Developing a Database to Examine Environmental Flows

Introduction

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Riparian corridors are lands bordering rivers or streams. Riparian ecosystems account for less than two percent of land area in the arid southwestern U.S. but support the highest abundance and density of species of all habitat types in the region, including endangered and threatened species (Albright et al., 2021). Additionally, riparian riparian
Definition of riparian habitat or riparian areas.

Learn more about riparian corridors help filter water, reduce erosion, mitigate floods, and increase groundwater recharge.

To maintain aquatic and riparian ecosystems, sufficient surface and groundwater flow is needed, commonly referred to as “environmental flows.” Environmental flows are the quantity, quality, and timing of water flowing into a freshwater resource that is required to sustain riparian and aquatic ecosystems. Environmental flows protect aquatic and riparian ecosystems in arid regions by moving water to minimize water pollution, stabilizing river beds, and increasing resilience to invasive species invasive species
An invasive species is any plant or animal that has spread or been introduced into a new area where they are, or could, cause harm to the environment, economy, or human, animal, or plant health. Their unwelcome presence can destroy ecosystems and cost millions of dollars.

Learn more about invasive species . 

In many cases data are lacking on the environmental flows needed to support riparian and aquatic ecosystems despite how critical they are to desert life. With funding from the Desert Landscape Conservation Cooperative (DLCC), the Water Resources Research Center (WRRC) at the University of Arizona and the Watershed Ecohydrology Program at Northern Arizona University created the Desert Flows Database (Database). The Database is a compilation of over 400 peer-reviewed pieces of literature that contains high-quality qualitative and quantitative information to help resource managers better understand environmental flows in desert streams in the U.S. and Mexico. The Database organizes environmental flow information from 41 desert watersheds and at-risk rivers and springs into six ecoregions: Sonoran Desert, Mojave Desert, Chihuahuan Desert, Sierra Madre Occidental, Madrean Archipelago, and Arizona/New Mexico Mountains and Plateau. Using the Database, the research team conducted a study to analyze the extent and distribution of environmental flow data, including the most frequently studied species and common stressors, throughout the desert river basins of the U.S. and Mexico. 

Key Issues Addressed

Impacts such as groundwater pumping, urban development, and pollution can hinder nature’s ability to provide the water needed to support ecosystems in arid regions. Furthermore, climate change climate change
Climate change includes both global warming driven by human-induced emissions of greenhouse gases and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change, since the mid-20th century humans have had an unprecedented impact on Earth's climate system and caused change on a global scale.

Learn more about climate change is changing the timing and intensity of rainfall while increasing temperatures are causing water to evaporate in larger amounts. All of these factors reduce replenishment of surface water and groundwater. As municipal, agricultural, and industrial water demands increase with growing populations in the Southwest, ensuring the availability of water for all uses, including for environmental benefit, becomes increasingly challenging.

Baseline data on environmental flows for most species in arid regions are lacking. Out of 280 peer-reviewed articles published from 2014 to 2015 that have the words “environmental flows,” only seven percent of the literature focused on desert and arid regions (Mott Lacroix et al., 2017). Without information on environmental flow extent, quality, quantity, and timing, resource managers cannot make quality environmental flow management decisions. For instance, managers in charge of riparian habitat areas cannot effectively protect these spaces without information on flow requirements for target species. Additionally, this lack of understanding makes it difficult to incorporate environmental flow needs into policy and law. This unequal distribution of data on flow needs and responses between species and geographic regions made it difficult to paint a complete picture of the environmental flows for the region.

Project Goals

• Survey resource managers to determine the most important and needed information for the management of riparian ecosystems
• Create a database to provide natural resource managers with information to better understand environmental flows in the desert rivers of the United States and Mexico. 
• The Database was intended to assess the following about desert watersheds in the U.S. and Mexico:
  • Determine the distribution of environmental flow data within the region
  • Determine where there are gaps in knowledge about species in environmental flow studies
  • Catalog methods researchers and managers use to determine environmental flow needs
  • Identify the most pressing risks and stressors to desert riparian ecosystems

Project Highlights

Database Reach: The U.S Forest Service uses the Database to help with environmental compliance, instream flow water right applications, and stream restoration in the Tonto National Forest Plan.

• Responding to Manager Needs: The research team surveyed 47 land and water managers in the United States and Mexico in Spanish or English to determine the most important information for the management of riparian and aquatic ecosystems. This survey concluded that the most important information for management was the depth to groundwater, surface water flows, and legal or regulatory requirements for the species that are being considered. The respondents also indicated that informed management and planning decisions would benefit from both quantitative and qualitative scientific information on aquatic and riparian ecosystems. With the results from these surveys, the methodology parameters were set to respond to manager needs.
• Methodology of Developing the Database: The WRRC established a strict set of query parameters to find all the articles, reports, and book chapters possible from reliable research sources. All studies were reviewed for information on study location, species studied, methods for determining flow response, quality of method used, risks/stressors, study elements, and relationships between surface water or groundwater and species. Many works were not developed as environmental flow papers but contained valuable information about flow needs and hydrology, allowing them to be part of the Database.
• Results of the Study: Among the six ecoregions in this study, the Arizona/New Mexico Mountains and Plateau made up 33% of the 310 studies mentioning water requirements for the environment. The Mojave Desert and the Sierra Madre Occidental had the fewest studies. In these six ecoregions, the most commonly studied species were cottonwood (Populus spp.), mesquite (Prosopis spp.), tamarisk (Tamarix spp.), willow (Salix spp.), and chub (Gila spp.), a group of freshwater ray-finned fish. The most common risks and stressors to riparian and aquatic species and ecosystems were altered flows, climate change, invasive species, groundwater impacts, water quality, and engineered structures such as dams. Overall, the Database compiled 34 different methods for determining environmental flow needs. Sixty-seven percent of these methods were qualitative, primarily focused on describing the distribution of fauna and flora of the region. The quantitative methods centered on budget and evapotranspiration methods.

Lessons Learned

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There was a bias toward researching specific systems and species. For example, significantly more environmental flow-related studies have been conducted on cottonwoods, but few on Arizona walnut (Juglans major). As such, basic data on certain systems are still limited. This data collection bias leads to data gaps on key species and does not accurately represent the region.

It is crucial to have a solid understanding of the regulatory framework to properly manage riparian and aquatic ecosystems. Managers will struggle to allocate environmental flows if the law does not warrant it. For that reason, it is essential to thoroughly examine policy standards and regulatory frameworks of the region so that environmental flow needs are met. However, even with this understanding of the regulatory framework, managers need to determine if any stakeholders are interested in preserving or restoring these ecosystems. Stakeholders need to be involved in the management of these systems since these changes will directly affect them. With this knowledge, the management of river systems can be more adaptive to both the flora and fauna of the region as well as human needs.

Although the Database is a useful tool, it needs to be marketed and updated; otherwise, it will not have adequate reach to its intended audiences and the usefulness of it will fade over time. This circumstance provides a partnership opportunity between the DLCC and WRRC to periodically update the Database. 

Next Steps

• The Database is up to date as of July 2015, but the long-term utility of the Database depends on periodic updates. The team is pursuing collaborations to use working groups from federal, state, local managers, non-profits, and academics to maintain the Database. 

Funding Partners

Desert Landscape Conservation Cooperative

Resources

• Mott Lacroix, E. K. et al. (2017). “Environmental flows in the desert rivers of the United States and Mexico: Synthesis of available data and gap analysis.” Journal of Arid Environments 140: 67-78.
• Desert Flows Methodology Guidebook
• Albright J., et al. 2022. Natural resource conditions at Glen Canyon National Recreation Area: Findings & management considerations for selected resources. Natural Resource Report. NPS/SCPN/NRR, 2022/2374. National Park Service. Fort Collins, Colorado.
• University of Arizona Water Resources Research Center
• Northern Arizona University Watershed Ecohydrology Program

Contacts

Kelly Mott Lacroix, Ecosystem Staff Officer, U.S. Forest Service-Tonto National Forest: kelly.mottlacroix@usda.gov

CART Lead Author

Tam Luong, CCAST Student Intern, University of California, Los Angeles

Suggested Citation

Luong, T. and Mott Lacroix, K. (2022). “Developing a Database to Examine Environmental Flows in Desert Rivers of the United States and Mexico.” CCAST. Retrieved from https://www.fws.gov/project/developing-database-examine-environmental-flows.