Assessing how accumulated precipitation and long dry sequences impact the soil water storage

Abstract

Precipitation or no precipitation persistent over time often became extreme weather conditions with greater regional economic impact. The temporal and spatial variability of these variables, together with the evapotranspiration, is crucial in the east‐northeast of Argentina, where rain‐fed agricultural production is carried out. In this work, the frequency of precipitation was studied from dry spells and complemented with an analysis of the accumulated precipitation and evapotranspiration. In particular, dry sequences longer than 15 days, return period and severity, were the focus of this study. Finally, the impact of the amount and frequency of precipitation on soil water storage was assessed through a decadal analysis. The region of study is characterized by northeast‐southwest gradient in accumulated precipitation and east–west gradient in winter long dry sequences. During summer, higher and more frequent precipitations (lower probability of long dry sequences and lower return period of 15 days and severity) were presented whereas the opposite was found in winter. However, the stations located to the west presented the highest probability of long dry sequences with higher severity and lower accumulated precipitation. This result highlights the vulnerability of the agriculture activity in the western stations. Regarding the impact of long dry sequences over soil water storage, the seasonality of evapotranspiration is also involved. The impact is stronger during austral summer because of higher values of evapotranspiration and it is lower during winter, in spite of the higher probability of long sequences. Decadal analysis suggested that soil water storage responds to precipitation amount or frequency depending on the magnitude of the anomalies. In this sense, the impact of precipitation over soil water storage depends on how it is distributed.