Final answer:
The finished floor of a basement in a flood-prone area should be constructed above the expected 100-year flood level, typically 1 to 2 feet (0.3 to 0.6 meters) higher, to ensure safety and conformity with local building codes.
Step-by-step explanation:
When constructing a building with a basement in a flood-prone area, it is essential to consider the potential flood stage to ensure that the structure remains safe and dry during such events. Reliable historical and environmental data, such as that provided by Willcocks (1913) and Julien Barois (2010), can inform the necessary elevation above the flood stage for the finished floor of a basement.
Although specific building codes can vary by region, a commonly recommended guideline is for the finished floor to be at least above the expected 100-year flood level, with some regulations requiring 1 to 2 feet (0.3 to 0.6 meters) above the flood stage for additional safety.
Considering the significant damage even a 2-meter flood could have, as observed by Barois, and the capacity of a sump pump in removing water from a flooded basement (for example, 0.750 L/s with an output pressure of 3.00×105 N/m²), it's clear that prevention is crucial. Building above known flood levels could prevent overwhelming situations where even efficient drainage systems like sump pumps cannot cope with the incoming water fast enough.
Ultimately, the required elevation will depend on several factors, including regional flood history, local building codes, and assessments of possible future flood events. By adhering to these considerations, structures with basements can be better protected against potential flood damage.