Abstract: Background, aim and scope The problem of water and soil loss in China was serious all over the world, and it was increasingly serious in Shandong Province in recent years. Rainfall erosivity is one of the driving force of this ecological issue while precipitation is the primary cause of rainfall erosivity, thus the research of precipitation and rainfall erosivity are necessary, which would contribute to comprehensively understand the knowledge about the regional climatic change and the water resources utilization situation. This paper wrote with the study area of the three topographic regions (Jiaodong Peninsula Hilly Area (JDPHA), Luzhongnan Mountainous Area (LZNMA), and Luxibei Plain Area (LXBPA)) in Shandong province for investigate the spatial and temporal variations of the precipitation and rainfall erosivity as well as their regional difference under the influence of topography, aim to provide insight into the prevention and control of water and soil loss as well as the protection and restoration of ecological environment. Materials and methods Based on the daily precipitation data of 34 meteorological stations in Shandong Province from 1961 to 2015, the spatio-temporal precipitation and rainfall erosivity variations respectively in Shandong Province and the three topographic regions were analyzed by using the mathematical statistics methods of coefficient of variation, Mann-Kendall test, wavelet analysis and Kriging interpolation. Results The results showed that annual precipitation and rainfall erosivity of Shandong Province fluctuated and declined slightly during the period from 1961 to 2015 with the average annual precipitation of 681.3 mm and the average rainfall erosivity of 4236.3 MJ·mm·hm-2·h-1·a-1. The three topographic regions all showed the same fluctuated and slightly declined trends during the 55 years, among which, JDPHA was more obvious with the climate tendency rate of -11.6 mm/10a and -100.3 MJ·mm·hm-2·h-1·a-1/10a in precipitation and rainfall erosivity, respectively. The annual precipitation and rainfall erosivity were concentrated mostly in the summer season, the sum of precipitation and rainfall erosivity in June to August occupy for 60% and 70% of the year, respectively. The rainfall erosivity had a main period of 25 years. For the spatial characteristics of precipitation and rainfall erosivity, they all decreased gradually from the southeast to the northwest, while the values of the three regions were in the order of LZNMA＞JDPHA＞LXBPA. The study area should be divided into two parts by the “S” type boundary line through Fushan, Laiyang, Zibo, and Dingtao weather stations. High precipitation and rainfall erosivity were at the southeast side of the line, while relative low precipitation and rainfall erosivity were at the northwest side of the line. Discussion Influencing factors of the distribution and variations of rainfall erosivity were discussed. Altitude and topography also played an important role in influencing precipitation and rainfall erosivity. High precipitation and rainfall erosivity emerged on the southeast side of hilly areas (JDPHA and LZNMA) due to high moisture, climbing airflow on the windward slope of mountains, derived from the Southeast Asian Monsoon, while relative low precipitation and rainfall erosivity emerged on the northwest side of hilly areas (LXBPA) due to the foehn effect. Statistics showed that the precipitation and rainfall erosivity would increase with the rising of elevation, of which, the stations which altitude higher than 50 m the correlation coefficients of precipitation, rainfall erosivity and elevation all showed the significant level at 0.01, while the stations which lower than 50 m were not so obvious but also showed the positive correlation. Conclusions The annual and monthly variations of the precipitation and rainfall erosivity of the three topographic regions all showed the same trends with Shandong province during the period from 1961 to 2015, but there are minor differences among each topographic region in the coefficient of variation, climate tendency rate and the periodical variations of rainfall erosivity. Shandong province have been divided into two parts by the “S” type boundary line that influenced by the altitude and topography, the southeast side had high precipitation and rainfall erosivity whereas the northwest side was quite the opposite. Besides, the higher the altitude the more obvious positive correlation of the precipitation, rainfall erosivity and elevation. Recommendations and perspectives It’s necessary to plan and deploy the water and soil conservation with the stress on prevent and control water and soil loss in summer in Shandong province, especially in JDPHA and LZNMA. The southeast monsoon is the key factor that influence the precipitation and rainfall erosivity, the altitude and topography work too, but in addition, other natural and human factors like temperature, vegetation coverage, soil property, agriculture development, urban expansion also play important roles in the spatial and temporal variations of precipitation and rainfall erosivity, that will be the further research to promote the rational use of regional water resources and accelerate the conservation and restoration of the eco-environment.
Keywords: rainfall erosivity; spatial and temporal variation; topographic region; Shandong Province