This winter, the U. S. state of California received unusually large amounts of rain and snow. Now, people worry that some areas will flood as the snow in the Sierra Nevada Mountains melts (融化).
Ron Caetano lives about half-way between the cities of Los Angeles and San Francisco. He is preparing to leave in case his community, called the Island District, floods.
More than 100 years ago, the Island District area was under a large lake named Tulare Lake. At one time, Tulare Lake was the largest freshwater lake west of the Mississippi River. But reservoirs (水库) and watering systems for agriculture caused it to disappear. However, in very rainy years, farmland can still get covered with water.
Experts say reservoirs near the area will likely receive three times more water than they can hold this year. That means officials must increase the amount of water they release (释放) from the reservoirs. If too much water is released, the area might flood.
The Island District has organized a community network to help prepare for floods. People are placing sandbags close to elderly neighbors' houses to block possible flooding. And they are looking at reports from water officials, county officials, and from each other.
California has had very dry weather in recent years. Both cities and farm communities acclaimed this year's winter rains. If the weather gets warmer slowly, the snow will not melt quickly and there may be little or no flooding. But if the weather gets hot quickly, that will bring trouble from too much melting snow.
Officials announced plans to close parts of Yosemite National Park because of threats of flooding. The park is about 270 kilometers east of San Francisco in the Sierra Nevada Mountains.
Nicholas Pinter is with the University of California, Davis Center for Watershed Sciences. He said the lake's size has always changed because of California's weather. He described the surrounding area this way. "It has been an engineering problem all along," he said. "This is a bathtub (浴缸) with no way out."
