Formation and evolution of the La Niña lagoon, using Modis-Aqua satellite images

Abstract

The La Niña lagoon is located in the Piura Region and its formation is produced by the increased flow of the Piura, Cascal and Motupe rivers when extraordinary El Niño events occur. This water mass has become an important aquatic ecosystem that allows the surrounding population to fish. During the El Niño Costero 2017 (January to November 2017) this lagoon was again formed, which was monitored daily from its formation using MODIS-Aqua satellite images with a spatial resolution of 500 m, received and processed by IMARPE’s TeraScan station. The lagoon area was determined based on the calculation of the Normalized Difference Vegetation Index (NDVI) and the volume of water was estimated with information from NASA’s GDEM-ASTER Digital Elevation Model (DEM). The lagoon was formed in late January 2017 and reached its maximum extension on April 5 (2,172 km2), with an approximate volume of 5.18x109 m3, this area was not greater than that recorded during El Niño 1997-98 when it was estimated at 2,326 km2. The growth rate was 33.3% per week from February 7 to April 5 and 34.1% of the maximum area was reduced until November 4.