Multi-Timescale-Based Precipitation Concentration Dynamics and Their Asymmetric Impacts on Dry and Wet Conditions in a Changing Environment

Abstract

Precipitation is one of the most important climatic factors affecting the natural environment and hydrological processes. The excessive concentration of precipitation at different time scales in spatial and temporal distribution could increase the possibility of floods or droughts and their disaster-causing extent in a changing environment. Nevertheless, the dynamics of precipitation concentration and its specific effects on dry and wet conditions remain unknown. To this end, the precipitation concentration indexes of different time scales was adopted to characterize the non-uniform distribution of precipitation within the year in this study, and the spatial and temporal variation characteristics of precipitation concentration was examined. The impacts of precipitation concentration dynamics on dry and wet conditions were then quantified based on the conditional probability of dry and wet conditions when unusual concentration of precipitation events occur under different scenarios. The Weihe River basin, the largest tributary of the Yellow River in China, was selected as a case study. The results show that: (1) the precipitation concentration in this basin is high and heterogeneous at different time scales; (2) in the same scenario, the precipitation concentration indexes exhibit stronger impacts on wet conditions than on dry conditions; (3) under different scenarios, the probability of dry conditions decreases and the probability of wet conditions increases as the precipitation concentration indexes increase. In general, this study provides new insights into the precipitation concentration dynamics and their asymmetric impacts on dry and wet conditions, which is highly relevant for drought and flood prevention.

Keywords: precipitation concentration degree, precipitation concentration period, conditional probability, dry and wet conditions