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The aim of this study is to analyse the occurrence of drought events at Europe scale through a previous regionalization. Droughts have been defined as natural phenomena characterised by an unusual temporary scarcity of water in a region. Spatial and temporal basis have an influence in defined droughts. So, an effort has been made to characterise dr...
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In this study we analyzed the spatio-temporal variability of streamflow
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develop a streamflow index (the Standardized Streamflow Index; SSI),
which facilitated comparison among regimes and basins, regardless of
st...
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Citations
... Yet, due to the lack of pan-European datasets of hydrological variables with long records and an adequate method to be applied across Europe, a review based on homogeneous data has been difficult. Álvarez & Estrela (2000) have analysed droughts in terms of precipitation anomalies since the beginning of the century. The largescale dry spells across Europe found in their study partly confirm other drought records. ...
... A comparison of the details on drought dynamics with some of the references, however, remains difficult, as they are based on different parameters, like annual precipitation deficit in Álvarez and Estrela (2000) or even on different documented studies (Bradford, 2000). The dynamics of streamflow deficiencies of the two longest and largest events 1976 and 1989/90 were discussed in detail by . ...
... Finally, the most recent period from 1991 to 1998, for which streamflow data was not available for all the stations in the clusters, should be mentioned. The most severe drought period in Spain (C18) lasting from 1990 to 1995 (Bradford, 2000, Álvarez & Estrela, 2000 was well reproduced by the model (Figure 8.1). In 1992, a severe drought caused crop losses in northeastern Germany (Bradford, 2000, Gierk & Jungfer, 1992. ...
Aiming at a better understanding of drought causes and processes, the present study investigated hydrological drought characteristics in space and time and their large-scale atmospheric driving forces in Europe. On the basis of daily streamflow data of more than 600 European rivers for 1962-1990, two types of events were defined: streamflow drought, defined by a seasonally constant threshold and streamflow deficiency, defined by a new varying threshold level method. By the means of cluster analysis, the 602 streamflow deficiency series across Europe were classified into 19 regions. A regional streamflow deficiency index (RDI) provided a parameter describing how strong a region is affected by streamflow deficiency. This index allowed a first assessment of the space-time characteristics of the major dry spells in Europe in 1962-90. Regions such as Spain, SE-UK, S-Scandinavia and N-Germany show a tendency to persistent dry spells while the index fluctuates more strongly in other regions.
Anomalies of atmospheric circulation patterns (Europäische Großwetterlagen) during severe regional streamflow deficit were analysed. The grouped circulation patterns (CP) provide an adequate input for a new model to predict the regional streamflow deficiency index. Two different applications of the CP-RDI link model were tested: historic reconstruction and scenario prediction of regional streamflow deficiency indices. The reconstruction since 1881 confirms the trend towards drier conditions in the end of the 20th century in Spain and shows changes towards longer dry spells after the 1960s in some regions. The response to the scenario, which was motivated by changes in circulation patterns attributed to climate change, confirm that Europe will be exposed to generally wetter conditions, however rare and severe drought may increase in some regions.
http://sp.lyellcollection.org/content/288/1/1.full.pdf
There is a general consensus that climate change is an ongoing phenomenon. This will inevitably bring about numerous environmental problems, including alterations to the hydrolo- gical cycle, which is already heavily influenced by anthropogenic activity. The available climate scenarios indicate areas where rainfall may increase or diminish, but the final outcome with respect to man and environment will, generally, be detrimental. Groundwater will be vital to alleviate some of the worst drought situations. The paper analyses the main methods,for study- ing the relationships between climate change and groundwater, and presents the main areas in which hydrogeological research should focus in order to mitigate the likely impacts. This article has two aims. The first is to present a
Groundwater regime in Bulgaria is influenced by climate variability. The impact is evident especially for karst water. A time series analysis of spring discharge for selected karst basins was performed. The impact of the 1982-1994 drought period on groundwater regime was detected. For springs that drain open and mountainous karst, the impact of climate variability is similar to that on surface waters. In fact, the difference in degree of influence of the drought period is related to the specific geological structure of the karst massifs and recharge conditions. Furthermore, the porous waters are characterized by a weaker reaction to such an effect. In general, groundwater use during the 1982-1994 drought period was impacted by climate variability due to limited resource availability.
