Lecture 10: Dams (Contd.)

A dam made of low permeability material (at least 50% has to be compacted sand, silt or clay).

• - there is more area contributing to deposition in the downstream area.
• - there is a balance between the erosion of the channel and sedimentation in the channel.

• Rises: where dep/erosion occurs will be higher.
• Drops: where dep/erosion occurs will be lower.

This recreates the base level for the region. Deposition will occur behind the dam, other side: erosion.

Laminar flow.

Turbulent flow.

Flow that follows straight of gently curving stream flow lines. There is no mixing.

• - An increase in the flow velocity
• - flow is no longer in parallel layers
• - velocity is highly variable

• - channel configuration
• - size of bedload

Beside a river.

The Omo River in Ethiopia.

150 km.

2006-2012

• - eliminates the natural flood cycle which affects fish spawning.
• - degraded habitats/ecosystems (e.g. wetland ecosystems like the Omo National Park).
• - lake-dependent forests.
• - reduced replenishing of natural minerals.
• - upstream flooding.

• - increased water level
• - increased Co2 emissions (submerged biomass) and methane.

• - reduced water level
• - reduced inflow
• - increased salinity

• - eliminates traditional farming techniques.
• - reduces fish catches
• - conflict between indigenous tribes in Lower Omo River Valley.

> 1800 MW.

$407 million.

$150.

11.75 billion m3

Water stress.

Water scarcity.

Pipes. Wells, surface water/tanker trucks, etc.