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Documentary evidence as a source of data for studying droughts in the Czech lands
Řezníčková, Ladislava ; Brázdil, Rudolf ; Kotyza, O. ; Valášek, H.
Information about past droughts may be derived from the various kinds of documentary evidence. Documentary data are particularly applicable to the pre-instrumental period but may also be used for the overlapping period with instrumental records. They are extracted from written narrative sources, weather diaries, personal and official letters, newspapers, religious records, epigraphic sources, and other sources. Direct descriptions of weather facilitate identification of meteorological droughts, while descriptions of drought impacts are used to identify agricultural and hydrological droughts. Documentary evidence enabled the creation of series of precipitation indices which classify dry months on a scale of –1 (dry), –2 (very dry), and –3 (extremely dry). In this way, it is possible to study the frequency, seasonality, severity, and impacts of drought episodes in the pre-instrumental period.
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Precipitation variability in the czech land since ad 1500. How strong is the signal contained within documentary sources?
Dobrovolný, Petr ; Brázdil, Rudolf ; Trnka, Miroslav ; Kotyza, O. ; Valášek, H.
Past climate may be reconstructed from a number of proxies. Some of them are “natural archives”, such as tree rings, ice cores and boreholes, most of which are sensitive to air temperature. Other valuable information can be also found in “man-made archives”. Various sources of documentary data very oft en refer not only to temperature but also to other aspects of past weather and climate, such as dry and wet periods. We use the long and homogeneous precipitation series from the recent instrumental period to calibrate precipitation indices derived from older documentary sources. Th e primary objective of this contribution is to provide a quantitative reconstruction of precipitation in the Czech Lands for the last 500 years. Calibration and verifi cation statistics are used to evaluate the strength of the signal. Reconstructed precipitation series are compared with similar Central European documentary-based reconstructions, as well as with reconstructions based on a range of natural proxies.
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Droughts in the Czech Lands during 18th century
Brázdil, Rudolf ; Řezníčková, Ladislava ; Kotyza, O. ; Valášek, H. ; Dobrovolný, Petr
Th is paper addresses dry episodes and droughts in the Czech Lands during the 18th century. It is based on various types of documentary evidence, including data describing phenomena related to drought patterns, from the occurrence of precipitation (or lack of it) to derived impacts (bad yields, water shortages, drying watercourses, etc.). Th e documentary data include various degrees of detail, but their interpretation allows work at the level of monthly resolution. Dry conditions for at least two consecutive months in a given year were considered as drought for our purposes. A total of 49 years with droughts were derived from documentary data, with the prevailing occurrence of dry months in the summer half-year (April–September: 66.0%) associated with the most severe impacts. Th is shows that probably all the droughts with two-year re-occurrence intervals were identifi ed from the documentary data available. As examples of impacts and their territorial extent, some years with severe droughts in the eastern part of the Czech Lands, Moravia, are described (1718, 1719, 1726, 1746, and 1790). Th e results obtained are an important contribution to the more broadly-oriented study of droughts in the Czech Lands during the past 500 years based on documentary and instrumental data.
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