Coastal Erosion Resilience on the U.S.—Mexico Border
Researchers conducting sampling on the beach
Diagnosis of Coastal Erosion and Wastewater Contamination in the Tijuana-San Diego Coastal Zone, is a report developed by Proyecto Fronterizo de Educación Ambiental A.C. in collaboration with the Permanent Forum of Binational Waters, the Instituto Tecnológico de Tijuana, and the City of Imperial Beach.
The main objective of the One Coast, One Community is to generate and disseminate accessible information about water quality and coastal erosion in the San Diego, Tijuana, and Rosarito region through an open science and citizen participation approach.
This approach aims to facilitate the understanding of climate vulnerability and promote binational community empowerment for greater resilience.
Justification
The increasing frequency of extreme weather events due to climate change highlights the importance of achieving greater coastal resilience.
According to the International Union for Conservation of Nature (IUCN), 94 trillion dollars will be invested in protection infrastructures worldwide in the next 20 years due to climate change.
The United Nations Environment Programme (UNEP) published the Adaptation Gap Report in 2023, emphasizing that investing in adaptation and mitigation can significantly reduce future climate costs.
Read the full report
In this context, the Tijuana-San Diego region faces significant challenges due to its climate vulnerability and high water stress. Intense and sudden rains, combined with rising temperatures, cause significant damage to the region’s infrastructure.
The projected decrease in rainfall by 2040, combined with high water stress, threatens water availability and exacerbates coastal erosion and contamination problems.
Download the full report “Diagnosis of Coastal Erosion and Wastewater Contamination in the Tijuana–San Diego Coastal Zone” and explore key findings to support smarter coastal management and cross-border solutions.
Description of the Study Area
The study area covers a total surface of 102.4 km², with 59.3 km² in Mexico and 43 km² in the United States. The coastal region of the United States includes the cities of Coronado and Imperial Beach, connected by the sandy bar of Silver Strand. In Mexico, the study area covers 24 km of the coastal zone in the municipalities of Tijuana and Playas de Rosarito.
The study area is home to 137,770 people, with 85,746 inhabitants in Mexico and 52,024 in the United States. Tijuana is the most populous municipality in Mexico, with 1,922,523 inhabitants, and Playas de Rosarito has 126,890 inhabitants.
The region has an arid and temperate climate, with an annual average temperature of 16.4°C in Tijuana and 262 mm of annual average precipitation. Playas de Rosarito has a similar climate, with an annual average temperature of 12-18°C and 206 mm of annual precipitation. Coronado and Imperial Beach enjoy a misty desert climate with an average seasonal precipitation of 247.1 mm.
The Tijuana coast features poorly consolidated sedimentary materials and layers of hard volcanic materials. In Playas de Rosarito, the dominant lithological units are igneous and sedimentary rocks. In Coronado and Imperial Beach, the coastal geomorphology mainly consists of loose sands and rocky cliffs.
The coastal region in the Mexican study area belongs to Hydrological Region 1 “Northwest Baja California.” In the United States, the San Diego Bay watershed and the Otay Hydrological Unit significantly influence coastal hydrology.
Vegetation cover is scarce and fragmented, with areas of induced vegetation, crops, and grasslands in the Mexican zone, and sand dune vegetation, vernal pools, and coastal marshes in the U.S. zone.
Urban development and tourism activities have increased pressure on coastal resources. In Tijuana and Playas de Rosarito, there is an increase in urban land and industrial and tourism activities. In the United States, land use management focuses on maintaining open and undeveloped spaces in much of the Otay watershed.
Main Problems Identified
Beach and cliff erosion affects both infrastructure and coastal ecosystems. The region's mixed geomorphology and the presence of poorly consolidated sedimentary materials exacerbate this problem.
The discharge of untreated wastewater contaminates marine water, affecting public health and biodiversity. Current sanitation systems are insufficient to handle the volume of wastewater in the region.
Key Findings
The infrastructure for wastewater treatment in the coastal zone is insufficient. It is necessary to improve the operational capacity of these facilities to increase community resilience to adverse conditions.
Marine water quality in the study area is compromised by wastewater and solid waste discharges. Water quality monitoring studies have identified critical contamination points that require immediate attention.
Coastal erosion and Sedimentation are critical problems affecting the stability of infrastructure and the health of marine ecosystems. The combination of natural and anthropogenic factors, such as urban development and industrial activity, exacerbates these problems.
Institutional Instruments
México: Has implemented policies and strategies for coastal management, including the Environmental Strategy for Integrated Coastal Zone Management and the creation of the Intersecretarial Commission for the Sustainable Management of Seas and Coasts. However, there are limitations in the execution and financing of these programs.
United States: Possesses an advanced coastal management system with programs such as the Coastal Zone Management Act and the National Estuary Program. Additionally, the San Diego Association of Governments (SANDAG) has developed coastal monitoring and preservation programs that have provided valuable data for resilience planning.
Conclusions
The diagnosis reveals that the Tijuana-San Diego coastal zone faces serious challenges related to erosion and water contamination. Current infrastructures are insufficient to manage the impacts of climate change, and greater coordination and funding are required to implement effective resilience strategies. Binational collaboration and community participation are essential to address these problems comprehensively.
Recommendations
Improve Sanitation Infrastructure
Invest in more efficient wastewater treatment systems to reduce marine water contamination.
Strengthen Coastal Management
Implement and fund sustained coastal monitoring and protection programs, ensuring coordination between various governmental and community entities.
Promote Education and Community Participation
Implement and fund sustained coastal monitoring and protection programs, ensuring coordination between various governmental and community entities.
Develop Nature-Based Solutions
Integrate hybrid approaches that combine traditional infrastructure with natural solutions for coastal protection, such as dune and wetland restoration.
Tools and Data to Build a Water Contamination Map
This section presents a series of detailed maps that illustrate erosion risks, hydrology, and land use across the region. These high-resolution files are valuable tools for coastal resilience planning and environmental protection along the U.S.–Mexico border.
Combined with water quality analysis available in the dashboard, these resources enable the creation of a comprehensive water contamination map. Users can also generate and export data from our dashboard to better visualize contamination patterns and inform coastal management strategies.
Mapa 1
Study area
Mapa 2
Popullation
Mapa 3
Population density
Mapa 4
Topography
Mapa 5
Geology
Mapa 6
Slopes
Mapa 7
Contour lines
Mapa 8
Hydrology
Mapa 9
Basin system, subbasin and micro basins
Mapa 10
Uncovered land index
Mapa 11
Eroded land
Mapa 12
Land use
Mapa 13
Unidentified water discharge points
Mapa 14
Infraestructure points
Mapa 15
Social gap
Mapa 16
Areas in Mexico that are not registered in INEGI
Mapa 17
Erosion potential
References
1. Proyecto Fronterizo de Educación Ambiental A.C. (2023). Diagnóstico de Erosión y Contaminación por Aguas Residuales en la Zona Costera de Tijuana-San Diego. Tijuana, México.
2. Union Internacional para la Conservación de la Naturaleza (IUCN). (2023). Informe sobre la Brecha de Adaptación 2023.
3. Programa de Naciones Unidas para el Medio Ambiente (PNUMA). (2023). Informe sobre la Brecha de Adaptación 2023.
4. Secretaría de Medio Ambiente y Recursos Naturales (SEMARNAT). (2022). Estrategia Ambiental para la Gestión Integrada de la Zona Costera. Ciudad de México.
5. Comisión Nacional del Agua (CONAGUA). (2023). Región Hidrológica 1 “Baja California Noroeste”.
6. Asociación de Gobiernos de San Diego (SANDAG). (2023). Programas de Monitoreo y Preservación de la Costa.
7. González, F., & García, R. (2022). Impacto del Cambio Climático en la Infraestructura Costera. Revista de Ingeniería y Medio Ambiente, 45(3), 123-135.
8. Gómez, L. et al. (2023). Impactos de la Contaminación por Aguas Residuales en Ecosistemas Marinos. Revista de Ciencias Ambientales, 78(2), 58-71.
9. Instituto Tecnológico de Tijuana (2023). Estudios de Geomorfología y Hidrología de la Costa Tijuana-San Diego. Tijuana, México.
10. National Oceanic and Atmospheric Administration (NOAA). (2022). Guía de Gestión Costera y Recursos Marinos de California.
