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1.
熵权法在水资源与水环境评价中的研究进展 总被引：1，自引：0，他引：1
随着人口增长和经济社会的发展,水资源的供需矛盾日益增多,对水资源进行合理开发、高效利用、优化配置、全面节约、有效保护、综合治理是至关重要的新任务。熵权法是研究水资源可持续利用的重要方法,可以剔除指标体系中对评价结果贡献较小的指标,减少人为因素对于主观权重的影响,其计算结果真实准确,能够客观地反映水资源与水环境的现状,因此被广泛应用于水资源与水环境评价中,从而为水资源的高效利用及水环境的综合评价提供科学依据。本文对熵权法的由来及在水资源与水环境评价中的发展进程进行了探讨,重点对熵权法在水资源量、水资源承载力、水环境质量和水生态环境评价四个方面的应用进行了讨论和总结,并发现熵权法在水资源与水环境评价中有着良好的应用前景;同时,针对当前熵权法在水资源与水环境评价中存在的不足,提出了改进建议,为水资源与水环境评价的研究方向提供了新思路。除此之外,对熵权法的未来进行了展望：熵权法可与其他方法创新结合共同使用,构建合理全面的评价指标体系,在水资源利用发展趋势、时空格局演变等领域推广应用。 相似文献
2.
An estimation of discharge using mean velocity derived through Chiu’s velocity equation 总被引：1，自引：1，他引：0
To estimate discharge through the year (dry season and flood season), a stage–discharge curve derived through monitoring discharge in about 20 rivers or channels every year has been generally used. As revealed in many studies, however, the stage–discharge curve is inevitably affected by their hydraulic characteristics. This suggests that the use of a stage–discharge curve derived without considering hydraulic characteristics unique to a river or channel may produce significant errors in estimating discharge at not only low stage (during dry seasons) but also high stage (during flood seasons). In this study, the authors proposed a method to calculate the mean velocity and to estimate the discharge considering the hydraulic characteristics of a river or channel (e.g. the bed slope, wetted perimeter, width, kinematic viscosity, etc.); the method was developed using Chiu’s velocity equation. With the proposed method, it is possible to calculate a maximum velocity that is difficult to measure in an open channel, derive an entropy function representing the equilibrium of the channel, and thereby, estimate reliable discharge even in a flood season. To comparatively verify the utility of the proposed method, relations between the results of analysis using Manning’s and Chezy’s mean velocity equations and the values of measured discharge were addressed together. The results of analysis using lab data sets and measured data sets revealed that the proposed method was significantly more accurate in estimating discharge, even in flood seasons, when compared with the conventional method. 相似文献
3.
Real-time flood forecasting of the Tiber river in Rome 总被引：3，自引：2，他引：1
An adaptive, conceptual model for real-time flood forecasting of the Tiber river in Rome is proposed. This model simulates
both rainfall-runoff transformations, to reproduce the contributions of 37 ungauged sub-basins that covered about 30% of the
catchment area, and flood routing processes in the hydrographic network. The adaptive component of the model concerns the
rainfall-runoff analysis: at any time step the whole set of the model parameters is recalibrated by minimizing the objective
function constituted by the sum of the squares of the differences between observed and computed water surface elevations (or
discharges). The proposed model was tested through application under real-time forecasting conditions for three historical
flood events. To assess the forecasting accuracy, to support the decision maker and to reduce the possibility of false or
missed warnings, confidence intervals of the forecasted water surface elevations (or discharges), computed according to a
Monte Carlo procedure, are provided. The evaluation of errors in the prediction of peak values, of coefficients of persistence
and of the amplitude of confidence intervals of prediction shows the possibility to develop a flood forecast model with a
lead time of 12 h, which is useful for civil protection actions. 相似文献
4.
由降雨侵蚀引起的山坡面水土流失预测的数学模型 总被引：3，自引：1，他引：3
数学模型包括：坡面水流连续方程、水流运动方程、泥沙连续方程（水土流失方程）、坡面变形方程。考虑到坡面流的流速及非线性双曲型方程，采用迎风有限差分显格式来离散方程，编制计算程序，进行了计算。研究成果可以描述动态坡面降雨侵蚀过程，并可将研究成果扩展到整个小流域，从而为治理水土流失提供依据。 相似文献
5.
Hand-pump wells in the Tarkwa gold mining district and the geologically similar Bui area were chemically analysed and compared in an effort to determine whether groundwaters in the Tarkwa area have been affected by mining. Significant chemical differences attributed to mine water discharges have been observed in streams in the Tarkwa area. Groundwater chemistry from hand-pump wells in Tarkwa and Bui areas reveal similar hydrochemical facies, predominantly Ca–Na–Mg–HCO3–Cl. However, except for SO42–, ionic concentrations of groundwaters from Bui are greater than those from Tarkwa probably due to differences in (1) water availability during sedimentation (2) water-rock interactions and/or residence times for water. No demonstrable impact of mining on groundwaters from hand-pumped wells in the Tarkwa area has been noted. Hydrogeological inference suggests that the main streams which receive mine water discharges are both gaining and are groundwater divides. The overwhelming majority of population centres and mining operations are located on opposite sides of these groundwater divides, therefore, it is unlikely aquifers tapped for drinking by these communities would be affected by mining. 相似文献
6.
根据Rodriguez Iturbe等和Gupta等导得的流域瞬时单位线即为雨滴汇流时间分布密度的结论,基于雨滴汇流时间等于其流路长度与其速度之商的基本关系式,提出了应用概率论理论建立由雨滴的流路长度分布律和速度分布律确定流域瞬时单位线的方法,并提出了由坡度分布律转换成速度分布律的原理和方法,以及由数字高程模型(DEM)自动获取雨滴流路长度分布律和坡度分布律的方法。此外,还应用最大信息熵原理给出了坡度分布密度的解析表达式。实例表明,作为一种新的毋须通过实测降雨径流资料确定流域单位线的方法,具有进一步研究和推广应用的前景。 相似文献
7.
采用Naot-Rodi代数应力模型(N-R模型),结合非均匀交错网格下的混合有限分析法(HFAM)来计算漫滩水流的三维流动。为了得到稳定的收敛解,作了两点改进:其一为非均匀网格中数值离散的导数项二阶格式的引入;其二为复式断面分块耦合技术的采用。给出了漫滩水流主流速等值线、二次流的断面分布、垂线平均流速的横向分布以及主槽与全断面流量比随相对水深的变化规律。部分结果与实验资料的对比,表明NR模型和HFAM能较好地用于研究漫滩水流流速、流量和水位的关系。 相似文献
8.
W. H. J. Strosnider F. S. Llanos López J. A. LaBar K. J. Palmer R. W. Nairn 《Environmental Earth Sciences》2014,71(7):3223-3234
Intensive mining and processing of the polymetallic sulfide ore body of Cerro Rico de Potosí (Bolivia) has occurred since 1545, leading to severe degradation of surface and subsurface waters, stream sediments, and soils at the headwaters of the economically vital, yet highly impacted, Rio Pilcomayo. Previous studies have documented extremely elevated concentrations of a limited suite of metals in local waterways from acid mine drainage (AMD), terrestrial and in-stream tailings, and ore processing plant discharges. However, contamination from a wider variety of ecotoxic metals/metalloids was considered likely due to the highly mineralized polymetallic nature of the ore body. To screen for this broader range of ecotoxic elements in AMD and receiving streams, data were gathered during two sampling events timed for the most extreme periods of the dry and wet seasons of one water-year. Concentrations of Ag, B, Ba, Mo, Sb, Se, Sn and V in AMD and receiving streams were greater than Bolivian discharge limits and receiving water body guidelines as well as international agricultural use standards. Locally, results indicate that contamination from mining Cerro Rico has a larger scope than previously thought and underscore the importance of remediation. Globally, the results raise the possibility that other mining regions could have unquantified hazards from overlooked ecotoxic elements and that screening for a broader range of contaminants may be warranted. 相似文献
9.
Yeon Moon Choo Gwan Seon Yun Tai Ho Choo Yong Been Kwon Su Yong Sim 《Environmental Earth Sciences》2017,76(17):616
In fluid mechanics, the shear stress is calculated from the frictional force caused by viscosity and fluctuating velocity. Shear stress equations are used widely because of their simplicity. On the other hand, they have a critical limitation of requiring an energy gradient, which is generally difficult to estimate in practice. In particular, measuring the shear stress and velocity gradient on the boundary layer is difficult. The point velocity throughout the entire cross section is needed to calculate the velocity gradient. This study proposes the shear stress distribution equations for laminar flow based on entropy theory using the mean velocity and entropy coefficient. The proposed equations were compared with the measured shear stress distribution using Nikuradse’s data. The results revealed a correlation coefficient of approximately 0.99, indicating that the proposed method fits the Nikuradse’s data. Therefore, the shear stress distribution can be estimated easily and accurately using the proposed equations, which can be used in future for the management and design of a water pipeline. 相似文献
10.
Xinwei Lu Loretta Y. Li Kai Lei Lijun Wang Yuxiang Zhai Meng Zhai 《Environmental Earth Sciences》2010,60(8):1693-1699
Wei River is the major source of water for the urban residents, industrial production and agricultural activities in the central Shaanxi plain of China. Water quality of the Wei River was determined by collecting water samples from 25 locations along the Baoji Xi’an reach and analyzing for pH, EC, BOD5, DO, COD, F, Se, As, and Hg. Fuzzy synthetic evaluation with the entropy method for weight determination was used to assess the water quality of the river. Results indicate that the water quality of 23 sampling sites fall into the fifth grade (bad level), whereas two sampling sites are in the fourth grade (poor level). The comparison of this method with the typical fuzzy synthetic evaluation shows that it is effective in water quality assessment. The assessment results indicate that the Wei River is heavily polluted at most of the sampling locations, with mercury as the major pollutant. Strict enforcement of the regulations for domestic and industrial wastewater discharges is vital to avoid damage to the water environment and to protect human and ecological health. 相似文献
11.
岩溶地区地下河系统水资源定量评价的问题与出路 总被引：6，自引：2，他引：4
岩溶地区含水介质的多重性和高度复杂性,给地下河系统的水资源量评价带来许多难题。在分析地下河系统水资源形成、分布和运移特征基础上,认为目前用于地下水评价的主要方法都不太适用来解决地下河系统水资源量的评价和预测问题。作者在比较地下河与地表水多方面的相似性后,建议引入现代水文学的理论方法和模型来解决岩溶地区地下河系统水资源评价问题,并分析了可能需要解决的若干关键问题。针对岩溶水资源的特征,作者认为,改变传统定量评价的思维、引进现代水文学理论方法和充分利用3S技术,是解决地下河系统水资源定量评价的主要出路。 相似文献
12.
Charles T. Roman 《Estuaries and Coasts》1984,7(3):259-264
Water volume discharge estimates were made at a sample cross-section of the Canary Creek salt marsh (Lewes, Delaware). To account for cross-sectional velocity variations, a dense spatial array of current meters was used. Simultaneous measurements were taken at hourly intervals over three complete tidal cycles. A practical method is presented whereby instantaneous average cross-sectional velocity, instantaneous cross-sectional discharge and tidal cycle discharge can be estimated from a dense current meter array, orideal data set. Based on theseideal estimates, it is shown that a simplified spatial array can be used to estimate water discharges within acceptable error limits. Instantaneous cross-sectional discharges and total tidal cycle discharges were estimated with uncertainties of ±11% and ±7%, respectively. To minimize errors when estimating material exchange between salt marshes and adjacent waters, it is suggested that a comprehensive assessment of cross-sectional lateral current velocity variations be conducted. 相似文献
13.
Jakub Langhammer 《GeoJournal》2010,75(2):185-198
This paper analyses the temporal dynamics and spatial trends in water quality changes in the Elbe River basin in the context
of the post-socialist economic transition of the Czech Republic (Czechia). During the 1990s, the Czech portion of the Elbe
River Basin underwent significant changes in the quality of surface waters. After a long period of massive discharges of pollution,
which reached a peak at the end of the 1980s, a reduction in effluent from industrial and municipal sources led to a substantial
decrease in the pollution of the Elbe River and its principal tributaries. The scope and speed of such water quality changes
was unprecedented in Czechia as well as throughout Europe. The classification of the spatial distribution of water quality
trends revealed that the majority of streams in the Czech Elbe River basin displayed improvement of surface water quality.
However, the decrease in pollution levels was spatially concentrated mainly in the Elbe River and its main tributaries. Many
of the peripheral streams are, on the contrary, experiencing deteriorating water quality, even in regions where water quality
improved in the early 1990s because of a decline in local economic activity associated with political changes in the former
Eastern Block countries. Further improvements in water quality are thus dependent on measures adopted across the entire river
basin, including the numerous minor streams. The current economic revival in a number of regions where decreases in water
pollution were not based on systematic pollution reduction measures, but only on the decline of industrial or agricultural
production, may result in a return to deteriorating water quality, primarily in the outer regions of the catchment. 相似文献
14.
We investigate the possibility of identifying substructures in velocity space in three well-known stellar streams (the Hyades, the Pleiades, and Ursa Major) using a cluster-analysis method (the maximum-density method). Only compact groups in velocity space with radii no greater than 5 km/s and containing at least 10 members were considered. As an example, we analyzed a sample of 5377 stars from the HIPPARCOS catalog with known radial velocities located within 75 pc of the Sun. We identified a total of 24 groups of stars. Monte Carlo simulations show that most (about 80%) of these groups could be the results of Poisson noise and observational errors. Bona fide identification (at a significance level greater than 90%) of compact moving groups based on kinematic data requires higher accuracy of the stellar spatial velocities (with errors no greater than 1–2 km/s in each component). 相似文献
15.
16.
D. S. Suresh Babu Atul Kumar Sahai Mauricio Almeida Noernberg Eduardo Marone 《Hydrogeology Journal》2008,16(7):1427-1439
The unconfined aquifer supported by the extensive Holocene coastal plain of southern Brazil is found dissected at several places by tidally forced streams. One such unit of coastal plain, falling within the watershed limits of Perequê Stream in Paraná state, was analyzed using MODFLOW to assess the surface and subsurface water components under different stress conditions. The steady-state simulation suggests that ~23,000 m3/day of water forms the total budget of the designated aquifer zone and this zone discharges ~16,000 m3/day across the interface between the freshwater aquifer zone and the sea as direct submarine discharge. The maximum evaporation loss was assumed to be 2,700 m3/day. Any change in effective aquifer storage was insignificant, as there is no large-scale exploitation of local groundwater reserves. A calibration exercise, based on field measurements lasting 1 year, supports validity of the model considered. Simulations representing two different transient conditions point to the dynamic hydraulic response exhibited by the aquifer. A schematic map, showing directions and velocity of subsurface flows, and a three-dimensional model of the groundwater reserve helped to visualize the hydrogeologic changes and to formulate management plans. 相似文献
17.
Determination of potential mine water discharge zones in crystalline rocks at Rozna,Czech Republic 总被引：3，自引：2，他引：1
Adam Ricka Tomas Kuchovsky Ondra Sracek Josef Zeman 《Environmental Earth Sciences》2010,60(6):1201-1213
The Rozna Mine is one of the last active uranium mines in Europe. When the mine is closed and flooded, the natural groundwater
flow pattern will be partly restored. Re-established groundwater flow system will be associated with an increase of groundwater
discharge into draining rivers and streams. Since the groundwater inflows to streams can be contaminated by the mine water,
the groundwater drainage characteristic of fractured aquifer should be carefully identified. Several methods of groundwater
discharge zones identification were used including morphological analysis, thermometry, and electrical conductivity (EC) measurements.
Stream temperatures and EC at more than 700 points in the area covering about 85 km2 were measured. The measurements were performed during winter period, when stream discharges were low and there was a maximum
temperature contrast. There was a frequent presence of preferential discharge zones with resulting anomalous temperatures
and electric conductivity values of stream water. The results show evident correlation of discharge zones with surface morphology
and geological settings. Just like the aquifer discharge characteristics, the aquifer is strongly heterogeneous. The thermometry
supported by measurement of EC proved to be a useful tool for large-scale investigation of groundwater flow and drainage in
fractured aquifers. 相似文献
18.
高拱坝表孔宽尾墩收缩射流水舌的扩散特性与其出口流速分布密切相关,为了求得收缩射流的水力特性,应用RNGk ε双方程湍流模型对高拱坝表孔不同体型及过流量条件下可能出现的降水曲线流态、急流冲击波流态、水跃壅水流态、缓流流态4种流态进行了数值模拟计算,水流自由表面的模拟采用VOF法,得到了溢流水面及流速分布。结果表明,无论在何种流态下,计算所得的水面曲线均与物理模型试验值吻合良好,所得的出口流速分布结构也验证了高拱坝宽尾墩收缩射流水舌不同流态下分散的机理。 相似文献
19.
National flood discharge mapping in Austria 总被引：5，自引：0，他引：5
This article presents the approach and the results of a study in which 30, 100 and 200 year return period flood discharges
were estimated for 26,000 km of Austrian streams. Three guiding principles were adopted: combination of automatic methods
and manual assessments by hydrologists to allow speedy processing and account for the local hydrological situation; combination
of various sources of information including flood peak samples, rainfall data, runoff coefficients and historical flood data;
and involvement of the Hydrographic Services to increase the accuracy and enhance the acceptance of results. The flood discharges
for ungauged catchments were estimated by the Top-kriging approach with manual adjustment to the local flood characteristics.
The adopted combination approach proved to be very efficient both in terms of the project time required and in terms of the
accuracy and acceptability of the estimated flood discharges of given return periods. 相似文献
20.
Alexander P. Petroff Olivier Devauchelle Arshad Kudrolli Daniel H. Rothman 《Comptes Rendus Geoscience》2012,344(1):33-40
Networks fed by subsurface flow are a natural, but dynamically simple, system in which to consider general problems of network growth. Here we present four examples in which this dynamic simplicity can be used to develop a quantitative understanding of a natural kilometer-scale network of streams. In these four sections, we investigate the relation between the position of a spring in the network and the groundwater flux into it, the flow of water through streams and the stream shape, and the influence of solar radiation on the rate of sediment transport around the streams. In each case, a quantitative comparison is made between theory and observation. 相似文献