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301.
ABSTRACT: A methodology has been developed to predict the responses of a range of water supply sources in Wales to global warming scenarios. Hydrologically effective rainfall is predicted from temperature and precipitation for each season based on site specific formulae developed using the Meteorological Office Rainfall and Evaporation Calculation System (MORECS) and UK Surface Water Archive databases. Comparisons are then made between the effects predicted for the scenarios established from equilibrium simulations and the new Hadley Centre High Resolution Model (UKHI) transient mode results. Though very different, both suggest increased stress on water resources late in the hydrological year. 相似文献
302.
Tiao J. Chang Xenia A. Kleopa 《Journal of the American Water Resources Association》1991,27(2):275-281
ABSTRACT: Existing definitions of drought have focused on limited hydrologic indicators and are less effective for the purpose of drought monitoring. This study uses historical records of streamflow, precipitation, ground water, temperature, and lake elevation to define drought. Based on the method of truncation, drought durations and conditional probabilities of each indicator were estimated to define the drought severity levels, namely, 70 percent, 80 percent, 90 percent, and 95 percent. A drought monitoring method was developed by a combination of truncation level, duration, and conditional probabilities of five indicators. A six-month period of the 1988 drought in the central Ohio region was used to test the monitoring method. It was found that the developed method could effectively detect an occurrence of drought. 相似文献
303.
中国内陆自然环境的干旱化与未来趋势 总被引:5,自引:2,他引:3
根据中国内陆陕西、甘肃部分地区509a旱涝资料和主要测站气象、水文实测数据,应用Word97图形处理系统,证明在526a序列中目前处在11a、50a滑动的干旱期。近46a气温上升了0.3℃,年降水减少了80mm,径流量减少了0.78%,出现了明显的干旱化,环境变化趋势不容乐观。 相似文献
304.
2001年我国主要气象灾害综述 总被引:7,自引:0,他引:7
2001年,我国气象灾害频繁,干旱,台风,暴雨,沙尘暴,高温,冻害,雪灾等都有不同程度的发生,特别是干旱尤为严重,各种气象灾害给国民经济造成较大损失,本文就几种主要气象灾害的发生特点及影响进行分析和评述。 相似文献
305.
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307.
华北地区干旱强度的表征形式及其气候变异 总被引:18,自引:4,他引:18
在分析1951-2001年华北地区降水量、气温及蒸发量变化特征的基础上,确定利用月降水量与蒸发量之差的Z指数表征干旱强度.该指数在时间及空问分布上的实际概率与理论概率均很接近,可以较好地表征华北地区干旱强度状况.分析表明,华北地区干旱强度不但具有显著的年代际变化特征,且年际振荡的信号也很强.华北地区四季的干旱强度变化在干旱期的开始时间、干旱持续时间和干旱强度等方面存在一定的差异. 相似文献
308.
Michael J. Scott Lance W. Vail John Jaksch Claudia O. Stckle Armen Kemanian 《Journal of the American Water Resources Association》2004,40(1):15-31
ABSTRACT: Using a case study of the Yakima River Valley in Washington State, this paper shows that relatively simple tools can be used to forecast the impact of the El Niño phenomenon on water supplies to irrigated agriculture, that this information could be used to estimate the significantly shifted probability distribution of water shortages in irrigated agriculture during El Niño episodes, and that these shifted probabilities can be used to estimate the value of exchanges of water between crops to relieve some of the adverse consequences of such shortages under western water law. Further, recently devised water‐trading tools, while not completely free under western water law to respond to forecasted El Niño episodes (ocean circulation patterns), are currently being employed during declared drought to reduce the devastating effects of water shortages in junior water districts on high valued perennial crops. Additional institutional flexibility is needed to take full advantage of climate forecasting, but even current tools clearly could prove useful in controlling the effects of climate variability in irrigated agriculture. Analysis shows the significant benefit of temporarily transferring or renting water rights from low‐value to high‐value crops, based on El Niño forecasts. 相似文献
309.
Ze'ev Gedalof David L. Peterson Nathan J. Mantua 《Journal of the American Water Resources Association》2004,40(6):1579-1592
ABSTRACT: A network of 32 drought sensitive tree‐ring chronologies is used to reconstruct mean water year flow on the Columbia River at The Dalles, Oregon, since 1750. The reconstruction explains 30 percent of the variability in mean water year (October to September) flow, with a large portion of unexplained variance caused by underestimates of the most severe low flow events. Residual statistics from the tree‐ring reconstruction, as well as an identically specified instrumental reconstruction, exhibit positive trends over time. This finding suggests that the relationship between drought and streamflow has changed over time, supporting results from hydrologic models, which suggest that changes in land cover over the 20th Century have had measurable impacts on runoff production. Low pass filtering the flow record suggests that persistent low flows during the 1840s were probably the most severe of the past 250 years, but that flows during the 1930s were nearly as extreme. The period from 1950 to 1987 is anomalous in the context of this record for having no notable multiyear drought events. A comparison of the flow reconstruction to paleorecords of the Pacific Decadal Oscillation (PDO) and El Nino/Southern Oscillation (ENSO) support a strong 20th Century link between large scale circulation and streamflow, but suggests that this link is very weak prior to 1900. 相似文献
310.
Stanley A. Changnon William E. Easterling 《Journal of the American Water Resources Association》1989,25(1):27-42
ABSTRACT: Drought is an interaction between physical processes and human activities. This study quantified the impacts of precipitation deficiencies on streamflow, reservoirs, and shallow ground water supplies. An in-depth analysis of newspaper accounts of droughts between paired cities, one in drought and one not in drought, were used to measure the differences in the types of drought impacts, and in the time of onset of impacts as related to developing precipitation deficiencies. Precipitation deficiencies related to the onset and the magnitude of surface water supply adjustments, and to shallow ground water problems, were established. Thus, monitoring and prediction of the onset and magnitude of drought problems can now be done from readily available data on precipitation deficiencies. Newspapers were found to be reliable indicators for the timing of drought impacts and adjustments as precipitation deficiency develops. A review of local and state adjustments during two recent droughts revealed most decision makers lacked information and experience in dealing with drought. 相似文献