Nowadays, in literature there are a lot of indices and factors designed to assess drought periods and water needs. Indices are presented in different spatial and temporal scale, from regional to global and chiefly are dedicated to agriculture and economy for making decision. Their application mainly depends on target and data availability. Such application imposes methodological approach; it means that obtained results should be comparable for different regions. Therefore drought indices are express as single number related to selected region. Some of them, especially the ones that are simple to calculate, are based only on one feature - precipitation for instance as a difference between total precipitation from investigated period and established norm from multiyear data. Others indices are based on more features as temperature, snow-cover, surface water and groundwater supply etc. Although it is hard to select a prori which index is the most effective, for each region the one that matches the best local environment and climatic conditions should be appointed. The paper presents a survey of indices for drought assessment and the results obtained for selected indices in Nysa Klodzka basin. ...
In the paper, the agricultural drought was defined as at least the 7-days constant period when the reserve of easily accesible water in the root zone is depleted. Calculations based on meteorological data 1996–2005 from Mochełek (near Bydgoszcz) brought the assessment of beginnings of droughts and their classification in regard of duration. The assumptions of balance method for irri-gation forecast were taken into account. Two types of soil (compact and pervi-ous) and five cultivated plants (spring wheat and barley, faba bean, potato, maize) were taken into consideration. Results of the studies confirmed that within 10-year period in Bydgoszcz surroundings 8–16 agricultural droughts occured (depending on the soil and cul-tivated plant type). The majority of droughts were moderate (series of 7–13 days with accesible water deplation). Severe (series of 14–20 days) and very severe droughts (series over 20 days) made 24% of the total number of drought spells. The qualitative assessment of severe and very severe agricultural droughts pre-sents a good compatibility to particular indexes used for atmospheric drought evaluation. ...
The aim of the study was to analyze and evaluate the occurrence of atmospheric drought during summer half-year in Wroclaw - Swojec over the 50 years 1961÷2010. For that purpose daily values of precipitation totals were used, measured at the Agro- and Hydrometeorology Observatory that belongs to the Wrocław University of Environmental and Life Sciences. Analyses were performed for particular months from May to October for 50-year period 1961÷2010. The assessment of atmospheric drought occurrence was based on the string of days without precipitation, using the criterion proposed by Schmuck for their designation. The analyzes carried out showed a decreasing tendency of the number of strings of days without precipitation lasting 9 days and more during the 50-year period 1961÷2010, but not statistically significant. This trend has stabilized during a 30-year period 1961÷1990. Mostly drought occurred in October and the least frequently in July. Longer periods without precipitation (moderate drought ) were characterized by more frequent occurrence in late summer (August ) and in September and October. In contrast, intensive drought on that area occurred sporadically and only in the period of September - October. The obtained results were consistent with the results of other authors obtained for Wroclaw for ...
An assessment of the variability of four climatic indicators of plant irrigation needs (air temperature, precipitation, frequency of atmospheric droughts, rainfall shortages) in the 1st zone of irrigation application in Poland was carried out. The analysis concerned four localities (Szczecin, Poznań, Kalisz, Toruń) during the reference multiyear period 1991-2020, in the entire period of active plant growth (V-VIII) as well as the parts of it. Results of the analysis have shown a fairly clear increase in irrigation needs in terms of the climatic criterion. It results primarily from a significant increase in air temperature, resulting in an increase in the water needs of plants. For the period 1991-2020 tendency to deepening rainfall shortages in the Szczecin Lowland and in Wielkopolska was demonstrated. The large numbers of atmospheric droughts with higher level of intensity were identified in the second part of the analysed period in the years 2015- 2020. ...
