STREAM DEPLETION BY WELLS IN THE SOUTH PLATTE BASIN-COLORADO1

The agricultural production from the Lower South Platte Basin in Colorado represents a significant portion of the state economy. Until the early 1950's the production had developed almost exclusively by use of river water. Drought conditions combined with improved well technology resulted in an inordinate amount of well development in the valley during the period 1952-56. These wells were used for supplemental supply in many cases, but the application of sprinkler irrigation brought many acres of here-to-fore dry land into irrigated production. As a result of the vast amounts of groundwater withdrawal by the newly developed wells, senior surface appropriators found a decreasing amount of water available for use in the streams. The legislature, observing the doctrine of prior appropriation, ruled that all surface and ground water in a tributary would be treated and administered as one resource. This, of course, spelled doom for the well-oriented segment of the economy. Analysis of a segment of the river on an inflow-outflow basis was made with careful determination of all inflow-outflow in the study reach to include correlations required to determine ungaged side-channel in-flow and unmetered irrigation wells. Results indicate that wells have intercepted normal return flows to the river resulting in a decreased amount of surface water during the irrigation season. Stream depletion appears to equal the expected consumptive use of well water which ranged between 40% to 50% of the groundwater extraction.     

滑坡体三维构造及稳定性分析

采用体元技术建立滑坡体真三维模型,通过基本三棱柱体构建具有复杂曲面结构的空间组合体,每个单元都赋予不同的属性,为滑坡体三维稳定性分析提供基本的前、后处理功能.以此为基础,并结合三维极限平衡分析计算方法,开发了相关的滑坡三维模拟与稳定性分析软件,并成功应用于清江库岸大型滑坡的三维仿真计算.     

A stochastic-advective transport model for NAPL dissolution and degradation in non-uniform flows in porous media

Remediation schemes for contaminated sites are often evaluated to assess their potential for source zone reduction of mass, or treatment of the contaminant between the source and a control plane (CP) to achieve regulatory limits. In this study, we utilize a stochastic stream tube model to explain the behavior of breakthrough curves (BTCs) across a CP. At the local scale, mass dissolution at the source is combined with an advection model with first-order decay for the dissolved plume. Field-scale averaging is then employed to account for spatial variation in mass within the source zone, and variation in the velocity field. Under the assumption of instantaneous mass transfer from the source to the moving liquid, semi-analytical expressions for the BTC and temporal moments are developed, followed by derivation of expressions for effective velocity, dispersion, and degradation coefficients using the method of moments. It is found that degradation strongly influences the behavior of moments and the effective parameters. While increased heterogeneity in the velocity field results in increased dispersion, degradation causes the center of mass of the plume to shift to earlier times, and reduces the dispersion of the BTC by lowering the concentrations in the tail. Modified definitions of effective parameters are presented for degrading solutes to account for the normalization constant (zeroth moment) that keeps changing with time or distance to the CP. It is shown that anomalous dispersion can result for high degradation rates combined with wide variation in velocity fluctuations. Implications of model results on estimating cleanup times and fulfillment of regulatory limits are discussed. Relating mass removal at the source to flux reductions past a control plane is confounded by many factors. Increased heterogeneity in velocity fields causes mass fluxes past a control plane to persist, however, aggressive remediation between the source and CP can reduce these fluxes.     

长江三峡水库气候效应数值模拟

在地形坐标系中建立了一个三维静力平衡的大气-土壤耦合模式,模式详细考虑了复杂地形、植被和水面的热力、动力过程。与其它中、小尺度模式相比其独特之处是：此模式在地表与植被冠层建立的辐射平衡方程和能量平衡方程中,均详细地考虑了坡度、坡向的影响。观测表明,长江三峡江面水温的日变化小于3℃。长江三峡段水流湍急,江水上下交换十分剧烈,各处水深变化较大,使模拟江水的动力、热力过程变得十分困难。所以,在研究中忽略了江水温度的日变化,模式中作为动力、热力外强迫因子,水库建成后的改变仅为水面海拔高度的升高和水面区域的扩大,水面温度是常数。用此模式模拟研究长江三峡建成前后气象要素场的日变化过程,通过计算它们的差别来分析水库的小气候效应。结果表明风、温、湿气象要素场在方圆近10 km范围内均有不同程度的改变,但变化幅度不大。     

Diverging response patterns of terrestrial and aquatic species to hydromorphological restoration

Although experiences with ecological restoration continue to accumulate, the effectiveness of restoration for biota remains debated. We complemented a traditional taxonomic analysis approach with information on 56 species traits to uncover the responses of 3 aquatic (fish, macroinvertebrates, macrophytes) and 2 terrestrial (carabid beetles, floodplain vegetation) biotic groups to 43 hydromorphological river restoration projects in Germany. All taxonomic groups responded positively to restoration, as shown by increased taxonomic richness (10–164%) and trait diversity (habitat, dispersal and mobility, size, form, life history, and feeding groups) (15–120%). Responses, however, were stronger for terrestrial than aquatic biota, and, contrary to our expectation, taxonomic responses were stronger than those of traits. Nevertheless, trait analysis provided mechanistic insights into the drivers of community change following restoration. Trait analysis for terrestrial biota indicated restoration success was likely enhanced by lateral connectivity and reestablishment of dynamic processes in the floodplain. The weaker response of aquatic biota suggests recovery was hindered by the persistence of stressors in the aquatic environment, such as degraded water quality, dispersal constraints, and insufficient hydromorphological change. Therefore, river restoration requires combined local- and regional-scale approaches to maximize the response of both aquatic and terrestrial organisms. Due to the contrasting responses of aquatic and terrestrial biota, the planning and assessment of river restoration outcomes should consider effects on both components of riverine landscapes.     

Heavy Metals in the Bed and Suspended Sediments of Anyang River, Korea: Implications for Water Quality

The objective of this study is to compare Anyang River bed sediments with water chemical composition and to assess the anthropogenic chemical inputs into the river system. Eight sampling locations were chosen along the river channel. Bed and suspended river sediments and water samples were collected, and analyzed for their chemical and physical composition. Data revealed that trace element concentrations in the river water were generally below world average, except for As, Mn, Ni and Cr. Among the three phases: water, bed and suspended sediment, more than 99% of the trace elements was associated with the bed sediment. Concentrations of trace elements in the sediment were a function a particle size distribution and organic content. The calculated degrees of enrichment based on the least influenced sample (ASD 1) indicated the river sediments were enriched with respect to background. The enrichment factors for Pb, Zn and As were relatively lower than for Cr, Co, Ni and Zn. The difference in the enrichment seems to reflect the human activities influence in the basin, and specially for Cd. Speciation of the elements in the five different chemical forms in the sediment by sequential extraction indicated that the reducible fraction was predominant for Fe, Zinc and Cu showed an irregular variation among the different fractions; whereas, Cd and Pb were more regular. Zinc and Cu highly existed mostly in exchangeable forms. Acid soluble and reducible forms were also important for most metals. The speciation implies that the metals associated with the sediment are subject to release into water bodies as goechemical variables (pH and Eh) change. Currently, the introduced metals are deposited near the source area and are mostly associated with the sediment, implying that the river bed sediment acts mainly as a sink, rather than a pool. The accumulated and enriched toxic trace elements can pose a potential pollution of river water.     

Set-up costs and the existence of competitive equilibrium when extraction capacity is limited

Although set-up costs are prevalent and substantial in natural resource extraction, it is known that a Walrasian competitive equilibrium cannot exist in simple extraction models with set-up costs. This paper demonstrates that this result is sensitive to the assumption of unlimited extraction capacity and derives sufficient conditions for existence. An equilibrium exists if extraction is limited such that each firm earns sufficient surplus to cover its set-up costs or if firms choose extraction capacity subject to non-increasing returns. The resulting competitive equilibrium price either grows at the rate of interest when total extraction is below industry capacity or is constant when industry capacity is fully utilized. In the equilibrium, identical deposits are opened simultaneously, and set-up costs for new deposits are incurred when the industry has excess capacity rather than when capacity is fully utilized.     

Radon Exhalation Rate of Some Building Materials Used in Egypt

Indoor radon has been recognized as one of the health hazards for mankind. Common building materials used for construction of houses, which are considered as one of the major sources of this gas in indoor environment, have been studied for exhalation rate of radon. Non-nuclear industries, such as coal fired power plants or fertilizer production facilities, generate large amounts of waste gypsum as by-products. Compared to other building materials waste gypsum from fertilizer production facilities (phosphogypsum) shows increased rates of radon exhalation. In the present, investigation solid state alpha track detectors, CR-39 plastic detectors, were used to measure the indoor radon concentration and the radon exhalation rates from some building materials used in Egypt. The indoor radon concentration and the radon exhalation rate ranges were found to be 24–55 Bq m⁻³ and 11–223 mBq m⁻² h⁻¹, respectively. The effective dose equivalent range for the indoor was found 0.6–1.4 mSv y⁻¹. The equilibrium factor between radon and its daughters increased with the increase of relative humidity.     

ESTIMATING THE Q100 IN BRITISH COLUMBIA: A PRACTICAL PROBLEM IN FOREST HYDROLOGY1

ABSTRACT. Estimates of peak flows, with specified return periods, are needed in practice for the design of works that affect streams in forested areas. In the province of British Columbia (B.C.), Canada, the new Forest Practices Code specifies the 100-year instantaneous peak flow (Q100) for the design of bridges and culverts for stream crossings under forest roads; and many practitioners are engaged in making such estimates. The state of the art is still quite primitive, very similar to the state of urban hydrology 30 years ago, when popular estimating techniques were used with little consideration given to their applicability. Urban hydrology then evolved on a much more scientific basis, such that within about a 10-year period, standard approaches to design were developed. Forest hydrology should follow the same pattern, at least as far as estimating design flows is concerned. Popular present day design procedures include the rational method and other empirical approaches based on rainfall data, as use of the standard flood frequency approach is limited by the paucity of relevant flow data. Estimating procedures based on peak streamflow measurements and statistics are likely to evolve, and these will include distinctions for rain, snowmelt, and rain on snow floods. Guidelines will also be developed for selecting and applying appropriate procedures for particular areas.     

长期侧流提取对EBPR系统除磷及其磷回收性能的影响

实验采用交替厌氧/好氧(An/O)运行模式的SBR反应器,考察310 d内分3个批次提取侧流比为0、1/4、1/3、1/2的厌氧放磷上清液后EBPR系统的脱氮除磷效果及相应的磷回收性能.结果表明,整个实验阶段系统对COD和氨氮的去除较为稳定,出水均能满足《城镇污水处理厂污染物综合排放标准》一级A标准,总氮去除因厌氧阶段反硝化不断增强有所提升,达标率由88.2%显著上升至98.6%.然而,随着厌氧上清液提取次数的增多,系统释磷能力整体下降,但前两个批次中系统除磷均稳定高效,去除率在90%以上,相应地出水磷达标率大于75%,仅第3批次实验中侧流比为1/2时系统除磷率出现大幅波动,最低降为54.2%,并贡献该批次出水磷不达标率的60%,说明长期提取1/2侧流比不利于主流工艺出水稳定维持.研究还发现,长期进行侧流磷回收实验有利于污泥减量,且对污泥沉降性能影响不大.因此,在EBPR系统内长期提取适当侧流比的厌氧上清液以进行磷回收与主流工艺同步高效脱氮除磷具有可行性.