WATER BALANCE AND RIVER REGIME - Coggle Diagram
WATER BALANCE AND RIVER REGIME
short term = water availability varies between days and months
long period = surplus and deficits cancel out
Precipitation = Discharge + Evaporation ± changes in stores
annual variation in discharge of a river at a particular location. Most of this river flow isn’t from immediate precipitation, but is supplied from groundwater between periods of rain, which slowly feeds water into the river system.
periods of high discharge followed by low discharge which are due to glacial meltwater, snowmelt or monsoons which cause sudden fluctuations in river input. Complex regimes tend to occur for larger rivers, that cross different reliefs and climatic zones (e.g. The Ganges, Mississippi).
FACTORS affecting characteristics of a rive regime
Channel capacity of the river
▪ Area and relief of the drainage basin
▪ Volume, pattern and intensity of precipitation
▪ Geology of the soil (affecting the input of groundwater)
▪ Anthropogenic (human) activities, such as building dams or terracing the land.
represent the variation in discharge within a short period of time (days, rather than years). Before a storm begins, the main supply of water to the river is through groundwater or base flow. However, as a storm develops, infiltration and surface runoff will increase which causes a greater throughflow.
Rising limb – The increase of river discharge, not necessarily instantaneously after precipitation.
▪ Peak flow - The maximum discharge, delayed after maximum precipitation has occurred.
▪ Lag time – The time delay between peak rainfall and peak discharge
▪ Falling limb – As the storm precipitation levels decrease, discharge will in turn decrease over time.
▪ Base flow – Eventually, the discharge returns to its normal level
PHYSICAL FACTORS AFFECTING HYDROGRAPHY determing of there flashy or subdude
pre existing conditions