Flood & Flash Flood
The most common natural weather event. A flood happens during heavy rains, when rivers overflow, when ocean waves come onshore, or when dams or levees break. Flooding may only be a few inches deep — or it may cover a house to the rooftop.
What is a Flood?
A flood happens during heavy rains, when a river overflows, when ocean waves come onshore, or when dams or levees break. This is the most common natural weather event. Flooding may only be a few inches of water, or it may cover a house to the rooftop.
Floods that happen very quickly — within minutes or hours — are called flash floods. These are the deadliest type, because there's almost no warning time and the water is moving fast enough to sweep cars, trees and people away.
Most flood-related deaths happen when people try to walk or drive through moving water. Just 6 inches of fast-moving water can knock an adult off their feet; 12 inches can carry away a small car; 2 feet can carry away a pickup truck. If you can't see the road surface — don't enter.
Where Do Floods Happen?
Floods can occur in every Caribbean region. Some floods develop slowly, and some can build in just a few minutes. People who live in low-lying areas near the beach are at an even greater risk. In Nevis the highest-risk zones include:
- Charlestown — drainage system overwhelms in heavy tropical downpours
- Newcastle — low-lying coastal flats vulnerable to surge and runoff
- Ghauts and watercourses across the island — fine in dry weather, deadly in flash floods
- Beach-front and coastal-road properties — at risk from storm-surge flooding
- Anywhere downhill from the Nevis Peak slopes during prolonged rainfall
What to Do
Before
Know your flood zone and prepare the home and family before the wet season.
- Build an emergency kit (water, food, flashlight, battery radio, first aid)
- Make a family communications plan and identify your meet-up point
- Tell an adult immediately if you hear a flood warning
- Know whether your home or street is in a 100-year flood zone (see maps below)
- Keep gutters and ghauts around your property clear of debris year-round
- Move valuables, electronics and important documents to upper floors / higher shelves
During
Get to higher ground. Never walk or drive through moving water.
- Listen to authorities and safety officials — follow evacuation orders immediately
- If there is any possibility of a flash flood, move IMMEDIATELY to higher ground
- Do not walk through moving water — even 6 inches can knock you off your feet
- Do not drive through flooded roads — 'Turn Around, Don't Drown'
- Stay out of basements, low-lying rooms and ghauts during heavy rainfall
- Disconnect electrical appliances if it's safe to do so — never if you're standing in water
After
The water that's left behind is contaminated — and the danger isn't over.
- Stay away from flood water — it could be contaminated with sewage, fuel or chemicals
- Stay away from moving water — it can knock you down even when it looks shallow
- Stay out of the way of emergency workers
- Wait for officials to declare drinking water safe before using tap water
- Beware of damaged roads, bridges and downed power lines
- Document damage with photos before cleaning up (for insurance and relief claims)
Types of Flood
Not every flood behaves the same way. Understanding the type helps you predict how much warning time you'll get — and where to go.
River / Stream Flood
Slow-onset flooding from heavy or prolonged rainfall causing rivers and ghauts to overflow their banks. May develop over hours or days, giving more warning time.
Flash Flood
Sudden, violent flooding triggered by intense rainfall, dam failure or upstream collapse. Builds in minutes. The deadliest type — most flood fatalities are from flash floods.
Coastal Flood
Saltwater pushed onshore by storm surge, high tides, hurricanes or tsunamis. Strikes low-lying beachfront areas — see also Storm Surge and Tsunami.
Urban Drainage Flood
Water that overwhelms storm drains and ghauts in built-up areas — Charlestown, Newcastle. Roads turn into temporary rivers; underpasses become traps for vehicles.
Nevis Flood Risk Maps
Official 100-year flood scenario maps from NDMD's hazard mapping programme. Each map shows the buildings expected to be affected during a 1-in-100-year flood event under Scenario A.
Island-wide (Nevis)
Charlestown
Newcastle
Nevis Flood Management System
Reference document for the island's flood management plan — drainage strategy, monitoring, and response coordination.
Words to Know
A Watch means conditions favour flooding — be ready. A Warning means flooding is happening or about to happen — act now. Don't wait for the warning to make a plan.
Volunteer With Us
NDMD trains Community Emergency Response Team (CERT) volunteers in flood-response, evacuation support and post-event damage assessment. Sign up online or pick up a form at the office.