Rainfall variability and trend analysis in coastal arid Ecuador

Abstract

ABSTRACTThe creation of baseline climate series is the first step towards the analysis of climate characteristics and behaviour in any region of the world. The objective of this article is to construct homogeneous precipitation series for the period 1982–2011, for the study of its spatial distribution and temporal evolution (dynamics) in the Province of Santa Elena, most occidental region of continental Ecuador. Data from 22 rainfall stations at the study location enabled the construction of five precipitation series using statistical and correlation techniques to complete information gaps. Precipitations present irregular temporal and spatial variation throughout the year, with a wet season between December and May. The December–January–February (DJF) and March–April–May (MAM) trimesters account for 59.7 and 39.1 of annual rainfall. The dry season, between June and November, presents almost zero rainfall. Small precipitations were also identified in coastal, topographically low areas, with precipitations more frequent events towards the continental region. Throughout the years, there has been high variability in precipitations, with the occurrence of wet‐dry episodes associated with the ‘El Niño–La Niña’ events, which were correlated with the sea surface temperature values of the Oceanic Niño Index. Trend analysis detected an average increase in rainfall of 2.1 mm year−1 in the Province, however, the trimestral rates oscillated between 2.2 and 4.3 mm quart−1. The construction of these precipitation series has been an important step for the spatial‐temporal characterization of this peculiar tropical climate region that presents arid characteristics. These series can be applied to base scenarios for the development of climate studies and water resource management in the region.