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71.
Herbert W. Greydanus 《Journal of the American Water Resources Association》1978,14(2):477-480
ABSTRACT: Most of California's precipitation falls at the wrong place in the wrong season in relation to the water needs. Redistribution and regulation are essential. Aquifer systems – groundwater basins – can provide a share of the future cyclic storage regulation. There are some differences in management concepts in using a full basin in comparison with a partially dewatered basin. Legal, water quality, and physical impacts on aquifer systems, including subsidence, are concerns. Storage may be for the benefit of overlying water users or for distant areas. Extraction during dry periods or recharge methods will require careful planning. Existing rights and uses and equitable treatment of all parties must be assured. Financial compensation may be involved. Changes in methods of operation or degree of self-determination by affected water agencies will require committed watermanship to resolve. Legislation or amendments to organic acts may be needed but much can be accomplished within existing statutes. Environmental impacts which can be avoided by not using large surface storage sites are important. Energy for pumping will be a key consideration. About 40 percent of California is underlain by aquifer systems. This resource offers major potential in overcoming the maldistribution of natural water resources. 相似文献
72.
J. Roger McHenry 《Journal of the American Water Resources Association》1974,10(2):329-337
ABSTRACT: Reservoirs, as well as lakes and estuaries, are subject to sediment accumulation. The rate at which sedimentation occurs is accelerated or diminished by man's activities. Acceptable rates of sedimentation are considered on the basis of costs of sediment storage and removal and a review of reservoirs constructed with sediment removal capabilities is given. The rates of reservoir sedimentation in the United States are summarized based on reliable data obtained from all sizes of reservoirs. Problems confronting the engineer concerning reservoir construction and maintenance are discussed on the basis of these data. 相似文献
73.
R.B. Grayson C. Kenyon B.L. Finlayson C.J. Gippel 《Journal of environmental management》1998,52(4):361-372
In this study, an analysis of bathymetric surveys of the Latrobe River delta conducted in 1879 and 1992 is combined with pollen analysis of cores from the delta sediments to assist in setting management priorities for the Latrobe River catchment, a 5000 km2catchment in the south-east of Australia. Reconstructed delta surfaces from 1879 (not long after European settlement of the area) and 1992 were compared to quantify areas of net erosion and deposition. These were compared to post-European deposition depths determined by the presence of exotic pollen species in the sediment. The results indicated that: (1) average sedimentation rates in the receiving lake for the Latrobe River are less than 1 mm yr−1; (2) the deposited material is fine with no material considered as bedload; and (3) the fine nature of the deposited material makes it suitable for carrying a large load of nutrients. These results created a shift in management focus from concern over sedimentation and erosion in general to a greater emphasis on nutrients. While the integrated management of catchments is implicitly contemporary, it should always be performed within a historical context. Failure to do this can lead to management priorities that do not concur with the facts of catchment response and can therefore result in inefficient resource allocation. The use of studies which provide a historical perspective on the problem are therefore critical. 相似文献
74.
Malchus B. Baker 《Journal of the American Water Resources Association》1986,22(5):847-851
ABSTRACT: After 25 years of operation on ephemeral streams in the semiarid Southwest, this supercritical flume has provided more than 350 station-years of reliable streamflow data, even under freezethaw conditions experienced at elevations of 1,500 to 2,100 m, in Arizona. The flume has also provided streamflow data during flood periods produced by high intensity summer thunderstorm conditions, where considerable sediment and other debris was moved downstream. 相似文献
75.
本文探索了微波作为辅助手段处理高炉煤气洗涤水过程中,微波辐射功率、微波辐射时间、聚合氯化铝(PAC)加入量、磷酸加入量对高炉煤气洗涤废水处理效果的影响。结果表明,微波和PAC混凝联用处理高炉煤气洗涤废水具有作用时间短、聚沉能力强等特点,可以有效去除废水中悬浮物,降低硬度及浊度。 相似文献
76.
The Aging of America's Reservoirs: In‐Reservoir and Downstream Physical Changes and Habitat Implications
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Kyle E. Juracek 《Journal of the American Water Resources Association》2015,51(1):168-184
Reservoirs are important for various purposes including flood control, water supply, power generation, and recreation. The aging of America's reservoirs and progressive loss of water storage capacity resulting from ongoing sedimentation, coupled with increasing societal needs, will cause the social, economic, environmental, and political importance of reservoirs to continually increase. The short‐ and medium‐term (<50 years) environmental consequences of reservoir construction and operation are well known and include an altered flow regime, lost connectivity (longitudinal, floodplain), an altered sediment regime, substrate compositional change, and downstream channel degradation. In general, reservoir‐related changes have had adverse consequences for the natural ecosystem. Longer term (>50 years) environmental changes as reservoirs enter “old” age are less understood. Additional research is needed to help guide the future management of aging reservoir systems and support the difficult decisions that will have to be made. Important research directions include assessment of climate change effects on aging and determination of ecosystem response to ongoing aging and various management actions that may be taken with the intent of minimizing or reversing the physical effects of aging. 相似文献
77.
水质安全的动态超声波强化混凝除藻水处理试验研究 总被引:2,自引:0,他引:2
超声波辐射能够破坏蓝藻气囊,在水处理工艺中达到强化蓝藻混凝沉淀的效果.然而不适当的超声处理会进一步破坏蓝藻细胞,导致胞内毒素大量释放,加重水质污染负荷.本研究为获得水质安全的超声波强化混凝沉淀蓝藻水处理方法,采用频率40~120 k Hz的超声波辐射蓝藻水,考察处理后蓝藻混凝沉淀去除效果及藻毒素释放情况.结果表明,频率68~120 k Hz、能量密度59.1~186.4 W·L-1的静态超声波作用10~15 s后进行混凝沉淀,藻类去除率达98%以上,且频率越高效果越好;然而各频率静态超声波作用5 s以上均会导致藻细胞内藻毒素释放.采用内衬吸声棉及动态超声方式,频率120 k Hz、能量密度38.5~196.6 W·L-1超声波作用7.5~30 s后,可避免胞内藻毒素释放,且能去除水中溶解性藻毒素18.7%~30.7%,混凝沉淀后藻类去除率97.0%以上,其它有机物也降低. 相似文献
78.
79.
提出一种新纳米零价铁反应器(Nanoscale Zero-Valent Iron Reactor,简称NIR)及"混凝沉淀+纳米零价铁"处理工艺,通过实际生产废水进行中试,考察和研究该工艺和NIR技术处理江苏省某市印刷电路板(Printed Circuit Board,简称PCB)工业园区废水的效果。结果表明,此工艺对PCB生产废水中Cu、TP及COD Cr去除率分别可达到97.3%、73.7%、26%,其中Cu处理效果最佳;XRD结果表明,纳米零价铁(Nanoscale Zero-Valent Iron,nZVI)与PCB生产废水反应后含有γ-Fe2O3、Fe3O4、γ-FeOOH、CuO、Cu2O、Cu0等产物。"混凝沉淀+纳米零价铁"工艺处理废水时具有处理效果好、工艺耐冲击性能好、产泥量小、不易造成二次污染等优点。 相似文献
80.
滇西北高原由于地处生态脆弱的石灰岩区,水土流失严重,探讨该区生态恢复过程中土壤侵蚀的变化规律,为开展人工植被建设提供依据。以时空互代的方法,通过径流小区,对坡面的产沙产流特性及其影响因素进行研究。结果表明:天然次生林和人工混交林均有较好的调节径流和减少泥沙的作用,产沙量分别比坡耕地减少了51.46%、43.18%,产流量也相应降低了39.39%、24.24%。在最大次降雨条件下,荒草丛、坡耕地、次生林和混交林单次降雨的产沙量分别占试验期产沙总量的55.38%、55.58%、58.35%和58.05%,产流量相应占产流总量的64.72%、64.63%、73.85%和55.39%。而且,产流产沙量与土壤有机质质量分数均存在明显正相关,与乔、灌层植物多样性及均匀度指数等呈显著负相关性(P<0.05)。因此,乔灌草结合的群落结构配置模式是滇西北地区水土保持林营造的目标和方向。 相似文献