Urban development under extreme hydrologic and weather conditions for El Paso-Juarez: Recommendations resulting from hydrologic modeling, GIS, and remote sensing analyses.

摘要

During the 2006 El Paso-Juarez flood there were many concerns regarding the capability of the existing stormwater system to handle 50- and 100-year flood events in El Paso, Texas and Juarez, Mexico area. Moreover in 2008, a considerable wet year from the normal 223 mm of annual precipitation for El Paso demonstrated that the area could very well received large amounts of precipitation at localized areas in short periods of time, representing a great flood threat to residents living in areas prone to flood. Some climate change projections for the area are exactly what had occurred over the last two decades; an increased number of torrential rainstorms over smaller concentrated pieces of land separated by longer years of drought between rainstorms.;This study consisted in three projects focused on three critical regions within the El Paso-Juarez area that were greatly affected by the 2006 Flood. The goal was to identify if natural arroyos or the existent built stormwater system, could properly managed the projected precipitation patterns. The three projects described in this dissertation touch on the following points: (a) the importance of a reliable precipitation model that could accurately describes precipitation patterns in the region under extreme drought and wet climates conditions; (b) differences in land use/land cover characteristics as factors promoting or disrupting the possibility for flooding, and (c) limitations and capabilities of existent stormwater systems and natural arroyos as means to control flooding.;Conclusions and recommendations are shown below, which apply not only to each particular project, but also to all study areas and similar areas in the El Paso-Juarez region. Urbanization can improve or worsen a pre-existing natural stormwater system if built under its required capacity. Such capacity should be calculated considering extreme weather conditions, based on a denser network of precipitation stations to capture the various microclimates found in the region and taking into account climate change predictions. Development of new areas needs to consider not only the watershed of study but its relation to other watersheds around them. Basin parameters seemed to be of low impact while comparing them with precipitation rates. High resolution DEMs, such as those derived from LiDAR can dramatically improve the accuracy and reliability of a hydrological model. Hardware capabilities and limitations however should be considered. The overall recommendations derived from this dissertation are to direct new studies, policies and regulations at the three levels of government---local, state and federal---to: limit urban development to areas of no or low potential for flooding; implementing some type of ecological, green corridors, or conservation easements to preserve these areas; build semi-natural or hybrid stormwater infrastructure to slowdown, collect, and ultimately, transport runoff to the Rio Grande or any other waterway; consider extreme wet and dry scenarios for designation of flood-prone areas and future construction of stormwater infrastructure; and design stormwater infrastructure to retrofit the existing natural and irrigation drains.