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1.
This study measures the impact of fanya juu terraces on the net value of crop income in a high‐rainfall area in the Ethiopian highlands using cross‐sectional multiple plot observations. Using propensity score matching methods we find that the net value of crop income for plots with fanya juu terraces is lower than for plots without fanya juu terraces. This finding makes it difficult to avoid concluding that while the technologies might reduce soil erosion and associated off‐site effects, they do so at the expense of poor farmers in the Ethiopian highlands. Therefore, fanya juu terraces cannot be characterized as a “win‐win” measure to reduce soil erosion. New agricultural technologies need to be profitable to the farmer if they are to be adopted and sustained.  相似文献   

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Evidence from cross-sectional growth regressions suggests that economies dependent on natural resource exports have had slower growth than resource scarce economies. Explanations for this “curse of resources” focus on institutional and market failures caused by resource abundance. With a simple two sector model exhaustible resource model, we demonstrate that the correlation between growth and natural resource abundance can be negative in the absence of market and institutional failures. Since there is no way to distinguish between efficient and inefficient equilibria on the basis of the negative correlation between growth and resource abundance, finding that correlation is not sufficient to conclude resources are a curse, nor is it necessary to find a positive correlation between growth and resources to overturn the resource curse interpretation. We show whether resources are a curse or a blessing for an economy can only be determined by an investigation of the correlation between resource abundance and income levels. Using panel data for U.S. states for the period 1970-2001, we show that resource abundance is negatively correlated with growth rates but positively correlated with income levels.  相似文献   

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In spring 2011, an unprecedented flood hit the complex eastern United States (U.S.)–Canada transboundary Lake Champlain–Richelieu River (LCRR) Basin, destructing properties and inducing negative impacts on agriculture and fish habitats. The damages, covered by the Governments of Canada and the U.S., were estimated to C$90M. This natural disaster motivated the study of mitigation measures to prevent such disasters from reoccurring. When evaluating flood risks, long‐term evolving climate change should be taken into account to adopt mitigation measures that will remain relevant in the future. To assess the impacts of climate change on flood risks of the LCRR basin, three bias‐corrected multi‐resolution ensembles of climate projections for two greenhouse gas concentration scenarios were used to force a state‐of‐the‐art, high‐resolution, distributed hydrological model. The analysis of the hydrological simulations indicates that the 20‐year return period flood (corresponding to a medium flood) should decrease between 8% and 35% for the end of the 21st Century (2070–2099) time horizon and for the high‐emission scenario representative concentration pathway (RCP) 8.5. The reduction in flood risks is explained by a decrease in snow accumulation and an increase in evapotranspiration expected with the future warming of the region. Nevertheless, due to the large climate inter‐annual variability, short‐term flood probabilities should remain similar to those experienced in the recent past.  相似文献   

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It is well established that wet environment potential evapotranspiration (PET) can be reliably estimated using the energy budget at the canopy or land surface. However, in most cases the necessary radiation measurements are not available and, thus, empirical temperature‐based PET models are still widely used, especially in watershed models. Here we question the presumption that empirical PET models require fewer input data than more physically based models. Specifically, we test whether the energy‐budget‐based Priestley‐Taylor (P‐T) model can reliably predict daily PET using primarily air temperature to estimate the radiation fluxes and associated parameters. This method of calculating PET requires only daily minimum and maximum temperature, day of the year, and latitude. We compared PET estimates using directly measured radiation fluxes to PET calculated from temperature‐based radiation estimates at four humid AmeriFlux sites. We found good agreement between P‐T PET calculated from measured radiation fluxes and P‐T PET determined via air temperature. In addition, in three of the four sites, the temperature‐based radiation approximations had a stronger correlation with measured evapotranspiration (ET) during periods of maximal ET than fully empirical Hargreaves, Hamon and Oudin methods. Of the three fully empirical models, the Hargreaves performed the best. Overall, the results suggest that daily PET estimates can be made using a physically based approach even when radiation measurements are unavailable.  相似文献   

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《中国环保产业》2005,(7):46-47
由福州桑莱思科技开发有限公司开发的G201光催化剂适用于新型环保建材光净化陶瓷和玻璃。主要技术内容一、基本原理利用高效光催化剂的强氧化性与超亲水性原理,以特定技术将上述高效光催化剂镀在陶瓷表面,形成的光催化膜可将光能转化为化学能,起到分解油污、降臭味、耐脏和自动杀灭细菌等作用。光催化膜本身也是一种纳米陶瓷涂层,生产该种陶瓷无需改变原有的陶瓷(包括瓷砖、卫生陶瓷和日用瓷等)生产工艺,仅需附加少量装置和增加两道工序。二、技术关键首先是使用专用高效光催化剂,其次是喷涂和热处理技术。光催化瓷砖环保性能优异,同时能保…  相似文献   

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The purpose of this short article is to set static and dynamic models for optimal floodplain management and to compare policy implications from the models. River floodplains are important multiple resources in that they provide various ecosystem services. It is fundamentally significant to consider environmental externalities that accrue from ecosystem services of natural floodplains. There is an interesting gap between static and dynamic models about policy implications for floodplain management, although they are based on the same assumptions. Essentially, we can derive the same optimal conditions, which imply that the marginal benefits must equal the sum of the marginal costs and the social external costs related to ecosystem services. Thus, we have to internalise the external costs by market-based policies. In this respect, market-based policies seem to be effective in a static model. However, they are not sufficient in the context of a dynamic model because the optimal steady state turns out to be unstable. Based on a dynamic model, we need more coercive regulation policies.  相似文献   

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Exploitation of certain resources within a protected area on a sustainable basis could contribute to higher living standards of rural people, particularly those in poor countries, and decrease conflicts between these populations and park authorities. This article presents data from a case study of Kopaonik National Park (NP), Serbia, which is a park with natural resources, most notably bilberries, which have always been relied on by local people. Vaccinium myrtillus traditionally has been collected for decades in Kopaonik NP and used by local people. However, little is known about the socioeconomic and ecological relations that affect the collection and use of this species. The aim of the present study was to understand how local people collect bilberries in Kopaonik NP and what their attitudes toward the park are. Household questionnaire data were used to examine how local people collect bilberries and how to improve the relations between local people and NP authorities. The survey questionnaire included 52 households from 7 local communities, and we applied a purposive sampling strategy. In addition, expert interviews were conducted, and from these data we obtained a broader understanding of the relation between local people and NP authorities. The results indicate that in Kopaonik NP, there is a conflict between pickers and NP authorities. Sustainable management should be directed toward the protection of bilberries. Education of local people is a key element in the sustainable collection and protection of natural resources.  相似文献   

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00070002;183产学研结合——全面拓展职教空间的有效途径王华利;戴葵堂;湖北三峡职业技术学院,湖北三峡职业技术学院 443003,4430030中国科技信息China Science and Technology Information187 192G710H132;1;A;H;H132_1;王华利;00030010;184 189现代展览馆视觉识别系统的现状与建设思路吴郑玲;郑州美术馆 450003展览馆;;缺  相似文献   

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《绿叶》2006,(8)
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The major aim of this paper is to analyze how government funding affects the pace of progress in four states of the remediation process of contaminated sites, from basic risk classification to cleanup. We introduce a methodological framework that takes into account the unobserved site-heterogeneity and simultaneously models duration in the different states. The results show that although site-heterogeneity contributes to make remediation a slow process, the third state, from the elaborate risk classification to the cleanup start, is a particular bottleneck. Even if government funding can speed up the process at this state, the effect is minuscule compared to the amounts of funding required. Thus, there is a need for policy to also focus on other barriers to remediation.  相似文献   

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《中国环保产业》2004,(5):25-25
美国戈尔公司基于"表面过滤"理论,开发的Gore-Tex 薄膜滤袋产品,为最严格的排放控制及电厂BOT运作的经济性提供了保障.其中,SuperflexTM滤袋产品及技术,为垃圾发电行业提供了超强的性能及极长的工作寿命.  相似文献   

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创建于1996年的福建丰泉环保在焚烧炉制造方面经过12年的努力,取得了一系列的重大技术突破,拥有十多项重大自主知识产权技术。公司为中国环保产业骨干企业和四个国家火炬计划项目实施单位,有两项产品被认定为国家重点新产品。  相似文献   

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