Drainage basins of Wales and the UK

Drainage Basins in Wales and the UK

General Overview

Drainage basins, otherwise called catchment areas, are geographical regions where water from rain or snow drains downhill into a body of water.
The boundaries of these basins are called watersheds and usually are elevated areas.

Key Parts of the Drainage Basin

A drainage basin comprises several key features: the source, river channel, tributaries, and the mouth.
The source is where a river starts, usually in highland areas, often marked by a spring.
The water then flows downstream through the river channel.
Tributaries are smaller streams or rivers that flow into the main river.
The mouth of a river is where it joins another river, a lake, or the sea.

Factors Affecting Drainage Basin Characteristics

Different characteristics of a drainage basin, such as its size, shape, and gradient, influence how rainfall is processed into discharge.
The underlying geology can impact how water moves through the basin: permeable rocks allow more infiltration, while impermeable rocks result in more overland flow.
Land uses, such as urbanisation or deforestation, can disrupt natural drainage patterns and increase surface runoff.

Main Drainage Basins in Wales and the UK

The Severn Basin, the largest in the UK, is a key example, with its tributaries including the rivers Wye, Usk and Teme.
In Wales, significant basins include the Wye Basin and the Taff Basin.

Drainage Basin Response to Rainfall

Responses to rainfall depend on different factors such as basin size, shape, slope angle, land use and rock type.
Heavy rainfall can lead to high river discharge and potential flooding if the drainage basin cannot process the rainwater quickly enough.

Hydrological Cycle and River Drainage

River drainage is a key part of the hydrological or water cycle, a process that describes how water circulates between the ocean, atmosphere, and land.
As part of this cycle, water falls as precipitation, travels over and through the ground into rivers, and eventually returns to the sea.

Human Impact on Drainage Basins

Humans can significantly impact drainage basins. Land use changes, such as agriculture or urban development, can affect how water moves through the basin.
Intensive farming or deforestation can lead to increased run-off and potential flooding.
Artificial structures like dams or reservoirs can drastically alter drainage patterns and water flow.