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961.
Woodruff Miller AIbert Rango 《Journal of the American Water Resources Association》1985,21(6):1029-1036
Thermal infrared radiation data were acquired by the Heat Capacity Mapping Mission (HCMM) satellite over the surface area (385 km2) of Utah Lake during periodic overpasses in 1978 and 1979. The thermal infrared data were converted to lake surface temperatures which were subsequently used in correlations with lake evaporation. Correlations between HCMM surface temperature and pan-derived evaporation exceeded r = 0.90 when HCMM night and day/night average temperatures and two-day average evaporation values were tested. Similar regression studies were done using monthly data from a conceptual evaporation model and the evaporation pan versus monthly HCMM temperature data. In this test both the HCMM day and night monthly temperature versus the monthly model or pan evaporation had correlations exceeding r = 0.95. Empirical estimates of both short and long term lake evaporation using satellite thermal infrared data seem feasible. Attempts to use the HCMM thermal information as direct input to a theoretical approach to calculating evaporation were inconclusive; however, a definite potential seems to exist. 相似文献
962.
Gini Index for Cities: A Preliminary Study on Regional Differences of Chinese City Size Distribution
Liu Wangbao & Zheng Bohong Department of Architecture Urban Planing Central South University Changsha Hunan 《中国人口.资源与环境(英文版)》2004,2(4)
City size distribution is of interest because of a number of key stylized facts, including notably Zipf's law for cities and the importance of urban primacy. But a new and more efficient method Gini index can be used for calculating regional city size distribution. This paper begins by developing a calculation method for the Gini index, dividing the whole country into 26 areas and then calculating each area's Gini index value. Based on these calculation results, this paper gives a preliminary study on regional differences of its city size distribution and the dynamics. 相似文献
963.
964.
Wesley P. James John Warinner Michael Reedy 《Journal of the American Water Resources Association》1992,28(3):623-635
ABSTRACT: A computer model was developed, based on the Green-Ampt infiltration equation, to computed rainfall excess for a single precipitation event. The model requires an estimate of parameters related to hydraulic conductivity, wetting front section, and fillable porosity of the soil layers. Values of parameters were estimated from soil textural averages or regression equations based on percent sand, percent clay, and porosity. Average values of effective porosity and wetting front suction were largely acceptable due to the relatively low variability and low model sensitivity to the parameters. Hydraulic conductivity was the most erratic constituent of the loss rate computation due to the high variability and the high sensitivity of the computed infiltration to the parameter. The performance of the Green-Ampt infiltration model was tested through a comparison with the SCS curve number procedure. Seven watersheds and 23 storms with precipitation of one inch or greater were used in the comparison. For storms with less than one inch of rainfall excess, the SCS curve number procedure generally gave the best results; however, for six of the seven storms with precipitation excess greater than one inch, the Green-Ampt procedure delivered better results. In this comparison, both procedures used the same initial abstractions. The separation of rainfall losses into infiltration, interception, and surface retention is, in theory, an accurate method of estimating precipitation excess. In the second phase of the study using nine watersheds and 39 storms, interception and surface retention losses were computed by the Horton equations. Green-Ampt and interception parameters were estimated from value sin the literature, while the surface retention parameter was calibrated so that the computed runoff volumes matched observed volumes. A relationship was found between the surface retention storage capacity and the 15-day antecedent precipitation index, month of year, and precipitation amount. 相似文献
965.
966.
在分散成若干片区、地形复杂的工业城市进行空气监测优化布设时,应先确定测点所在的片区。优化时必须考虑地形和气象特点、污染源的分布和片区的功能特征。再根据片区内主要污染物及源分布确定决策团子。优化时再考虑片区内的污染气象条件,采用适当的空气扩散模式和动态模拟的方法。经过夏、秋两季实测结果证明,优化的测点代表性良好。 相似文献
967.
Nathaniel B. Guttman 《Journal of the American Water Resources Association》1991,27(5):797-807
ABSTRACT: The sensitivity of the Palmer Hydrologic Drought Index to departures from average temperature and precipitation conditions is examined. A time series of zero index values was calculated and then one monthly temperature or precipitation value was perturbed. The resulting time series shows the effects on the index of one anomalous value. Independent series were calculated for temperature anomalies of plus and minus 1, 3, 5, and 10F and for precipitation anomalies of 25, 50, 75, 125, 150, and 200 percent of normal for each calendar month for Colorado, Indiana, Nevada, New York, Oklahoma, South Carolina, South Dakota, Washington, and Wisconsin. Analysis of the time series showed that the period of time required for the index to reflect actual rather than artificial initial conditions could be more than four years. It was also found that the effects of temperature anomalies are insignificant compared to the effects of precipitation anomalies. In some cases, one anomalous precipitation value could result in established wet or dry spells that last for up to two years. Although not examined in detail, the time series suggest that distributions of index values may be asymmetrical and possibly bimodal. 相似文献
968.
Phosphorus export by runoff from agricultural field plots with different crop cover in Lake Taihu watershed 总被引:5,自引:0,他引:5
IntroductionWatereutrophicationisoneoftheglobalenvironmentalproblems ,andagriculturalnonpointsourcepollutionhasbeengivenincreasedattention (Sharpley ,1994 ;Harris ,1995;Tiessen ,1995;Tonderski,1996;Daniel,1998) .Lakeeutrophicationhasbeenidentifiedasacriticalproblemofsur… 相似文献
969.
实施“新昆明”规划与建设,滇池盆地土地利用状况将有较大的改变,无疑会产生一系列生态后果。为此,需加强恢复天然湿地,大幅减少人工湿地以保护滇池,尽早开展关于昆明原有高原湖泊景观保护的研究。采取措施克服“水泥化”带来的负面影响并解决好城市原有水系的问题。 相似文献
970.
云南省省控地表水监测断面优化认证 总被引:1,自引:0,他引:1
通过对地表水监测点位的代表性、合理性、数据获取率、可操作性等指标的分析和论证,对设置欠合理的点位进行了调整,对存在漏设监测点或监测点不足的水域增设了点位,全面考虑了全省饮用水源地和城市综合整治定量考核对地表水环境的要求。 相似文献