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《Geomorphology》1988,1(2):161-189
Bank recession at twenty stations along the eastern end of 286 km long Lake Sakakawea, North Dakota, measured regularly between 1983 and 1986, showed a recession range from essentially zero to almost 9 m yr−1 with an average of 1.6 m yr−1. Between 1969 and 1979, rates were greater, the declining rate a normal consequence of the factors affecting bank recession. Rates of recession vary with seasons, with 78% of the annual recession occurring during the warmer season (May–October) as a result of wave erosion. The remaining 22% occurs during thaw failure in spring.Prediction of ultimate (500 yr) bank recessions attempted using historical recession data, the three years of detailed field measurements, and regression analysis of the erosion factors. An equation, presented here, requires field measurement of bank orientation and height, batch width and composition, and slope of the offshore area. Effective fetch must be measured, as well. The resulting equation for the monthly warm season recession rate is: Rs=154.9 −, (18.8 √ A+ 25.1 √ B +10.1 √ c +6.9 √ 0+5.0 √ E + 1.1 √ F) where: A = sine of angle between bank orientation and dominant wind; B = offshore slope angle; C = beach width; D = bank height; E = effective fetch; and F = percentage of coarse beach clasts. The colder season recession percentage is: Rw = Rs [(2.05D = 0.043G) − 2/100] where D is bank height and G the bank orientation with respect to sun. The total yearly predicted recession (cm yr−1) is: Rt = 6 (Rw) + 6 (Rs) 6 being the number of months of “cold” and “warm” weather at Lake Sakakawea.For this rate to be projected into the future, it is necessary to assume a declining rate of recession, employing a parabolic trend. From this, the ultimate bank recession for Lake Sakakawea is predicted to range up to 542 m. 相似文献
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W.H.Wong. 《地理学报(英文版)》1935,(4)
In the lamented death of Dr. V. K. Ting on January 5th, 1936, at the age of49, China suffered an irredeemable loss. He may be called the founder of thescience of geology in China, and it was in geological field work that his con- 相似文献
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In the lamented death of Dr. V. K. Ting on January 5th, 1936, at the age of49, China suffered an irredeemable loss. He may be called the founder of thescience of geology in China, and it was in geological field work that his con- 相似文献
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《The Professional geographer》2013,65(2):222-223
Abstract The combination of detailed sample data with less detailed but fully enumerated marginal subtotals is the focus of a wide range of research. In this article we advocate careful modeling of sample data, followed by Iterative Proportional Fitting (IPF). The modeling aims to estimate accurately the interaction or odds ratios of complex tables, which is information not contained in the marginal subtotals. IPF ensures consistency with the subtotals. We advance this work in three practical ways. First, we show that detailed small-area estimates of both counts and proportional distributions usually gain accuracy by combining data for larger areas containing the small areas, and we illustrate the multilevel framework to achieve these estimates. Second, we find that a general classification or socioeconomic typology of the small areas is even more associated with the within-area interactions than is membership of the larger area. Third, we show how the Statistical Package for the Social Sciences (SPSS) can be used for IPF in any number of dimensions and with any structure of constraining marginal subtotals. Throughout, we use an example taken from the 1991 U.K. Census. These data allow us to evaluate various methods combining 100 percent tabulations and the Samples of Anonymised Records. 相似文献
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Vivienne Jones 《Journal of Paleolimnology》2006,36(4):439-440