Frequency Trend Analysis of Heavy Rainfall Days for Germany
by Detlef Deumlich
1,* [OrcID] and Andreas Gericke
2 [OrcID]
1
Leibniz Centre for Agricultural Landscape Research (ZALF), Eberswalder Str. 84, 15374 Müncheberg, Germany
2
Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Justus-von-Liebig-Str. 7, 12489 Berlin, Germany
*
Author to whom correspondence should be addressed.
Water 2020, 12(7), 1950;
https://doi.org/10.3390/w12071950Received: 17 June 2020 / Revised: 3 July 2020 / Accepted: 7 July 2020 / Published: 9 July 2020
(This article belongs to the Section Water Quality and Contamination)
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Abstract
Climate change is expected to affect the occurrence of heavy rainfall. We analyzed trends of heavy rainfall days for the last decades in Germany. For all available stations with daily data, days exceeding daily thresholds (10, 20, 30 mm) were counted annually. The Mann–Kendall trend test was applied to overlapping periods of 30 years (1951–2019). This period was extended to 1901 for 111 stations. The stations were aggregated by natural regions to assess regional patterns. Impacts of data inconsistencies on the calculated trends were evaluated with the metadata and recent hourly data. Although the trend variability depended on the chosen exceedance threshold, a general long-term trend for the whole of Germany was consistently not evident. After 1951, stable positive trends occurred in the mountainous south and partly in the northern coastal region, while parts of Central Germany experienced negative trends. The frequent location shifts and the recent change in the time interval for daily rainfall could affect individual trends but were statistically insignificant for regional analyses. A case study supported that heavy rains became more erosive during the last 20 years. The results showed the merit of historical data for a better understanding of recent changes in heavy rainfall.
Keywords: frequency of heavy rainfall days; rainfall erosivity; water erosion; Mann–Kendall trend test; climate change; uncertainties; change of locality; time interval
1. Introduction
https://www.mdpi.com/2073-4441/12/7/1950/htm
