Chapter 1 Minimum Flows and Levels - Southwest Florida Water ...

Flow Regime – The variable pattern (magnitude and frequency) of high and low
flows exhibited by rivers and streams that are critical to the integrity of river
ecosystems.
Gage Height – The water surface elevation referenced to the gage datum. Gage
height is often used interchangeably with the more general term "stage".
Although gage height is more appropriate when used with a reading of a gage.
Groundwater – In general, all subsurface water that is distinct from surface
water, specifically, that part which is in the saturated zone of a defined aquifer.
Habitat – The physical and biological surroundings in which an organism or
population (living and non-living) lives; includes life requirements such as food or
shelter.
Habitat Suitability Curves – An input to the PHABSIM model where continuous
variable or univariate curves designed to encompass the expected range of
suitable conditions for water depth, water velocity and substrate/cover type
unique to a given target species at a specific life stage is exhibited.
HEC-RAS – The model acronym for Hydraulic Engineering Center-River Analysis
System. It is a water-surface profile model for river simulation. In this report it is
utilized to evaluate steady, one-dimensional, gradually varied flow.
High Flow Step –.The high flow step is designed to assure that when out-ofbank
flows occur they are protected by criterion specific to high flow conditions,
rather then by criterion developed to protect in-channel features. The high flow
step is therefore, a flow, often the 15% exceedance flow, above which the more
restrictive of the seasonally specific percent-of-flow reduction is used, or the high
flow percent-of-reduction, developed to protect floodplain inundation during block
three.
Hydric Soils – Any one of a class of soils usually formed under conditions of
saturation, flooding, or ponding long enough during the growing season to
develop anaerobic conditions in the upper part that favor the growth and
regeneration of hydrophytic vegetation.
Hydrophytic Vegetation – The sum total of macrophytic plant life growing in
water or on a substrate that is at least periodically deficient in oxygen as a result
of excessive water content.
Hypertrophied Lenticels – An exaggerated (oversized) pore on the surface of
stems of woody plants through which gases are exchanged between the plant
and the atmosphere. The enlarged lenticels serve as a mechanism for increasing
oxygen to plant roots during periods of inundation and/or saturated soils.
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