![]() ![]() For example, the mean flood date has altered especially in the high latitude north hemisphere due to warming induced earlier snowmelt 3, 19. On the regional or continent scales, these influential factors include short-term heavy rainfall, rainfall on saturated soil, snow melt water, which individually or jointly stimulate the flood events 3, 37, 38, 39. For a specific flood event, the influential factors are well documented in terms of hydro-meteorological or circulation aspect 35, 36. The underlying mechanism under exploitation includes the atmospheric conditions and others, and the atmospheric factors are much more influential than the catchment and river system factors 11, 23, 34. Shifts in flood timing is often used as a monitor to interpret the mechanisms that cause floods 20, 33. The spatial pattern of mean flooding date has been identified in Europe 3, 19, 22, 26, north America 23, 27, 28, 29, Australia 30, Brazil 31, Africa 32 or globally 10, 21. Recently, there have been more studies on flood timing 3, 19, 20, 21, 22, 23, 24, 25. The influencing factors in flood magnitude changes have also been investigated extensively including climatic and human factors, e.g., precipitation, soil moisture, snow, dam construction, land-use change, river training 14, 15, 16, 17, 18. There are intensive studies on flooding, most of which focus on the historical trends in flood magnitude and intensity and could not reach a consistent signal in flood magnitude change on global scale 8, 9, 10, 11, 12, 13, 14. This study provides an insight on the shifting mechanism of flood timing, and supports decisions on the global flood mitigation and the impact from future climate change.įloods are one of the most dangerous climate-related disasters, and climate change has altered the distribution, intensity and timing of floods worldwide 1, 2, 3, 4, 5, 6, 7. Earlier flood timing in the north America and Europe was caused by earlier snowmelt while delayed extreme soil moisture excess and precipitation have jointly led to delayed floods around the monsoon zone, including south Africa, India and Japan. Earlier floods were found extensively in the north America, Europe and northeast Australia while delayed floods were prevailing in the Amazon, Cerrado, south Africa, India and Japan. The shift in flood timing has a trend from − 22 days per decade (earlier) to 28 days per decade (delayed). There is a clear global pattern in the mean flooding date: winter (Dec–Feb) across the western Coastal America, western Europe and the Mediterranean region, summer (Jun–Aug) in the north America, the Alps, Indian Peninsula, central Asia, Japan, and austral summer (Dec–Feb) in south Africa and north Australia area. The shift in flood timing and its relationship with three influential factors (maximum 7-day precipitation, soil moisture excess, and snowmelt) are investigated. This paper studies the shifting in flood timing at 6167 gauging stations from 1970 to 2010, globally. Climate change will have an impact on not only flood magnitude but also on flood timing. ![]()
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