Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
28 Cards in this Set
- Front
- Back
River |
A river is water in a channel moving downhill under the influence of gravity |
|
Drainage basin |
The areas of land drained by a river system |
|
4 things a river will always try and do |
1. Flow downhill 2. Find the easiest way downhill 3. Carry the most sediment 4. Reduce its gradient |
|
4 features that can describe a river |
1. The number, size and shape of the channel 2. Discharge 3. Sediment load Gradient |
|
Size and shape |
Based on measurements of width and depth w/d |
|
Discharge |
The volume of water moving in a channel in a given time Q= W x D x V |
|
Sediment load |
This is the sediment that is moving or may move if discharge increases |
|
Gradient |
This is the slope of the channel bottom |
|
Water flow in a channel |
Water velocity will vary depending upon proximity to the channel sides and bottom Fastest moving water is found at the top centre. Zero at the sides and bottom due to friction |
|
Types of flow in a river |
1. Laminar 2. Turbulent |
|
Laminar flow |
The water moves down stream as a series of parallel layers with no vertical or lateral mixing. Rare in nature |
|
Turbulent flow |
Water follows an irregular path. Significant vertical and lateral mixing. Turbulence is the result of friction with the bottom and within the water |
|
River processes |
1. Weathering 2. Erosion 3. Transport 4. Deposition |
|
Weathering |
The disintegration of matter - rocks and minerals - by physical and chemical means |
|
Erosion |
In a river, sediment is set in motion in three different ways |
|
3 ways sediment is set in motion in a river |
1. Physical impact of moving water 2. Physical impact of other moving sediment 3. Hydraulic lift |
|
Hydraulic lift |
A process whereby changes in water velocity and pressure around a grain cause it to move more |
|
Abrasion |
Physical impact of moving water and sediment eroding sediment in a river |
|
Transport |
The way sediment moves once it is in motion |
|
4 ways sediment in a river can be transported |
1. Solution 2. Suspension 3. Saltation 4. Traction |
|
Solution |
Dissolved elements and molecules in the water |
|
Suspension |
The finest solid particles that are carried in the water column that rarely make contact with the bottom |
|
Saltation |
Large solid particles that bounce along the bottom. They make frequent short term contract with the bottom |
|
Traction |
The largest solid particles that roll or slide along the bottom. These grains are in constant contact with the bottom |
|
Bed load |
Traction and salutation together |
|
Deposition |
Moving sediment in a river is deposited when water velocity drops. It also takes place when molecules or elements in solution precipitate to form new solid minerals |
|
Types of rivers |
1. Meandering 2. Braided |
|
Thalweg |
The line that shows where the deepest, fastest water is |