The municipal territory contains a number of small rivers and streams as well as mountainsides, making it susceptible to flooding. Two most recent major floods occurred in 1999 and 2007. Major flooding occurred in and around the city in 1999, with communities such as La Rosa, on the outskirts, the hardest hit, when rivers and streams overflowed. The flooding was caused by heavy and prolonged rainfall which affected several states in the region. Over 500 houses were abandoned in the city at the height of the disaster. Hurricane Dean caused flooding damage again in 2007, when in less than 12 hours of rain, eighteen colonias were underwater with water pouring off mountainsides. Many houses were completely destroyed and a number flooded by sewerage. Those here were among the estimated 100,000 affected in Hidalgo state.