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61.
Rainwater harvesting is increasingly viewed as a major strategy for enhancing agricultural productivity and boosting farm income in many drought-prone areas. While this technology is being promoted in many developing countries, there is conflicting evidence in the literature about its impact on welfare of farm households. This study uses propensity score matching and discrete choice regression techniques to assess the impact of rainwater harvesting ponds on farm household income and factors that influence adoption of such technologies in Rwanda. It finds that households with rainwater harvesting ponds have significantly higher income than their counterparts of comparable observable characteristics. It further finds evidence that increase in farm income occurs via increased input use and that household size, asset endowments and participation in farmer organizations condition adoption of rainwater harvesting ponds. The study concludes that adoption of rainwater harvesting technologies has positive benefits on farm households. It discusses the policy implications that adoption of rainwater harvesting ponds presents a pathway for reducing rural poverty.  相似文献   
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Environmental Management - The interactive and cumulative impacts of climate change on natural resources such as coral reefs present numerous challenges for conservation planning and management....  相似文献   
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Urban waste collection system is a pivotal component of all waste management schemes around the world. Therefore, the efficient performance and the success of these schemes in urban pollution control rest on the ability of the collection systems to fully adapt to the prevailing cultural and social contexts within which they operate. Conceptually, institutions being the rules guiding the conduct of public service provision and routine social interactions, waste collection systems embedded in institutions can only realize their potentials if they fully evolve continuously to reflect evolving social and technical matrices underlying the cultures, organizations, institutions and social conditions they are designed to address. This paper is a product of an analysis of waste collection performance in Ghana under two different institutional and/or organizational regimes; from an initial entirely public sector dependence to a current mix of public-private sector participation drawing on actual planning data from 1985 to 2000. The analysis found that the overall performance of waste collection services in Ghana increased under the coupled system, with efficiency (in terms of total waste clearance and coverage of service provision) increasing rapidly with increased private-sector controls and levels of involvement, e.g. for solid waste, collection rate and disposal improved from 51% in 1998 to about 91% in the year 2000. However, such an increase in performance could not be sustained beyond 10 years of public-private partnerships. This analysis argues that the sustainability of improved waste collection efficiency is a function of the franchise and lease arrangements between private sector group on the one hand and public sector group (local authorities) on the other hand. The analysis therefore concludes that if such franchise and lease arrangements are not conceived out of an initial transparent process, such a provision could undermine the overall sustainability of private sector initiatives in collection services delivery in the long term, as in the case of the Accra example.  相似文献   
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This paper examines the institutional framework of artisanal mining in the forests of the Sangha Tri-National Landscape (TNS) in the Congo Basin. Artisanal miners in Cameroon and the Central African Republic (CAR) commonly make sacrifices to their god of diamonds, to improve fortunes. This study looks into ‘the other forces’; institutions that play a role in shaping the sector and its outcomes. These institutions comprise formal and informal institutions at a local, national, regional and international level. Although artisanal miners in TNS benefit by gaining cash income, this activity also carries risks as income is highly disparate and environmental impacts in this priority forest conservation area are expected to increase due to the growing competition over land use. It was concluded from a literature review, interviews and site visits that informal arrangements dominate the sector, especially in Cameroon, leading to poor relations between officials and miners and meaning that miners have few rights and no voice. The current institutional setup is inadequate to deal with current and anticipated social and environmental issues. Future interventions need to take into account the existing (local) types of organization, vulnerable groups, the interests of multiple actors and the fact that most miners are experienced but combine mining with other activities, such as agriculture, fishing and harvesting forest products. African initiatives concerning ASM offer opportunities to Cameroon and CAR to collaborate with other countries to combat similar issues. A regional integrated approach of both the forest and mining sector would be especially relevant for trans-boundary agreements, such as concerning the TNS, to reinforce positive outcomes for the landscape and the area's population.  相似文献   
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Labile soil C and N play vital roles in soil–plant nutrient dynamics, especially in the low input cropping system and are vulnerable to perturbation. Surface (0–0.15 m) soils from three land clearing methods (slash and burn, bulldozed non-windrowed and bulldozed windrowed) and each with two cropping systems (5-and 4-year cropping/2-year cassava fallow) were collected in the humid forest ecosystem of Nigeria.The soils were analysed for total C and N, microbial biomass C and N (SMB C and N), particulate organic matter C and N (POM C and N), water-soluble C, potentially mineralizable N (PMN) and mineral N. The size of the labile C and N and their relative contributions to the organic C and total N differed significantly among land clearing methods, irrespective of the cropping system. Soils under slash and burn had a significantly (p > 0.05) higher particulate organic matter C, N (10.80 and 0.16 g kg−1, respectively) and microbial biomass C and N (1.07 and 0.12 g kg−1) compared to the bulldozed windrow, regardless of the cropping system. Four years cropping/2-year cassava fallow resulted in a significant higher labile C and N, relative to 5-year cropped plots across the land clearing methods. Effect of the treatments on the concentration of PMN and mineral N mirrored the SMB N and POM N. However, the quantity of most of the labile C and N pool and crop yield obtained from the slash and burn and bulldozed non-windrowed treatment did not differ significantly. Hence, bulldozed non-windrowed clearing could be a viable alternative to slash and burn in the case of large-scale farming in ensuring reduced losses of soil organic matter and nutrient during land clearing in the humid tropics.  相似文献   
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Mesoscale transport and dispersion of air pollutants from a few major point sources in the Mississippi Gulf coastal region is calculated using a coupled modeling system consisting of the atmospheric dynamical model WRF and the lagrangian particle model HYSPLIT. The sensitivity of the dispersion model results to the meteorological fields is studied by conducting an ensemble of simulations using the WRF model for the same dispersion case. Several parameterization schemes for the physical processes of boundary layer turbulence and land surface temperature/moisture prediction in WRF are used in various combinations to produce different meteorological members which are then used for dispersion simulation. The uncertainty in the simulated concentration probabilities to the meteorological model configurations and the ensemble mean are presented. The parameters used for determining the uncertainties include the wind fields, temperature, area of concentration and the levels of concentration. The results indicate that dispersion model results are influenced by the choices made in respect of the planetary boundary layer and land surface schemes in the mesoscale model to produce the meteorological forecast thereby leading to certain amount of uncertainty in the resultant concentrations. Results show that the specific choices made about the atmospheric model configuration can significantly after the simulated concentrations.  相似文献   
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