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Hydrology The amount of water stored and transferred exceeded, saturation occurs and flooding.
varies between drainage basins. Heavy thunderstorms = interception rate
Inputs: precipitation and sediment. The five main variables that influence the stores exceeded and flooding. Snow = exceed
Outputs: extraction, river discharge and and transfers are;- of infiltration rate and surface storage and
transpiration. - Precipitation. The intensity, duration and flood.
Stores: lakes, reservoirs, dams and puddles. variability can affect the water input and
Flow and evaporation. the infiltration rate. E.g. thunderstorms Urbanisation:
Drainage basin is an open system, with a can cause standing water and surface No trees ­ less interception ­ increased
parameter called a water-shed. runoff. Flash floods may occur. Continued infiltration rate ­ evapotranspiration levels
More vegetation cover + increased interception = light rain could also have the same decrease ­ more surface runoff / storage.
less infiltration. effects. No infiltration ­ concrete doesn't allow infiltration
Less vegetation cover + decreased interception - Temperature. If the ground d frozen, the to occur ­ increased surface runoff ­ flooding
rates = more infiltration. water remains on the surface, water flows Channel runoff ­ water directed into drains ­
The maximum amount of infiltration within a soil is also become water stores with cold increased discharge ­ flooding on flood plain.
called infiltration capacity. temperatures. Less interception and
The infiltration capacity depends on the following transpiration because plant and trees are Agriculture:
factors: bare. Can slow down or prevent Urban ­ less interception ­ less infiltration ­ more
- The texture of the soil. Low number of evaporation. Warmer weather = more surface runoff.
pore spaces = lower infiltration capacity. interception, transpiration and Rural ­ more interception ­ more infiltration ­ less
E.g. clay (impermeable or non-pourus). evaporation + decrease in infiltration and surface runoff.
- The structure of the soil. A crumby percolation. Colder weather = less Moorland grasses ­ low interception rate.
structure has more pore space than a interception, transpiration and Deciduous woodland ­ high interception rate.
platy structure. evaporation + increase in infiltration and
percolation. Type and duration of precipitation:
- Temperature. If the ground is frozen, Heavy thunder storms ­ interception capacity
infiltration cannot occur. - Land use. Natural vegetation cover, exceeded ­ flooding occurs.
- Current level of moisture within the agricultural and urban or rural area. Snow ­ infiltration rates falls ­ increased surface
soil. Pore spaces may be fill of water if Natural vegetation cover = open ground, storage ­ flooding.
there has been a continuous rain. no interception, forested areas, more Prolonged light rain ­ vegetation storage capacity
Saturated soil can hold no more water. interception. Agricultural land use = exceeded ­ eventual saturation ­ flooding.
Can produce surface runoff or surface permanent crops slow down the water
storage. Flooding can occur if conditions flow compared to annual crops. Urban = Temperature:
persist. more impermeable surfaces and Hot summer ­ lower water levels on surface ­
increased surface runoff. An increase in evapotranspiration levels increase ­ vegetation
Once in the soil, the water moves laterally the flood risk since the rain is prevented uptake increases ­ less surface storage ­ lower
through the ground in a system called from infiltrating and the transfer is infiltration levels.
throughflow. speeded up. Cold winter ­ higher water levels on surface ­
Some water will reach the bed rock; if it is an - Soil and rock type. Impermeable rocks evapotranspiration decreases ­ vegetation
aquifer the rock is permeable. Water within these and soils prevent infiltration, clay and uptake decreases ­ more surface storage ­ high
rocks, such as limestone and chalk are called granite. Permeable rock and soils allow infiltration levels.
groundwater. infiltration to occur, such as sands, chalk
and limestone.
Factors that influence the stores and transfers - Physical characteristics of the
within a drainage basin: drainage basin. Mountainous region =
Water is stored by plants, lakes, soil or as surface runoff increases, same applies to
groundwater. compact or small basins.
Water is transferred by streams, rivers, overland - Weather and climate. Prolonged light
flow, throughflow and groundwater flow. rain = vegetation storage capacity


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