ENVR 150 2-2 Lanes Balance Basins (2) PDF

School of Environment and Geomatics ENVR 150 Terms Stream Morphology Channel – Watercourse Bankfull channel – btw high-water marks, indicates Q2 water flows Stream Bed – bottom surface Substrate (bed composition) Channel banks – sloping sides...

School of Environment and Geomatics ENVR 150 Terms Stream Morphology Channel – Watercourse Bankfull channel – btw high-water marks, indicates Q2 water flows Stream Bed – bottom surface Substrate (bed composition) Channel banks – sloping sides Left and right bank – looking downstream Thalweg – fastest, deepest flows Sediment – sand-silt-clay, gravels, cobbles and boulders moved by the river Vegetation Large woody debris (LWD) Riparian areas - Streamside vegetation which protects banks and reduces run-off Norns Creek Fan  What Do Rivers Do? Primary task is landscape change Collecting materials and moving them downstream Gravity is the energy source Water does the work Rocks and vegetation provide the resistance This dynamic system creates habitat, and manages flood waters and drought Whangnui River in New Zealand. It is the first river to have legal status (2017) and the Maori are trustees Giveout Creek Giveout Creek Fairly High Trail Fairly High Trail May 15, 2020 September 12, 2020 River Channels are Dynamic Under natural conditions channels are constantly changing High flows Major floods occur infrequently and do a lot of work Move large amounts of sediments and alter the channel Medium flow Average high flows Bankfull flow – Q2 ( 2-year discharge) (90% of particles are in motion) These flows do most of the work of shaping rivers but over longer time than high flows Low flow These flows occurs often, but minimally influence the channel and floodplain Balance between the load and size of sediment and the slope and stream flow of a system Climate, geology, topography and Depositing Degrading vegetation and landuse affect this balance Based on Schumm et al. 1984 Lane’s Balance How will this balance move if you add more water? How will this balance move if debris from a landslide enters the stream? How will this balance move if you steepen the slope? How will this balance move as the stream moves toward base level?  A Drainage Basin  Drainage Basin – any water catchment area Continental divide – major mnt ranges Drainage divide – denotes water catchment area Interfluve – high ground that separates one valley from another Figure 14.4 Basin measurements Basin Area Greater the area = increased flow Drainage Density Ratio of Stream length: Area 20 km: 23km2 Stream Order – a measure of the number of contributing tributaries Drainage Patterns Dendritic Stream networks or drainages www.usda.gov/stream_restoration/chap1.html www.aquatic.uoguelph.ca/rivers/chwater.htm Drainage Patterns Figure 14.8