排序方式： 共有18条查询结果，搜索用时 78 毫秒
1.
2.
3.
The decision in 1988 by the Rangitikei-Wanganui Catchment Board to allocate flows away from use for electricity generation into recreation use brought into focus the conflict between market and non-market valuation of river uses. The travel cost method (TCM) of non-market valuation is used to estimate the in-stream recreation values of the Upper Wanganui and Whakapapa rivers. 相似文献
4.
A suldge ash reference sample has been prepared. It has been analyzed by twenty-one independent laboratories. Information is presented on the number of analysts reporting each element, and the various instrumental methods used. Results are reported for twenty-six elemental determinations. Recommended elemental composition of the sample is given for twenty-one elements. 相似文献
5.
6.
ALISTAIR FRASER 《Geographical review》2008,98(3):309-321
ABSTRACT. In this article I examine a range of issues raised in recent geographical studies of land reform. I briefly discuss the career of land reform, review a selection of geographical publications on land reform in a range of places in the global south and even the global north, note some prominent themes and silences, and raise points for discussion and debate about the direction a geography‐of‐land‐reform literature might take. My aim is to help geographers who are interested in land reform identify ways in which they might more purposively develop a literature that heretofore has not been considered a whole. 相似文献
7.
JOHN FRASER HART 《Geographical review》2003,93(2):153-170
ABSTRACT. Census data do not support the widespread popular perception that urban encroachment on cropland in California is serious enough to justify programs of farmland preservation. Between 1949 and 1997 the acreage of harvested cropland declined near Los Angeles, in the San Francisco Bay area, and near Sacramento, but the high‐value specialty agricultural production displaced from these areas has been relocated to more distant areas, where it has replaced lower‐value field crops, and specialized agricultural production has increased steadily in the state. Vegetable production in the Salinas Valley and dairying near Los Angeles illustrate the twin processes of relocation and replacement. Urban encroachment actually has been a boon to California agriculture, because it has transferred massive amounts of urban capital to cash‐strapped farmers and enabled them to develop efficient modern operations. Much of the concern about loss of farmland really is concern about loss of open space and amenities, and urban demand for water probably will be a greater constraint on California agriculture than will urban demand for land. 相似文献
8.
D.C. FRASER 《Geophysical Prospecting》1981,29(4):639-651
Dipole-dipole induced polarization (IP) data are displayed typically as multi-level profiles, or as contours on vertical sectional plots referred to as pseudo-sections. The dipole-dipole array tends to yield IP anomalies in which the most anomalous values are displaced laterally from the source body. The data patterns are fairly interpretable on pseudo-sections or on multi-level profiles but are sufficiently complex to discourage the contouring of the data in plan. A method was developed for the presentation of dipole-dipole IP data on a contour map. The method consists of a simple averaging of data which can be performed manually if desired. It yields a single output value per station which reflects all levels of the pseudo-section, and is suitable for contouring in plan. The advantage of the technique is that it provides a quantitative picture of IP anomalies in their background or regional setting. 相似文献
9.
10.
JOHN FRASER HART 《Geographical review》2001,91(3):525-543
ABSTRACT. The census concept of total cropland is a better measure of effective agricultural land than is total farmland, which includes extensive areas of woodland owned by farmers. The cropland area of the United States dropped from 478 million acres in 1949 to 431 million acres in 1997, for a net loss of less than 1 million acres, or roughly one‐fifth of 1 percent, per year. In the midwestern agricultural heartland most counties changed less than 5 percent in the half‐century, and more counties gained than lost. The West was a crazy quilt of change, and in the East most counties lost more than 10 percent. Major metropolitan counties lost a few percentage points more than did adjacent areas, but at a lower rate per capita than the nation as a whole. Most of the loss of cropland was in marginal agricultural counties with soils of low inherent fertility and topography unsuited to modern farm machinery. The loss of cropland to suburban encroachment may be cause for intense local concern, but attempts to thwart development cannot be justified on grounds of a net national loss of good cropland. 相似文献