Hydrologic Cycle

Hydrologic Cycle Robert K. Hall USEPA Region IX WTR-2 San Francisco, CA 94105 (415) 947-4123 Hall.robertk@epa.gov

Hydrologic Cycle • “Hydrologic cycle”—circulation and conservation of earth's water • Begins with evaporation of water from earth (20%) and ocean (80%) surface • As moist air rises, it cools, and water vapor condenses to form clouds • Moisture is transported around globe via oceanic gyres (N and S hemispheres) until it returns to surface as precipitation

Hydrologic Cycle (cont.) • Once water reaches the ground • Evaporates back into atmosphere • Runs off into streams and lakes, eventually back to ocean • Penetrates surface, becomes groundwater • Groundwater will • Seep into lakes, rivers, streams • Return to atmosphere through transpiration

Earth’s Water Budget (0.001%) (2.4%) (97.5%) Diagram adapted from: Peixoto and Kettani (1973). http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hyd/home.rxml

Adapted from Lynne Talley, 2000, SIO 210 Talley Topic 3: Dynamical quantities, transports and forcing http://sam.ucsd.edu/sio210/lect_3/lecture_3.html

Transport Condensation Condensation Evaporation 20% (inland water and vegetation) (rain, hail, sleet, snow, freezing rain) Evaporation 10% Convection Surface Layer Zone of Aeration Ground water flow Zone of Saturation Evaporation 80% Adapted from The Hydrologic Cycle. Illustration by Tom Schultz

Hyporheic Zone • Region beneath and lateral/adjacent to stream bed • Mixing of shallow groundwater and surface water • Hyporheic flow is important for • Surface water/groundwater interactions • Fishspawning • Benthic macroinvertebrate distribution and community structure

Hyporheic Zone (cont.) RHEIC ZONE Hyporheic Flow Adapted from Hall, RK, RL Watkins, DT Heggem, KB Jones, PR Kaufmann, SB Moore and SJ Gregory, in review, Quantifying Structural Physical Habitat Attributes Using LIDAR and Hyperspectral Imagery Adapted from National park Service (http://www.nps.gov/archive/sitk/Natural%20Resources/Stream%20Ecology/Stream/hyporheic.htm)

EcologicalFunction • Natural riparian-wetland areas characterized by interactions of vegetation, soils, hydrology • Riparian-wetland areas function properly with adequate vegetation, landform, or large woody debris • Dissipates stream energy associated with high waterflows • Reduces erosion, improves water quality…. • Changes in ecological function result from alterations (e.g., fire, invasive species, anthropogenic activity)

Ecological Function (cont.) • Human influences accelerate changes in ecosystem character • Over time, ecosystems develop spatial patterns characteristic of human disturbance and alterations • Necessary to recognize • Different geographic patterns and • How they respond to alterations and resource-management activities

Illustration by Tom Schultz www.buffer.forestry.iastate.edu/Photogallery/...

Riparian Function Nonfunctional Functional Functional at Risk

Impacts: Watershed Morphology and Invasive Species Classification: Humboldt River, NV Area shown is part of the Special Recreation Management Area Near Elko, NV Source: BLM Nevada State Office and BAE Systems Advanced Technologies Inc.

Conclusion • Hydrologic Cycle • Impacts to the Hydrologic Cycle • Preservation • Tribal-oriented Best Management Practices (BMPs) to achieve ecological function

Hydrologic Cycle