Trend Analysis of Precipitation, Groundwater Level and Flow Rate Data by using Mann-Kendall and Sen's Slope Estimator Statistical Tests in the Petorca Communer

Abstract

This article analyses one of the most complex socio-environmental conflicts in Chile: The Petorca water crisis. Petorca has been experiencing a shortage of water for several years. The cause of these variations has not yet been completely analyzed and the problem has remained unchanged. This paper evaluates hydrology variables to identify, quantify and demonstrate the cause of water shortages in the study area. Mann-Kendall and Sen’s slope test statistically are applied to evaluate records of rainfall monitoring stations, water level and flow rate. To determine the existence of trends over time and quantify its magnitude. A total of 760 years of data were used by analyzing 4974 precipitation events, 788 water level and 1384 flow rate records. The results indicated that (1) There is no positive or negative trend in precipitation data over the years; (2) four well-monitoring stations have a positive trend but with an insignificant magnitude; (3) all flow-monitoring stations have a negative trend. Likewise, it was evidenced that water levels and flow rates have been affecting abruptly since 2014, obtaining null records and remain constant over time. For the same period, there is no evidence of precipitation anomalies. As a result, water resources face a host of serious threats, all of which are caused primarily by human activity. Finally, the community of Petorca is experiencing a water shortage event, which is evidenced for the first time with this scientific article.