Flashcards
GEOG2002
Cards in this deck (19)
- 1what is the water balance equationused for?assesses the relative flux of water to and from surface with a storage term incorporated.
- large part of hydrology is associated with measuring or estimating amount of water involved in flux transfer or storage - 2what are the problems with the water balance equation?- problems with the spatial and temporal scale. processes occur at different scales of the measurment.
- often estimate evaporation so not accurate.
- different techniques are used to get different answers.
- catchments are not uniform. - 3what is infiltration exess flow?rainfall rate is higher than infiltration rate of the soil.
- 4when does saturation excess overland flow occur?occurs when the soil is saturated
- 5What is return flow?water which has been beneath ground returns to the surface.
- 6what is runoff?* movement of water to a channelised stream, after it has reached the ground as precipitation.
- 7what are the controls of peak magnitude?* volume of rain
* proportion of rain that generates quickflow- rainfall intensity, amount of saturation, catchment geology and time
* time taken for the water to reach an outlet - 8what is the total runoff in a hydrograph?total runoff= storm flow and base flow (quick flow and slow flow)
- 9what are the hydrograph seperation techniques?- graphical separation
- chamical seperation
- filtering - 10what are the three types of graphical separation?CONSTANT DISCHARGE METHOD = assumes baseflow remains constant through storm.
CONSTANT SLOP METHOD = assumes instant response in base flow to storm.
CONCAVE METHOD = assumes baseflow continues to decline until Qmax is reached, then increases to join inflection point of falling limb. - 11what are the reason for restoration?* change in management philosopy (engineering to sustainable)
* drivers for change (ecosystem + habitat restoration, flood control/ defence)
* sustainable management of river functions
* river recognised as dynamic system
* physical and ecological integrity important - 12headwater streams- 75-90% of catchment river network.
- steepest channels in a catchment.
- smallest catchment areas.
- naturally ephemeral flows.
- bedrock.
- support high order river systems. - 13what are the new forest streams like?- low anthropogenic catchment disturbance
- low pollution and nutrient inputs from catchment
- nutrient-poor, low primary productivity
- Riprian woodland
- Analogue for natural streams - 14what is flow resistance?measure of drag exterted by channel boundary.
drag arises through energy disspation.
main components....
grain resistance
bedfroms
channel irregularities - 15What are the Hydraulic effects?+ hydraulic jumps
+ form drag
+ dissipate energy
+ increase flow resistance
+ increase travel time of flood peaks
+ increase overbank flow
+ increase connectivity - 16what are the geomorphological effects of logjams and dams?- hydraulic and geomorphological diversity
- redirects flow, mid channel bars, meander cutoffs, pool formation, variation in channel width and depth
- sediment storage: trapping effect
- decrease bedload transport: energy dissipation
- increase channel stability - 17What are the ecological effects of log jams?* morphological diversity- stream habitat diversity.
* stability- refuge for fish.
* retain organic detritus: increase secondary productivity.
* directly provide food and habitat for microinvertebrates.
* recycling and retinition of energy and nutrients.
* important becasue of low primary productivity. - 18what are forested floodplains?they are transitional areas between terretrial and aquatic envronment.
- 19—