Evaluation of the on-site impact of water harvesting in southern Tunisia   总被引：1，自引：0，他引：1  

L. Fleskens  L. Stroosnijder  M. Ouessar  J. De Graaff 《Journal of Arid Environments》2005,62(4):613-630

Water harvesting techniques (WHT) play an important role in water resources conservation in (semi-) arid environments. However, the impacts of WHT are not clearly understood. This paper presents a method to measure increased water availability to olive (Olea europeae) trees grown on the terraced area of a traditional WHT site in southern Tunisia (jessr) and to translate these measurements into effects on yield. Although the WHT were shown to greatly enhance possibilities for olive growing, yields remain dependent on water supply (rainfall+run-on) in spring. Critical factors in the method described are the maximum available soil water capacity (ASW_max), crop and yield response factors (kc, ky_veg and ky_fruit) and the yield consistency index (YCI). Detailed accounts are presented for the costs and benefits of jessr construction and olive production, and the WHT are evaluated using cost-benefit analysis. Difficulties and assumptions are discussed and it is concluded that on-site effects alone might not justify investing in the construction of WHT.  相似文献   

Policy Performance and Brownfield Redevelopment in Milwaukee,Wisconsin*   总被引：1，自引：0，他引：1  

Christopher De Sousa 《The Professional geographer》2005,57(2):312-327

The redevelopment of brownfield sites has become a central focus of government efforts aimed at developing and revitalizing urban areas in the U.S. This article examines brownfield redevelopment efforts in Milwaukee County, Wisconsin, which gained momentum in the mid‐1990s, in order to determine how Milwaukee is performing in terms of redevelopment activities, what the effects of government support of such activities have been, and how performance outcomes are currently being measured. Through an examination of government data and interviews with key stakeholders, the Milwaukee case reveals that redevelopment is indeed progressing well as government becomes more effective at tackling the barriers to private‐sector redevelopment. However, progress in redeveloping brownfields is still being measured primarily in terms of economic development outcomes rather than in terms of the broader social, economic, and environmental objectives that both policy makers and private‐sector stakeholders associate with such redevelopment.  相似文献   

集水农业——河南省旱地农业持续发展的战略选择   总被引：1，自引：0，他引：1  

丁圣彦 《地域研究与开发》1997,(Z1)

介绍了旱地农业、集水、集水农业的基本概念和内容，分析了河南省历史上发生的旱灾及导致旱灾的主要因素，阐述了发展集水农业的必要性和可行性，并通过实例分析说明了集水农业在该省的发展前景，提出旱地农业可持续发展的最佳战略选择是集水农业。  相似文献   

A cladoceran-based paleolimnological assessment of the impact of forest harvesting on four lakes from the central interior of British Columbia, Canada   总被引：1，自引：0，他引：1  

Emma L. Bredesen  Darren G. Bos  Kathleen R. Laird  Brian F. Cumming 《Journal of Paleolimnology》2002,28(4):389-402

To investigate the impact of forest harvesting on lake ecosystems, six lakes (four impact, two reference) from central British Columbia, Canada were assessed using cladoceran remains preserved in the lake sediment cores. Two temporal resolutions were analyzed: a decadal scale for the past 70 years, and a high-resolution scale (2 year intervals for ten years before and after harvesting). Three lakes which experienced forestry activity in their watersheds in the early 1960s, and one lake which experienced forestry activityin the mid 1970s, showed subtle but statistically significant changes in cladoceran species composition following forest harvesting (analysis of similarity tests) at the decadal scale, whereas only two of these lakes showed significant changes at the higher resolution. These changes may be due to increased nutrient levels that might be associated with forest harvesting. The two reference lakes, which had not experienced any known large-scale anthropogenic watershed disturbances in the past century, showed no significant shifts in the cladoceran species assemblages at either temporal scale.  相似文献   

伐区采集作业综合效益评价   总被引：17，自引：4，他引：13  

周新年  沈宝贵  游明兴  吴远彬  林海明 《山地学报》2002,20(3):331-337

在计算各伐区作业模式的经济效益指标和定位测定由诸作业造成的土壤肥力和蓄水保土等指标变化量的基础上,采用集对分析法对各伐区作业模式的综合效益（经济效益和生态效益）进行计算和评价,为确定伐区生产工艺提供科学的决策依据。计算结果表明,“皆伐作业－全悬索道集材”是目前伐区采集作业的优化作业模式,但对常绿阔叶林经营的基本方针是保护,生态效益为主,从长远利益考虑,则“择伐作业－人力集材”为最优作业模式。  相似文献   

Indigenous knowledge for natural resource management: a comparative study of Māori in New Zealand and Dusun in Brunei Darussalam     

Rohana Ulluwishewa  Nick Roskruge  Garth Harmsworth  Bantong Antaran 《GeoJournal》2008,73(4):271-284

Indigenous people often exclusively depend on the natural resources available within the ecosystems where they live, and commonly manage their resources sustainably. They have developed, and continue to develop indigenous knowledge systems which encompass sustainable management of natural resources. This study compares indigenous knowledge of natural resource management developed by two different communities in two different environments—Maori in the temperate environment in New Zealand and Dusun in the tropical environment in Brunei Darussalam, and comparatively evaluates the role of indigenous knowledge in sustainable resource management in three categories of knowledge such as spatial and seasonal distribution of natural resources, sustainable harvesting, and habitat management. The comparison reveals that despite the differences in environment and the great geographical distance between the two communities, there are remarkable similarities between the two knowledge systems in concepts, principles, strategies and technologies used in natural resource management.

Rohana UlluwishewaEmail:

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Can traditional harvesting methods for cockles be accommodated in a Special Area of Conservation?     

McLaughlin  Emma; Portig  Alex; Johnson  Mark P. 《ICES Journal of Marine Science》2007,64(2):309-317

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From regulated access to transferable harvesting rights: Policy insights from New Zealand     

Basil MH Sharp 《Marine Policy》1997,21(6):501-517

The dramatic decline in yields from many of the world's fisheries has prompted an assessment of traditional regulatory approaches to management. Transferable harvesting rights provide an alternative institutional structure in fisheries management. This paper has two aims. First, it links outcomes in the fishery with institutional structure. Second, the paper identifies several important institutional variables if a transition is to be made to from command-and-control management to tradeable rights. In particular, the transition phase must deal with the expectations that attach to the status quo structure of rights in the fishery. The paper's empirical content is drawn from New Zealand's experience with the introduction of transferable harvesting rights.  相似文献   

柴达木盆地油气资源战略调查成果与下步工作重点     

甘贵元尹成明  张冰清孟丽赵明君  韩秦鹏 《地质通报》2006,25(9):1068-1073

柴达木盆地是中国七大含油气陆相盆地之一,油气资源总量丰富,勘探潜力巨大.柴达木盆地油气资源战略调查及评价项目研究工作开展2年以来,取得了重要的成果和认识:德令哈断陷内大面积分布中-下侏罗统烃源岩;盆地东部石炭系具有生烃能力;盆地北缘东段红山地区地震勘探采集到较好品质的资料;狮子沟地区天然地震勘探得到初步成果;综合应用地震、钻井等资料,确定了狮子沟构造的深层构造.下一步工作的重点是进一步加强盆地东部石炭系评价的力度,深化狮子沟、红山、德令哈等地区深层构造的研究及圈闭资源量评价工作.  相似文献   

An octo-generator for energy harvesting based on the piezoelectric effect     

《Applied Ocean Research》2017

A renewable energy harvester using the piezoelectric effect is developed for the ocean tidal and wind flow. The harvester is made of connected driving blades to an octo-generator, which has a rotator with n blades and a stator attached by eight mass-spring-piston-cylinder-piezoelectricity devices. The resonance and force magnification are utilized to increase the power output of the harvester. A corresponding mathematical model is developed to calculate the root mean square of the generated electric power. The simulation results indicate that the generated power is largely enhanced when the near-resonant condition is established. The power increases with increases in the magnetic flux density, the large-to-small diameter ratio of the cylinder, the size of magnetic bar face, and decreases in the gap between two magnetic faces and the size of the piezoelectric bar face. A generated power of 5 kW is realized by the harvester working under an ocean tidal speed, V = 1.75 m/s, and its geometric and material properties of driving length L = 7.5 m, spring constant k_v = 65000 N/m, gap between the two magnets s = 0.0015 m, large to small diameter ratio of the cylinder z = 6, and magnetic flux density Br = 1.45 T.  相似文献