Water Insecurity - EQ2

Question 1

What is a drought?

Answer 1

An extended period where rainfall is lower than the average for an area

Question 2

Types of drought

Answer 2

Meteorological drought: occurs when long-term precipitation is lower than usual
Agricultural drought: occurs when there is insufficient soil moisture to meet the needs of a particular crop at a particular time.
Hydrological drought: occurs when there are deficiencies in surface and sub-surface water supplies as measured in rivers, reservoirs, etc.
Socio-economic drought: occurs when the water demand for social and economic purposes exceed the availability

Question 3

Drought risk from human activities

Answer 3

• Abstracting water from rivers and groundwater contributes to droughts taking place
• reducing the downstream supply of water by building dams and reservoirs
• deforestation and overgrazing reduce vegetation cover leading to reduced rates of evapotranspiration, thereby reducing atmospheric moisture

Question 4

Drought - The Sahel case study

Answer 4

Desertification is taking place due to over-cultivation and over-grazing from farming, El Niño events also increase flood risk in the region. The area has straddles across high poverty countries with fast increasing populations, which puts pressure on farmland and natural resources

Question 5

Impact of drought on wetland ecosystems

Answer 5

Loss of water causes loss of habitat and a decline in soil moisture which leads to soil erosion taking place, which can decrease the capability of soil to store water during flood events, it can also damage the food chain and cause some species, such as semi-aquatic birds, to decline

Question 6

Impact of drought on forest ecosystems

Answer 6

Living trees take an average 2-4 years to recover and resume normal growth after a drought takes place. A combination of higher temperatures and severe drought led to a mass dying of piñon pines in the four corners region of the USA, as the hot temperatures made them more susceptible to pine bark beetle attacks

Question 7

Meteorological causes of flooding

Answer 7

Flash floods are usually caused by intense heavy rainfall associated with thunderstorms or tropical storms, meanwhile
prolonged rainfall, potentially caused by a series of mid-latitude depressions passing over the same area, can cause a slower buildup to river flooding

Question 8

Flood risk from human activities

Answer 8

Land use changes and removal of vegetation leads to less infiltration and interception, and an increase in surface run off which leads to water reaching rivers faster causing more flash floods. Urbanisation also increases flood risk due to the increase in impermeable surfaces such as roads and pavements which causes more surface run-off