Stream and Water Management Flashcards
What are the physical characteristics used to differentiate wetlands?
Soil Nutrient Regime
Soil Moisture Regime
pH
Hydrodynamic Index
Why are wetlands so important?
The role of wetlands in an ecosystem
Wetlands prevent flooding by holding water much like a sponge. By doing so, wetlands help keep river levels normal and filter and purify the surface water. ( wetlands have been compared to kidneys)
Erosion Control
Emergents are able to radically slow the flow of water.
Wetlands and Water Purification
Wetlands also clean the water by filtering out sedimentation, decomposing vegetative matter and converting chemicals into useable form.
What is a S6 stream, and S5, and a S4?
If the stream is not a fish stream or in community watershed,
S6 stream is a stream with an average channel width less or equal to 3m.
S5 stream is a stream with an average channel width larger than 3m.
If the stream is a fish stream or in a community watershed,
S4 stream is a stream with an average channel width smaller than 1.5m.
How steep should a stream gradient be for the stream to be considered free of fish?
Greater of equal to 20%
What is the basis (根据) of BC’s stream, lake and wetland classification?
Stream, based on if it is a fish stream or in community watershed. Then classify them by average channel width.
Lake, based on their size and which BGCZ they are located
Wetlands, based on their size and whether they are simple or complex, also, which BGCZ they are located
What is a riparian reserve zone, a riparian management zone?
Riparian reserve zone:
Is a riparian management area adjacent to a stream that harvesting is no permitted.
Riparian Management Zone:
Is a riparian management area adjacent to a stream that is constraint to forest practices and harvesting apply.
What are riparian areas and what are the benefits of maintaining their integrity?
A riparian zone or riparian area is the interface between land and a river or stream.
They protect water quality by controlling
water temperature
stabilize stream banks
supply long term large organic debris that creates aquatic habitat
acts as a source of food for stream and wetland organisms
provides linkage to the uplands biological diversity critical habitat for specific species travel corridors for wildlife
What is a weir and what is it used for?
A weir is a barrier across a river designed to alter its flow characteristics.
Weirs are commonly used to alter the flow of rivers to prevent flooding, measure discharge, and help render rivers navigable.
What is a stream hydrograph and describe it.
A stream hydrograph is a visual depiction of a stream’s response to a precipitation event, often referred to as storm hydrograph.
A hydrograph shows flow pattern relative to base or normal flow. The time that it takes for a stream to reach peak flow from base flow is the basin lag time. The crest can also be referred to as peak flow.
What are some indicators of bank full location?
Height of depositional features (especially the top of the pointbar, which defines the lowest possible level for bankfull stage);
Change in vegetation (especially the lower limit of perennial常年生的 species)
Slope or topographic breaks along the bank;
Change in the particle size of bank material, such as the boundary between coarse cobble or gravel with fine-grained sand or silt;
Undercuts in the bank;
Stain lines or the lower extent of lichens on boulders
How are streams classified as a function of width?
The average channel width is a factor of classifying streams.
How is stream discharge calculated?
Q= 1/n A r[2/3] S[1/2]
Simplified version of discharge is Q=AV
List and describe the characteristics of a stable stream compared to a disturbed stream
Stable Streams Channelized Stable conifers on banks Large Organic Debris Shallow undercuts Meanders Clean gravel Poll-riffle complexes (~7:1)
Disturbed Streams Braided channels lack of channelization Deciduous trees Large meandering gravel banks Dirty gravel Lack of structure and complexity In stream woody debris that runs parallel to flow Piles of small woody debris
List the methods that stream sediments including CFC’s move through a stream
Traction牵引
Saltation跳跃
Suspension悬浮
What is the ideal number of pools that should be found in a stream as a function of stream width?
There should be one poor per every 7 stream width of length (1:7).
List the various stream structure (features) and explain how they are used by fish.
pools riffles bank undercuts cascades falls calm stretches
What is meant by watershed complexity?
Watershed complexity is defined in terms of its stream types distribution frequency(numbers) flashiness or response to precipitation events
What is a littoral zone?
A littoral zone is the part of a sea, lake or river that is close to the shore.
What is a stream reach?
A stream reach is a relatively homogeneous section of a stream having a sequence of repeating structural characteristics (or processes) and fish habitat types. The key physical factors used to determine reaches in the field are channel pattern, channel confinement, gradient and streambed and bank materials. Stream reaches generally show uniformity in those characteristics and in discharge.
To what is the difference between field capacity and permanent wilting point?
Field capacity-
Is the amount of water remaining in the soil a few days after having been wetted and after free drainage has ceased. The metric potential at this soil capillaries at the soil surface when the water table is between 3 to about 10 feet below the soil surface, respectively.
Permanent wilting point-
Is defined as the minimal point of soil moisture the plant requires not to wilt.
Field capacity- Capillary pores are full, macro pores have air
Wilt point- Water films are thin around soil particles
What are the differences between perennial, intermittent and ephemeral streams?
Perennial: flow throughout the year because they are fed by ample rainfall, snowmelt, and groundwater sources.
Intermittent间歇的: flow for at least one month a year, typically in response to seasonally generated runoff.
Ephemeral短暂的: do not flow year-round, due to periods of little or no precipitation or groundwater discharge
How much water can the average coastal soil hold?
oh no
How would soil type and depth influence water movement in a watershed?
By influencing infiltration rate，percolation and storage.
What is the value of lakes and wetlands in a watershed relative to precipitation response?
Lakes and wetlands in watersheds act as temporary water storage sites, stabilize flow and minimize drainage flashiness.
How is the Horton’s classification applied?
Horton’s stream classification is used to classify watershed size according to the number of drainage features. The larger the stream order at the mouth of the watershed, the larger and more complex the watershed system.
How do the above (Field capacity and permanent wilting point) vary with soil texture?
The smaller pore size, or more fine textured, the stronger Field capacity and wilting point is.
How can the Horton classification be used to describe a watershed behaviour and flashiness?
The larger stream order at the mouth of the watershed, the larger and more complex the watershed system. The larger and more complex the watershed system, the more flashiness.
How are watersheds defined?
A watershed is a definable area with one outflow system that is enclosed by a height of land.
Watersheds are defined in terms of their Size Stream configuration Water ponding areas Sidewall steepness Basin geology
