Droughts in the Czech Lands, 1090–2012 AD

Abstract

This paper addresses droughts in the Czech Lands in the 1090–2012 AD period, basing its findings on documentary evidence and instrumental records. Various documentary sources were employed for the selection of drought events, which were then interpreted at a monthly level. While the data on droughts before 1500 AD are scarce, the analysis concentrated mainly on droughts after this time. A dry year in 1501–1804 period (i.e. pre-instrumental times) was defined as a calendar year in the course of which dry patterns occurred on at least two consecutive months. Using this definition, 129 dry years were identified (an average of one drought per 2.4 yr). From the 16th to the 18th centuries these figures become 41, 36 and 49 yr respectively, with the prevailing occurrence of dry months from April to September (73.7%). Drought indices – SPEI-1, Z-index and PDSI – calculated for the Czech Lands for April–September describe drought patterns between 1805 and 2012 (the instrumental period). N-year recurrence intervals were calculated for each of the three indices. Using N ≥ 5 yr, SPEI-1 indicates 40 drought years, Z-index 39 yr and PDSI 47 yr. SPEI-1 and Z-index recorded 100 yr drought in 1834, 1842, 1868, 1947 and 2003 (50 yr drought in 1992). PDSI as an indicator of long-term drought disclosed two important drought periods: 1863–1874 and 2004–2012. The first period was related to a lack of precipitation, the other may be attributed to recent temperature increases without significant changes in precipitation. Droughts from the pre-instrumental and instrumental period were used to compile a long-term chronology for the Czech Lands. The number of years with drought has fluctuated between 26 in 1951–2000 and 16 in 1651–1700. Only nine drought years were recorded between 1641 and 1680, while between 1981 and 2012 the figure was 22 yr. A number of past severe droughts are described in detail: in 1540, 1590, 1616, 1718 and 1719. A discussion of the results centres around the uncertainty problem, the spatial variability of droughts, comparison with tree-ring reconstructions from southern Moravia, and the broader central European context

Drought reconstruction based on grape harvest dates for the Czech Lands, 1499-2012

“…These years have been reported and described in many studies of the area of the recent Czech Republic (e.g. Brázdil et al 2013a,b, 2015, 2016b.…”

“…The SPEI has been applied extensively in recent climatological and hydrological studies (e.g. Potop 2011, Heim & Brewer 2012, Li et al 2012, Paulo et al 2012, Potop et al 2012, Brázdil et al 2013a, Beguería et al 2014, Yu et al 2014, Potopová et al 2016). …”

Drought trends over part of Central Europe between 1961 and 2014

“…However, even here, drought episodes have played an important role since the early Neolithic Age, when relatively short drought periods significantly influenced the location of early settlements (Kalis et al 2003). The dendroclimatic data and documentary sources indicate several cases of droughts with intensity not recorded during the instrumental period (Büntgen et al 2011a, Brázdil et al 2013, Cook et al 2015, Dobrovolný et al 2015. However, even the relatively short instrumental records provide a clear indication of the occurrence of persistent drought periods (e.g.…”

“…The most severe of these events in the last 100 yr was recorded in 1947 (Bráz dil et al 2016b this Special) with less pronounced episodes since then in 1953−1954, 1959, 1992, 2007(Bráz dil et al 2015b) and most recently in 2011−2012 (Zahradní<ek et al 2015) and 2015. Recent drought episodes after 2000 led to increased research efforts focusing on drought climatology, causes and impacts , Škvarenina et al 2009, Brázdil et al 2013, Potop et al 2014, Bochní<ek et al 2015. In the case of Austria, drought studies have focused on alpine hydrology, drought impacts on agriculture and hydrological factors such as runoff and groundwater tables (Blaschke et al 2011, Thaler et al 2012, van Loon et al 2015 but have not assessed the trends in drought indicators.…”

Disturbances can control fine-scale pedodiversity in old-growth forests: is the soil evolution theory disturbed as well?

“…In addition to strong winds and snow storms, Chadt (1908), Kruml (1960) and Brázdil et al (2004) also found biotic disturbance factors (Ips typographus L.) in the region in the past. Strong wind events originate mainly in connection with convective storms that generally occur during the summer half-year (April to September) or in the form of gales along conspicuous horizontal pressure gradients that usually occur during the winter half-year (October to March, Dobrovolný and Brázdil, 2003); tornadoes as well as tropical cyclones are generally absent in Central Europe (but see Setvák et al, 2003).…”