Lec 6: CS 1 ctd.

Question 1

What is the Sudd?

Answer 1

A flat wetland area in South Sudan

Question 2

What were the pressures to act on the creation of the Aswan High Dam?

Answer 2

population pressures
- large population residing in Nile river basin, with reproduction rates growing

rising expectations for quality of life

technical capacity
- we now have the capacity to build huge dams, so it is now an option

Question 3

What are the expected benefits of the high dam?

Answer 3

add irrigated land
- basin irrigation and hydraulic heads ad water and sediment to soil

drain the delta
- by avoiding the periodic floods in the delta, you can use its rich soil for agriculture

shift to permanent irrigation
- by storing water the dam allows permanent irrigation. Thus, you can have 2 crops a year, essentially doubling productivity

save water and stabilize flow
- catch flood water before it flows into bigger bodies of water and is wasted

generate hydro-electric power to allow other industries to develop

Question 4

What were the KNOWN externalities to building the Aswan High Dam?

Answer 4

1) The loss of antiquities

2) The displacement of populations
New reservoir has larger width than existing river, displacing communities along river banks

3) The loss of sediment
Sediment in still water settles at the bottom of the reservoir

Question 5

What were the “surprises” (UNKNOWN externalities)?

Answer 5

1) Water loss
Reservoir filled much slower than expected. Why?
- Water seeped into desert floor
- High rate of evaporation because of high surface area of basin in an area with desert winds

2) Soil nutrient loss

3) erosion on banks and delta

4) salinization
- if fresh water from delta no longer pushes out salt water from sea = salt water flows in
- more water + high evaporation = more salt

5) Collapse of fisheries
- less fish downriver because of the loss of nutrients

6) Spread of diseases
- stagnant water = mosquitoes and snails breed = spread of malaria, trachoma, schistosomiasis

Question 6

Why does the Aswan High Dam show that EIA is needed?

Answer 6

• externalities need to be included in the cost-benefit analysis
• EIA is a means to ensure “zero regret planning”
• EIA is a means to account for social justice component of projects. People of Wadi Halfa essentially became refugees on their own land.

Question 7

CS 1 showed us that:
- environmental systems are complicated
- our predictive abilities are limited
- social dimensions are inextricably connected to environmental issues

What do we need to do despite all of the above?

Answer 7

Find a better way to meet human needs within the limits of ecological capability (the ability of an ecosystem to retain its original condition).

basically: how to meet human needs without messing with the environment