Wetland Water Budget & Hydrology PDF

1. Describe the components of a wetland water budget and their interrelationships Water budget is the balance between the inflows and outflows The equation is Water volume change = net precip + surface water inflows + ground water inflows - evapotranspiration - surface water outflows - ground...

1. Describe the components of a wetland water budget and their interrelationships Water budget is the balance between the inflows and outflows The equation is Water volume change = net precip + surface water inflows + ground water inflows - evapotranspiration - surface water outflows - ground water outflows +- tidal in/outflow Inflows - precipitation, surface flow, groundwater Outflows - evapotranspiration, surface outflows, groundwater outflows 2. Discuss the influence of precipitation and surface flow to wetland water budgets Gross precipitation - liquid or solid water falling onto earths surface Net precipitation - amount of water that reaches the surface (throughfall and streamflow) Interception - water that is intercepted by vegetation or buildings Throughfall - water that falls through or drips from leaves Streamflow - water that runs down the main stem of vegetation, usually trees Infiltration - water that enters the soil Surface flow - water that travels overland and not infiltrating the soil; may be dispersed (sheet) or in channels (stream) Overland flow - travels in sheet over surface, often creates rivulets Streamflow - more permanent, often channelized Flood pulse - seasonal or episodic flood flow, may or may not be hydrologically connected outside floor window Riparian wetlands - wetland areas adjacent to rivers or streams, occasionally flooded by those waters 3. Define key hydrological terms and concepts Recharge wetland - water level in wetland is higher than water table; water flows out Discharge wetland - water lever of wetland is lower than the water table; water flows in Flow-through wetland - groundwater inflows at one location but outflows at another Novitski groundwater flow patterns Surface water depression - little groundwater outflow, low permeability soils, water table separated from wetland Surface water slope - little groundwater outflow, adjacent to lakes, rivers, streams, water table usually below, may be connected Groundwater depression - high groundwater inflow, low point/deep depression, water table connected to coarse soils Groundwater slope - high groundwater inflow, slopes/hills, water table connected to surface, seeps/springs Evaporation - water that vaporizes from water or soil Transpiration - water that passes through vascular plants to atmosphere Seiches - wind tides, common in Great Lakes, periodic fluctuations in nontidal inland wetlands adjacent to lakes 4. Explain the influence of groundwater, evapotranspiration and tides to wetland water budgets Groundwater affects water budget cuz it plays a factor in where the wetland gets its water from (see Novitski flow patterns). Evapotranspiration affects water budget because it is water leaving the wetland (vegetation decreases with the loss of water. Tides create zonation that is periodic and predictable, bring stressors (submergence, saline intrusion, and anaerobic conditions but brings subsidies (removal of excess salts, reestablishing aerobic conditions, nutrient pulse. Seiches also affect it by changing water levels 5. Discuss the four main principles underscoring the importance of hydrology on wetland structure and function 1. Hydrology leads to a unique vegetation composition but can limit or enhance diversity a. Selection for water-tolerant spp, exclusion of flood intolerant spp, diversity decreases by long flooding duration & high energy waters & flowing/periodic hydrology, diversity increases when niches are created such as ecotones, riparian corrido movement and tidal zonation 2. Primary productivity and other ecosystem functions in wetlands are often enhanced by flowing conditions and a pulsing hydroperiod and are often depressed by stagnant conditions a. Bogs clog (less diverse, not much water flow, dominated by sphagnum moss) b. fens flush (more diverse, water flow flushes nutrients, dominated by graminoids, forbs, shrubs, stunted conifers) 3. Accumulation of organic material in wetlands is controlled by hydrology through its influence on primary productivity, decomposition and export of particulate organic matter a. Wetlands accumulate and decompose organic material (hydrology modifies chemicals, moisture, nutrients and temperature, which all influences decomposition rates) b. Wetlands export organic material (isolated wetlands have less export, wetland connected to flowing water have more export 4. Nutrient cycling and availability are both significantly influences by hydrologic conditions a. Nutrients enter and leave via hydrology, internal cycling depends on productivity and decomposition, beaver marsh = high productivity, bog = low productivity b. Nutrient transformations, availability to plants, and loss to atmosphere are all influenced by hydrology, N & P are more available in anaerobic conditions (no oxygen) or flooded soils 6. Identify techniques for studying wetland hydrology Determine the following: Water levels - recorders/loggers, staff gauge Evapotranspiration - thornthwaite equation, evaporation pans, diurnal water-level fluctuation Precipitation - rain gauges, weather station info Surface flow - water-level following events, stream weir Groundwater - piezometers/wells, models, online data 7. Generate hypothetical water budgets for unfamiliar wetlands Identify inflows and outflows, make a diagram? 8. Define key soil terms and concepts Hydric soils - wetland soils, formed under conditions of saturation, flooding or ponding long enough during the growing season to develop anaerobic conditions in the upper part  9. Describe the 2 main types of wetland soil Organic soils - more than 20-35% organic material Peat - undecomposed organic soil, identification of plant forms is possible Muck - highly decomposed organic soil material, identification of plant forms impossible Wetland organic soils: organic:clay content, ≥ 18% organic carbon if mineral fraction ≥ 60% clay, ≥ 12% organic carbon in mineral fraction has no clay, proportional organic carbon (12-18%) if mineral fraction has 0-60% clay Mineral soil - all other soils; less than 20-35% organic material 10. Explain how organic soils differ from mineral soils 11. List soil features that characterize wetland soils Organic - origin of plant material (mosses, graminoids (sedges, rushes and grasses), woody debris), decomposition state/humification (slower in flooded and cold conditions, plant organic compounds leached into water) Mineral - redoximorphic features (characteristics that develop in mineral wetland soils that allow for their identification, formed by reduction, translocation, and/or oxidation of iron and manganese oxides, mediated by micro-biological process (microbes, plant cellular processes) 12. Explain redox potential and its importance in wetland soils Redoximorphic feature development requires: sustained anaerobic conditions, sufficient soil temp >5°C, and organic matter. reduced matrices and redox depletions, gleization/gleying - black or gray occasionally greenish or blue gray soil color (indicates semipermanently - permanently  flooded soils, caused by reduces iron and manganese leaching from soil, aka redox depletions), clay depletions - clay is removed along root channels and redeposited as clay coatings on soil particles below; oxidized rhizosphere (plants transport oxygen to roots, excess oxygen diffuses to the soil, iron is oxidized along these small roots); redox concentrations (mottles) - orange reddish brown (iron) or dark reddish brown/black (manganese) spots in otherwise gray (gleyed) soil matrix, indicates variable hydrology, remain long after draining. Redox potential and wetland soils - all soils are complex matrix of minerals/rock, soil organic matter, clay, air, water, bacteria, roots, fungal hypha, air/pore spaces fill with water during flooding (oxygen diffusion 10,000x slower in water, flooding -> rapidly anaerobic = reduced soil, very thin oxidized layer remains at surface Redox potential - measure of the electron availability in a solution, degree of reduction, wetland soil indicator Oxidation - uptake of oxygen, removal of hydrogen or lose electron Reduction - losing oxygen, gaining of hydrogen or electron OIL RIG (oxidation is loss, reduction is gain of electron) Redox importance in wetland soils a) Nutrient cycling - regulates availability of key nutrients for plant growth and health b) Microbial activity - regulates microbial communities which influences productivity and decomposition c) Climate change - regulates carbon sequestration and greenhouse gas release to atmosphere d) Water quality - regulates the generation and transformation of toxic compounds (pollutants, metals and cyanobacteria) 13. Characterize wetland soils using field indicators Check for redoximorphic features, sulfate reduction (rotten egg odor), organic matter accumulation, color (munsell color wheel: hue value/chroma) Texture (rub test) Rub 1 = gritty = mineral soil Rub 2 = greasy = mucky mineral or organic Rub 3/4 = gritty = mucky mineral Rub 3/4 = greasy = organic