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961.
The provision of human-designed floods in regulated rivers is still an incipient worldwide practice. However, these floods have already been shown to have relevant effects on the ecogeomorphic integrity of rivers altered by flow regulation. In Spain, experimental floods were legally established in 2008 and were stipulated in two subsequent Basin Management Plans as compulsory practice for improving the functioning of strategic river reaches. Since that time, a number of flooding events have been carried out in rivers of Mediterranean condition. This paper reviews the main consequences of experimental flood releases in three Spanish river sites downstream of major hydraulic infrastructures. In each case, the ecologic and geomorphic effects of the releases are analysed in parallel with their causes and consequences, thereby providing a detailed understanding of the dynamics of each scenario. The Spanish examples and the lessons learned from them are contrasted with examples of experimental floods from other countries (U.S.A., Switzerland, Australia). Lastly, recommendations are proposed to improve the implementation of future experimental floods in Spain and other Mediterranean countries.  相似文献   
962.
相对于传统发展模式。可持续发展在发展目标与内容上更具有公共性和长期性的取向。从而使政府能力将面临着更大的挑战.“卡尔多-希克斯改进”原则为政府推动可持续发展和走向“帕累托改瞢”提供了思路,并决定了政府能力的核心是制度供给能力。为了充分发挥政府能力。制度安排应遵循市场优先、地方政府优先、公众参与、遵循法治四个原则。  相似文献   
963.
The Montreal Protocol on Substances that Deplete the Ozone Layer has led to rapid reductions in the use of ozone-depleting substances worldwide. However, the Protocol provides for "essential use exemptions" (EUEs) if there are no "technically and economically feasible" alternatives. An application that might qualify as an "essential use" is CFC-powered medical metered-dose inhalers (MDIs) for the treatment of asthma and chronic obstructive pulmonary disease (COPD), and the US and other nations have applied for exemptions in this case. One concern is that exemptions are necessary to ensure access to medications for low-income uninsureds. We examine the consequences of granting or withholding such exemptions, and conclude that government policies and private-sector programs are available that make it economically feasible to phase out chlorofluorocarbons (CFCs) in this application, thereby furthering the global public health objectives of the Montreal Protocol without compromising the treatment of patients who currently receive medication by means of MDIs.  相似文献   
964.
Land and water resource development can independently eliminate riparian plant communities, including Fremont cottonwood forest (CF), a major contributor to ecosystem structure and functioning in semiarid portions of the American Southwest. We tested whether floodplain development was linked to river regulation in the Upper Colorado River Basin (UCRB) by relating the extent of five developed land-cover categories as well as CF and other natural vegetation to catchment reservoir capacity, changes in total annual and annual peak discharge, and overall level of mainstem hydrologic alteration (small, moderate, or large) in 26 fourth-order subbasins. We also asked whether CF appeared to be in jeopardy at a regional level. We classified 51% of the 57,000 ha of alluvial floodplain examined along >2600 km of mainstem rivers as CF and 36% as developed. The proportion developed was unrelated to the level of mainstem hydrologic alteration. The proportion classified as CF was also independent of the level of hydrologic alteration, a result we attribute to confounding effects from development, the presence of time lags, and contrasting effects from flow alteration in different subbasins. Most CF (68% by area) had a sparse canopy (50% canopy cover occupied <1% of the floodplain in 15 subbasins. We suggest that CF extent in the UCRB will decline markedly in the future, when the old trees on floodplains now disconnected from the river die and large areas change from CF to non-CF categories. Attention at a basinwide scale to the multiple factors affecting cottonwood patch dynamics is needed to assure conservation of these riparian forests.  相似文献   
965.
胡森林  鲍涵  郝均  曾刚 《自然资源学报》2022,37(6):1572-1585
环境规制与绿色发展的关系及其作用机制是复杂且有争议的议题。基于长三角41个地级及以上城市2003—2018年的面板数据,首先科学构建绿色发展水平测度的指标体系,计算各城市的绿色发展水平及空间动态演变;其次,借鉴可拓展随机性的环境影响评估模型(STIRPAT),构建面板计量模型,深入探究环境规制对城市绿色发展的影响。研究发现:(1)长三角地区环境规制和绿色发展水平均呈上升趋势,但区域差异显著,绿色发展水平从东南向西北,呈现圈层式递减态势,而环境规制强度重心经历了由东南向西北转移的演变。(2)总体上,环境规制显著影响城市绿色发展,两者间存在倒“U”型关系,即过强的环境规制会抑制城市绿色发展水平的提升。(3)环境规制与技术创新之间存在紧密的联动关系,即环境规制主要通过技术创新这一中介路径促进城市绿色发展转型,其中介效应占总效应的比例约为50.1%。因此,在推动长三角一体化高质量发展过程中,应该根据城市绿色发展效率来制定本地的环境规制,并重视提升本地的技术创新水平,进而实现城市绿色发展转型的目标。  相似文献   
966.
政府承担生态环境损害赔偿责任的理论基础是政府对环境质量负责,政府对环境质量负责的实质是政府作为公共环境的管理者和控制者对维护公共环境利益所负担的安全保障义务。根据政府的环境安全保障义务,政府承担生态环境损害赔偿责任应以过错推定为归责原则,责任构成的核心是政府负有其职责范围内特定的环境安全保障义务,因未尽环境安全保障义务间接引发生态环境损害。由于政府未尽环境安全保障义务的行为并非直接也并不必然导致生态环境损害,所以政府一般仅根据自身行为的可责性及其程度对生态环境损害承担补充性的赔偿责任,只有在特殊情况下才承担连带赔偿责任,在政府不负有特定环境安全保障义务的情况下政府不承担赔偿责任。  相似文献   
967.
共同做好防震减灾工作,政府各职能部门要各司其职,各负其责仅靠领导重视及部门之间的密切配合还不够,必须用相应的制度做保证。还要通过不断的加强宣传,在各级领导的思想中树立起“经济建设与防震减灾工作同等重要”的观念。  相似文献   
968.
Abstract: Five commonly used methods for measuring embeddedness the — degree to which fine particles surround coarse substrate on the surface of the streambed — are assessed and used to evaluate the sedimentation pattern resulting from impoundment on tributaries of the Connecticut River. Results show that the U.S. Environmental Protection Agency (USEPA) method best reflects the sediment regime on these rivers. On the Ompompanoosuc River, regulated by a run-of-the-river/flood control dam, embeddedness increases significantly directly downstream of the dam. On the unregulated White River, no downstream trends in embeddedness are observed. The USEPA results on the Ompompanoosuc River reflect the movement of a local decrease in embeddedness, interpreted as a moving region of scour, with a calculated transport rate of approximately 5 to 25 m/day. Observed transport rates are similar to previously measured sediment transport rates and consistent with results from a multifraction sediment transport model. Application of the USEPA method to an additional regulated tributary demonstrates the effects of dam management on embeddedness. Flow regulation with high sediment trapping efficiency results in a decrease in embeddedness downstream of the dam. Results provide insight into the utility of available methods for evaluating the effects of management practice on streambed composition.  相似文献   
969.
/ Implemented in the context of a long history ofintense public debate, forestry practices applied on private forest land areregulated in some form by 38 states. State regulatory activities can involvemany agencies implementing numerous regulatory laws, a single forestry agencyadministering a comprehensive regulatory program, or a combination of thetwo. Regulatory programs are designed to protect resources such as soils,water, wildlife, and scenic beauty. Program administration often involvesrule promulgation, harvest plan reviews, coordination of interagency reviews,and pre- and postharvest on-site inspections. Forest practice rules usuallyfocus on reforestation, forest roads, harvest procedures, and wildlifehabitat protection. Emerging regulatory trends include growth of multiagencyregulatory authority and associated jurisdictional conflicts, increasedtendencies to narrowly specify standards in statutes and rules, emergence ofcontingent regulations, growing sensitivity to processes enabling theadoption of new forest practice technologies and an ability to addresscumulative effects, interest in collaborative rule-making stemming fromheightened concern over legalization of administration processes, and growingconcern over the constitutional foundations for regulatory programs and thegovernment and private sector cost of implementing such programs.KEY WORDS: Ecosystem management; Forestry practices; Private landowners;Regulatory programs; State government  相似文献   
970.
为了深入探究我国环境规制的政策效应及其区域差异,采用我国30个省区2004—2014年的面板数据(不含港澳台及西藏自治区数据,下同),分别以能源强度、产业结构和FDI(外商直接投资)作为门槛变量,以环境规制为核心解释变量,利用面板门槛模型分析我国环境规制对碳排放的门槛效应及其在东部、中部和西部存在的区域差异.结果表明:由于能源强度、产业结构、FDI这3个门槛变量的作用,环境规制对碳排放的影响体现出非线性特征,且环境规制的政策效应在东部、中部和西部3个区域内存在较为明显的差异.东部地区的环境规制在3个门槛变量的中低门槛区间均不能促进碳减排,处于高门槛区间时,能源强度会促进碳排放,而产业结构和FDI这两个门槛变量则对碳排放有抑制作用,其中能源强度跨过第2个门槛值(1.111 8)后仍表现出对碳排放的促进作用,产业结构(0.566 1)和FDI(1 159.40×108元)分别跨过第2个门槛值后,对碳排放表现出抑制作用;中部地区在能源强度的影响下,环境规制对碳排放一直为抑制作用,在产业结构和FDI的影响下则一直是促进作用;西部地区的能源强度与碳排放呈倒“U”型关系,两个门槛值分别为1.200 8与2.153 3,以产业结构和FDI为门槛变量时,环境规制均未能发挥碳减排作用,一直体现为促进作用.因此,政府在实施环境规制政策时不能采取一刀切的措施,要根据东部、中部和西部的不同情况针对性地实施相应的环境规制政策.   相似文献   
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