Predicting Environmental Consequences of Urban Development on the US-Mexico Border

The SLEUTH (Slope, Land cover, Exclusions, Urban areas, Transportation, Hydrologic) model, which was developed to predict urbanization patterns based on current and historical information about an area, was focused on a fifty-five year time period. This was calibrated based on analyses of growth and land use data between 1975 and 2002, using a time series collection of Landsat imagery, and growth was projected up to 2030. Some areas previously identified as hazardous were predicted to be heavily developed, suggesting sedimentation downstream (fig. 3).

Erosion and sediment modeling has been completed across the International border to describe conditions based on current urban extent (Norman, 2007). The Universal Soil Loss Equation (USLE) was applied with the Spatially Explicit Delivery MODel (SEDMOD) to calculate that amount of eroded material that would be available for transport ultimately being deposited along hillslopes and streams. Total watershed gross erosion was calculated as 265,760 tons per acre per year and estimated delivery to the streams as 42,360 tons per acre per year. These results are spatially distributed and maps identifying hazardous areas are useful for planning purposes (fig. 4).

The models were coupled to manipulate this effect by denying growth of potential pollution sources using alternate scenarios in the models to see if water quality predictions can be improved by curbing expansion to non-source areas ((Norman and others, 2007b). The results of this effort are meant to serve in the development of these models in combination with each other for water quality investigations and also be useful in the actual development patterns mitigated by the communities of study.

Flooding affects low-lying areas throughout Ambos Nogales, where many major streets follow the course of natural arroyos; and in the hills, landslides caused by rushing waters damages homes and streets (fig. 5). Most recently, the twin city area has experienced monsoonal flood events that the area’s infrastructure is not equipped to handle (Link to nogalesinternational.com article). Efforts are underway to identify flood control measures by means of sediment ponds, check dams, and other response mechanisms to better control flooding and runoff. Local governments are trying to get estimates of volume of runoff for better management.

We plan to assess the impact of land-use change using hydrological models and predict runoff volumes and peaks. We will apply models to predict the effects of various artificial features such as urban developments, small detention reservoirs, or lined channels on flood hydrographs and sediment yield. The Automated Geospatial Watershed Assessment Tool (AGWA) is a GIS interface jointly developed by the USDA Agricultural Research Service, the U.S. Environmental Protection Agency, the University of Arizona, and the University of Wyoming to automate the parameterization and execution of the Soil Water Assessment Tool (SWAT) and KINEmatic Runoff and EROSion (KINEROS2) hydrologic models. AGWA's current outputs are runoff (volumes and peaks) and sediment yield from KINEROS2 and from SWAT, these outputs and several water quality measures. AGWA uses commonly available GIS data layers to fully parameterize, execute, and visualize results from both SWAT and KINEROS2. It has recently been adapted to incorporate International datasets.

Publications and Websites:

Norman, Laura M., 2007. United States-Mexican Border Watershed Assessment: Modeling Nonpoint Source Pollution in Ambos Nogales, Journal of Borderland Studies 22 (1): 20 p.

Norman, Laura M., Feller, Mark, and Guertin, D. Phillip, 2007 In Review, Forecasts of Cross-border Urban Growth Using the SLEUTH Model; Ambos Nogales Watershed, United States-Mexican Border, submitted to The International Journal of Urban Policy and Planning

Norman, Laura M., Guertin, D. Phillip, and Feller, Mark, 2007 In Review, A Coupled-Model Approach to Control Sediment Dispersion Resulting from Predicted Urban Growth in a Binational Watershed, submitted to International Journal of Geographical Information Science.

Norman, Laura M., Feller, Mark, and Guertin, D. Phillip, 2007. Modeling Future Scenarios to Decrease Nonpoint Source Pollution in a US-Mexico Border Watershed: Proceedings, Arizona Hydrological Society/Southwest Hydrology Regional Water Symposium, Aug. 29-Sep. 1, 2007, Tucson, Arizona (POSTER)

Norman, Laura M., Guertin, D. Phillip, Feller, Mark, Donelson, Angela, and Lam, Alven H., 2007. A Comprehensive Plan for Sustainable Development in the Ambos Nogales Watershed, Using Geospatial Prediction Models: Proceedings, 27th Annual ESRI International User Conference, June 18-22, 2007, San Diego, California.

Norman, Laura M., Guertin, D. Phillip and Feller, Mark, 2007. An Approach to Prevent Nonpoint-Source Pollutants and Support Sustainable Development in the Ambos Nogales Transboundary Watershed [abs.]: Facing Tomorrow's Challenges along the US-Mexico Border, JW Marriott Resort and Spa, March 20-22, Tucson, Ariz.

Norman, Laura, Feller, Mark, Suarez-Barnett, Alberto, and Austin, Diane, 2007. Multiple Applications of Hot Spot Predictive Modeling for Ambos Nogales. Proceedings of the US-Mexico Binational Center for Environmental Sciences and Toxicology: Inaugural Ceremony and Global Environmental Health Workshop, March 12-14, Lowes Ventana Canyon Resort, Tucson, Arizona (POSTER)

Norman, Laura Margaret, 2005. Modeling Land Use Change and Associate Water Quality Impacts in the Ambos Nogales Watershed, U.S.-Mexico Border. Dissertation. University of Arizona, Tucson, Arizona. 216 p.

Norman, Laura M., Guertin, D. Phillip, Hernandez, David Pena, Barnett, Alberto Suarez and Ashton-Reis, Kelly, 2004, Binational Digital Soils Map of the Ambos Nogales Watershed, Southern Arizona and Northern Sonora, Mexico: U.S. Geological Survey Open File Report: OF 2004-1335. http://pubs.usgs.gov/of/2004/1335/