lec 6 Riparian systems Flashcards
where was human civilization born
fertile crescent
what are characteristics of rivers and streams based on
- where in the watershed they are found
where do riparian communities occur
-along natural water sources lined by thin strips of lush vegetation
t or f- riparian communities influence settlement patterns
true
in ontario, what is the flood risk area defined by
-flooding hazard limit; determined by the 100- yr peak flow, regional storm or teh highest observed flood
t or false; flooding is a natural process and is necessary for maintaining function and biodiversity of aquatic and terrestrial systems
true
what 4 things do floodwaters create?
- critically important habitat
- return nutrients to land
- recharge groundwater
- replenish topsoil
–% of all wetland life is born and raised in the first _ -_ m of the water’s edge. what is this called?
90; 10-15m
-shoreline
where is the riparian zone located?
-land closest to the shore, between developed land and water
why is the riparian zone essential?
-lessens movement of sediment, nutrients and pesticides and other debris from getting into water
t or f; grasses are better at preventing erosion along the shoreline vs other shrubs such as willows and dogwoods
false; naturally occurring, deeper root system
what are 3 outcomes of removing natural vegetation from a shoreline
- increase pollution
- reduce shade
- destroy habitat for spawning fish
how can we preserve natural shorelines?
bioengineering- retention and enhancement of the stream edge with natural materials
what are the 5 methods of bioengineering?
- live stakes
- fascines
- brush layering
4, brush mats - live crib walls
describe live stakes, where is it effective?
- installation of live cuttings that act as stakes ; most have opportunity to grow
- good on slopes to help minor erosion/ uncomplicated areas via root system of plant
what is a fascine? what are benefits? where applied?
- rope shaped bundle of live cuttings, put together with twine and then installed along the edge
- little site disturbance, effective erosion control
- small streams less than 5m wide, 1.5m bank heights
what is brush layering?
-live woody plant material woven into geotextiles placed into slope face along trenches excavated along slope contours; acts as live fence
what is a live crib wall?
3d structure created from untreated lumber, fill and live cuttings –> retaining wall
-results in wood decomposing and resulting root mass binds to soil fill to create single coherent mass
what are the 4 most popular plants to be implemented in bioengineering?
dogwood, willow, cottonwood and popular
what is our role as landscape designer to improve/ implement ecological engineering?
- deal with managing stormwater on site
- use low impact development
what is low impact development (LID)
innovative stormwater management approach that treats, infiltrates, filters and retains runoff at the source
what 4 things most architects, engineers, ecologists and planners work together to do
- cluster development
- minimize total disturbed area
- protect natural flow pathways
- protect riparian buffers
what are the 5 LID principles?
- use existing natural systems as the integrating framework for site planning
- focus on prevention
- treat stormwater close to the source
- emp. simple, nonstructural low tech low cost methods
- create multifunctional landscape
what are vegetative filter strips
- vegetated open space that treat stormwater by slowing t down and allowing sediment and pollutants to settle out of run off
- less than 5% slope and dense vegetation
what is a bioswales
- vegetated channels that slowly convey, filter and infiltrate stormwater
- 1-6% slope - vegetation shouldn’t need additional irrigation or fertilizer
what is a rain garden
shallow, vegetated depressions that collect and absorb runoff from surrounding areas
-should infiltrate 30% more stormwater than lawn
what are stormwater planters
specialized containers designed to capture stormwater runoff and treated pollutants within urban area
-plants must be std water tolerant and not invasive
what % runoff gets reduced by using green roofs
50%
