Rivers

 Things included:

• Soft engineering (+ and -)
• Hard engineering (+ and -)
• Physical causes and effects of flooding
• Human causes and effects of flooding
• Deposition and erosion
• How does deposition and erosion create levees?
• How does deposition and erosion create levees-continued.

Soft engineering Advantages

• Low cost
• Less Time to construct
• Environmentally friendly

Soft engineering Disadvantages

• Not always reliable
• Not always effective
• Can't be used where there are floodplains present already

Hard engineering Advantages

• More effective
• Dams and reservoirs provide Hydroelectric power.
• Job opportunities available
• Building lood banks is relatively cheap

Hard engineering Disadvantages

• Most methods are very expensive
• Can harm the environment and destroy wildlife habitats
• Building dams can cause flooding upstream and produces methane gas.
• Not asthetically pleasing (don't look good)
• Skilled workers needed to build dams or straighten river channels

Physical Causes of Flooding

• Surface Run-off
• Long periods of rain
• snowmelt
• impermeable rocks
• compacted or dry soil
• very wet or saturated soil

Physical Effects of Flooding

• Wildlife habitats destroyed by floodwater
• Contaminated floodwater can pollute the rivers and habitats
• silt and sediment can destroy crops and farmlands
• river banks and natural levees can be destroyed as rivers reach bankfull capacity.

Human Causes of flooding

• Building
• Deforestation
• Infrastructure issues
• Impermeable surfaces
• Bridge Constriction
• Climate Change

Human effects of flooding

• Loss of lives
• damage to properties
• destruction of crops
• economy suffers

What is Deposition?

Deposition is exactly what it sounds like. It is the act of depositing sediment in an area. In rivers, they help to form meanders, and an Ox-Bow Lake, and they also can create levees.

What is erosion?

Erosion is the wearing away of something. There are four types:

• Corrasion (also known as abrasion)
• Attrition
• Solution
• Hydraulic Action

These erosion processes also help to create a meander and an Ox-Bow Lake too.

What is a levee?

A levee is an embankment built to prevent the overflow of a river.

How can deposition and erosion create a levee (BBC Bitesize is used for this part. Everything in this section is copied from this. [just to give them credit])?

• Levees occur in the lower course of a river when there is an increase in the volume of water flowing downstream and flooding occurs. Sediment that has been eroded further upstream is transported downstream. When the river floods, the sediment spreads out across the floodplain. When a flood occurs, the river loses energy.

• The largest material is deposited first on the sides of the river banks and smaller material further away. After many floods, the sediment builds up to increase the height of the river banks, meaning that the channel can carry more water (a greater discharge) and flooding is less likely to occur in the future.