Drainage Basin

Human Effects on Cycle

- Changes in flow & storage (dams) - Irrigation and land drainage - Large scale abstraction

Decreased Evaporation

- Cold calm conditions - Polar climates

Outputs

- EVT - Runoff - Leakage

Groundwater Losses

- EVT (esp. low lying areas where water table close to surface) - Natural flow by spring & seepage into surface water bodies. - Leakage & outflow through aquicludes & into adjacent aquifers. - Artificial abstraction

Interception Factors

- Grasses = less interception due to smaller area - Agri crops = More crop density, high interception

Groundwater Recharge

- Infiltration of part of precipitation - Seepage through banks and beds of surface water bodies. - Inflow from adjacent rocks & aquifers - Artificial from irrigation, reservoirs etc.

Interception Types

- Interception Loss - Throughfall - Stemflow

Factors affecting Evaporation

- Meteorological (most important) - Humidity - Wind Speed - Amt. of water available - Vegetation Cover - Albedo of surface

Inputs

- Precipitation

Precipitation Types

- Rainfall - Snow - Frost - Hail - Dew

Factors Affecting Infiltration

- Rainfall duration - Antecedent soil moisture - Soil porosity - Vegetation cover - Raindrop size - Slope angle

Precipitation Factors affecting Hydrology

- Total amount - Intensity - Type - Geographic distribution - Variability

Water Storage Stages

- Vegetation - Surface - Soil Moisture - Groundwater - Water Channels

Increased Evaporation

- Warm Dry Weather - Arid/Semi-Arid Climates

Open System

Allows movement of energy and matter across its boundaries.

Field Capacity

Amount of water held in soil after excess water drains away.

Drainage Basin

Area of land drained by a river and its tributaries, including surface runoff and water table.

Throughflow

Lateral unsaturated flow of water in soil. Water flowing through soil in natural pipes and percolines.

Percolines

Lines of concentrated water flow between soil horizons.

Infiltration Capacity

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

Aquifer Benefit

Natural regulator in hydrological cycle, absorbing water which would otherwise reach streams rapidly.

Baseflow

Part of a river's discharge provided by groundwater seeping into river bed.

Phreatic Zone

Permanently saturated zone within solid rocks and sediments. Upper layer is water table.

Evaporation

Process by which liquid/solid is changed into a gas Conversion of solid/liquid precipitation into water vapour in atmosphere

Infiltration

Process by which water soaks into or is absorbed by soil. Inversely related to overland runoff

Transpiration

Process by which water vapour escapes a living plant into the atmosphere

Abstraction

Process of removing water from a source

Wilting Point

Range of moisture content in which limit to plant growth occurs.

Recharge

Refilling of water in pores where water has dried up or been extracted by human activity.

Aquifers

Rocks that contain significant quantities of water.

Aeration Zone

Seasonally wetted/dried zone.

Groundwater

Sub surface water

Water Table

The level below which the ground is permanently saturated with water.

Throughfall

Water falling through vegetation gaps or dropping from leaves and twigs

Springs

Water flow reaching the surface.

Potential EVT

Water loss that would occur if there was an unlimited supply of water in the soil for use by vegetation.

Percolation

Water moving slowly downwards from soil to bedrock

Interception Loss

Water retained by plant surface which is either evaporated or absorbed

Overland Flow

Water that flow's over the land's surface.

Interception

Water that is caught & stored by vegetation

Stemflow

Water trickling down twigs/branches then down stem/trunk

Evapotranspiration

Combination of Evaporation & Transpiration Most important aspect of water loss

Precipitation

Conversion and transfer of moisture in atmosphere to land.

Hydrological Cycle

Cycle of water between atmosphere, lithosphere & biosphere.