Abstract
The magnitude and spatiotemporal distribution of precipitation are the main drivers of hydrologic and agricultural processes in soil moisture, runoff generation, soil erosion, vegetation growth and agriculture activities on the Loess Plateau (LP). This study detects the spatiotemporal variations of individual rainfall events during a rainy season (RS) from May to September based on the hourly precipitation data measured at 87 stations on the LP from 1983 to 2012. The incidence and contribution rates were calculated for all classes of rainfall duration and intensity to identify the dominant contribution to the rainfall amount and frequency variations. The trend rates of regional mean annual total rainfall amount (ATR) and annual mean rainfall intensity (ARI) were 0.43 mm/year and 0.002 mm/h/year in the RS for 1983–2012, respectively. However, the regional mean annual total rainfall frequency (ARF) and rainfall events (ATE) were −0.27 h/year and −0.11 times/year, respectively. In terms of spatial patterns, an increase in ATR appeared in most areas except for the southwest, while the ARI increased throughout the study region, with particularly higher values in the northwest and southeast. Areas of decreasing ARF occurred mainly in the northwest and central south of the LP, while ATE was found in most areas except for the northeast. Short-duration (≤6 h) and light rainfall events occurred mostly on the LP, accounting for 69.89% and 72.48% of total rainfall events, respectively. Long-duration (≥7 h) and moderate rainfall events contributed to the total rainfall amount by 70.64% and 66.73% of the total rainfall amount, respectively. Rainfall frequency contributed the most to the variations of rainfall amount for light and moderate rainfall events, while rainfall intensity played an important role in heavy rainfall and rainstorms. The variation in rainfall frequency for moderate rainfall, heavy rainfall, and rainstorms is mainly affected by rainfall duration, while rainfall event was identified as a critical factor for light rainfall. The characteristics in rainfall variations on the Loess Plateau revealed in this study can provide useful information for sustainable water resources management and plans.
Highlights
Rainfall has undergone significant changes globally mainly due to global warming that causes large-scale changes in water vapor cycle and an increase in extreme weather events [1,2]
We examine the spatiotemporal variations in individual rainfall characteristics with regard to amount, frequency, intensity and the numbers of rainfall events using the hourly precipitation data monitored at 87 meteorological stations on the Loess Plateau (LP) from 1983 to 2012
Employing the hourly precipitation data from 1983 to 2012 at 87 meteorological stations in the LP, this study analyzed the spatiotemporal changes of rainfall events during the rainy season (RS)
Summary
Rainfall has undergone significant changes globally mainly due to global warming that causes large-scale changes in water vapor cycle and an increase in extreme weather events (e.g., flooding, droughts, and storms) [1,2]. The alterations in rainfall characteristics have affected the utilization, development, and management of water sources and the sustainable development of ecological systems on a regional (or local) scale across the world [3,4,5]. It is necessary to analyze the regional rainfall changes to better understand and address the impacts of regional climate changes [6]. Water vapor from the land surface has been affected by human influences on the hydrological cycle as well as alterations in the rainfall amount, intensity, frequency and type under climate change [13,14]
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