Variations in Soil Salinity and Riparian Vegetation Coverage as Indicators of Stress in an Arid Watershed

Soil salinity and riparian vegetation coverages of an arid area in northern Mexico through time were investigated. The study area comprises a 10 km segment of the lower Rio Conchos and surrounding undeveloped, non-irrigated land. The amount of area affected by salinity and the type of salinity were determined using EC (electrical conductivity) in conjunction with satellite images and corroborated by field analysis. The soil salinity derived from the remote sensing data was tied to precipitation, greenness of vegetation and water level of a nearby reservoir. The most appropriate method to assess soil salinity was found to be the selective principal component (SPCA) technique of Chavez and Kwarteng while the techniques utilized to discriminate vigorously-growing vegetation were tasseled cap transformation and the normalized difference vegetation index (NDVI). With this region undergoing a severe drought for the last ten years, the response of different parts of the ecosystem and changes in vegetation that so closely affect wildlife and other natural resources in this area can be better evaluated.