Developing a large‐scale water‐balance approach to seasonal forecasting: application to the 2012 drought in Britain     

V. A. Bell  H. N. Davies  A. L. Kay  T. J. Marsh  A. Brookshaw  A. Jenkins 《水文研究》2013,27(20):3003-3012

Seasonal hydrological forecasts, or outlooks, can potentially provide water managers with estimates of river flows and water resources for a lead time of several months ahead. An experimental modelling tool for national hydrological outlooks has been developed which combines a hydrological model estimate of sub‐surface water storage across Britain with a range of seasonal rainfall forecasts to provide estimates of area‐wide hydrological conditions up to a few months ahead. The link is made between a deficit in sub‐surface water storage and a requirement for additional rainfall over subsequent months to enable sub‐surface water storage and river flow to return to mean monthly values. The new scheme is assessed over a recent period which includes the termination of the drought that affected much of Britain in the first few months of 2012. An illustration is provided of its use to obtain return‐period estimates of the ‘rainfall required’ to ease drought conditions; these are well in excess of 200 years for several regions of the country, for termination within a month of 1 April 2012, and still exceed 40 years for termination within three months. National maps of sub‐surface water storage anomaly show for the first time the current spatial variability of drought severity. They can also be used to provide an indication of how a drought situation might develop in the next few months given a range of possible future rainfall scenarios. © 2013 CEH/Crown and John Wiley & Sons, Ltd.  相似文献   

AbnormalSq behaviour     

E. C. Butcher 《Pure and Applied Geophysics》1989,131(3):463-483

It is well-known that the amplitude and phase of theSq(H) variation show considerable variability from day to day. In this paper we consider one aspect of the phase variability—that associated with AQDs. AQDs (or abnormal quiet days) are defined as magnetically quiet days where the maximum excursion ofH at a mid-latitude station on the poleward side of the focus occurs outside the normal time range 0830–1330 LST. Such days exhibit properties, many of which appear quite distinct from the properties of the normalSq(H) variation. The properties of AQDs, and the proposals that have been made to explain them, are considered in detail. The consequences of these proposals and some problems which need to be addressed in order to obtain a fuller understanding of the dynamics of the ionosphere on AQDs are also discussed.  相似文献   

A comprehensive approach to drought and desertification in Northern Nigeria     

E. O. Oladipo 《Natural Hazards》1993,8(3):235-261

Drought has been a recurring feature of the arid and semi-arid areas of Nigeria. This paper reviews the extent, severity, and consequences of drought and desertification in Nigeria with particular emphasis on the northern part of the country. The haphazard manner in which these environmental hazards have been tackled is examined and a systematic approach for the formulation of a national policy is proposed. It is recommended that a detailed formulation and implementation of the proposed policy plan is imperative to mitigate the often devastating impacts of drought and desertification in the very prone areas of Nigeria. Until such is done, some areas of Nigeria will always be vulnerable to the whims of an inevitable climatic hazard of drought and associated land degradation in the form of desertification.  相似文献   

Some aspects of the spatial characteristics of drought in northern Nigeria     

E. Olukayode Oladipo 《Natural Hazards》1993,8(2):171-188

A long-period instrumental data set (1916–1987) of monthly growing season (April–October) rainfall totals for 34 stations in northern Nigeria is used to quantify drought following the method of H. N. Bhalme and D. A. Mooley. It is established that there are remarkable seasonal changes in the patterns of wetness and dryness over the region with no consistent recurrent spatial patterns in the moisture anomalies. In general, large-scale droughts only rarely cover the region as a whole, and there are distinct spatial differences dominating the wet and dry years. The length and severity of drought varies from sub-area to sub-area with very low interannual persistence. Although discrete areas do catch the brunt of drought on a year-by-year basis, drought occurrence in the region is largely sporadic in its spatial distribution. The rather noisy spatial characteristics of drought in northern Nigeria suggests that the seasonal shift in the Intertropical Discontinuity (ITD) is not likely the most important causal mechanism of drought in the region.  相似文献   

近三十年来非洲的旱灾与环境变化   总被引：3，自引：0，他引：3  

丁登山 《地理研究》1994,13(4):43-49

本文简要介绍了近三十年来非洲旱灾的基本情况,分析了其形成的原因,并指出,总的说来,干旱是形成非洲旱灾的一个自然因素,但它不等于旱灾.从环境的角度来看,非洲旱灾更重要的原因是人类不适当的土地利用和管理.文章最后提出了非洲防止旱灾的若干战略原则和建议.  相似文献   

全球增暖下我国旱涝灾害可能情景的初步研究   总被引：6，自引：0，他引：6  

陈家其  施能 《地理科学》1995,(3)

在全球变暖的情况下,我国东南沿海、西南、西北、内蒙古和东北部分地区,洪涝灾害可能增加;而黄河中游以南和华北平原干旱可能增加.这一变化特征与本世纪暖期降水分布变化,以及与CO_2倍增情况下气候模似结果基本一致.  相似文献   

应用土壤水模拟模型研究区域干旱   总被引：1，自引：1，他引：1  

余晓珍  夏自强 《水文》1995,(5):4-9

旨在应用平原地区土壤水模拟模型，给出区域旱精分析所需的干旱信息。以多年平均土壤含水量为判断旱情发生的临界函数，经过统计分析后，提出了一种适用于平原地区分析 区域旱情严重程度的实用方法和拟定评价旱情的定量标准。  相似文献   

低纬和中高纬度火山爆发与我国旱涝的联系   总被引：4，自引：0，他引：4  

刘永强  李月洪  贾朋群 《气象》1993,19(11):3-7

根据５００年旱涝等级资料，采用时序迭加方法，分析了低纬和中高纬火山爆发对我国降水的影响。此外，还对１６００－１９７９年南方涛动指数的变化进行了类似的分析。结果表明，低纬和中高纬火山爆发发后全国旱涝分布型和部分地区降水变化趋势有很大差异。爆发当年华北就可能明显变旱，而次年长江流域才出现明显的降水异常。计算不明，１９９１年皮纳图博火山及去仙岳火山爆发与江淮特大洪涝有直接联系的可能性不大。  相似文献   

Drought forecasting: Methodological topics from a systems perspective     

R. Krzysztofowicz 《Stochastic Environmental Research and Risk Assessment (SERRA)》1991,5(4):267-279

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Drought monitoring     

J. A. Dracup 《Stochastic Hydrology and Hydraulics》1991,5(4):261-266

Drought detection, monitoring and indices are closely related to its definition. The specific definition chosen for a particular drought analysis will affect the procedures one uses in drought detection and monitoring. The traditional Palmer Drought Severity Index (PDSI) has been proven to be ineffective in regions of predominantly irrigated agriculture.The recently developed ALERT (Automated Local Evaluation in Real Time) system is proposed for use in monitoring the spatial and temporal variations of drought in real time. The ALERT system uses standardized instruments, radio frequencies, software and hardware. It was originally developed as a flash flood waming system by local flood control districts and the National Weather Service. However, now it has expanded to over 100 other uses in the areas of natural and man-made disaster detection and warning. The successful ALERT system indicates the need for the continued development of a national drought monitoring index that is applicable to a wide range of climate, hydrologic and water resource environments.  相似文献