People and Habitats of the Colorado River Delta

   Water is fundamental to life, so many disputes occur over water rights in the arid west, especially over the federally-owned, operated, and managed Colorado River, which is diverted and altered by dams. The surface water that does flow is often diverted for agricultural use, in plots that have replaced the riparian vegetation along the banks of the river. (Agriculture is the most widespread source of pollutants impairing rivers and streams.) The agriculture plots not only replace riparian forests, but also promote the dumping of pesticides and other chemicals into the river to be carried further down-stream, polluting the water and increasing the salinity such that by the time it reaches Mexico, the riparian vegetation becomes diseased and water-stressed and this results in lost habitat. The species of trees and shrubs in the riparian zone is important for migrating or nesting birds that require particular habitats. The quality of the water and the connectivity of the bio-diverse regions are fundamental to many species who use only these islands or pockets of land as breeding grounds. More critical is that the local human population often becomes at risk either from reduced food production or from reduced water quality and quantity.

   Political and technical applications are needed. The political solution must come from two key negotiations that will guide the ecological status of the river in the future: (i) the lower Colorado River multi-species conservation program (LCR MSCP) and (ii) the redefinition of surplus flow criteria to guarantee a minimum water delivery to the delta. The technical solution requires a GIS to help researchers identify the stretches of prime riparian habitat for providing for and protecting this endangered species area that connect the diverse eco-regions of the delta and to make it into the species-rich area that it was before the system of dams was put on the Colorado river.

   Additionally, a monitoring program for water resources is needed in the delta region. This requires determining the extent and magnitude of land cover change using remote sensing to aid in the assessment of the lack of water. Although Thematic Mapper (TM ) images have been used to make critical assessments of the habitat in the delta, the Moderate Resolution Imaging Spectrometer (MODIS) has been recommended for use because of its improved spectral, radiometric, and geometric features. The characterization of characterize the biomes within the delta must occur not only with teams of ground-crews evaluating the species present, but also with long-term monitoring of the river flow itself, surface wetness, wetland area and rainfall. The areas of interest which can be monitored include the following: Land cover / Land use, Vegetation Dynamics, Bio-diversity and Habitat Analysis, Surface Temperature, Water Resources, Surface Wetness, Wetlands, and Atmospheric Precipitation. Most important to monitor is land cover change because the riparian vegetation boundaries shrink or swell with the amount of water available and monitoring the extent and magnitude of such changes may tell us something about the percent cover and acreage per species. Naturally, the magnitude of the vegetation will change with the seasons, and the vegetation dynamics often follow El Nino and monsoon weather conditions in this arid and semi-arid regions.

   With ground measurements of transpiration and aerial sensor techniques to measure canopy temperatures, plant stress may itself be monitored. Plant stress can be due to (i) high salinity in the water such that plants cannot take up water, (ii) not enough surface flow was released from altered / dammed rivers, (iii) the aquifer has been reduced by urban infrastructure build-up that comes with population increases, or (iv) due to land clearing. The biogeochemistry on an ecosystem is affected by these water stresses and their impact on the extent of riparian vegetation coverage. Once the ecosystem has been altered, there is room for urban growth which comes with a higher demand for water, the energy balance gets disrupted due to differential surface temperatures that correspond to different land covers, and the infrastructure has greater room to spread into what was once natural. With new sensors and techniques for estimating transpiration in riparian plants, the percent of water lost through surface evaporation and that lost through transpiration can be quantified for a better estimate of water balance in the delta.