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Western Geographic Science Center


Alternative Scenario Developments on the US-Mexico Border

The sister cities of Nogales, Arizona and Nogales, Sonora, Mexico, known collectively as Ambos (both) Nogales, suffer from environmental problems attributed to decades of urban growth (fig. 1; fig. 2). In this project, results derived from coupling urban growth and nonpoint source pollution models in a virtual environment help make estimates of current, future, and hypothetical conditions using Geographic Information Systems (GIS), remote sensing, and a watershed approach.

Image and map of study area Image and map of study area
Figure 1: Study Area
Figure 2: Aerial photograph of Nogales, Ariz. (upper left), the United States-Mexican border (diagonally from right to left), and Nogales, Sonora, Mexico (lower right). Photograph by Pamela L. Nagler, 2004.
Landsat satellite images showing predicted urban growth
Urban area digitized form 2002 Landsat satellite image (left) and predicted growth in 2030, using SLEUTH model (right).

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).

Image showing predicted erosion for years 2002 and 2030
Figure 4: Results of the USLE model used for identifying hot spots of erosion based on future urban growth trends.

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.

Image showing Floodwaters
Figure 5: Floodwaters flow down Calle Reforma toward downtown Nogales, Sonora, near the Marisposa port of entry (Ibarra, Ignacio, 2003. Nogales, Sonora, flooded, Storms kill two, choke city with mud and debris: published in The Arizona Daily Star on Tuesday, July 29, 2003).

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.

Methodologies for predicting watershed response associated with land-use change within a spatial and temporal context through the use of a hydrological model in a cross-border setting. The KINEROS2 model is implemented via the AGWA 2.0 GIS interface to evaluate the watershed of Nogales, Arizona and Nogales, Sonora, Mexico to assess flood vulnerability by quantifying volumes of runoff and peak flow, based on alternative land-use scenarios.

Ambos Nogales watershed runoff map.
Figure 6. Ambos Nogales watershed runoff (mm) based on a 10 year-1 hour flood event.

Simulations of various climatic scenarios, increased urbanization, increased plant cover at high-risk locations as recommended for sustainable development in the future, and planned detention reservoirs to identify areas that will be most impacted by these features/events and provide these immediate results to decision-makers. Under these scenarios, simulated runoff, sediment yield, and pollutant loads in the main sub-watershed channels were estimated.

In 2010, this research was adopted by the U.S. and Mexican Sections of the International Boundary and Water Commission (IBWC/CILA), who have contracted the USGS, in cooperation with Mexico's National Water Commission (CONAGUA), the University of Arizona, the City of Nogales, Sonora, Mexico, the Nogales, Sonora Wastewater Utility (OOMAPAS-NS), Mexico's National Water Commission (CONAGUA), Arizona Department of Water Resources, and Arizona Department of Environmental Quality (ADEQ) to predict the impacts of the flooding and help situate flood management efforts in Ambos Nogales. Our watershed modeling approach will quantify estimates of the amount of water being detained by of newly constructed detention basins in Nogales, Sonora.

Photograph of meeting participants.
Figure 7. Photograph of meeting (January 19, 2010) of agencies collaborating in Ambos Nogales Watershed Planning.


Point of Contact: Laura M. Norman, Ph.D.

Publications and Websites:

Norman, Laura M., 2010, Flash-Flood Forecasting at Ambos Nogales, In the Border Climate Summary, Climate Assessment for the Southwest (CLIMAS) program, University of Arizona, Tucson, Ariz., http://www.climas.arizona.edu/files/climas/pdfs/periodicals/BorderClimateSummary_Jun10.pdf (NEWSLETTER)

Norman, L.M., Levick, L., Guertin, D.P., Callegary, J., Quintanar Guadarrama, J., Zulema Gil Anaya, C., Prichard, A., Gray, F., Castellanos, E., Tepezano, E., Huth, H., Vandervoet, P., Rodriguez, S., Nunez, J., Atwood, D., Patricio Olivero Granillo, G., and Octavio Gastelum Ceballos, F., 2010, Nogales flood detention study: U.S. Geological Survey Open-File Report 2010-1262, 112 p. [http://pubs.usgs.gov/of/2010/1262/].

Norman, Laura M., Villarreal, Miguel, Wallace, Cynthia S.A., Gil Anaya, Claudia Zulema, Diaz Arcos, Israel and Gray, Floyd, 2010, A High-Resolution Land-Use Map: Nogales, Sonora, Mexico: U.S. Geological Survey Open-File Report 2010-1156, 28 p.

Norman, Laura M., Huth, Hans, Levick, Lainie, Burns, I. Shea, Guertin, D. Phillip, Lara-Valencia, Francisco, and Semmens, Darius, 2010, Flood Hazard Awareness and Hydrologic Modeling at Ambos Nogales, US-Mexico Border, Journal of Flood Risk Management, Volume 3: Issue 2, 15 p

Norman, Laura M., Feller, Mark, and Guertin, D. Phillip, 2009, Forecasts of Cross-border Urban Growth Using the SLEUTH Model; Ambos Nogales Watershed, United States-Mexican Border, Computers, Environment, and Urban Systems, 33: pp. 150-159.

Norman, Laura M., Guertin, D. Phillip, and Feller, Mark, 2008. An Approach to Prevent Nonpoint-Source Pollutants and Support Sustainable Development in the Ambos Nogales Transboundary Watershed, p. 29-32 In Norman, Laura M., Hirsch, Derrick D., and Ward, A. Wesley, eds., 2008, Proceedings of a USGS Workshop on facing tomorrow's challenges along the U.S.-Mexico border; monitoring, modeling, and forecasting change within the Arizona-Sonora transboundary watersheds: U.S. Geological Survey Circular 1322, 63 p. (http://pubs.usgs.gov/circ/1322/).

Norman, Laura M., Guertin, D. Phillip, and Feller, Mark, 2008. A Coupled-Model Approach to Reduce Nonpoint Source Pollution Resulting from Predicted Urban Growth: A Case Study in the Ambos Nogales Watershed, Journal of Urban Geography, 29 (5): pp. 496-516.

Norman, L.M., and Wallace, C.S.A., 2008, Mapping land use/land cover in the Ambos Nogales study area: U.S. Geological Survey Open-File Report 2008-1378, 42 p. [http://pubs.usgs.gov/of/2008/1378/].

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. 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, 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.

Recent Presentations (Abstracts):

Norman, Laura M., Gray, Floyd, Callegary, James, Huth, Hans, Gastelum Ceballos, Francisco Octavio, Gil Anaya, Claudia Zulema, Goodrich, David, Woodard, Gary, Quintinar, Jesus, Nunez, Jose, Oliveros, Gilberto, Molina, Roberto, Guertin, D. Phillip, and Canizales, Eduardo, 2010, Collaborative Work for Flash-Flood Forecasting at Ambos Nogales, International Conference on Urban and Global Environmental Change, Arizona State University, Tempe, AZ, October 15-17.

Gray, Floyd, Norman, Laura M., Quintinar, Jesus, Callegary, James, Woodard, Gary, Huth, Hans, Gil Anaya, Claudia Zulema, Canizales, Eduardo, and Goodrich, David, 2010, Early Hazard Warning and Modeling Network in Nogales, Mexico, to be presented at the National Association of Black Geologists and Geophysicists 29th Annual Technology Conference "Unearthing Future Geoscientists", September 08 – 11, 2010, San Antonio, Texas.

Caldeira, Felipe, Norman, Laura M., Callegary, James, Nubes Ortiz, Gerardina, O’Rourke, Mary Kay, de Zapien, Jill, Gray, Floyd and Rosales, Cecilia, 2010, Water Quality and Health Analysis in Two Different Colonias of Nogales, Sonora, Mexico, [abs.], Arizona Hydrological Society, Sept 1-4, Tucson, Ariz.


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