Semiarid Riparian Ecosystems: Understanding Corridors of Water and Biodiversity in the Desert

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Semiarid Riparian EcosystemsUnderstanding
Corridors of Water and Biodiversity in the Desert

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The Nature Conservancys Mission

• To preserve the plants, animals and natural
  communities that represent the diversity of life
  on Earth by protecting the lands and waters they
  need to survive.

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The Upper San Pedro River supports a diversity of
riparian habitats

• Fremont cottonwood/Goodding willow forests
• Mesquite bosques
• Riverine marshlands or cienegas
• Big sacaton grasslands

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The Upper San Pedro River also supports a rich
assemblage of species

• 390 bird species, between one and four million
  songbirds use this riparian corridor for
  migration each year
• 80 species of mammals, one of the richest
  assemblages of land mammal species in the world
• 40 species of reptiles and amphibians

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The San Pedro Riparian National Conservation Area

• Congress established the San Pedro Riparian
  National Conservation Area in 1988.
• The U.S. Bureau of Land Management manages over
  56,000 acres along the river for the purpose of
  maintaining, protecting, and enhancing the
  riparian area for wildlife and fish habitat,
  scientific, educational, and recreational uses.

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SIMPLE CONCEPTUAL MODEL OF GROUND-WATER FLOW IN
THE UPPER SAN PEDRO BASIN
INFLOW OUTFLOW
INFLOW AND OUTFLOW AT CONSTANT RATES
S
Water Table
D
N
A
M
L
A
T
E
INFLOW FROM SURFACE WATER
E
R
W
T
S
BEDROCK
OUTFLOW AS BASE FLOW TO STREAM AND TO
VEGETATION
AQUIFER
BEDROCK
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How do human uses affect the system?

• Estimated groundwater deficits (ac-ft)
• Year 1990 2000 2030
• Deficit 7,770 7,270 12,570
• Commission for Environmental Cooperation
• (CEC, 1999)
• By the year 2020 the Arizona Department of Water
  Resources projects annual extractions of 13,000
  acre feet.

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How can we best manage groundwater resources to
meet both human and natural resource needs?
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The Upper San Pedro Partnership

• A consortium of eighteen agencies and
  organizations that cooperate in the
  identification, prioritization, and
  implementation of a list of comprehensive
  policies and projects to assist in meeting the
  water needs of the Sierra Vista sub-watershed of
  the Upper San Pedro River.

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Members of the Partnership

• Local Cochise County, Sierra Vista, Bisbee,
  Huachuca City, Tombstone, Hereford NRCD
• State Arizona State Land Department, Arizona
  Department of Water Resources, Arizona Department
  of Environmental Quality, AZ Association of
  Conservation Districts
• Federal/National/NGOs U.S. Forest Service, U.S.
  Army/Fort Huachuca, U.S. Bureau of Land
  Management, U.S. Geological Survey, Agricultural
  Research Service, National Park Service, The
  Nature Conservancy, National Audubon Society

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Organizational Structure
Partnership Advisory Commission
Coordinating Committee
Administrative Subcommittee
Public Outreach Subcommittee
Technical Subcommittee
Open Space Subcommittee
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The Partnerships first priority task

• To develop a San Pedro Conservation Plan that
  will ensure that an adequate long-term
  groundwater supply is available in the area to
  meet the reasonable needs of both the residents
  and property owners (current and future), as well
  as the San Pedro Riparian National Conservation
  Area.

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Three conservation strategies of the Plan

• Reduce water consumption
• Reclaim water resources (effluent recharge/reuse)
• Augment water resources (stormwater recharge)

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Objectives of the SPRNCA Water Needs Study

• Define temporal and spatial water needs of
  riparian vegetation
• Quantify the total consumptive use of riparian
  vegetation within the SPRNCA
• Determine the source of water consumed by key
  riparian plant species

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Determination of temporal and spatial water needs

• How do baseflows and depth to groundwater vary
  spatially?
• How does riparian vegetation vary spatially?
• Is the variability of vegetation strongly related
  to baseflows and/or groundwater conditions?

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Determination of temporal and spatial water needs

• What size of flood flows are important for
  regeneration of riparian forest, and how often do
  they occur?

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Quantify total consumptive water use

• What are the ET losses from mesquite bosques?
• From the entire riparian corridor?

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Determine the source of water consumed by key
riparian plants

• What kind of water do different vegetation types
  utilize? Groundwater or surfacewater?
• How much can consumption be reduced without
  sacrificing ecological integrity?
• What locations might be most effective for these
  management actions to occur?

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Organizational Structure
Partnership Advisory Commission
Coordinating Committee
Administrative Subcommittee
Public Outreach Subcommittee
Technical Subcommittee
Open Space Subcommittee
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The water management challenges within the basin
remain complex and challenging. Collaborative
efforts are our only hope of finding long-term
solutions for both people and the river.
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What does Partnership mean?

• Working together to gather and share data,
  information, and ideas

• Lending political and/or institutional support
  for each others projects
• Identifying and leveraging funding resources