Detección de agua en superficie en el río Negro con índices espectrales y análisis del impacto sobre el acuífero freático

Abstract

The Irrigation and Drainage Consortium of Villa Regina, Río Negro is part of a vast, irrigated valley. Its main production is pears and apple crops. Throughout the years, water and drainage problems have been detected due to a water table raise. Studying the zone extensively becomes crucial in order to understand the groundwater and surface water sources interaction and remote sensing information may enable the analysis and understanding of the hydrological behavior of the basin. The aim of this study is to detect variations in the surface water area in the Río Negro in years with contrasting hydrological conditions by using spectral indexes and relate them to water table levels. Sentinel 2 images were used in order to analyze the surface water area. Spectral indexes NDWI and MNDWI were calculated for periods of different flows: 318.66 m3/s (August 2017) y 1157.18 m3/s (August 2018). Unconfined aquifer piezometers near to the river were selected to elaborate piezometric graphs and calculate water table average elevation. The NDWI and the MNDWI indexes were consistent with the river flood in 2018, showing an increase of the water covered area of 420,000 m2 with regard to 2017. The analysis of piezometric graphs during the specific period showed an average elevation of the water table level of 0.7 m. These results suggest the interaction between the river flood and the water table in the studied area. It is possible to conclude that the use of geographical information can contribute to analyze and understand this interaction and can be used as a complement to design proper integrated water management programs for the Alto Valle of Rio Negro and Neuquén.