How do hydrologists measure flood potential?
Hydrologists – people who study the effects of water on the earth’s surface and in the atmosphere – use gauges to measure the water levels in streams, rivers and lakes. They also measure the water content of snow using snow gauges. They take into account recent precipitation amounts (because soil moisture affects how much rain will soak in and how much will run off), and how much more precipitation forecasters expect. The data are sent to a river forecast center where computers analyze the information to predict river and stream levels in their area. When local forecasters receive the data they compare it with charts for their area and issue a flood warning if necessary. Forecasters can usually tell in advance when conditions are right for flash floods to occur, but there is often llittle lead-time for an actual warning. (By contrast, flooding on large rivers can sometimes be predicted days ahead.) Scientists are working to understand the types of storms that have high precipitation ra
