Abstract

LOPEZ BLANCO, Jorge  and  ZAMBRANO GONZALEZ, Luis. Limnological characterization of small freshwater systems in Acambay, Mexico: correlation between field data and color video images. Invest. Geog [online]. 2001, n.44, pp.64-84. ISSN 2448-7279.

A method to evaluate the ecological characteristics of five small ponds in Acambay, Central Mexico is presented. The method was based on video remote sensing and image processing techniques in a Geographical Information System (GIS) environment, using a set of color video imagery obtained from 100 to 700 m (height above ground). Our analysts is based on establishing statistical correlations between the average values of the following limnological variables, which are considered as important for pond dynamics: 1, Suspended solids; 2. Water Turbidity/Transparency (Secchi Disk); 3. Total areas covered by macrophytes (emergent, submergent and free-floating); 4. Area covered by surface macrophytes (emergent and free-floating); 5. Zooplankton abundance (organisms per liter), and 6. Concentration of chlorophyll-a in water. All these variables were determined with respect to average reflectance values contained in video imagery (digital numbers DN per RGB band). Values were obtained from samples taken within the ponds. Results showed high correlation levels between DN values of image's bands and suspended solids concentration or water turbidity (R=0.85 to 0.98), but were low in relation to phytoplankton or zooplankton abundance. This method can be used to estimate some physica variables within ponds, but is not useful to determine biological variables.

Keywords : Ponds; limnological variables; video remote sensing; Acambay; Mexico.