Lecture Slides on Wetland Hydrology | WFS 560, Study notes of Animal Biology

Download Lecture Slides on Wetland Hydrology | WFS 560 and more Study notes Animal Biology in PDF only on Docsity! 1 Wetland Hydrology Matthew J. Gray University of Tennessee Wetland Hydrology USACE Definition “…all hydrologic characteristics of areas that are periodically inundated or have soils saturated to the surface at some time during the growing season.” Hydrologic Zones: Permanently inundated Semi-permanently Regularly I II III 100% 76−99% 26−75% Seasonally Irregularly Intermittingly IV V VI 12.6−25% 5−12.5% <5% Hydrology is the single most important determinant of the establishment and maintenance of specific wetland types and processes (oxidation and reduction) Unique Physicochemical Conditions Hydrologic Flows & Processes Groundwater Surface Flows Note: Differences between terrestrial, wetland, and deepwater systems. 2 Hydrologic Influence Model Starting Points •Wet, Cool •Flat, Steep •Rivers, Tides Hydro- geomorphology Physiochemical hydrology+climate +geomorphology Physical+Chemical Properties Oxygen Chemical Transformations •Nutrient Availability •pH •Toxicity (H2S) A = sedimentation B1 = microbes (catalyze), plants (retain nutrients, shade), animals (consume & input nutrients) B2 = plants (detrital accumulation, sediment trapping, transpiration) and animals (physical modifications) Feedbacks: Nutrients 1 2 Feedbacks Wetland specialists Animal Biotic Feedbacks Beaver American AlligatorMuskrat (Ondatra zibethicus) (Alligator mississippiensis) (Castor canadensis) Animal Biotic Feedbacks Snow Geese Nutria (Myocastor coypus) (Chen caerulescens) 5 Hydrologic Pathways Precipitation Stemflow (SF) Throughfall (TF) Interception (I) Water retained in vegetation •Total amt of precipitation •Intensity of precipitation •Vegetation morphology •Vegetation strata Water passes through vegetation to wetland Water intercepts vegetation & passes to wetland via stem Pn= TF+SF P = I+TF+SF (Approximately 85%) I = 8−35% IDecid = 13% 71% Hydrologic Pathways Surface Flow: Overland Runoff Nonchannelized sheet flow usually following rainfall and spring thaw or as tides rise Percent of precipitation that becomes surface runoff Tennessee ~35% Hydrologic Response Coefficient Rational Runoff Coefficient Climate Considers Land Use! Urban Rural Business District Residential Sandy Pasture Loamy Cultivated Loamy Woodland 0.75−0.95 0.30−0.50 0.15 0.40 0.30 0.35 ( )iS c I A= × C A = watershed area (km2) Si = runoff to wetland (m3/s) I = rainfall intensity (mm/hr) p.129 Hydrologic Pathways Surface Flow: Streamflow Channelized water flow into a wetland Flo w Bankfull Discharge Recurrence Interval Overbank Flow Probability When water begins to flow over its bank into the floodplain Average duration that a river floodplain experiences bankfull discharge. 0RI = 1.5 yrs ( )i xS v A= On average, the chance of bankfull discharge in a year. P(0RI) = (0RI)−1 = (1.5)−1 = 67% Ax 6 Hydrologic Pathways Groundwater Subsurface flow of water into or out of a wetland 1) Discharge Wetland: Water table of surrounding landscape is higher than water in wetland. Water Flows into the Wetland ⇒ Water table loses Water “Spring or Seep” Wetland Base of Steep Slope Most Freshwater Marshes Hydrologic Pathways Groundwater Subsurface flow of water into or out of a wetland 2) Recharge Wetland: Water Flows out of Wetland ⇒ Water table gains Water Water table of surrounding landscape is below water in a wetland. Playa wetlands Darcy’s Law ( )G k A sx= k = soil permeability s = hydraulic gradient Ax = groundwater cross- sectional area perpendicular to the direction of flow(slope of water table) G = flow rate of groundwater pp. 134, 137 Hydrologic Pathways Evapotranspiration Combined water loss from evaporation and transpiration Evaporation: Water that vaporizes from water or soil in a wetland. Transpiration: Water loss through vascular plants generally at the stomata of leaves. •Leaf-surface Area Does wetland vegetation increase or decrease water loss from a wetland? •Orientation •Protected Stomata •Lipid Cuticle Water Resources Research 2:443-453 Ecological Monographs 51:403-427 E cf u e ew a= −( )( ) Wind, vapor pressure 20-30% Lower 7 Hydrologic Pathways Estuarine Wetlands Galveston, TX San Diego, CA Gravitational Pull of Moon > Sun on Oceans •Semi-diurnal (two) •Diurnal (one) •Spring (full, new) •Neap (1st,3rd) Tides Types A) Frequency B) Magnitude Gradual Transition Vertical Stratification Saltwater Wedge Hydrologic Pathways Estuarine Wetlands Saltwater Wedge Salinity is negatively related with distance from the ocean and positively related with depth Human Influences Stressors: submergence, saline soils/water, soil anoxia Saltwater Intrusion Species and Latitudinal Zonation Geography: Mangrove Wetlands •Mangrove <30o N/S •Emergent Estuarine Wetlands 30−70o N/S Red Black White