Trophic State Index estimation from remote sensing of lake Chapala, México

  • Alejandra Selene Membrillo-Abad Posgrado en Ciencias de la Tierra, Instituto de Geofísica, Universidad Nacional Autónoma de México, Ciudad Universitaria, C.P. 04510, Ciudad de México, Mexico.
  • Marco Antonio Torres-Vera Asociación para Evitar la Ceguera en México, Vicente García Torres 46, San Lucas Coyoacán, C.P. 04030, Ciudad de México, Mexico.
  • Javier Alcocer Facultad de Estudios Superiores-Iztacala, Universidad Nacional Autónoma de México, Av. de los Barrios No. 1, Los Reyes Iztacala, 54090 Tlalnepantla, Estado de México, Mexico.
  • Rosa Ma. Prol-Ledesma Instituto de Geofísica, Universidad Nacional Autónoma de México, Ciudad Universitaria, C.P. 04510, Ciudad de México, Mexico.
  • Luis A. Oseguera Facultad de Estudios Superiores-Iztacala, Universidad Nacional Autónoma de México, Av. de los Barrios No. 1, Los Reyes Iztacala, 54090 Tlalnepantla, Estado de México, Mexico.
  • Juan Ramón Ruiz-Armenta Instituto de Geofísica, Universidad Nacional Autónoma de México, Ciudad Universitaria, C.P. 04510, Ciudad de México, Mexico.
Keywords: Water quality, SPOT, Trophic State Index, Chlorophyll reflectance.

Abstract

The Trophic State Index (TSI) was estimated for Lake Chapala by remote sensing techniques as an indicator of water quality. Our results show that multispectral satellite images can be successfully used to monitor surface water parameters related to trophic state (i.e., chlorophyll-a and Secchi disc depth). Lake Chapala is the largest water body in Mexico and supplies Guadalajara City with over 60% of its freshwater requirements. The Lerma River is the main tributary of Lake Chapala and exhibits significant water quality deterioration associated with nutrient enrichment coming from drainage from urban, agriculture and livestock areas. This study is based on the modification of the optical properties of the water caused by increased values of turbidity and Chl-a. We estimated turbidity on the basis of empirical relationships between reflectance data in band SPOT S2 and Secchi disc depth, and Chl-a concentration values from the relationship between band ratio SPOT S3/S2 and Chl-a concentration in the water samples. The results show that application of defoliants to eradicate aquatic weeds did not ameliorate the trophic state of the lake. The Trophic State Index determinations are based on multispectral image reflectance values, which revealed Chapala to be in the range from oligotrophic to mesotrophic. The use of remote sensing data allows a more efficient, continuous and low-cost Trophic State Index monitoring of Lake Chapala to assist in the implementation of regulations toward water quality improvement.

Published
2017-05-02
Section
Articles