Chapter 1 Flood Risk Management

1. Integrated Urban Flood Management Chapter 1 Flood Risk Management

2. Flood Risk Management Goal In this chapter is presented the concepts of water related risk management with emphasis on natural disaster and floods. Objectives After this section the students will be able to understand the main impacts of natural disasters and the aspects related to floods, the main terminology used and what approaches could be developed for these issues.

3. Urban environment and natural disasters • 90 % of natural disasters have been related to weather or climate conditions; • 15 million people killed and 25 million affected by disasters; • Developing and least developed countries have higher risk of disasters in terms of lives, injured inhabitants and economic losses; • Water related risk is one of the main challenges for poverty reduction • population grow and occupation of risk areas (flood plains and coastal); • pressure on the environment and urbanization as a consequence of economic development; • climate variability and change which includes the changing conditions of the input in the basin.

4. Water related Impacts • Urban Development • Energy: demand and production (hydropower); • Transport: navigation • Agriculture • Urban development • Natural and Antropic disasters: floods, droughts, health, etc • Environment: fragile environments due to change of natural climate variables and human impacts

5. Natural Disasters • Hydro-meteorological disasters: including floods and wave surges, storms, droughts and related disasters (extreme temperatures and forest/scrub fires), and landslides & avalanches; • Geophysical disasters: divided into earthquakes & tsunamis and volcanic eruptions; • Biological disasters: covering epidemics and insect infestations Increase of the number of hydro-meteorological events along twenty century by decade data (ISDL,2005).

6. Floods Impacts • Floods account for 15% of all deaths related to natural disasters; • Approximately 66 million people suffered flood damage from 1973 to 1997; • Between 1987 and 1997, 44% of all flood disasters affected Asia, claiming 228,000 lives (roughly 93% of all flood-related deaths worldwide); • Economic losses for the region totaled US$136 billions.

7. Main Sources of Risk • Social and economic vulnerability • Climate change and variability • Impact of Economic and social development on the natural systems. • Vulnerability is the lack of capacity of the society to recovery from an impact. • The vulnerabilities are related to the source of risk

8. Social and Economic Vulnerability • Poor countries and regions; • Weak institutions; • Lack of decisions • Limited institutional management • Lack of prevention. • Lack of capacity building • Lack of funds and investments

9. Climate change and variability • Change in hydrologic series change the risk in water use and impacts on the society and environment. • This changes can be natural or antropogenics together with soil use and water pollution. • Natural changes has been part of the earth behavior. Long term change are still not well understood; • The adapted itself to seasonal and short inter-annual changes but no to inter-decadal.

10. Examples • In Brazil, 93% of electric energy is from hydropowers. In the last 30 years the mean flow of Parana River (in which 60% of Brazilian electric energy is produced) increased of about 30%, creating a new level of available energy. Since this increase could be mainly due to climate variability and could decrease for other level, the system vulnerability is high. • A sequence of bad water years for agriculture without irrigation could be enough to create an important economic stress in a country, which has been the scenario in many countries in Africa after the 70’s; • According to the IPCC (2001), it is likely that extreme weather events will increase the frequency and severity during the 21st century as result of the climate variability.

11. The pressure that society exerts on the environment • scenario where the water and environment are in danger and impact is on the resource. • reflect on the man, since damaging the natural system through pollution, its physical conditions such as river channel, basin characteristics, among other • Development tends to exert pressure on natural resources particularly when: the control of human activities is ineffective; and the complex impacts of the development

12. Urban development • The main vulnerabilities related to urban waters are: • Change in the water availability: demand increase, population of the water source and decrease of the flow due to climate variability and change. The impacts are in amount of water and the pollution of the existing water flow due to the lack of treatment; • Environment impacts: water quality deterioration (river and aquifers), gas emissions, environment fragmentation, among others. • Increase of flood frequency and its effects on the health. Changing the flood conditions and impacts

13. Risk Management in Water Resources • Management of water uses, such as hydropower, water supply irrigation, navigation, flood control and environment conservation are dependent on the amount of water in the river systems, population demand and environment conservation. • Since the future climate is uncertain, all these water uses are planned based in the stationary historical flow statistics. • There are many uncertainties(*) related to climate, human demand, and environment together with complex interactions among these aspects. (*) uncertainties error in estimation of statistics of the series

14. Main Uncertainties • Climate trends have been detected in a number of flow series and the possible effects of climate change of hydrologic regimes; • Soil use has consequence on the water systems such as: deforestation, urbanization (flow increase and occupation of flood plains), change in agriculture practices etc; • Water demand and pollution: increasing population, irrigation and degradation of water quality due to diffuse and point pollution sources and decreasing the available clean water for human, animal and industrial use, together with the supply for agriculture, conditions for energy production and navigation; • Urban developments are increasing the impervious surfaces, occupation on flood plains and coast areas which increasing and amplification of the disasters risks.

15. Water resource risk management framework

16. Questions 1. Identify the three more important natural disasters of your country. 2 - Describe the main source of the impacts related to the natural disasters mentioned in question 1. 3 - Describe the vulnerability and the resilience of a community you know in your country 4 - What could be the planned actions which would help in the community of the former question?