Water budgets and river discharge Flashcards
What do water budgets indicate?
Water budgets indicate how much water is stored in drainage basins.
What is the water budget formula?
P = Q + E + ∆S
P is precipitation
Q is channel discharge
E is evapotranspiration
∆S is the change in storage.
What happens during wet seasons in the water budget?
Precipitation exceeds evapotranspiration, creating a water surplus.
What occurs in drier seasons regarding water budgets?
Precipitation is lower than evapotranspiration, depleting ground stores and creating a water deficit.
What is the water surplus period in a temperate zone?
From January to April, there is a water surplus with greater levels of precipitation than evapotranspiration.
What is the water deficit period in a temperate zone?
Between April and September, the water budget moves from a surplus to a deficit.
What are the physical influences of river regimes?
Seasonal changes and climate affect river discharge.
What is a river regime?
The variations of river discharge over a year.
What is peak discharge in a storm hydrograph?
When the river discharge is at its greatest.
What does lag time refer to in storm hydrographs?
The delay between peak rainfall and peak discharge.
What is the rising limb of a storm hydrograph?
The part of the graph up to peak discharge, showing increasing river discharge.
What is the falling limb of a storm hydrograph?
The part of the graph after peak discharge, showing decreasing discharge.
What is base flow in the context of river discharge?
The normal discharge flow of the river.
What is bankfull discharge?
The point when the water level reaches the top of the river channel without flooding.
What characterizes a flashy hydrograph?
A short lag time and high peak discharge with steep rising and falling limbs.
What characterizes flat or delayed hydrographs?
Hydrographs with limbs that rise more steadily.
How is discharge measured?
cubic metres per second (m3/s) or cumecs.
What causes the Amazon River’s discharge to rise gradually?
High levels of rainfall in most months.
How does the Indus River’s discharge vary seasonally?
It flows at a lower level in the dry season and swells during monsoon months.
What geological structures affect infiltration rates?
Highly porous and permeable structures allow quick percolation and increase baseflow.
What is the effect of sandy soils on water infiltration?
Sandy soils allow water to infiltrate quickly due to larger air spaces between grains.
What is the impact of impermeable rocks on river discharge?
They cause greater levels of direct runoff and higher levels of saturated overland flow.
How does the size of a drainage basin affect a storm hydrograph
Larger basins have higher peak discharge due to more precipitation. Smaller basins have shorter lag times because water travels shorter distances.
What is the impact of drainage density on a storm hydrograph?
High drainage density (many streams) leads to flashy hydrographs due to rapid water entry. Low drainage density results in flatter hydrographs.
