Drainage basin hydrological cycle

Drainage Basin Hydrological cycle; the water balance

Dynamic Equilibrium; rivers are constantly changing to get to a state of balance of inputs and outputs from their processes, the varying flows of energy and materials in the system causes the river to change to reach equilibrium such as the formation of underground streams to help compensate for higher levels of precipitation in attempt to balance the inuts and outputs.

Groundwater storage; the storage of water in permeable rock strata e.g. chalk aquifers may occur if there is no restriction of water passing through different soil horizons allowing for water to permeate further down although infiltration and saturation excess overflow may prevent larger quantities of water reaching this far

Evapotranspiration; the loss of water from a drainage basin into the atmosphere from the leaves of plants, which often determines the soil moisture as plants may photosynthesize more in months where there is increased solar activity which can cause a soil moisture deficit and subsequently more condensation

Precipitation is the first stage in the hydrological cycle when all forms of moisture reach the Earth's surface including snow, rain or dew. The process is an important input into the hydrological system, the vital input can change the dynamic equilibrium e.g. excessive snow in the mountains may trigger a larger spring melt which in turn changes the structure of the river due to increased erosion.

After the precipitation reaches the Earth's surface it often infiltrates into the soil horizons in this case infiltrating the subsoil.Throughflow then occurs as the water moves downslope within the soil layer often exfiltrating when it reaches an area of saturation at the base of the slope

Evaporation; the transformation of water droplets into water vapour by heating. The solar energy helps to increase the temperature of the water giving more energy to the water molecules, once a certain energy level occur the water molecules evaporate.

This concludes the hydrological cycle with precipitation occurring after this process.

Surface storage; the total volume of water held on the Earth's surface in lakes, ponds and puddles often from overland excess flow caused by infiltration excess as often the soil type cannot withstand the weight of the water causing the precipitation to not infiltrate causing ponding which may result as a lake. Saturation excess overland flow may also help to provide surface storage as water as at the bottom of a slope the throughflow causes the area to become saturated which then results in the precipitation exfiltrating into surface storage as there is no where else to go.

Overland flow; the movement of water over the surface of the land usually when the ground is saturated or frozen. When precipitation is too intense for infiltration to occur therefore leading to ponding which ultimately leads to the formation of streams.

Percolation; the gravity flow of water within soil, this process is important for precipitation to reach the underlying rock strata allowing for the formation of aquifers as a result of water being able to percolate through soil horizons

Groundwater flow; the deeper movement of water through underlying rock strata. This process eventually links the water back to the sea through a complex series if caerns and underground streams normally with impermeable rock on the soil horizon underneath the groundwater.