Drowning will be the most frequent cause of death during a flood. Many of the drownings will have a trauma as a secondary cause. In addition to changing the landscape, floodwaters can cause riverbanks to erode and collapse. Pollutants like sewage, industrial chemicals, debris, and pesticides used on farms can contaminate floodwater. Floods most frequently cause infectious disease outbreaks linked to the weather. Flooding incidents increase the potential for the spread of cholera and hepatitis A, two waterborne diseases.