No abstract

In Central Europe, river flooding has been recently recognized as a major hazard, in particular after the 1997 Odra /Oder flood, the 2001 Vistula flood, and the most destructive 2002 deluge on the Labe/Elbe. Major recent floods in central Europe are put in perspective and their common elements are identified. Having observed that flood risk and vulnerability are likely to have grown in many areas, one is curious to understand the reasons for growth. These can be sought in socio-economic domain (humans encroaching into floodplain areas), terrestrial systems (land-cover changes -urbanization, deforestation, reduction of wetlands, river regulation), and climate system. The atmospheric capacity to absorb moisture, its potential water content, and thus potential for intense precipitation, are likely to increase in a warmer climate. The changes in intense precipitation and high flows are examined, based on observations and projections. Study of projected changes in intense precipitation, using climate models, for several areas of central Europe, and in particular, for drainage basins of the upper Labe/Elbe, Odra/Oder, and Vistula is reported. Significant changes have been identified between future projections and the reference period, of relevance to flood hazard in areas, which have experienced severe recent floodings.

Several episodes of extreme precipitation or extreme lack of precipitation (and high temperature) leading to dramatic and high-impact floods and droughts have occurred in Europe in recent years. Climate scenarios suggest that problems of too little or too much water may become more severe in the future. Using data from the Hadley Centre's HadRM3 model, this paper analyzes future changes in the characteristics of intense precipitation (mean daily precipitation amounts and number of days with intense precipitation in a year) and the duration of dry (also dry and hot) spells over the European continent, comparing the time periods of 1961-1990 and 2070-2099. The potential for intense precipitation is likely to increase in the warmer climate of the future, contributing to the growth of flood hazard in areas where inundations are typically triggered by heavy rain. The projected number of days with intense precipitation and the maximum daily precipitation are likely to increase over much of Europe, especially in the central and northern parts. According to projections, 'dry and hot' extremes may become more severe for most of Europe. The areas already affected by water stress in the present climate (e.g. southern Europe) are expected to experience even more severe conditions. KEY WORDS: Precipitation · Intense precipitation · Floods · Droughts · Climate projectionsResale or republication not permitted without written consent of the publisher

Despite costly flood risk reduction efforts, material damage and death toll caused by river floods continue to be high in Europe. In the present review paper, after outlining a process-based perspective, we examine observed and projected changes in flood hazard. Spatial and temporal variability of large floods is analyzed, based on a time series of flood information, collected by the Dartmouth Flood Observatory in 1985–2016. Model-based projections of future flood hazard are critically reviewed. It is difficult to disentangle the climatic change component from strong natural variability and direct human impacts. The climate change impact on flood hazard is complex and depends on the river flood generation mechanism. It has not been possible to detect ubiquitous changes in flood characteristics in observation records in Europe, so far. However, we found an increasing tendency in the number of floods with large magnitude and severity, even if year-to-year variability is strong. There is a considerable spread of river flood hazard projections in Europe among studies, carried out under different assumptions. Therefore, caution must be exerted by practitioners in charge of climate change adaptation, flood risk reduction, risk insurance, and water resources management when accommodating information on flood hazard projections, under considerable uncertainty.

Abstract. Multi-model ensemble climate projections in the ENSEMBLES Project of the EU allowed the authors to quantify selected extreme-weather indices for Poland, of importance to climate impacts on systems and sectors. Among indices were: number of days in a year with high value of the heat index; with high maximum and minimum temperatures; length of vegetation period; and number of consecutive dry days. Agricultural, hydrological, and human health indices were applied to evaluate the changing risk of weather extremes in Poland in three sectors. To achieve this, model-based simulations were compared for two time horizons, a century apart, i.e., 1961-1990 and 2061-2090. Climate changes, and in particular increases in temperature and changes in rainfall, have strong impacts on agriculture via weather extremes -droughts and heat waves. The crop yield depends particularly on water availability in the plant development phase. To estimate the changes in present and future yield of two crops important for Polish agriculture i.e., potatoes and wheat, some simple empirical models were used. For these crops, decrease of yield is projected for most of the country, with national means of yield change being: −2.175 t/ha for potatoes and -0.539 t/ha for wheat. Already now, in most of Poland, evapotranspiration exceeds precipitation during summer, hence the water storage (in surface water bodies, soil and ground) decreases. Summer precipitation deficit is projected to increase considerably in the future. The additional water supplies (above precipitation) needed to use the agro-potential of the environment would increase by half. Analysis of water balance components (now and in the projected future) can corroborate such conclusions. As regards climate and health, a composite index, proposed in this paper, is a product of the number of senior discomfort days Correspondence to: M. Szwed (mszwed@man.poznan.pl) and the number of seniors (aged 65+). The value of this index is projected to increase over 8-fold during 100 years. This is an effect of both increase in the number of seniors (over twofold) and the number of senior-discomfort days (nearly fourfold).

Floods, Adaptation, Risk, Vulnerability, Climate projections, Climate change impacts,

There is a strong inter-annual and inter-decadal variability in time series of flood-related variables, such as intense precipitation, high river discharge, flood magnitude, and flood loss at a range of spatial scales. Perhaps part of this variability is random or chaotic, but it is quite natural to seek driving factors, in a statistical sense. It is likely that climate variability (atmosphere–ocean oscillation) track plays an important role in the interpretation of the variability of flood-related characteristics, globally and, even more so, in several regions. The aim of this review paper is to create an inventory of information on spatially and temporally organized links of various climate-variability drivers with variability of characteristics of water abundance reported in scientific literature for a range of scales, from global to local. The climate variability indices examined in this paper are: El Niño-Southern Oscillations (ENSO), North Atlantic Oscillations (NAO), Atlantic Multi-decadal Oscillation (AMO), and Pacific Decadal Oscillations (PDO). A meta-analysis of results from many studies reported in scientific literature was carried out. The published results were collected and classified into categories after regions, climate variability modes, as well as flood-related variables: precipitation, river flow, and flood losses.

On the basis of temperature observations at 60 meteorological stations in Poland, changes in the indices associated with the presence of extremely high air temperatures were examined. Indices associated with heat waves, such as the number of hot days (T max ≥30°C) in the summer months (June, July, August) and beyond the summer months (May, September), the number of extremely hot days (T max ≥35°C), the duration of the longest hot spell in the year, as well as the number of tropical nights (T min ≤20°C) were calculated. Spatial distribution of change rate in days per decade for the studied indices as well as the significance level of the observed trends is illustrated. Also current values of the studied indices (for 1991-2013) are examined and compared with the reference period, . For eight of 11 analysed indexes, increase has been detected in last decades with the help of the Mann-Kendall test at a significance level ≥0.05 or better, for a large group of stations. Statistically significant increases of the number of hot days in summer, the number of tropical nights in a year, and duration of the longest hot spell in summer were found for more than half of the stations. Distinct changes in the duration of heat waves were also noted. In 1961-1990, the longest hot spell lasted for 10 days while in 1991-2013, there were many hot spells longer than that, while the longest hot spell recorded in this period lasted for 17 days. Beyond summer, changes in the number of hot days were smaller. In May, a statistically significant increase was recorded for only three stations, while in September the downward trend was dominating and for eight stations it was statistically significant.