基于 Budyko 假设的若尔盖流域径流变化归因分析

变化环境下的水文循环研究是当今水科学研究的热点之一,研究流域水文过程变化的响应机制,对未来流域水资源规划及管理具有重要的现实意义。以若尔盖流域为研究区域,基于Budyko假设理论,应用敏感性分析方法,对若尔盖流域径流变化进行归因分析,结果表明:若尔盖流域径流对降水、潜在蒸散发和流域特征参数的敏感性系数分别为0.645 1、-0.234 7和-182.205 0,即若尔盖流域降水每增加1mm将导致流域径流增加0.645 1mm,潜在蒸散发每增加1mm将导致流域径流减少0.234 7mm,流域特征参数每增加1将导致流域径流减少182.205 0mm;若尔盖流域逐年径流呈明显的下降趋势,与基准期(1960-1990年)相比,变化期(1991-2011年)径流量减少了56.23mm(20.48%),其主要影响因素为流域下垫面特征的变化,其贡献率可达93.46%,而气候变化的影响仅占5.57%。     

Hydrology under climate change in a temporary river system: Potential impact on water balance and flow regime

The potential impacts of future climate scenarios on water balance and flow regime are presented and discussed for a temporary river system in southern Italy. Different climate projections for the future (2030–2059) and the recent conditions (1980–2009) were investigated. A hydrological model (Soil and Water Assessment Tool) was used to simulate water balance at the basin scale and streamflow in a number of river sections under various climate change scenarios, based on different combinations of global and regional models (global circulation models and regional climate models). The impact on water balance components was quantified at the basin and subbasin levels as deviation from the baseline (1980–2009), and the flow regime alteration under changing climate was estimated using a number of hydrological indicators. An increase in mean temperature for all months between 0.5–2.4 °C and a reduction in precipitation (by 4–7%) was predicted for the future. As a consequence, a decline of blue water (7–18%) and total water yield (11–28%) was estimated. Although the river type classification remains unvaried, the flow regime distinctly moves towards drier conditions and the divergence from the current status increases in future scenarios, especially for those reaches classified as I‐D (ie, intermittent‐dry) and E (ephemeral). Hydrological indicators showed a decrease in both high flow and low flow magnitudes for various time durations, an extension of the dry season and an exacerbation of extreme low flow conditions. A reduction of snowfall in the mountainous part of the basin and an increase in potential evapotranspiration was also estimated (4–4.4%). Finally, the paper analyses the implications of the climate change for river ecosystems and for River Basin Management Planning. The defined quantitative estimates of water balance alteration could support the identification of priorities that should be addressed in upcoming years to set water‐saving actions.     

A stochastic dynamic programming model for stream water quality management

This paper deals with development of a seasonal fraction-removal policy model for waste load allocation in streams addressing uncertainties due to randomness and fuzziness. A stochastic dynamic programming (SDP) model is developed to arrive at the steady-state seasonal fraction-removal policy. A fuzzy decision model (FDM) developed by us in an earlier study is used to compute the system performance measure required in the SDP model. The state of the system in a season is defined by streamflows at the headwaters during the season and the initial DO deficit at some pre-specified checkpoints. The random variation of streamflows is included in the SDP model through seasonal transitional probabilities. The decision vector consists of seasonal fraction-removal levels for the effluent dischargers. Uncertainty due to imprecision (fuzziness) associated with water quality goals is addressed using the concept of fuzzy decision. Responses of pollution control agencies to the resulting end-of-season DO deficit vector and that of dischargers to the fraction-removal levels are treated as fuzzy, and modelled with appropriate membership functions. Application of the model is illustrated with a case study of the Tungabhadra river in India.     

Sensitivity of reservoir operation performance to climatic change

The potential impacts of changing climatic conditions on the operational performance of water resource systems was investigated in this paper. A multi-site streamflow generation model was used to synthesize potential monthly flow sequences reflecting two different sets of climatic conditions. The generated data were subsequently employed as input to a reservoir operation model that was used to determine the reservoir response to the inflow resulting from the implementation of the reservoir operating policy. The performance of an example reservoir system, the Shellmouth Reservoir located in the Canadian province of Manitoba, was evaluated and compared for the two sets of conditions. The operational performance was evaluated in terms of the reliability of the system for meeting the three purposes of the actual reservoir. The reservoir performance was determined to be sensitive to the inflow data. The results indicate that climatic change has potentially important implications for the operation of the example reservoir system.     

New acoustic system for continuous measurement of river discharge and water temperature

In many cases,river discharge is indirectly estimated from water level or streamflow velocity near the water surface.However,these methods have limited applicability.In this study,an innovative system,the fluvial acoustic tomography system(FATS),was used for continuous discharge measurement.Transducers with a central frequency of 30 kHz were installed diagonally across the river.The system's significant functions include accurate measurement of the travel time of the transmission signal using a GPS clock and the attainment of a high signal-to-noise ratio as a result of modulation of the signal by the 10th order M-sequence.In addition,FATS is small and lightweight,and its power consumption is low.Operating in unsteady streamflow,FATS successfully measured the cross-sectional average velocity.The agreement between FATS and acoustic Doppler current profilers(ADCPs)on water discharge was satisfactory.Moreover,the temporal variation of the cross-sectional average temperature deduced from the sound speed of FATS was similar to that measured by a temperature sensor near the bank.     

EFCAM: A METHOD FOR ASSESSING ALTERATION OF ENVIRONMENTAL FLOW COMPONENTS

The environmental flow components (EFCs) are a set of 34 streamflow statistics computed by the Indicators of Hydrologic Alteration software, which are used for environmental flow assessments and developing environmental flow recommendations. The objective of this paper is to demonstrate a methodology for analysing and summarizing the alteration of EFCs, called the EFC assessment method (EFCAM). EFCAM uses non‐parametric rank‐sum statistical tests, sometimes in conjunction with per cent change, to produce ratings of alteration for each EFC statistic, for both central tendency and range of variability. These ratings are combined into summary indexes of alteration, by event type (extreme low flow, low flow, high‐flow pulse, small flood and large flood), flow characteristic (frequency, magnitude, duration, timing and rise/fall rates) and overall. EFCAM is demonstrated by analyzing typical patterns of EFC changes in 66 rivers across the United States where flow is altered by dams. The results reported here show that EFCAM is an effective method for efficiently summarizing flow alteration of ecologically relevant components of flows, and hence would be a useful addition to the Indicators of Hydrologic Alteration software. Results of this study show an overall trend towards compression of the hydrograph from above and below into a more limited overall range on these 66 rivers. The results shown here add to previous findings on dam impacts on river flows by separating out alteration in different segments of the hydrograph, and identify some patterns of alteration not previously reported. Although the version of EFCAM used here is believed to be appropriate for most situations, it is flexible and can be tailored to the needs of a particular project by including or excluding certain flow statistics or using a different weighting system. Copyright © 2013 John Wiley & Sons, Ltd.     

Diffusion method of routing in channels with storage areas

Abstract

The diffusion equation of flood wave propagation in channels with storage areas has been derived and its solution is expressed in the form of error functions. From this solution, two types of peak discharge are identified. Their behaviors are examined and compared with numerical solution of complete equations of motion and continuity. A subsidence parameter is defined in terms of diffusion coefficient and inflow characteristics, and evaluated from the results of numerical solution. Hydrographs computed using the diffusion method compares favorably to those obtained from the numerical solution.     

Impacts of precipitation and temperature changes on annual streamflow in the Murray–Darling Basin

The relationship between the interannual changes in streamflow, precipitation and temperature of the Murray–Darling basin is investigated by using a two-parameter climate elasticity of streamflow approach. The non-linear relationship between streamflow and both precipitation and temperature indicates a greater streamflow sensitivity to precipitation than to temperature but a more significant impact of temperature change on streamflow than previously reported. The physical mechanisms producing high streamflow sensitivity to temperature change are not well understood, but may relate to concurrent changes in sub-annual precipitation characteristics such as seasonality, spatial distribution and intensity. Thus these characteristics need to be assessed and accounted for when attempting to project how streamflow, and hence water availability, may change in a future warmer world.     

王家山水库来水来沙预测研究

采用前人的研究方法,对甘肃靖远煤矿王家山水库运行使用期间的来水来沙情况作了预测分析。为水库的有效运行提供依据和建议。     

Simulating system‐wide effects of reducing irrigation withdrawals in a disputed river basin

Stakeholders in river systems often target larger upstream water consumers as an intuitive solution for increasing flows for downstream ecological needs. Within regulated river systems, simplistic panaceas may have unexpected and unintended results at a watershed level. The Apalachicola–Chattahoochee–Flint River Basin is a large watershed in the south‐eastern United States whose management has been the source of conflict for several decades. This paper tests the hypothesis of whether a reduction in consumptive losses to Flint River flows through the large‐scale implementation of water‐saving agricultural irrigation technologies and practices will have a positive effect on downstream ecosystem water requirements in the Apalachicola River. An existing integrated reservoir/reach model was used to explore multiple irrigation water use scenarios. Because of current federal reservoir operating rules in the Chattahoochee River, irrigation decreases in the Flint River do not always directly translate to elevated flows downstream in the Apalachicola River. In drought years, a large percentage of the Flint River water savings is captured as greater storage volume at upstream Chattahoochee reservoirs because of a requirement to supplement downstream flows to a prescribed minimum level. In nondrought years, the majority of irrigation decreases translate to increased flow in the Apalachicola River. Given these simulation results, public policy decisions need to be formulated with regard to what portion of the Flint River water savings from changing irrigation practices in drought years should be allocated to the upstream Chattahoochee storage reservoirs and what portion to supporting downstream environmental and social needs in the Apalachicola watershed.