SAJC Cluster 2 Lecture 9 Notes (Fluvial Flood Management Strategies)

St Andrew’s Junior College H2 Cluster 2: Tropical Environments H2_Cluster 2 Lecture 9_2024/pg1 Lecture 9 Floods in the Humid Tropics (III): Fluvial Flood Management Strategies KEY QUESTIONS: ✓ Can fluvial floods be effectively managed? With the completion of this lecture, attached readings and tutorial, you should be able to understand the: • Strengths and limitations of strategies to manage fluvial floods • Varying success of strategies to manage fluvial floods • Extent to which humans can control natural phenomenon such as fluvial floods Lecture Outline 9.1 Introduction: Categorising Flood Management Strategies 9.2 Prediction 9.2.1 Recurrence intervals 9.2.2 Forecasting and warning Box 1: Flood forecasting in India 9.3 Mitigation 9.3.1 Hard-engineering Strategies (a) Levees (or Dykes) (b) Dams (c) Channelisation (i) Channel resectioning (ii) Channel realignment 9.3.2 Soft-engineering Strategies (a) Land Use Planning and Zoning (b) Dredging (c) Reforestation of Channel Banks 9.4 Responses 9.4.1 Disaster aid 9.4.2 Community preparedness

St Andrew’s Junior College H2 Cluster 2: Tropical Environments H2_Cluster 2 Lecture 9_2024/pg2 9.1 Introduction: Categorising Flood Management Strategies • The impacts of floods can be managed through broadly three categories of strategies, and each of these categories serve different purposes. Ideally they should be adopted together to provide a more comprehensive approach to help prepare for the adverse impacts of floods. o Prediction: These involve the use of scientific methods, historical data, and meteorological information to forecast the occurrence, extent, and severity of flooding events. The primary goal of flood prediction is to offer early warnings, allowing people to take precautionary measures, evacuate if necessary, and prepare for the flood event before it happens. (See Section 9.2) o Mitigation: These focuses on reducing the impact of flooding events by implementing strategies and measures that minimise the extent of damage and disruption caused by floods. Unlike flood prediction, flood mitigation addresses the long-term aspect of flood risk reduction. (See Section 9.3) o Responses: These are often the implemention of pre-planned activities, usually during and after flooding to reduce the adverse impacts of flooding on the population and property at risk. (See Section 9.4) 9.2 Prediction 9.2.1 Recurrence Intervals • The magnitude of a flood and how frequent it can occur is of interest to us. • We can calculate the likelihood or statistical probability of flooding from flood frequency graphs, or flood recurrence interval graphs (see Fig. 1). Usually, the relationship between magnitude and frequency of floo