1: B
2: A dam can also be used to collect water or for storage of water which can be evenly distributed between locations. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates
3: Long periods of unusually low precipitation are called ... A small storm often accompanied by heavy precipitation and frequent thunder
4: Even when there are no signs of a flood, be alert to conditions that can cause floods: Heavy rain for several hours, or steady rain for several days, can saturate the ground and cause a flood.
5: China and India ranking first and second respectively for the highest absolute number of people affected.
6: a