Monthly precipitation patterns in a region vulnerable to climate-related hazards-a case study from Poland

Abstract

Precipitation totals at annual and monthly scale are key elements affecting water availability for a number of human activities. Thus, the multi-year variability and probability distribution of precipitation form the basis information for water management and damage risk assessment (caused by drought and heavy rains). The main goal of this paper is to analyse the precipitation patterns and to determine the non-exceedance probability (p, %) of extreme monthly precipitation in the region influenced by lignite mining and dominated by traditional agricultural production. Monthly precipitation totals recorded in 1961-2010 at four weather stations close to the analysed region were examined, including comparative analysis of precipitation patterns between the stations. Different non-exceedance probability (p, %) was determined with focus on extreme precipitation. Annual and monthly precipitation was characterised by a large variation of values. Temporal variability was larger than the spatial variability. The highest average sums were registered in July and the lowest in February. Minimum monthly precipitation (<10 mm) were recorded between January and April, and in October at all four weather stations. Maximum totals, amounting to more than 200 mm, were noted in July. The largest share of absolute minimum and maximum monthly precipitation was recorded at the turn of 20th and 21st centuries. Temporal and spatial distribution of precipitation for very dry, abnormally dry and extremely dry months (p ≥ 20%) were characterised by lower dispersion of values compared with wet months (p ≤ 80%). The precipitation probability distribution at p ≥20% may be useful to determine agricultural drought risk assessment in the region. Monthly precipitation at p ≤ 80% may be the background for planning drainage system efficiency and assessment of flooding risk of lignite deposits.