There are concerns that recent climate change is altering the frequency and magnitude of river floods in an unprecedented way
. Historical studies have identified flood-rich periods in the past half ...millennium in various regions of Europe
. However, because of the low temporal resolution of existing datasets and the relatively low number of series, it has remained unclear whether Europe is currently in a flood-rich period from a long-term perspective. Here we analyse how recent decades compare with the flood history of Europe, using a new database composed of more than 100 high-resolution (sub-annual) historical flood series based on documentary evidence covering all major regions of Europe. We show that the past three decades were among the most flood-rich periods in Europe in the past 500 years, and that this period differs from other flood-rich periods in terms of its extent, air temperatures and flood seasonality. We identified nine flood-rich periods and associated regions. Among the periods richest in floods are 1560-1580 (western and central Europe), 1760-1800 (most of Europe), 1840-1870 (western and southern Europe) and 1990-2016 (western and central Europe). In most parts of Europe, previous flood-rich periods occurred during cooler-than-usual phases, but the current flood-rich period has been much warmer. Flood seasonality is also more pronounced in the recent period. For example, during previous flood and interflood periods, 41 per cent and 42 per cent of central European floods occurred in summer, respectively, compared with 55 per cent of floods in the recent period. The exceptional nature of the present-day flood-rich period calls for process-based tools for flood-risk assessment that capture the physical mechanisms involved, and management strategies that can incorporate the recent changes in risk.
The close relationship between the onset and severity of agricultural and hydrological drought is considered self-evident, yet relatively few studies have addressed the effects of applying ...agricultural drought adaptation to hydrological drought characteristics. The present study applies a model cascade capable of simultaneously considering the interactions between agricultural and hydrological droughts. The study area covers all river basins in the Czech Republic and includes the periods of 1956–2015 (baseline) and 2021–2080 (future). The model cascade was shown to explain 91% of the variability in the seasonal and annual accumulated runoff and allows for the analysis of increasing/maintaining/decreasing available water capacity (AWC) across the 133 defined basins with a total area of c. 78,000 km2. The study reports that the probability and extent of agricultural drought increased over the entire period with higher AWC scenario showing slower pace of such increase especially from April to June. The trends in the extent or severity of hydrological droughts were of low magnitude. The future climate has been projected through the use of ensembles of five global (CMIP5) and five regional (EURO-CORDEX) climate models. The results showed a significant increase in the duration of agricultural drought stress and in the area affected throughout the year, particularly in July–September. The hydrological drought response showed a marked difference between areas with a negative and positive climatic water balance, i.e., areas where long-term reference evapotranspiration exceeds long-term precipitation (negative climatic water balance) and where it does not (positive climatic water balance). The overall results indicate that increasing soil AWC would decrease the frequency and likely also impact of future agricultural droughts, especially during spring. This result would be especially true if the wetter winters predicted by some of the models materialized. Hydrological droughts at the country level are estimated to become more pronounced with increasing AWC, particularly in catchments with a negative climatic water balance.
•We analyzed the past and projected agricultural and hydrological droughts in 133 basins in the Czech Republic.•The area and severity of the agricultural drought during the growing season has increased since 1956.•The runoff and hydrological droughts have increased insignificantly since 1956 except for June.•The increase in the water holding capacity decreases area and severity of agricultural droughts but exacerbates hydrological ones.•Adaptation studies have to consider drought impacts simultaneously to avoid maladaptation.
The history of early meteorological observations using instruments in the Czech Lands is described (the longest temperature series for Prague-Klementinum starts in 1775, precipitation series for Brno ...in 1803). Using the PRODIGE method, long-term monthly temperature and precipitation series from selected secular stations were homogenised (for 10 and 12 stations, respectively). All the seasonal and annual temperature series for the common period 1882–2010 show a significant positive linear trend with accelerated warming from the 1970s onwards. No significant linear trends were disclosed in the series of seasonal and annual precipitation totals. Correlation coefficients between the Czech series analysed decrease as distances between measuring stations increase. A sharper decrease of correlations for precipitation totals displays much weaker spatial relationships than those for mean temperatures. The highest correlations between all stations appeared in 1921–1950, the lowest in 1891–1920 (temperature) and 1981–2010 (precipitation). Wavelet analysis reveals that very distinct annual cycles as well as the slightly weaker semi-annual ones are better expressed for temperature series than for precipitation. Statistically significant cycles longer than 1 year are temporally unstable and sporadic for precipitation, while in the temperature series cycles of 7.4–7.7 and 17.9–18.4 years were recorded as significant by all stations in 1882–2010 (quasi-biennial cycle of 2.1–2.2 years for half the stations). Czech homogenous temperature series correlate best with those of the Northern Hemisphere for annual, spring and summer values (with significant correlation coefficients between 0.60 and 0.70), but this relation is temporally unstable. Circulation indices, such as the North Atlantic Oscillation Index (NAOI) and the Central European Zonal Index (CEZI), may explain the greater part of Czech temperature variability, especially from December to March and for the winter; however, this relationship is much weaker, or even random, for precipitation series. Further, relationships with the Southern Oscillation Index (SOI) are weak and random. Relatively weak coincidences exist between statistically significant cycles in the Czech series and those detected in NAOI, CEZI and SOI series.
Weather diaries constitute an important source of data for historical climatology, employed in the analysis of weather patterns for both the pre-instrumental and the early instrumental periods. Among ...the many weather diaries that exist in Europe, the daily records kept by the Reverend Šimon Hausner from Buchlovice in south-east Moravia (Czech Republic), covering the 1803–1831 period, are particularly useful. His qualitative daily weather descriptions enable the construction of series for temperature, precipitation, cloudiness, wind, and other weather phenomena (particularly thunderstorms and fogs), supplemented by a number of phenological and agricultural work records. His data related to temperature and precipitation patterns were quantified into a series of weighted temperature and precipitation indices on 7-degree scales, which were subsequently compared with standard meteorological observations from the secular meteorological station in Brno. This comparison indicates that Hausner's observations are highly reliable and confirms the importance of his data for a better understanding of the variability in the regional climate in the period of early instrumental measurements in Moravia. At the same time, it reveals the importance of weather-related documentary data in the overlap period with instrumental meteorological observations.
Scholarly and economic management societies played an important role in the beginnings of meteorological observations in Central Europe. In Bohemia, one such was the “Imperial Royal ...Patriotic–Economic Society of Bohemia” which, as well as making meteorological observations, organised a network of phenological stations and published the results of their observations from 1828 to 1847. The phenological observations covered 31 different forest plants, fruit trees and field-crops. Some of the phenological stations continued to make observations within the network of the Central Institute for Meteorology and Earth Magnetism established in Vienna in 1851. Analysis of the above observations led to the collation of information on the temporal and spatial distribution of the observed phenological characteristics (beginning of budding and/or foliage, beginning and end of flowering, ripeness of seeds and fruits) in the 1828–1847 period, which was cooler and generally wetter with respect to more recent temperature and precipitation patterns (1961–1990) in the study area. Phenophases of flowering and ripeness for selected plants are presented for the Hradec Králové and Loket stations, showing late onsets in this period in comparison with recent phenological stations located nearby and taking measurements in 1993–2009. Working up this topic makes a contribution to the historical phenology of the nineteenth century in the Czech Lands and in Central Europe as well.
Aims/hypothesis
The aim of the study was to compare the effect of six (A6 regimen) vs two meals a day, breakfast and lunch (B2 regimen), on body weight, hepatic fat content (HFC), insulin resistance ...and beta cell function.
Methods
In a randomised, open, crossover, single-centre study (conducted in Prague, Czech Republic), we assigned 54 patients with type 2 diabetes treated with oral hypoglycaemic agents, both men and women, age 30–70 years, BMI 27–50 kg/m
2
and HbA
1c
6–11.8% (42–105 mmol/mol), to follow two regimens of a hypoenergetic diet, A6 and B2, each for 12 weeks. Randomisation and allocation to trial groups (
n
= 27 and
n
= 27) were carried out by a central computer system. Individual calculations of energy requirements for both regimens were based on the formula: (resting energy expenditure × 1.5) − 2,092 kJ. The diet in both regimens had the same macronutrient and energy content. HFC was measured by proton magnetic resonance spectroscopy. Insulin sensitivity was measured by isoglycaemic–hyperinsulinaemic clamp and calculated by mathematical modelling as oral glucose insulin sensitivity (OGIS). Beta cell function was assessed during standard meal tests by C-peptide deconvolution and was quantified with a mathematical model. For statistical analysis, 2 × 2 crossover ANOVA was used.
Results
The intention-to-treat analysis included all participants (
n
= 54). Body weight decreased in both regimens (
p
< 0.001), more for B2 (−2.3 kg; 95% CI −2.7, −2.0 kg for A6 vs −3.7 kg; 95% CI −4.1, −3.4 kg for B2;
p
< 0.001). HFC decreased in response to both regimens (
p
< 0.001), more for B2 (−0.03%; 95% CI −0.033%, −0.027% for A6 vs −0.04%; 95% CI −0.041%, −0.035% for B2;
p
= 0.009). Fasting plasma glucose and C-peptide levels decreased in both regimens (
p
< 0.001), more for B2 (
p
= 0.004 and
p
= 0.04, respectively). Fasting plasma glucagon decreased with the B2 regimen (
p
< 0.001), whereas it increased (
p
= 0.04) for the A6 regimen (
p
< 0.001). OGIS increased in both regimens (
p
< 0.01), more for B2 (
p
= 0.01). No adverse events were observed for either regimen.
Conclusions/interpretation
Eating only breakfast and lunch reduced body weight, HFC, fasting plasma glucose, C-peptide and glucagon, and increased OGIS, more than the same caloric restriction split into six meals. These results suggest that, for type 2 diabetic patients on a hypoenergetic diet, eating larger breakfasts and lunches may be more beneficial than six smaller meals during the day.
Trial registration
ClinicalTrials.gov number, NCT01277471, completed.
Funding
Grant NT/11238-4 from Ministry of Health, Prague, Czech Republic and the Agency of Charles University – GAUK No 702312.
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