CHANGING WATER BALANCE OVER TIME IN RUSH CREEK,EASTERN CALIFORNIA, 1860–19921

ABSTRACT: Rush Creek, the principal tributary to Mono Lake, has undergone profound hydrologic modifications as a result of flow regulation for hydroelectric generation and irrigation, diversions for irrigated agriculture, and diversions for water export to the City of Los Angeles. Lower Rush Creek (the lowermost 13 km downstream of Grant Lake Reservoir) was dry by 1970, but now receives flow as a result of court-ordered efforts to restore former ecological conditions. Using available historic data and recent field measurements, we constructed the water balance for Lower Rush Creek, identifying six distinct historical periods characterized by very different patterns of gain and loss. The hydrologic patterns must be understood as a basis for modeling ecosystem response to stream-flow alteration. A gradually gaining stream under natural conditions, the advent of irrigation diversions caused the middle reaches of Lower Rush Creek to be often completely dry, while irrigation-recharged springs still maintained a baseflow in the downstream “Meadows” ranch. Increased water exports from the basin subsequently reduced irrigation and dried up the springs.     

DETERMINATION OF UNGAGED TRIBUTARY FLOWS AND INTERSEGMENTAL RESERVOIR FLOWS USING SPREADSHEET SOFTWARE1

ABSTRACT: Spreadsheet software was utilized on two related large scale trial and error problems. Gaged streamflow data and known reservoir volumes were used to construct a daily continuity balance in order to estimate the daily mean flows from ungaged portions of a study watershed over one year. Watershed yield coefficients were determined for two diverse types of watersheds with and without significant ground water contribution. Subsequently, a spreadsheet template was devised to ensure than an EPA supported water quality model, WASP, would successfully model the actual segmental volumes of a flood control reservoir. Inlet, outlet, and intersegmental advective flows were determined on a two week average basis using a continuity balance, segmental routing, and known segmental volumes. The protocols described relate the use of microcomputers to the resolution of hydraulic and hydrologic problems requiring iterative solutions.     

循环水冲洗生态厕所及其污水处理方法

主要研究了循环水冲洗生态厕所对冲厕污水有机污染物和NH4 -N的去除效果.结果表明,在进水COD和NH4 -N负荷分别为1.2～1.4 kg COD/m3·d和0.1～0.11kg NH4 -N/m3·d时,循环水冲洗生态厕所出水COD和NH4 -N稳定维持在15 mg/L和5 mg/L,达到我国中水回用相关标准,满足了循环冲洗水水质要求,根本上实现了冲厕污水源头治理和资源化.     

Numerical Simulation of Interaction of the Heavy Gas Cloud with the Atmospheric Surface Layer

The numerical time-dependent three-dimensional model [Kovalets, I.V. and Maderich, V.S.: 2001, Int. J. Fluid Mech. Res. 30, 410–429] of the heavy gas dispersion in the atmospheric boundary layer has been improved by parameterizing momentum and heat fluxes on the surface of Earth using Monin–Obukhov similarity theory. Three parameterizations of heat exchange with the surface of Earth were considered: (A) formula of Yaglom A.M. and Kader B.A. [1974, J. Fluid Mech. 62, 601–623] for forced convection, (B) interpolation formula for mixed convection and (C) similarity relationship for mixed convection [Kader, B.A. and Yaglom, A.M.: 1990, J. Fluid Mech. 212, 637–662]. Two case studies were considered. In the first study based on experiment of Zhu et al., J. Hazard Mater 62, 161–186], the interaction of an isothermal heavy gas plume with an atmospheric surface layer was simulated. It was found that stable stratification in the cloud essentially suppresses the turbulence in the plume, reducing the turbulent momentum flux by a factor of down to 1/5 in comparison with the undisturbed value. This reduction essentially influences velocities in the atmospheric boundary layer above the cloud, increasing the mean velocity by a factor of up to 1.3 in comparison with the undisturbed value. A simulation of cold heavy gas dispersion was carried out in the second case based on field experiment BURRO 8. It was shown that both forced and free convections under moderate wind speeds significantly influence the plume. The relative rms and bias errors of prediction the plume’s height were σ_H ≈ 30% and ɛ_H = − 10%, respectively, for parameterization B, while for A and C the errors were σ_H ≈ 80% and ɛ_H ≈ − 65%. It is therefore advised to use the simple parameterization B in dense gas dispersion models.     

Surfactant-enhanced flushing enhances colloid transport and alters macroporosity in diesel-contaminated soil

Soil contamination by diesel has been often reported as a result of accidental spillage,leakage and inappropriate use. Surfactant-enhanced soil flushing is a common remediation technique for soils contaminated by hydrophobic organic chemicals. In this study, soil flushing with linear alkylbenzene sulfonates(LAS, an anionic surfactant) was conducted for intact columns(15 cm in diameter and 12 cm in length) of diesel-contaminated farmland purple soil aged for one year in the field. Dynamics of colloid concentration in column outflow during flushing, diesel removal rate and resulting soil macroporosity change by flushing were analyzed. Removal rate of n-alkanes(representing the diesel) varied with the depth of the topsoil in the range of 14%–96% while the n-alkanes present at low concentrations in the subsoil were completely removed by LAS-enhanced flushing. Much higher colloid concentrations and larger colloid sizes were observed during LAS flushing in column outflow compared to water flushing. The X-ray micro-computed tomography analysis of flushed and unflushed soil cores showed that the proportion of fine macropores(30–250 μm in diameter)was reduced significantly by LAS flushing treatment. This phenomenon can be attributed to enhanced clogging of fine macropores by colloids which exhibited higher concentration due to better dispersion by LAS. It can be inferred from this study that the application of LAS-enhanced flushing technique in the purple soil region should be cautious regarding the possibility of rapid colloid-associated contaminant transport via preferential pathways in the subsurface and the clogging of water-conducting soil pores.     

ON AN ECONOMIC VALUATION OF THE COLUMBIA-SNAKE RIVER COMPLEX1

This paper is an effort to establish a lower bound on the economic value of the Columbia and Snake Rivers to the State of Washington, so as to assess the economic consequences of diversion of waters of these rivers to other geographic regions. The uses recognized in this paper are for power generation and irrigation, although the dynamic-programming model constructed is capable of incorporating, with minor changes, returns from other uses of the rivers when the economic data can be obtained.     

REFORESTATION WITH CONIFERS - ITS EFFECT ON STREAMFLOW IN CENTRAL NEW YORK1

During the early 1930's, more than 340,000 acres of abandoned farmland in New York State were purchased by the State Conservation Department for the planting, growing, and harvesting of trees. Since then, this land has developed from a heavy cover of weeds and brush into dense coniferous woodlands with trees averaging well over 30 feet high. Hydrologic data have been collected since 1932 in Central New York to determine the effect of the reforestation on streamflow. Data are available for three small partly reforested areas and for one non-reforested control area. Intensive statistical analyses of the data from the four study areas were made in 1958. It was determined at that time that significant reductions in total runoff had occurred which were attributed to increases in interception and transpiration. Reductions in peak discharges during the dormant season also were indicated which were attributed to increased interception and sublimation of snowfall, and gradual desynchronization of snowmelt runoff from the wooded and open areas of partly reforested watersheds. Updating of the studies relating to peak discharges was completed in 1967 and indicated that no further changes in relative peaks had taken place since 1958. From this it is concluded that the influence exerted by the forest had become maximum by 1958 and has remained stable since then.     

Controlling substance flows: The case of chlorine

The contribution of chlorinated hydrocarbons (CHCs) to environmental problems in the Netherlands is discussed in an economic context. The economic interactions within the chlorine market, including the link to caustic soda production, are described, and PVC is taken as a case study. Key policy options are evaluated in terms of their potential for environmental improvement. It appears that 95% of CHC emissions causing environmental problems are due to dissipative applications. With respect to the specific problems of ozone depletion and global warming, only a small group of compounds is responsible for most of the impact. Moreover, economic interactions within the group of CHCs can strongly influence the net effect of environmental policy measures. Policies aimed at a reducing volume output of certain specific groups of CHCs will inevitably lead to trade-offs between environmental problems. The environmental impact of a hypothetical ban on CHCs is discussed in relation to the use of PVC as a sink for chlorine. Both these options appear to have drawbacks. Moreover, no absolute conclusion can be drawn until the environmental impact of CHC substitutes is known.     

Assessment of future scenarios of climate and land-use changes in the IMPRINTS test-bed areas

The main objective of this work is to identify and evaluate the potential impacts produced by climate and land-use changes in six European test-bed basins (Llobregat, Guadalhorce, Gardon d’Anduze, Linth, Verzasca and Sambuco). Data to build future scenarios that can modify the different basins’ flash flood and debris flow risk level has been analyzed in this paper. High resolution climate scenarios have been obtained from several European projects and/or National initiatives, depending on each case. Climatic variables have been widely analyzed, with a special focus on extreme precipitation. Typical generalized extreme value (GEV) distributions have been fitted to observed and projected rainfall data to assess impacts in the frequency distributions of extreme rainfall up to 2100. Regarding climate, the main conclusion is the importance of using data at the maximum spatial and temporal resolution applying downscaling methodologies adapted to basin scale (test-bed areas ranging from approx 200 to 5000 km²) and oriented to obtain extreme rainfall values.In general, high variability has been detected, obtaining very different results for the different models and scenarios. Data corrections may lead to better representations of present situations and, therefore, more reliable future projections, but currently some of them are not suitable for extreme precipitation assessment.Regarding land-use changes, a cellular automata-based model has been used (MOLAND) to simulate the 2000–2040 period taking the CORINE land-use dataset as input data. Llobregat, Guadalhorce and Gardon d’Anduze basins have been identified as potentially interesting for simulating urban land-use dynamics due to the existence of important urban areas within their limits. The assessment of the rural land-use changes has been carried out using the results from the EURURALIS project (2000–2030 period), available for all the basins.The results of this paper are framed in the FP7 project IMPRINTS that has the aim of analyzing impacts of future changes to provide guidelines for mitigation and adaptation measures and, in general, to improve the application of the EC Flood Risk Management Directive.     

京福高铁对旅游目的地区域空间结构的影响——以黄山市为例

随着高速铁路网络化发展,旅游发展新要素的介入,目的地旅游发展产生新变化。以黄山市为案例地,京福高铁开通前后为时间分割点,通过实地调研和网络检索获取旅游者空间流动轨迹及相关出行属性数据,利用Excel、SPSS、SNA、GIS和CorelDraw等方法,探析京福高铁对黄山市旅游目的地区域空间结构的影响。结果显示：1）高铁开通后,国内客源市场半径向外延伸,且高铁沿线福建、山东、北京等省市客流量出现“逆衰减”现象。2）高铁开通后,旅游目的地区域节点数量改变,空间范围扩展。整体网络流量在高铁开通前后都呈现高频节点对以区域间组合（黄山+长三角、黄山+江西省域）为主、区域内组合为辅（黄山+合肥、池州、宣城）的空间分布特征。整体网络功能发育欠完善,网络结构分层明显。高铁开通后,整体网络核心区发生改变,核心节点空间分布由集中趋向分散,核心区与边缘区联系松散,旅游辐射效应较弱。目的地区域核心节点和重要节点的程度中心性值变化较大,核心中介节点较少,核心节点结构洞水平较高,功能突出。3）高铁开通前后,黄山市旅游目的地区域空间结构呈现“板块式”的发展格局,包括黄山+长三角地区,皖南旅游区（黄山+池州、宣城）、黄山+江西省域三个板块,目的地区域整体空间结构由“单核-外围”向“双核-外围”变化,由凝聚趋向扩展,空间发展模式发生改变。探析高铁对黄山市旅游发展的影响,可为黄山市及周边地区的旅游地发展提供借鉴价值。