Droughts

• A drought is a long period when rainfall is below average
• Water supplies - e.g lakes and rivers - are depleted during a drought because people keep using them but they aren't replenished by rainfall
• High temperatures often occur with droughts which increases the rate of evaporation, so water supplies are depleted faster
• The length of a drought is different in different places

Climatic conditions that cause periods of drought:

• Droughts are caused when changes in atmospheric circulation mean it doesn't rain much in an area for years e.g Ethiopia
• Changes in atmospheric circulation can also make the annual rains fail e.g monsoon rain does not come when they normally do in places like India
• Droughts are also caused when high pressure weather systems (called anticyclones) block depressions (weather systems that cause rain) e.g the UK

Areas most at risk from drought are: North-eastern Africa; the Sahel; southern Africa; the Middle East; Australia and parts of eastern South America and Indonesia

• They've always lived there
• They've got a job in the area
• They don't think a drought will happen again

Primary Impacts:

• Vegetation dies - including crops
• People and animals die from dehydration
• Aquatic animals die because lakes and rivers dry up
• Soil dries out and is easily eroded by the wind and rain

Secondary Impacts:

• Animals die from starvation because there's no vegetation
• Shortage of food because crops have failed and livestock has died -> people die from starvation
• Soil erosion is increased because there's less vegetation to hold it together- causes desertification (where land becomes unsuitable for growing vegetation)
• Conflicts over water supplies
• People move out of the area to find water
• Farms close - causing unemployment
• People may suffer psychological problems e.g stress from losing their business
• Dried out vegetation can be easily ignited e.g by lightning -> causing wildfires
• Winds pick up dry soil - causing dust storms

Overgrazing:

• Reduces vegetation in an area
• Makes soil erosion even worse - with fewer plants, soil isn't held together as strongly so it's eroded more easily

Excessive Irrigation*:

• Depletes rivers and lakes - increases the impact of drought because there's less water
• When irrigation water evaporates, salts are left in the soil (salinisation) - crops don't grow well in salty soil -> also increases impact of drought

* Irrigation is where water is artificially supplied from rivers or lakes to farmland to increase crop production

• More people depend on farming - if crops and livestock die lots of people will lose their livelihoods -> also causing starvation
• Less money to prepare for droughts or respond to them - e.g can't afford to buy resevoirs, so the impact of droughts are more severe

Prediction:

• Droughts can be predicted by monitoring rainfall
• To reduce impact e.g banning hosepipes, rationing water, moving people out of areas that will be affected badly

Water Conservation:

• Install low volume flush toilets, take showers instead of baths
• Install water butts to collect rainwater
• Reduces demand of water, so more is available during drought

Farming Techniques:

• Drought resistant crops (ones that need little water) e.g olives, millet, sorghum
• Drip irrigation delivers small volumes of water directly to crop roots
• Food production becomes more reliable

Increase Water Supplies:

• Resevoirs and wells can be built to increase water supplies
• More water becomes available during drought - reducing deaths from dehydration and making food production more reliable

Aid:

• Emergency aid e.g food and water, to stop dehydration and starvation
• Fund development projects e.g building wells or water pipes - making water more availale during droughts

Sustainable Strategies:

• Most strategies are sustainable because they're effective and environmentally friendly
• Building wells can deplete groundwater supplies - less water for people in the future -> not sustainable
• Building resevoirs can reduce other people's water supply downriver -> not sustainable because it doesn't meet the needs of people alive now
• Some are more sustainable because they're more cost efficient - e.g buying pipes for drip irrigation is expensive but it saves a lot of water -> can be more cost effective than emergency aid