5.3 Flashcards
What does a positive and negative water budget mean?
positive= surplus
inputs>outputs = flood
negative= deficit
outputs>inputs = drought
What are the inputs and outputs of the water budget in a drainage basin?
Inputs:
-precipitation
-water diversion
-surface runoff
-surface flow
-groundwater flow
Outputs:
-evapotranspiration
-water diversion
-surface runoff
-surface flow
-groundwater flow
-industrial and residential use
What is the water budget equation?
P = Q + E +/- S
Precipitation = River discharge + Evapotranspiration +/- Groundwater storage
What is field capacity?
This is when there is maximum capacity in the soil
What is recharge?
precipitation after a dry period
What is a river regime?
this shows the fluctuations in flow of a river throughout a season or year
Why is there fluctuations in a river regime?
due to seasonal rainfall patterns, seasonal temp patterns, geology, soil type, human influence
What are the types in river regime?
simple- seasonally high and low flow, usually small river
complex- lots of high and lows, usually large river crossing climate zones E.g. Mississippi river
What are the factors influencing the regime of a river?
- climate
- vegetation
- geology and soils
- land use
- water abstraction and dams
What is a storm hydrograph?
it shows the discharge change in a river over a short period of time
What are the features of a storm hydrograph?
Rising limb - discharge increasing after rainfall
Falling limb - discharge decreasing as inputs decrease
Lag time - time between peak rainfall and peak discharge
Base flow - normal level of river
Types of hydrographs….
Flashy- steep limb, rising limb, short lag time
Flatter- gentle limb, long lag time
What are the factors which affect a hydrograph?
-Geology
-Vegetation
-Soil
characteristics
-relief
-urbanisation
-land use
-catchment size
-drainage
density
-catchment
shape
-water
management
What are flood risk management strategies?
● Strengthen river bank
● Manage development like not building on high risk areas like flood plains
● create procedures in case of flood
Who are some key players?
Planners as they cover and manage risks from naturally high risk areas
