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The Nogales Early Warning Flood Hazard project

Project contact: Floyd Gray - - 520-670-5582


Natural processes such as hurricanes, thunderstorms, and snowmelt can cause floods.  Flooding also can occur as a result of failure of levees and dams and inadequate drainage in urban areas.  On the average, floods kill about 140 people each year (in the US) and cause $6 billion (2012) in property damage. When considering international, trans-boundary scenarios, the western half of the US-Mexico border twin cities configuration of Nogales, Sonora and Nogales, Arizona (Ambos Nogales) demonstrates heighten potential for calamitous events due to lack of coordination as well as steep economic and technical gradients between the adjoining response structures of the two countries.

To monitor the situation online and in real-time, go to the Alert Map to view the precipitation gages at Nogales, including gages that Floyd Gray (USGS), has established in Nogales, Sonora, Mexico for a Flood Warning project (this site works best when viewed using Google Chrome or Firefox).

Additional Real-Time gauge and climatology data as well as forecast information analyzed using the Water Resources and Climate Assessment Tool (WARCAT) can be found at the Santa Cruz Active Management Area website. This site is designed to provide water managers, stakeholders and other interested individuals with information that facilitates assessment of the current hydrologic conditions in the Santa Cruz Active Management Area (SCAMA).

Flooding in Nogales Inspecting damage from flooding Installing equipment on roof topClose-up image of equipment Station overlooking Nogales

The US Geological Survey, US Northern Command (NORTHCOM), International Boundary and Water Commission (IBWC), and the Mexican government will enable joint monitoring, tracking, and the development of strategies for flood mitigation.  This will be achieved through a weather monitoring and stream gage network in critical Mexican headwaters of Nogales, Sonora and the establishment a cooperative program between borderlands emergency personnel and  managers in the sister cities.

Map Showing Rain Gage Network

Weather map showing storms associated with flooding events

Weather map showing storms associated with flooding events

The Early Warning Flood Hazard System will consist of NOAA-specified weather stations, an rain-gage network, and USGS stream gages having remote downloading capacity.  Additionally, the supporting base-station, software, and flood-modeling software will be made available to both Mexican and US participants. The USGS will compile physiographic data on trans-boundary streams and drainage-basin characteristics including geology and three-dimensional basin configuration, erosion and reconstructed historic flood features from the region to develop an events scenario to guide emergency response personnel. The USGS and collaborators will train emergency managers in Nogales, Sonora on the interpretation of data outputs and potential impact on both the land and people with the goal of improving their ability to develop effective responses to impending hazards.


Real-time network

Resulting data will be modeled using KINEROS2 (K2) software on a GIS platform that encompasses the trans boundary Ambos Nogales watershed.  The K2 model has been implemented to simulate watershed response and predict volumes of runoff, peak flow, and watershed discharge rate based on alternative land-use scenarios. K2 model results identify flood prone areas, simulate the impact of land use change, and evaluate the impact of potential flood-control interventions in the Ambos Nogales Watershed. Products from this research will intricate real-time weather and stream-flow data into the model to calibrate it and create creating credible forecasts of flood hazard.  This is being used in a comprehensive plan for sustainable development in broader regional upper Santa Cruz U.S. - Mexico border watershed.

Results of the model at Ambos Nogales watershed, where  runoff (mm) based on a 10 year-1 hour flood event.

Results of the model at Ambos Nogales watershed, where runoff (mm) based on a 10 year-1 hour flood event.

Project contact: Floyd Gray - - 520-670-5582


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