Hard Engineering

Hard engineering defences are man-made structures that reduce flooding.

• Expensive to build and maintain
• Disrupt natural processes
• Not aesthetically pleasing
• Can make flooding disasters worse if defence breaks.

Types of hard engineering:

• Dams
• Channel Straightening
• Levees
• Diversion Spillways

What they are

Dams are huge walls built across rivers. A reservoir is formed behind the dam to catch floodwater to prevent flooding downstream. Water is released steadily throughout the year.

Strengths

• Turbines often built into dams to generate electricity
• Steady water release = irrigation of land below dam throughout the year
• Reservoir can be used for recreational activities.

Weaknesses

• Very expensive
• Land has to be flooded to create reservoir = farmland destroyed and people forced to move
• Affect wildlife
• Trap sediment = can cause dam to fail and cause inc. erosion downstream

What it is

Meanders are removed by building artificial cut-throughs so water flows faster = flooding reduced as water drains downstream quickly.

Weaknesses

• Flooding may occur downstream instead
• More erosion occurs downstream due to river flowing faster
• Disrupts wildlife habitats

What they are

Most common form of hard engineering. They are man-made embankments built along rivers so the river can hold more water without overflowing.

Strengths

• Allows floodplain to be built on

Weaknesses

• Quite expensive
• Risk of severe flooding if breached.

What they are

Diversion spillways are channels that take water elsewhere if water level is too high.

Weaknesses

• If spillways are overwhelmed, water can flood areas not used to flooding = can cause bigger problems.