Weather Radar Rainfall Summer Analysis of Irrigated vs Rainfed Nearby Areas

Abstract

The objective of this work is to study rainfall characteristics (frequency, amount and type) in a semi-arid region in the Eastern Ebro basin (Iberian Peninsula). The region is included approximately in a 20 km per 30 km rectangle and is divided in two different areas, one irrigated with an artificial channel, and another one non-irrigated. The two areas may present a big difference of surface temperature in a short distance, particularly during midday hours of summer months due to high evapotranspiration contrasts. The study focusses in finding possible differences in rainfall characteristics between two areas. The methodology used is based on the analysis of radar reflectivity data, which is processed to determine the rainfall type, classified in convective and non-convective, a part of rain occurrence and amount. The work examined June, July and August data from years 2014 to 2020 analysing daily, monthly and total rain events distributions in both areas. The results show a big variability of the rainfall in the region depending on the year and as expected, an increase in convective rain in both areas during the afternoon. Although there is not a significant difference in the rainfall type nor in the convective rainfall rate between areas, there is a difference in the convective rain distribution along each area, being the rain in the irrigated part less homogenous than the non-irrigated part. This study has been performed in the framework of the Analysis of Precipitation Processes in the Eastern Ebro Subbasin project (WISE-PreP, RTI2018-098693-B-C32/AEI).