17. River Flows Flashcards
are droughts natural?
Yes
What does a river normally show?
A flow regime
Where do we often see high flows in the uk?
Spring melt and autumn floods
How do river reigimes vary in the Southern Hemisphere?
Large peaks in winter floods little flow in the summer
What can droughts be considered as?
A disturbance effect
Why might flow be lower in winter?
water is frozen
Why do we expect low flows?
they occur naturally, expected to happed
Can low flows be due to human activity?
Yes, diversion of water, agriculture ect
What is a drought
extreme low flow periods
Are fresh water systems resilient to drought effects?
Yes they can often bounce back
How long can droughts last?
From a few weeks to a few months
Which animals could be effected by dorught
fish, different time of year can effect damage to orgaisms
How can the type of river determine flow
perennial, temporay, bed fed, consecutive
What can excaserbate drought
human impact
Why are droughts more complex than floods
can be longer, supra seasonal, more regional effect
What is a press disturbance
a single disturbance, with one response
What is ramp disturbance
continuing disturbance overtime
Which year did we see a very dry summer followed by a wet winter?
1976
What is a supraseasonal drought
long periods over time of drought
Which type of river was more effected due to drought,
bed fed rivers
how do we decided how low a river flow is in the summer
summer low flow, qL, lowest average of severn consequtive summers
How do droughts affect river organisms
reduced depth and wetted area, reduction in current veolocity
how can reduced veolocity effect organims
could effect breathing, now given enough oxygen, less food for fishes
If there is low flow, how are sediments effected
sediments get stuck in gravels and reduced breeding fish
