What is a flood?

A flood is water inundating land that is normally dry.

Causes of flood

• Short, intense bursts of rain which overwhelm drainage systems.
• Flash floods often result when a storm moves slowly, so that a small area receives most of the rain. The drainage and runoff characteristics on the ground can also determine the area of greatest impact.
• Other causes of flash floods include dam failures or burst water mains.

Types of flood?

• Slow-onset floods - flooding of river systems in the northern pastoral areas of South Australia can spread for thousands of square kilometres and last for many weeks causing damage to road and rail with potential for loss of stock and isolation of settlements and homesteads.
• flooding of the River Murray can last for many days or weeks and impact towns and agricultural industries situated in the flood plain.
• Rapid on-set floods occur in steeper terrain such as the Mount Lofty Ranges and in rivers draining to the coast. These floods can be more damaging and pose a greater risk to life and property because there is less warning and much less time to take preventative and preparative action.
• Flash floods pose the greatest threat to loss of life and can result in substantial damage to property. Increased building density in urban areas is increasing the likelihood of flash flooding because drainage systems can no longer cope with the velocity and volume of water run-off.

Likely impact

Unless you are prepared, floods can cause great damage to homes and communities. People can drown.

Warnings

• The Bureau of Meteorology monitors weather patterns and makes rain forecasts.
• However, it's difficult to give warnings about flash flooding because many heavy rainstorms can happen very quickly and the location may be difficult to predict.

Emergency action: flood

Given that weather conditions that cause flooding are possible in most regions, the drainage and runoff characteristics on the ground will determine the area of greatest impact.

Before

• Do you live in a flood-prone area? Check your local flood history -- ask your local council.
• Flood damage is rarely covered by insurance. Be prepared.
• If your area has a flood risk, prepare a flood emergency plan.
• Decide whether to stay or go if a flood occurs. Tell everyone in the family.
• If a flood appears highly likely, and you decide to stay, prepare your home and yourself.
• Store a battery radio, torch and spare batteries, gardening gloves, a first aid kit, canned food, fresh water in sealed containers and waterproof bags for clothing and valuables.
• Be prepared to move vehicles, equipment, garbage, chemicals and poisons to higher locations.
• Plan which items to rise if water threatens your home - furniture, clothing, valuables.
• Never camp in a dry creek bed when bush-walking. Creek trickles can turn into torrents very quickly.

During

• Most flood-related deaths result when people attempt to drive, walk, swim or play in flood waters. Don't take risks. It only takes an average of a half a metre of water to float an average-sized vehicle.
• If you are stranded in a vehicle in flood water, leave it and move to higher ground before the water level rises further.
• Don't exceed knee-depth in flowing water.
• At home, put sandbags in the toilet bowl and over all laundry and bathroom drain holes to prevent sewage back-flow into your home.
• Empty freezers and refrigerators and leave doors open. This will help avoid damage or loss if they float about.
• Boil all drinking water. Don't eat food that has been in flood water.
• Check for gas leaks and if you suspect there are exposed wires nearby, avoid the area.
• Check for home damage as the flood subsides. Watch out for safety risks if your home is badly damaged. If doors won't open, it may be a sign that the house structure is being affected.

After

• Remember that although most people can clean up flood damage, qualified tradesmen are necessary for some repair work.
• Disinfect all cuts and scratches and wash hands before eating or drinking, especially after working in flood water.
• Bury deposits of sewage or contaminated food.
• Don't use gas or electrical appliances that have been in flood water until they have been checked for safety.
• On dry days, open doors and windows to dry your home.
• Find out about important house repairs to be done when the flood has gone. Floods can cause a range of hidden dangers to home structures.