occurred between 2 and 10 cm with reduced irrigation rates occurring below this. These coefficients calculated from the sulfate distribution were similar to ones calculated from previously published radon measurements at the same stations, indicating that this formulation of irrigation exchange may be useful in modelling the exchange of dissolved solutes between the pore water and the bottom water. 相似文献
6.
Assessment of surface water resources and evapotranspiration in the Haihe River basin of China using SWAT model 总被引：2，自引：0，他引：2
Quantitative assessment of surface water resources (SWRs) and evapotranspiration (ET) is essential and significant for reasonably planning and managing water resources in the Haihe River basin which is facing severe water shortage. In this study, a distributed hydrological model of the Haihe River basin was constructed using the Soil and Water Assessment Tool, well considering the reservoirs and agricultural management practices for reasonable simulation. The crop parameters were independently calibrated with the observed crop data at six experimental stations. Then, sensitivity ranks of hydrological parameters were analysed, which suggested the important parameters used for calibration. The model was successfully calibrated using the monthly observed data of discharge in around 1970–1991 and actual ET (ETa) in 2002–2004 for the mountainous area and Haihe plain, respectively. Meanwhile, good agreements between the simulated and statistical crop yields in 1985–2005 further verified the model's appropriateness. Finally, the calibrated model was used to assess SWRs and ETa in time and space during 1961–2005. Results showed that the average annual natural SWRs and the ETa were about 17.5 billion cubic metre and 542 mm, respectively, both with a slight downward trend. The spatial distributions of both SWRs and ETa were significantly impacted by variations of precipitation and land use. Moreover, the reservoir in operation was the main factor for the noticeable decline of actual SWRs. In the Haihe plain, the ETa with irrigation was increased by 46% compared with that under rainfed conditions. In addition, this study identified the regions with potential to improve the irrigation effects on water use. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
7.
Relatively few studies have addressed water management and adaptation measures in the face of changing water balances due to climate change. The current work studies climate change impact on a multipurpose reservoir performance and derives adaptive policies for possible future scenarios. The method developed in this work is illustrated with a case study of Hirakud reservoir on the Mahanadi river in Orissa, India, which is a multipurpose reservoir serving flood control, irrigation and power generation. Climate change effects on annual hydropower generation and four performance indices (reliability with respect to three reservoir functions, viz. hydropower, irrigation and flood control, resiliency, vulnerability and deficit ratio with respect to hydropower) are studied. Outputs from three general circulation models (GCMs) for three scenarios each are downscaled to monsoon streamflow in the Mahanadi river for two future time slices, 2045–65 and 2075–95. Increased irrigation demands, rule curves dictated by increased need for flood storage and downscaled projections of streamflow from the ensemble of GCMs and scenarios are used for projecting future hydrologic scenarios. It is seen that hydropower generation and reliability with respect to hydropower and irrigation are likely to show a decrease in future in most scenarios, whereas the deficit ratio and vulnerability are likely to increase as a result of climate change if the standard operating policy (SOP) using current rule curves for flood protection is employed. An optimal monthly operating policy is then derived using stochastic dynamic programming (SDP) as an adaptive policy for mitigating impacts of climate change on reservoir operation. The objective of this policy is to maximize reliabilities with respect to multiple reservoir functions of hydropower, irrigation and flood control. In variations to this adaptive policy, increasingly more weightage is given to the purpose of maximizing reliability with respect to hydropower for two extreme scenarios. It is seen that by marginally sacrificing reliability with respect to irrigation and flood control, hydropower reliability and generation can be increased for future scenarios. This suggests that reservoir rules for flood control may have to be revised in basins where climate change projects an increasing probability of droughts. However, it is also seen that power generation is unable to be restored to current levels, due in part to the large projected increases in irrigation demand. This suggests that future water balance deficits may limit the success of adaptive policy options. 相似文献
8.
《水文科学杂志》2013,58(1):124-134
Abstract The three-route South-to-North Water Diversion Project (SNWDP), transferring water from the water-rich Yangtze River and its tributaries to the much drier area of North China for irrigation, industrial and domestic use, has been implemented in China since 2002. Thus, water quality in the Danjiangkou Reservoir, the water source area of the SNWDP's Middle Route, is of great concern. We investigate its water quality from 2004 to 2006 by monitoring some important physical (T, turbidity and SPM) and chemical (DO, pH, alkalinity, TDS, SpCond, ORP, CODMn and BOD) parameters and nutrient (nitrogen and phosphorus) contents. Consequently, their spatial and temporal patterns in the reservoir were examined. The results indicate that the water of the reservoir is of a Ca and HCO3 type, and the major pollutants are nitrogen and CODMn. Comparisons among the sampling sites show that water quality increases downstream, implying the self-purification capacity of the reservoir. The reservoir in general has better water quality in the dry season than in the wet season. Integrated basin management would be critical of the water quality in the Danjingkou Reservoir for the interbasin water transfer project. 相似文献
9.
《水文科学杂志》2013,58(4):857-867
Abstract Water abstraction for irrigation upstream of a reservoir and its impact on reservoir yield and reliability are studied. Water demand and availability are strongly related in semi-arid environments where the irrigation sector is responsible for a large part of consumptive water use. Variations in water abstractions for irrigation depend on irrigation requirements per hectare and the size of the irrigated area. The Orós Reservoir in semi-arid Northeast Brazil has been taken as a case study. The results show that water abstracttion for irrigation is of significant importance for reservoir yield and reliability. Yield—reliability simulations for the study area show that taking into account upstream water abstraction for a reservoir yield of 20.0 m3/s results in a water-scarcity probability of 10% on an annual basis (90% reliability). This is only 5% if up-stream abstraction for irrigation is ignored. This study shows that observed land-use changes in the study area do have a significant impact on reservoir yield reliability. The variability of upstream water abstraction was found to be of low importance for reservoir yield and reliability. 相似文献
10.
Operation analysis of Eleviyan irrigation reservoir dam by optimization and stochastic simulation 总被引：1，自引：0，他引：1
M. Taghi Sattari Halit Apaydin Fazli Ozturk 《Stochastic Environmental Research and Risk Assessment (SERRA)》2009,23(8):1187-1201
Rainfall distributions in Iran are spatially and temporally heterogeneous, a fact probably linked to the mostly arid and semi-arid
climate of the country. On the other hand, water demand is increasing with increasing population and improving life style.
At present, the optimal utilization of water resources and irrigation dams is the primary concern of water resource managers.
The Eleviyan dam (with a capacity of 60 hm3) was constructed to meet the irrigation and municipal water needs of the Maraghan region (Northwestern Iran). In this study,
the efficiency of the Eleviyan irrigation dam system was investigated in three phases by setting up the optimization model
that maximized the water release for irrigation purposes after municipal water need were met. In the first phase, the inflows
measured in the 21 years prior to the construction of the reservoir, and in the second, the inflows generated by the Monte
Carlo simulation method, and in the third phase, the inflows after the construction of the reservoir were used. The results
demonstrate that the capacity determined during the preliminary studies was accurate and the operation carried out in the
recent periods of operation life was up to a satisfactory standard. 相似文献
11.
12.
在广西龙滩库区布置2条北北西-南东东向大地电磁探测剖面进行了32个测点的观测,观测频段为320 Hz~1000 s.对2条剖面上测量和计算得到的各种电磁参数、深部电性结构图像以及库区地质构造、岩性和水域分布等进行分析研究.结果显示库区发育的6条断裂在电性上表现为不同程度的电性差异边界,其中拉浪-达良断裂和拉色-辉马断裂为库区主要断裂带.库区深部电性结构总体表现为纵向上自地表到20 km深度呈现高-低-高的波浪起伏的三层结构,横向上呈明显的高低电阻块状组合样式.龙滩库区4个地震丛集区的震源都位于高、低电阻接触带附近,其中3个地震丛集区的震源位于低阻特性的石炭系地层的下部,为岩溶水体诱发地震;发生最大震级的地震丛集区的震源位于上宽下窄似"铆钉状"的高阻体下部,推测是因水库蓄水后水体压力增大和库水渗透作用下在聚集高变形能的脆性高电阻体内部发生的地震. 相似文献
13.
Humans have strongly impacted the global water cycle, not only water flows but also water storage. We have performed a first global-scale analysis of the impact of water withdrawals on water storage variations, using the global water resources and use model WaterGAP. This required estimation of fractions of total water withdrawals from groundwater, considering five water use sectors. According to our assessment, the source of 35% of the water withdrawn worldwide (4300 km3/year during 1998–2002) is groundwater. Groundwater contributes 42%, 36% and 27% of water used for irrigation, households and manufacturing, respectively, while we assume that only surface water is used for livestock and for cooling of thermal power plants. Consumptive water use was 1400 km3/year during 1998–2002. It is the sum of the net abstraction of 250 km3/year of groundwater (taking into account evapotranspiration and return flows of withdrawn surface water and groundwater) and the net abstraction of 1150 km3/year of surface water. Computed net abstractions indicate, for the first time at the global scale, where and when human water withdrawals decrease or increase groundwater or surface water storage. In regions with extensive surface water irrigation, such as Southern China, net abstractions from groundwater are negative, i.e. groundwater is recharged by irrigation. The opposite is true for areas dominated by groundwater irrigation, such as in the High Plains aquifer of the central USA, where net abstraction of surface water is negative because return flow of withdrawn groundwater recharges the surface water compartments. In intensively irrigated areas, the amplitude of seasonal total water storage variations is generally increased due to human water use; however, in some areas, it is decreased. For the High Plains aquifer and the whole Mississippi basin, modeled groundwater and total water storage variations were compared with estimates of groundwater storage variations based on groundwater table observations, and with estimates of total water storage variations from the GRACE satellites mission. Due to the difficulty in estimating area-averaged seasonal groundwater storage variations from point observations of groundwater levels, it is uncertain whether WaterGAP underestimates actual variations or not. We conclude that WaterGAP possibly overestimates water withdrawals in the High Plains aquifer where impact of human water use on water storage is readily discernible based on WaterGAP calculations and groundwater observations. No final conclusion can be drawn regarding the possibility of monitoring water withdrawals in the High Plains aquifer using GRACE. For the less intensively irrigated Mississippi basin, observed and modeled seasonal groundwater storage reveals a discernible impact of water withdrawals in the basin, but this is not the case for total water storage such that water withdrawals at the scale of the whole Mississippi basin cannot be monitored by GRACE. 相似文献
14.
AbstractThe objectives of this study were to discover the relationship between variables in a water reservoir and the hydrochemical variations related to acid mine drainage (AMD), and to describe the horizontal stratification related to vertical salinity and variations in metals present in the region. The information obtained may be used for establishing risk evaluation criteria and to design future remediation strategies, which could be useful for new dams. The hydrochemical characterization was based on a sampling campaign performed in October 2011. A total of 28 samples, at 1-m-deep intervals, were obtained. The hydrogeochemical study of the polluted reservoir shows that the dilution effect is not sufficient to neutralize AMD contributions from mining activity. Sampling carried out from the surface water to the deepest points reveals stratification of the reservoir that allows it to be included in the group of monomictic and holomitic lakes.
Editor D. Koutsoyiannis; Associate editor M.D. Fidelibus 相似文献
15.
Upward discharge to surface water bodies can be quantified using analytical models based on temperature–depth (T-z) profiles. The use of sediment T-z profiles is attractive as discharge estimates can be obtained using point-in-time data that are collected inexpensively and rapidly. Previous studies have identified that T-z methods can only be applied at times of the year when there is significant difference between the streambed–water interface and deeper sediment temperatures (e.g., winter and summer). However, surface water temperatures also vary diurnally, and the influence of these variations on discharge estimates from T-z methods is poorly understood. For this study, synthetic T-z profiles were generated numerically using measured streambed interface temperature data to assess the influence of diurnal temperature variations on discharge estimation and provide insight into the suitable application of T-z methods. Results show that the time of day of data collection can have a substantial influence on vertical flux estimates using T-z methods. For low groundwater discharge fluxes (e.g., 0.1 m d−1), daily transience in streambed temperatures led to relatively large errors in estimated flow magnitude and direction. For higher discharge fluxes (1.5 m d−1), the influence of transient streambed temperatures on discharge estimates was strongly reduced. Discharge estimates from point-in-time T-z profiles were most accurate when the uppermost point in the T-z profile was near the bed interface daily mean (two time periods daily). Where temperature time series data are available, daily averaged T-z profiles can produce accurate discharge estimates across a wide range of discharge rates. Seasonality in shallow groundwater temperature generally had a negligible influence on vertical flow estimates. These findings can be used to plan field campaigns and provide guidance on the optimal application of T-z methods to quantify vertical groundwater discharge to surface water bodies. 相似文献
16.
地表陆地水负荷变化是引起重力场和地壳形变呈现季节性特征的主要因素,并且能够利用地表及空间大地测量技术对其进行有效的监测.本文通过对质量负荷形变效应的理论模拟,描述了水平分量的形变指向以及垂直与水平分量的幅值比可以提高对负荷区域的辨别程度,并且联合GPS坐标时间序列及GRACE模型对喜马拉雅山地区的季节性负荷形变进行了详细对比分析,研究结果显示两者垂直分量的季节性变化具有较好的一致性,且GPS周年项幅值要大于GRACE.而由GRACE解算得到的水平分量结果表明该地区季节性形变主要受东南亚及印度东北部地区的陆地水负荷控制,位于喜马拉雅山地区多数GPS台站的垂直分量及北向分量的初相位与GRACE模型解算结果相近,而部分GPS台站的东向分量与GRACE模型存在明显不同,由此导致GPS与GRACE监测到的形变指向存在差异.通过对GRACE估算精度以及GPS垂直与水平分量幅值比的深入分析,发现GPS对局部周边地区的河流、谷地及农田灌溉等负荷变化造成的形变效应较为敏感,而GRACE由于截断阶次及平滑滤波等影响因素,不仅造成在水平分量上的分辨率远低于垂直分量,而且整体估算精度要低于GPS观测得到的形变信息. 相似文献
17.
新安江水库(千岛湖)湖泊区夏季热分层期间垂向理化及浮游植物特征 总被引：20，自引：8，他引：12
2010年7月对亚热带特大型水库——新安江水库湖泊区水体的垂向物理、化学参数以及浮游植物群落进行了观测研究,并应用Water-PAM对水体浮游植物垂向光合作用参数进行了测定.研究结果表明:夏季该水库湖泊区在水下10～20 m处形成明显的温跃层,垂向pH值、溶解氧及浊度的变化同叶绿素a浓度呈现高度一致;夏季浮游植物群落以硅藻占绝对优势,水体表层以梅尼小环藻(Cyclotella meneghiniana)为主,表层以下其它各层均以巴豆叶脆杆藻(Fragilaria cro-tonensis)为绝对优势种,垂向分布表现为5～10 m区间为浮游植物高密度区域,温跃层以下浮游植物密度显著下降,水温分层可能是决定浮游植物垂向分布的重要因素之一.浮游植物最大光合效率从表层向下层逐步降低,实际光合效率最大值出现在垂向10 m区域. 相似文献
18.
《Limnologica》2016
Rising concentrations of dissolved organic carbon (DOC) are negatively affecting the water quality in several drinking water reservoirs. The presence of beaver dams can influence surface water quality on a catchment scale. In recent years, beavers have been re-introduced in numerous locations in Central Europe. We investigated whether the presence of beaver dams in the catchment of a German drinking water reservoir impacts DOC quantity and quality in the streams entering the Wehebach reservoir in Germany.By comparing water quality upstream and downstream of beaver dams during three low discharge situations we did not find a significant effect of dams both on DOC quantity and quality. The analysis of long term monitoring data at the gauges showed that beaver dams had a negligible effect on the DOC load to the reservoir. DOC quantity was closely linked to iron concentration in the streams. Co-precipitation with iron minerals was an effective process removing DOC from the stream-water. By analyzing fluorescence excitation emission indices we show that beaver dams did not have a clear effect on DOC quality. We conclude that the presence of beaver dams has only small effects on water quality and is not a problem for water quality in the downstream drinking water reservoir. 相似文献
19.
Validating the KAGIS black‐box GIS‐based model in a Mediterranean karst aquifer: Case of study of Mela aquifer (SE Spain) 
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下载免费PDF全文 Javier Valdes‐Abellan Concepción Pla Miguel Fernandez‐Mejuto José Miguel Andreu 《水文研究》2018,32(16):2584-2596
Karst Aquifer GIS‐based model (KAGIS model) is developed and applied to Mela aquifer, a small karst aquifer located in a Mediterranean region (SE Spain). This model considers different variables, such as precipitation, land use, surface slope and lithology, and their geographical heterogeneity to calculate both, the run‐off coefficients and the fraction of precipitation which contributes to fill the soil water reservoir existing above the aquifer. Evapotranspiration uptakes deplete water, exclusively, from this soil water reservoir and aquifer recharge occurs when water in the soil reservoir exceeds the soil field capacity. The proposed model also obtains variations of the effective porosity in a vertical profile, an intrinsic consequence of the karstification processes. A new proposal from the Nash–Sutcliffe efficiency index, adapted to arid environments, is presented and employed to evaluate the model's ability to predict the water table oscillations. The uncertainty in the model parameters is determined by the Generalized Likelihood Uncertainty Estimation method. Afterwards, when KAGIS is calibrated, wavelet analysis is applied to the resulting data in order to evaluate the variability in the aquifer behaviour. Wavelet analysis reveals that the rapid hydrogeological response, typical of a wide variety of karst systems, is the prevailing feature of Mela aquifer. This study proves that KAGIS is a useful tool to quantify recharge and discharge rates of karst aquifers and can be effectively applied to develop a proper management of water resources in Mediterranean areas. 相似文献
20.
M. Behm 《Geophysical Prospecting》2017,65(2):563-580
The analysis of seismic ambient noise acquired during temporary or permanent microseismic monitoring campaigns (e.g., improved/enhanced oil recovery monitoring, surveillance of induced seismicity) is potentially well suited for time‐lapse studies based on seismic interferometry. No additional data acquisition required, ambient noise processing can be automatized to a high degree, and seismic interferometry is very sensitive to small medium changes. Thus there is an opportunity for detection and monitoring of velocity variations in a reservoir at negligible additional cost and effort. Data and results are presented from an ambient noise interferometry study applied to two wells in a producing oil field in Romania. Borehole microseismic monitoring on three component geophones was performed for four weeks, concurrent with a water‐flooding phase for improved oil recovery from a reservoir in ca. 1 km depth. Both low‐frequency (2 Hz–50 Hz) P‐ and S‐waves propagating through the vertical borehole arrays were reconstructed from ambient noise by the virtual source method. The obtained interferograms clearly indicate an origin of the ambient seismic energy from above the arrays, thus suggesting surface activities as sources. It is shown that ambient noise from time periods as short as 30 seconds is sufficient to obtain robust interferograms. Sonic log data confirm that the vertical and horizontal components comprise first arrivals of P‐wave and S‐waves, respectively. The consistency and high quality of the interferograms throughout the entire observation period further indicate that the high‐frequency part (up to 100 Hz) represents the scattered wave field. The temporal variation of apparent velocities based on first‐arrival times partly correlates with the water injection rate and occurrence of microseismic events. It is concluded that borehole ambient noise interferometry in production settings is a potentially useful method for permanent reservoir monitoring due to its high sensitivity and robustness. 相似文献