9,800 properties in Belfast are at ‘significant’ risk of flooding from rivers and 6,000 of which are also at risk of flooding by the sea.The floodplain of Northern Ireland is designed to protect the surrounding areas from 1 in 100 year floods. This is the light blue colour on the diagram and illustrates the large portion of the city which lies within the floodplain. To prevent future flood damage, the mitigation techniques in place are mainly soft engineering, in the way of avoiding any further developments in the floodplain or coast that do not reduce the risk of flooding or harm the environment. In terms of attack, defend, retreat the plan for Belfast is heading towards retreat and defend. The council will retreat from building in the floodplain in hopes of reducing flood risk. In addition to this the finished floor level of new developments should be set to protect the owner in the event of a flood and to reduce damages. There are 4 causes of floods; Rivers, Coastal, Surface run-off and water impoundment (Reservoirs). Surface runoff is the one that can cause the most unpredictable damage in the form of flash floods.