Rivers Flashcards
What are drainage basins?
Areas surrounding rivers where rain falling on the land flows into that river.
What kind of systems are drainage basins and the hydrological cycle?
The hydrological cycle is a closed system and global. Drainage basin systems are open and local.
What’s a watershed?
The boundary between drainage basins. Any rain beyond this point flows into a different basin.
What are the inputs to a drainage basin system?
Precipitation - rain, hail, snow etc.
What is interception?
Where precipitation lands on vegetation or buildings before it reaches the soil. Temporary as evaporates quickly.
What is groundwater storage?
Water in the ground (soil or rocks)
What’s the water table
The top of the zone of saturation (the bit of the soil with water in it)
What are the 5 ways of storage in a drainage basin system?
Interception. Vegetation storage. Surface storage. Groundwater storage. Channel storage.
What’s throughfall
Water dropping from one leaf to another
What’s throughflow
Water moving downhill through the soil.
What’s infiltration
Water soaking into the soil
What’s percolation
Water seeping through the soil into the water table
What’s groundwater flow
Water flowing slightly below the water table through permeable rock
What’s baseflow
Groundwater flow that feeds into rivers through banks and beds
What are the 10 flows in drainage basin systems
Surface runoff. Throughfall. Stem flow. Through flow. Infiltration. Percolation. Groundwater flow. Base flow. Inter flow. Channel flow/River discharge.
What are the 4 outputs of drainage basin systems
Evaporation. Transpiration. Evapotranspiration. River discharge.
What’s the water balance like in the wet season?
There’s more precipitation so water surplus. Groundstores fill with water so higher discharge so river levels rise.
What’s the water balance like in dry seasons?
Evaporation is highest. Groundstores depleted as some water used (eg by plants) and some flows into river. There’s a deficit that’s recharged next season.
What is river discharge and what’s it measured in
Volume of water that flows past w certain point per second. Measured in cumecs which are cubic metres per second - m^3/s
What affects river discharge
Precipitation. Heat (increases evaporation) and abstraction (removal of water)
In a hydrograph, what’s peak discharge
The point where river discharge is highest
In a hydrograph, what’s lag time
The delay between peak rainfall and peak discharge
What’s a rising limb
The part of the hydrograph up to peak discharge where discharge is increasing.
What’s a falling limb
The part of a hydrograph after peak discharge where discharge is decreasing