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Unit 2 Hydrology_Lecture 3 - Hydrologic Indicators

Unit 2 Hydrology_Lecture 3 - Hydrologic Indicators -...

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Unformatted text preview: Wetlands and Water Quality Unit 2: Hydrology Lecture 3: Hydrologic Indicators Field indicators of hydrology Under ideal conditions, stage data for any wetland you visited would be available, but obviously this is typically not the case. However, for delineation purposes, research or simple curiosity, it is necessary to know something about the hydrologic characteristics of a site even though flooded conditions may not exist when you are there. Luckily, the influence of hydrology on soils and vegetation as well as the physical presence of water at a given location often leaves behind indicators that can be used to infer some of the hydrologic characteristics of the wetland. These we call field indicators. There are thirteen indicators recognized in Florida. Hydrologic Indicators Algal mats The presence or remains of non-vascular nonplant material which develops during periods of inundation and persists after the surface water has receded. 1 2 Hydrologic Indicators Aquatic mosses or liverworts Mosses and liverworts are in a group of plants collectively called bryophytes. They lack true roots and leaves and are generally found in shaded, moist environments. Look for epiphytic or epipteric mosses and liverworts along rivers, streams, bayous, sloughs and strands as they typically occur in shaded, forested floodplains that experience prolonged, seasonal inundation. 3 Hydrologic Indicators Aquatic plants Aquatic plants are defined as plants which typically float on water or require water for its entire structural support, or which will desiccate outside of water. Aquatic plants naturally grow in areas where inundation is permanent or nearly so. Presence of aquatic plants at a site not presently inundated by water is an excellent indicator that the normal condition at the site is much wetter or, in the case of floating plants, that the site experiences periodic flooding by an adjacent surface waterbody. (typical floating aquatic plant genera are Riccia, Ricciocarpus, Azolla, Salvinia, Pistia, Eichhornia, Lemna, Spirodela, Wolffia and Wolffiella. 4 5 Hydrologic Indicators Aufwuchs The presence or remains of the assemblage of sessile, attached or freefreeliving, nonvascular plants and invertebrate animals (including protozoans and freshwater sponges) which develop a community on inundated surfaces. Previous Water Level 6 Hydrologic Indicators Drift lines and rafted debris Vegetation, litter and other natural or manmade material deposited in discrete lines or locations on the ground or against fixed objects, or entangled above the ground within or on fixed objects in a form an manner which indicates that the material was waterborne. Caution must be used with this indicator to determine that the rafted debris represents usual and recurring events typical of inundation or saturation at a frequency and duration sufficient to meet a specific definition criterion. 7 Hydrologic Indicators Elevated lichen lines Lichens area symbiotic associate of a fungus and an alga. Typical lichen forms include crustose foliose and fruticose. Lichens are obligate aerobes and not tolerant of inundation. When water routinely stands around the trunks of trees it abruptly limits the growth of lichens producing a distinct line. 8 Hydrologic Indicators Evidence of aquatic fauna This indicator considers the presence or indications of the presence of animals which spend all or portions of their live cycle in water. Only those life stages which depend on being in or on water for daily survival are included in this indicators. 9 Hydrologic Indicators Hydrologic Data Data consists of reports, measurements, or direct observations of inundation or saturation which support the presence of water to an extent consistent with the provisions of the definition of wetlands and the criteria within the rule, including evidence of a seasonal high water table at or above the surface according to methodologies set for the in Soil and Water Relationships of Florida Ecological Communities. Hydrologic Indicators Morphological plant adaptations Specialized structures or tissues produced by certain plants in response to inundation or saturation which normally are not observed when the plant has not been subject to conditions of inundation or saturation. These are often observed in the form of hydric adventitious roots and hypertrophied lenticels. Other morphological adaptations include propproproots of Rhizophora mangle (red mangrove) Knees of Taxodium distichum (bald cypress), buttressing of tree bases exhibited by cypress Nyssa sylvatica var. bifloria (swamp tupelo), Ulmus americana (American elm). 10 Hydrologic Indicators Secondary flow channels Discrete and obvious natural pathways of water flow landward of the primary bank of a stream watercourse and typically parallel to the main channel. These often occur in conjunction with sediment deposition and water marks. Look for these along streams and rivers, especially adjacent to or within floodplain forests. 11 Hydrologic Indicators Sediment Deposition Mineral or organic matter deposited in or shifted to positions indicating water transport. The current of a river or stream during high flow carries sediment that is normally in equilibrium with the lower flow velocity and is thus retained near the bottom as bed flow. Look for material deposition on rocks and plants especially when the deposition is observed on the upstream surface and not on the downstream surface. Sediment deposited as erosion from uplands is not included in this indicator. 12 13 Hydrologic Indicators Vegetated tussocks or hummocks Areas where vegetation is elevated above the natural grade on a mound built up of plant debris, roots and soils so that the growing vegetation is not subject to the prolonged effects of soil anoxia. Hummocks 14 Hydrologic Indicators Water Marks Water marks are created by the staining effect of a sustained water elevation. This will appear as a distinct line created on fixed objects, including vegetation. The length of time the object has been inundated influences the expression of this indicator, as does the color and sediment burden of the water. Water Mark 15 16 Assignment Locate, Identify and Photograph six (6) of the 13 hydrologic indicators. On the image (either printed or electronic) identify the hydrologic indicator. You can submit your assignment electronically, but make sure your name is part of the file name. Send file to both TA and me. Due in one week submit by end of class Thursday 1/21 17 ...
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