Freshwater geography

drainage basin+ geomorphology

drainage basin

The area drained by a river and its tributaries.

watershed

Boundary that is marked by a ridge of high land beyond which any precipitation will drain into adjacent basins.

discharge

The volume of water passing a given point over a set time.

infiltration

Infltration is the process by which water soaks into or is absorbed by the soil.

infiltration capacity

The maximum rate at which rain can be absorbed by a soil in a given condition.

overland flow

Water that flows over the land’s surface-when precipitation exceeds the infiltration rate or when the soil is saturated

base flow

Part of a river’s discharge that is provided by groundwater seeping into the bed of a river.

throughflow

Water flowing through the soil in natural pipes and percolines (lines of concentrated water flow between soil horizons).

steamflow

Water that runs down a tree's stem

or bole to the ground surface

troughfall

Water that either falls through gaps in the vegetation or which drops from leaves, twigs or stems

interception

Water that is retained by plant surfaces and which is later evaporated away or absorbed by the plant

wilting point

The range of moisture content in which permanent wilting of plants occurs, it defines the approximate limits to plant growth.

aquifers

Rocks that contain significant quantities of water, they maintain stream flow during long dry periods.

field capacity

The amount of water held in the soil after excess water drains away, that is, saturation or near saturation

evaporation

The process by which a liquid or a solid is changed into a gas for example water into vapour.

precipitation

The conversion and transfer of moisture in the atmosphere to the land. It includes all forms of rainfa, snow, frost, hail and dew

velocity

Velocity is the speed that the water is flowing.

hydraulic ratio

It is the ratio between the length of the wetted

perimeter and the cross-section area, used to

describe the shape of a channel

cryosphere

The cryosphere is the snow and ice environment. Up to 66 per cent of the world’s freshwater is in the form of snow and ice.

endorheic/closed drainage basins

Drainage basins that do not reach the sea but drain into an inland depression

friction

Obstacles that create costs and impede movement of water.

transpiration

The proces where plants release water vapour into the atmosphere through pores in their leaves.

percolation

Percolation is the movement of water through the soil itself.

cavitation

Rapid changes in fluid pressure cause the formation and collapse of vapor-filled bubbles within a liquid.

phreatic zone

Area below a water table, where groundwater saturates the rocks and soil

turbulent flow

Chaotic flow of water which can bedue to meanders and high velocity and cavitation.Turbulence provides the upward motion in the flow which allows the lifting and support of fine particles

laminar flow

Laminar flow is the movement of water in a series of sheets. To occur there must be slow velocities, smooth and shallow channels.

decidous trees

Broad-leaved trees that shed their leaves seasonally as a survival strategy, typically in winter or during a dry season, to cope with cold temperatures or lack of water.

coniferous trees

Trees that grow needles instead of leaves and cones instead of flowers

Hydrological cycle

A conceptual model that describes the storage and movement of water between the biosphere, atmosphere, lithosphere and the hydrosphere.

Physacal water scarcity

Lack of available water where water resource development is approaching or has exceeded unsustainable levels.