drainage basin
an area of land drained by a river and its tributaries
what is water balance? and what does it monitor?
water balance is the annual balance between inputs and outputs at a particular time.
it helps to monitor the amount of water held in storages.
role of precipitation?
whats the relationship between the intensity and duration of rainfall event?
precipitation is a major input of the system, often coming in the form of rain, snow, or hail.
it is derived through the condensation of clouds.
the greater the intensity, the shorter the rain period.
infiltration
the downward entry of water into the surface of the soil by forces of gravity and capillary action.
infiltration capacity
the maximum rate at which water can be absorbed at a steady state
percolation + 3 facts
the verticle downward movement of water through the soils and its layers.
- occurs at a greater depth than infiltration
- underlying rocks must be permeable
- process is slower than infiltration due to the compactness of the underlying rocks
throughflow + 3 facts
horizontal movement of water within soil layers
- slow process
- occurz when water that originally was moving downwards, starts moving sidewards due to the soil being more compacted and less permeable with increasing depth
- move at speed of 0.005m/h to 0.3m/h
baseflow + 2 facts
the horizontal movement of GROUNDwater in the zone of saturation.
- slowest process amongst all
- contributes to channel flow
overland flow + 1 fact
rain or melt water that travels over land surfaces from an area of higher elevation to an area of lower elevation.
- consist of IEF and SOF
infiltration excess flow (3pts)
- occurs when rainfall intensity> infiltration capacity
- excess water accumulate on ground surface shortly after rainfall event
- normally occurs at urban areas due to impermeable surfaces and limited infiltration capacity
saturation overland flow (SOF) (5pts)
- occurs when infimtration capacity> rainfall intensity
- does not occur shortly after rainfall event.
- requires antecedent soil in order for SOF to occur
- form at base of slopes
- contribute to channel flows
interception storage + 2 facts
water caught by vegetation and stored on canopy
- intercept up to 50%
- greatest at early stage of rainfall
soil water storage
amount of water held in the subsurface soil layer above the water table by gravity or capillary action.
ground water storage + 1 fact
water stored in the pore spaces within the bed rock and regolith
- able to control level of water table
ground water recharge
refilling if water in pore spaces that has been dried up by extraction or hunan activities
channel storage + 2 fact
water that is stored along the depressions of the surface (aka river)
- contributed by direct rain, overland flow, through flow, and groundwater flow.
- largest during flood events
evapotranspiration
the subsequent loss of water from soils, vegetation, and water bodies
- account for 75% of water loss in humid tropics and 100% in arid tropics
river discharge
the movement of water into river channels (either through direct precipitation or diff flows)
-can vary seasonally due to climate
