Assessing the degradation of saline wetlands in an arid agricultural region in Spain

Abstract

A constellation of saline wetlands in the Spanish Monegros Desert is currently subjected to increasing agricultural pressure. Until now, no systematic study of their degradation status has been performed, and no comprehensive map of these wetlands has been available. Both subjects are addressed for the first time in this study. In addition, we set up a conceptual tool for assessing saline wetlands degradation that improves upon available methods within geomorphological, sedimentological or hydrological frameworks. A wetlands inventory was produced and updated using satellite data, field observations, and orthophotographs, together with the available disperse data about these wetlands' toponymy and location. The degraded landscape appearance of the surviving wetlands, mainly affected by agricultural intensification ― dumping and farming ― has been qualitatively assessed.

Systematic descriptors of these saline wetlands ― escarpment, stone dumping, vegetation, and water ― were selected and analyzed to identify the status and the increase in degradation of these wetlands between 1988 and 2003. At present, 50% of the wetlands registered in 1988 have disappeared. Of the remaining wetlands, 30% have been invaded by crops and stone debris has increased in 63%. The smoothing of the escarpment appears to be a key degradation symptom. In the absence of field monitoring programs, the integration of remote sensing and GIS with field data was a powerful tool to track recent changes and assess wetland disturbance. A baseline for comparative analyses and further agro-environmental monitoring has been established.