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71.
Jeffrey J. Opperman Ryan Luster Bruce A. McKenney Michael Roberts Amanda Wrona Meadows 《Journal of the American Water Resources Association》2010,46(2):211-226
Opperman, Jeffrey J., Ryan Luster, Bruce A. McKenney, Michael Roberts, and Amanda Wrona Meadows, 2010. Ecologically Functional Floodplains: Connectivity, Flow Regime, and Scale. Journal of the American Water Resources Association (JAWRA) 46(2):211-226. DOI: 10.1111/j.1752-1688.2010.00426.x Abstract: This paper proposes a conceptual model that captures key attributes of ecologically functional floodplains, encompassing three basic elements: (1) hydrologic connectivity between the river and the floodplain, (2) a variable hydrograph that reflects seasonal precipitation patterns and retains a range of both high and low flow events, and (3) sufficient spatial scale to encompass dynamic processes and for floodplain benefits to accrue to a meaningful level. Although floodplains support high levels of biodiversity and some of the most productive ecosystems on Earth, they are also among the most converted and threatened ecosystems and therefore have recently become the focus of conservation and restoration programs across the United States and globally. These efforts seek to conserve or restore complex, highly variable ecosystems and often must simultaneously address both land and water management. Thus, such efforts must overcome considerable scientific, technical, and socioeconomic challenges. In addition to proposing a scientific conceptual model, this paper also includes three case studies that illustrate methods for addressing these technical and socioeconomic challenges within projects that seek to promote ecologically functional floodplains through river-floodplain reconnection and/or restoration of key components of hydrological variability. 相似文献
72.
Gregory M. Southard Loraine T. Fries Aaron Barkoh 《Journal of the American Water Resources Association》2010,46(1):14-23
Southard, Gregory M., Loraine T. Fries, and Aaron Barkoh, 2010. Prymnesium parvum: The Texas Experience. Journal of the American Water Resources Association (JAWRA) 46(1):14-23. DOI: 10.1111/j.1752-1688.2009.00387.x Abstract: Golden alga Prymnesium parvum was first identified in Texas during a fish kill investigation on the Pecos River in 1985. Since then golden alga kills occurred sporadically in a variety of waters in the western part of the state until 2001 when the alga became endemic in the Brazos, Canadian, Colorado, Red, and Rio Grande river systems, including the water supplies of two public fish hatcheries, the Possum Kingdom and Dundee state fish hatcheries. The increasing area adversely affected by the alga and frequent massive fish kills heightened public and political awareness and concerns regarding the ecological and economic impacts of P. parvum blooms. The Texas Parks and Wildlife Department (TPWD), the wildlife conservation agency of the state, responded to these concerns with a program to assess the ecological and economic impacts and to develop management options. To date 33 water bodies have been affected and losses are conservatively estimated at 34 million fish valued at US$13 million. Several sport fisheries, including smallmouth bass Micropterus dolomieu, striped bass Morone saxatilis, channel catfish Ictalurus punctatus, and blue catfish Ictalurus furcatus, have been severely affected. Additionally, 26 imperiled fish species occur in the affected water basins and some have been adversely affected. Economic losses associated with reduced fishing and other water-based recreational activities appear considerable. The combined economic losses to three counties (Palo Pinto, Stephens, and Young) surrounding Possum Kingdom reservoir for 2001 and 2003 were estimated at US$2.8 million and US$1.1 million, respectively. This paper describes how the TPWD responded to public and political concerns relative to the emergence of golden alga, its harmful effects to fisheries, and its historic and current statewide distribution. 相似文献
73.
不同氮磷比对多年生水生植物生长特性影响的研究 总被引:1,自引:0,他引:1
从氮、磷等植物生长的环境因子出发,研究了高低氮磷营养水平下,不同氮/磷比例的富营养化水体对聚草(Myriophyllum spicatum)、黄花水龙(Jussiaea stipulacea Ohwi)、喜旱莲子草(Alternanthera philoxeroides)生长特性的影响。结果表明,聚草在氮磷比2:1时生物量最大,且生物量在高浓度水平处理明显大于低浓度水平处理(P〈0.01);黄花水龙在氮磷比10:1~20:1时生物量最大,高低浓度水平处理问生物量无显著性差异;喜旱莲子草在较高氮磷比20:l~40:1时生物量最大,高浓度水平处理时生物量显著性高于低浓度水平处理(P〈0.05)。在低浓度水平处理时,氮为黄花水龙和喜旱莲子草生长的主要限制因子,磷为聚草生长的主要限制因子,且喜早莲子草叶绿素增长期较其他处理提前,而黄花水龙的叶绿素变化在高低营养水平下差异不显著。营养盐水平对聚草茎长和生物量的影响较对黄花水龙和喜旱莲子草的影响明显。 相似文献
74.
Lauren Patterson Jennifer Phelan Chris Goudreau Robert Dykes 《Journal of the American Water Resources Association》2017,53(1):56-66
The health of freshwater biota is dependent on streamflow, yet identification of the flow regimes required to maintain ecological integrity remains challenging to states in the United States seeking to establish ecological flows. We tested the relationship between decreases in streamflow and Shannon‐Weaver diversity index of fish species for four flow‐based habitat guilds: riffle, riffle‐run, pool‐run, and pool in North Carolina. We found species that prefer shallow habitats, such as riffles and riffle‐runs were the most sensitive to decreases in streamflow; whereas no significant relationships were found for pool or pool‐run species. The sensitivity to decreases in streamflow was greatest during summer and fall, when streams are naturally lower. When all fish habitat guilds were included in the assessment of flow‐biology relationships, there were no significant relationships to decreases in streamflow. As the sensitivity of fish to reductions in streamflow is not constant across habitat guilds, combining all fish species together for flow‐biology analyses may greatly underestimate the response of fish species to decreases in flow and should be acknowledged when establishing ecological flows. 相似文献
75.
Fish and Invertebrate Flow‐Biology Relationships to Support the Determination of Ecological Flows for North Carolina 下载免费PDF全文
76.
河流筑坝拦截的水环境响应——来自地球化学的视角 总被引:11,自引:0,他引:11
大规模筑坝拦截是当前世界河流普遍面临的共同趋势,"蓄水河流"在物理、化学及生物等多层次上区别于天然河流和湖泊,改变了河流水文、河流物质转化和输送通量以及河流生态环境.因此,认识和了解水库建成后河流一水库体系水环境演化的关键过程是评价水坝的水环境影响的基础.广泛综述国内外最近的一些涉及水库效应的研究成果,并结合作者对乌江流域梯级水库的初步研究,从蓄水河流水文情势改变、生源要素(磷和硅为例)形态和通量变化、温室气体释放、水生生态系统演替几个方面进行分析.认为,水能开发的巨大经济效益和面临的潜在生态风险之间的平衡关系需要进一步详尽的分析研究. 相似文献
77.
78.
Michael J. Paul David W. Bressler Alison H. Purcell Michael T. Barbour Ed T. Rankin Vincent H. Resh 《Journal of the American Water Resources Association》2009,45(2):320-330
Abstract: Urbanization represents a strong and increasingly more prevalent impact on stream quality worldwide. One of the characteristic effects of increased urbanization is a consistent decline in biological stream condition. The characterization of this biological degradation with increasing urbanization presents a number of advantages for the study and management of urban streams and catchments. In this paper, the limitation of biological condition with urbanization, called observed biological potential, is characterized. Using an urban intensity index and a biological index developed specifically for urban systems in the Baltimore, Maryland; Cleveland, Ohio; and San Jose, California regions, two principal techniques were compared (quantile regression and bin regression) to define observed biological potential along urban gradients. Quantile regression was selected as the preferable tool for describing observed biological potential given the consistency with which it can be applied and its statistical efficiency, however, bin quantile regression performed similarly. Having identified a numeric approximation of observed biological potential, two methods for identifying factors related to distance from potential as a way of identifying critical environmental factors affecting biological condition in urban areas were explored. The results of this work can be used for identifying benchmarks for urban stream biological condition, identifying limiting catchment characteristics, and prioritizing urban stream management efforts. 相似文献
79.
人工神经网络方法在拟建小区域环境质量评价中的应用 总被引:1,自引:0,他引:1
人工神经网络的评价方法用于小区域环境质量评价中,根据本地区特点因地制宜地选择环境质量参数,代入模型中进行环境质量评价及预测,对用于环境质量评价的BP人工神经网络模型进行了改进,即对网络模型的训练样本进行了扩充,从而提高了模型的抗干扰能力和准确性.将改进了的BP人工神经网络模型应用于四川省资阳市沱江二桥拟建项目小区域的大气、地表水环境质量评价中, 对该市小区域大气、地表水环境质量状况进行评价,评价结果表明,BP人工神经网络模型用于环境质量评价是可行的,且评价结论客观,评价模型普遍适用. 相似文献
80.
基于人工免疫原理的事故预防研究 总被引:1,自引:1,他引:0
介绍生物免疫识别模式,分析事故预防过程的实质是抑制潜在危险转化成事故的控制过程,分析比较事故预防与生物免疫识别模式在作用、生存环境、动作触发源等的共性,构建了基于免疫识别模式的事故预防系统并建立了事故预防数学模型;定义事故预防系统的识别率、失效率、误判率并给出了数学表达式,指出监测生产系统各环节状态信息是否符合系统的安全要求就是识别潜在危险的过程,是事故预防的关键,基于人工免疫原理的事故预防数学模型具有较强的健壮性、自适应性和动态防护性等特点。 相似文献