Drought has many causes. It can be caused by not receiving rain or snow over a period of time. We learned in the discussions about the water cycle and weather that changes in the wind patterns that move clouds and moisture through the atmosphere can cause a place to not receive its normal amount of rain or snow over a long period of time.

If you live in a place where most of the water you use comes from a river, a drought in your area can be caused by places upstream from you not receiving enough moisture. There would be less water in the river for you and other people who live along the river to use. 

People can also play a big role in drought. If we use too much water during times of normal rainfall, we might not have enough water when a drought happens. These can be the situations that lead to droughts.
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Droughts occur when a long period of abnormally dry weather leads to a severe water shortage. Droughts are also often caused by the activity of humans and can have devastating effects.
Human activities causing drought

Human activities that can help trigger droughts include:
Widespread cutting down of trees for fuel reduces the soil’s ability to hold water - drying out the ground, triggering desertification and leading to drought.
Constructing a dam on a large river may help provide electricity and water to irrigate farmland near the reservoir. However, it may also cause drought downstream by severely reducing the flow of water.