FLOODING: AN ISSUE TO HANDLE IN FAST GROWING COUNTRIES 1. The - PowerPoint PPT Presentation

MYANMAR – ITALIAN TECHNICAL SYMPOSIUM FLOODING: AN ISSUE TO HANDLE IN FAST GROWING COUNTRIES 1. The problem of flooding 2. Factors affecting flooding hazards 3. Approach to flood mitigation: structural and non structural approache and measures 4. Virtuous international models: SUDS (Sustainable Urban Drainage System) • BMP (Best Management Practices) • LID (Low Impact Development) • Dott. Eng. Beatrice Majone

MYANMAR – ITALIAN TECHNICAL SYMPOSIUM 1. The problem of flooding: numbers By 2050, flood damage in the world’s coastal cities is expected to reach US$1 trillion a year as sea levels rise and global warming triggers more extreme weather River flooding will affect more people and cause significantly more damage by 2030, as climate change and socioeconomic development accelerate. In South Asia alone, an estimated 15 million will be affected. One of the hardest‐hit areas is predicted to be South Asia, a region where more than 9.5 million people are already being affected every year by floods. Last year alone, unusually heavy monsoon rains triggered floods in India and Pakistan claiming more than 500 lives.

MYANMAR – ITALIAN TECHNICAL SYMPOSIUM 1. The problem of flooding: Myanmar Flood of 01 July 2016 - Myanmar Rakhine State 24,306 people displaced : Minbya (13,123), Ann (4,659), Mrauk-U (3,696) and Kyauktaw (2,828 ) Water extents on 2,549 Km ter extents on 2,549 Km² ² corresponding corresponding to ~8% of the total area of Rakhine State to ~8% of the total area of Rakhine State Affected transportation network: ~ 230 Kms of Rakhine State roads affected ฀ - ~ 60 Km of major roads. ฀ - ~172 Km of other types of roads. UNITA UNITAR-UN R-UNOSAT, AT, using Sentinel-1 SAR imag using Sentinel-1 SAR image of 14 July 2016: Rakhine State e of 14 July 2016: Rakhine State

MYANMAR – ITALIAN TECHNICAL SYMPOSIUM 2. Factors affecting flooding hazards : flash floods Flood 2002 Valtellina-Italy The worst for fatalities !!! • Small-scale catchment • Steep slope – short flood wave transit time • High flow velocities – destructive forces • Entrains sediment transport and debris flow

MYANMAR – ITALIAN TECHNICAL SYMPOSIUM 2. Factors affecting flooding hazards : coastal floods Flood Schiavonea Marina - Italy • Involve high density cities and turistic cities • Although the sea level does not grow a lot both the natural drainage system and the urban drainage system can not discharge the flow; backup effect • Cause sea pollution due to bad functioning of combined sewer systems

MYANMAR – ITALIAN TECHNICAL SYMPOSIUM 2. Factors affecting flooding hazards : urban floods • Not correct design of drainage system or combined sewer system • Not proper maintenance of drainage system or combined sewer system • River flood or coastal flood

MYANMAR – ITALIAN TECHNICAL SYMPOSIUM 1. Natural Environment Characteristics • Basin area/shape/topography  Drainage area affects discharge  Regular shaped basins are more flood prone than longer, narrower basins  Steeper slopes are more flood prone  Geology and soil features  Hydro-geological conditions  Vegetational features

MYANMAR – ITALIAN TECHNICAL SYMPOSIUM 2. Built‐environment Characteristics – Shorter time of – Urbanization increases concentration (Rain Run total impervious area off) – Decrease infiltration, – Wetland alteration increase runoff

MYANMAR – ITALIAN TECHNICAL SYMPOSIUM 1. The problem of flooding: what exactly is flood risk ? R = P x V • Risk of flooding is not an abstract concept: is a number • If one of these elements is zero there is no flood risk • The decision makers must know both the value of the two elements that quantify the risk

MYANMAR – ITALIAN TECHNICAL SYMPOSIUM 3. Approach to flood mitigation: Water Framework Directive • Directive of the European Parliament and of the Council on the assessment and management of flood risk Art. 1: …to establish a framework for the assessment and management of the flood risk, aiming at the reduction of the adverse consequences for human health, the environment, cultural heritage and economic activity associated with floods in the Community. The Directive requires: Flood hazard Flood risk Preliminary risk mapping and management flood risk assessment plans mapping

MYANMAR – ITALIAN TECHNICAL SYMPOSIUM 3. Approach to flood mitigation: structural and non structural measures • Structural: • Non-Structural  Aimed at flood  Considered soft measures protection  Focus on changing the natural  Permanent conditions of the catchment, the channel or the flood plain  Hydraulic  Aimed at monitoring, detecting Engineering works and forecasting floods

MYANMAR – ITALIAN TECHNICAL SYMPOSIUM Structural Measures: Levees

MYANMAR – ITALIAN TECHNICAL SYMPOSIUM Structural Measures: Detention basins Water levels Flow directions Water velocity Hydrodinamic 2D model of the poject solution

MYANMAR – ITALIAN TECHNICAL SYMPOSIUM Non Structural Measures • Environmentally sensitive area protection

MYANMAR – ITALIAN TECHNICAL SYMPOSIUM 4. Virtuous international models: • SUDS (Suastainable Urban Drainage System) • BMP (Best Management Practices) • LID (Low Impact Development)

MYANMAR – ITALIAN TECHNICAL SYMPOSIUM SUDS (Suastainable Urban Drainage System) Sustainable Urban Drainage Systems a new approach to water management in urban area.

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