Evaluation of Wetland Hydrology in Formerly Irrigated Areas

Abstract : The application of irrigation waters has the potential to alter soil morphology, patterns of hydrology, and the distribution of plant communities. As a result, the identification of wetlands in irrigated areas remains challenging. The following report is the first to evaluate the capacity of wetland hydrology to persist following the cessation of external water inputs for the purposes of wetland identification. Twelve of the thirteen study locations examined met the established criteria for wetland identification. The spatial extent of wetland hydrology was determined on-site and compared to estimates based upon an analysis of aerial imagery. Findings suggest that aerial image interpretation provides a useful, but conservative approach to identifying areas of wetland hydrology in formerly irrigated areas. A framework is proposed to support wetland delineations conducted in formerly irrigated areas incorporating off-site evaluations, site visits conducted during the regular wet portion of the year, and analysis of rainfall normality.