Water budgets and river systems Flashcards
Define ‘water budget’
The annual balance between inputs and outputs
Positive = surplus
Negative = deficit
How is precipitation calculated?
P = Q + E +or- S
Discharge + EVT +/- Storage
What is a storm hydrograph?
Shows variations in a river’s discharge over a short period of time during a storm event to record how a river responds to precipitation
How can urbanisation affect a river’s carrying capacity?
Tend to be channelized so if the capacity is breached flooding will increase downstream
How does a greater population density impact a river regime?
- More infrastructure
- Contribute to pollution
- Bridges can act as pin points to dam water when they get blocked
How do drains and sewers impact a river regime?
- Decrease lag time
- Increase velocity
How can the impacts of urbanisation be managed?
- Consider appropriate land use
- Limit urbanisation
- Flood management strategies
- Use permeable surfaces where possible
- Flood proof property design
Define ‘flood’
When the capacity of a river to transport water is exceeded and water flows over its banks
Define ‘base flow’
Average day-to-day discharge of the river
Define ‘bankfull discharge’
The volume of discharge that a particular river channel is capable of carrying without flooding
Define ‘rising limb’
The part of a storm hydrograph in which discharge increases
Name the two types of hydrograph
Flashy and flat
Describe the weather of a flashy and flat hydrograph
Fy - Antecendent rainfall so soil is saturate
Ft - Dry soil allowing infiltration if it is not compacted
Describe the geology of a flashy and flat hydrograph
Fy - Igneous rocks (impermeable) e.g. granite
Ft - Permeable e.g. sandstone
Describe the soil of a flashy and flat hydrograph
Fy - Clay based to not allow infiltration/ compacted e.g. farm machinery
Ft - Sandy soils
