Lesson 3 - Temporal Variations in river discharge Flashcards
What is a river regime?
The annual variations in a rivers discharge.
What is the difference between a simple and complex river regime?
A simple regime usually consists of a ‘wet season’ where discharge is high and a ‘dry season’ where discharge is lower. A complex regime usually has more varied levels, tributaries may extend to many areas.
What physical factors affect a rivers regime?
The annual precipitation, temperatures and evaporation rates. The relief, vegetation, geology and soils of the river.
What human factors affect a river regime?
The irrigation for agriculture etc. The demand for industrial and domestic use.
What are the key stages of a storm hydrograph?
- Rising limb, how quickly the river responds to the storm
- The peak discharge, highest amount of discharge
- Falling limb, decline in river discharge after the event.
What is the lag time on a storm hydrograph?
The time between peak rainfall and peak discharge.
What is the base flow on a storm hydrograph?
The amount of rainfall that would be in the river without the addition of the storm water.
What are the climate factors that affect a storm hydrograph?
Type, intensity and amount of precipitation. Temperature, evaporation and antecedent conditions.
What is a flashy storm hydrograph?
When the lag time is much shorter, usually an intense storm.
How might high intensity precipitation affect a storm hydrograph?
High intensity precipitation would result in excess infiltration ground flow meaning that the rate of rainfall will exceed the rate of infiltration causing excess run off. This would contribute to a slower lag time.
Non climatic factors that affect a hydrograph?
- Catchment size, shape and drainage density.
- Porosity and permeability of rocks and soil.
- Slope angles, vegetation and land use.
