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621.
中国季风边缘带的自然灾害及成因 总被引:2,自引:0,他引:2
本文提出并讨论了季风边缘带的概念范围,并按大气圈、岩石圈和生物圈等三个方面对自然灾害的特点和成因进行了论证。认为这个地区之所以成为一个自然灾害多发区是因该区气候、地质、地貌等均有利于自然灾害的形成和发展,人为作用加剧了灾害。 相似文献
622.
Jeffrey L. Jordan 《Journal of the American Water Resources Association》1994,30(5):871-877
ABSTRACT: Economic theory clearly indicates that the use of increasing rate structures will reduce the demand for water and produce monetary incentives for consumers to conserve. One problem with estimating the effectiveness of using rate structures as a conservation program is that they are usually accompanied by other conservation efforts. Thus, it is difficult to determine the effectiveness of any one conservation component. This paper examines the effectiveness of increasing rate structures in a situation where no other conservation program was introduced. The paper uses customer data from the Spalding County (Georgia) Water Authority where an increasing rate structure replaced a descending rate structure in January 1991. Since the imposition of the increasing rate structure, the number of customers has increased 21 percent while total water demand has gone up only 15 percent and per customer water use has declined 5 percent. The daily water use per connection has declined from 243 gallons in 1990 to 231 in 1993, and monthly use has gone from 7,381 gallons to 7,028 per connection over the same period. Statistical tests indicate that water consumption during the two periods was significantly different while weather factors were not. 相似文献
623.
我国耕地保护的最优化分析 总被引:5,自引:0,他引:5
王卫 《中国人口.资源与环境》1999,9(1):27-32
本文把耕地保护置于国民经济发展的框架下,运用经济学、土地资源学原理,构建了我国耕地保护的最优化分析方法。在此基础上,提出了我国耕地保护最佳规模调控指标的具体测算方法,并粗略估算了我国现状及未来半个世纪耕地保护最佳规模调控指标。 相似文献
624.
M. R. Karlinger A. J. Hansen 《Journal of the American Water Resources Association》1983,19(6):967-975
ABSTRACT: Appraisal-level, engineering economic analyses for two types of irrigation systems are compared: (1) a surface-water irrigation system, and (2) a ground-water recharge irrigation system. An artificial recharge irrigation system is an economically viable alternative to surface-distributed irrigation in a conjunctive irrigation plan if electric power rates remain sufficiently low. As electric rates increase, this viability generally decreases until it becomes completely unattractive at rates of about 0.012 dollars per kilowatt hour. 相似文献
625.
G. R. Soltani 《Journal of the American Water Resources Association》1977,13(1):137-142
ABSTRACT: The possibility of increasing the water supply for irrigation through adoption of more efficient water-application techniques as an alternative to new irrigation projects was studied in an irrigated region of Iran. Excessive water application at the farm level ranks high among the causes of water shortages in the selected region. An empirical analysis of the effect of water-saving technology on the farm operator's net return was made choosing two farms in the region as a case study. The problems facing these farms are common to most farms throughout the country. The results of the budgeting analysis of the selected farms indicated that an improvement in irrigation technique can result in the expansion of water supply and higher marginal value product for water. Comparing the costs of irrigation systems with the net returns resulting from the higher efficiency showed that such an investment is economically feasible. 相似文献
626.
Clayton W. Ogg Ralph Heimlich Harry Pionke 《Journal of the American Water Resources Association》1980,16(6):967-970
ABSTRACT: Several problems that make it difficult to deal with water pollution from cropland are identified. The most immediate need is for a rational framework for determining where conservation programs can make an impact on eutrophication problems in reservoirs draining rural watersheds. This includes estimating the level of control that would be required for each local farm situation and the economic impacts for the planning area. A modeling approach is suggested for a planning area in Southeastern Pennsylvania. 相似文献
627.
Jackie Sellers Ronald M. North 《Journal of the American Water Resources Association》1979,15(1):189-197
ABSTRACT: In this article a managerial approach to developing and implementing National Water Resources policy is suggested. Proper consideration can be given to national economic development (NED), environmental quality (EQ) and conservation and still result in an implementable policy at the operational level if proper incentives are built into the process with proper attention to alternate non-Federal cost sharing rates. Not only can these multiple objectives be entertained but the Administration and Congress will have a management tool that should ensure a certain probability of success. 相似文献
628.
Janusz R. Rydzewski Saeed Nairizi 《Journal of the American Water Resources Association》1979,15(2):316-325
ABSTRACT: The deliberate underwatering of a larger land area, as practiced in Southern Asia, has provided impetus for a systematic investigation into the effects of designing projects for crop water deficits on Benefit-Cost performance. The study began with the derivation, from published experimental results, of functions relating ultimate crop yield to the magnitude and timing of water deficits, i.e., of the productivity of irrigation water. To obtain the net benefit of the project, the relation between the harvested area and output and the on-farm production costs was then suggested. The cost of supplying the irrigation water to the proposed area and of distributing and applying it to the field was determined, thus completing the Benefit-Cost equation. A computer simulation model was then established to search for the irrigation project design capacity and area to maximize the net present value in the Benefit-Cost analysis for the development proposed. 相似文献
629.
Jon R. Miller Daniel A. Underwood 《Journal of the American Water Resources Association》1983,19(4):631-640
ABSTRACT Financing and repayment provisions of western water projects effect transfers of income among federal taxpayers, electric power users, local water users, and property owners. We use the Bonneville Unit of the Central Utah Project as a case study in the distribution of municipal and industrial water costs. We examine the distribution of costs among taxpayers and water users in different political/geographical jurisdictions, and how this distribution is affected by water law, cost allocation procedures, and the choice of revenue source for local repayment of reimbursable costs. In light of the magnitude of distributional effects of present water policy, we conclude that lack of open debate on water issues is unfortunate. We conclude with speculation on the relationship of western water policy to the motivation of western water leaders who are instrumental in its formulation 相似文献
630.
Donald A. Downing 《Journal of the American Water Resources Association》1975,11(2):345-355
ABSTRACT. The article proposes the use of certain water and sewer extension pricing and investment policies. Such policies would complement an urban growth policy designed to guide the location and timing of growth in urbanizing areas. Proposed pricing policies are based upon marginal cost principles. The types of pricing policies discussed include benefit assessments, connection fees, and user charges. Proposed investment policies deal with the division of financing responsiblities between the public and private sectors. Discussion of each proposal explains the economic influence of the proposed policies upon key decision makers in the land development process. The application of proposed pricing and investment policies in the case study communities is mixed. In Knoxville, Tennessee, where pricing and investment policies reflect the proposed policies, no urban growth policy exists. In Lexington, Kentucky, mixed pricing and investment policies do not complement what is a relatively good urban growth policy. In Greensboro, North Carolina, reasonably effective pricing and investment policies complement other policies which provide some guidance to the urban growth pattern. It is hoped that the article will increase the recognition of utility pricing and investment policies as one means of implementing urban growth policy. 相似文献