Chapter 3 Urban Waters

1. Integrated Urban Flood Management Chapter 3 Urban Waters

2. Urban Waters Goals Management of Urban Floods is related to water utilities such as water and sanitation, urban drainage and total solids services. The goal of this chapter is shows an overview of the components of urban waters and its relation with floods. Objectives The learning objective of this chapter is that the students understand the Urban Water components and their interface in managing the urban environment together floods management.

3. Urban waters facilities • Urban Waters systems generally include both water supply & sanitation facilities (WSS). • Sanitation refers to domestic and industrial sewage collecting and treatment; it usually does not include urban stormwater or solid waste management systems. • Urban water components of a sustainable urban environment includes the services as Water and Sanitation, stormwater and solid waste together with environment conservation. • Integrated water resource management (IWRM) is the modern concept of planning these components

4. Water supply and Sanitation Manancial

5. Key aspects WSS components • Water sources: surface and groundwater. The key aspects is the protection of water sources • Water supply treatment plant: • Water supply distribution network: important losses of treated water in the distribution • Sewer network: lack of connections in the houses and leakages • Sewage treatment plant: eficciency of the treatment • Effluent disposal: load disposal in rivers or other systems.

6. Billings São Paulo Contamination of water sources in São Paulo

7. Water yield – lack of water • Lack of quantitative water: high demand for small water yield; • Lack of qualitative water: reduction of water available because if its quality Bad management • Increase of water demand with population grow and decrease of quality because of lack of treatment • High losses of water in the water supply distribution network.

8. Conservation of water supply sources • The tendency is the urban occupation of water supply basin or contamination of groundwater; • In order to conservate these source the “comand-control “ management is not efficient; • The tendency is to buy the land or to pay for environment services and introduce this cost in the water price. • Using this concept the cost of paying for environment services (such as rent) would increase about 10% in the water price. • It could even be lowest if the reduction cost of water treatement is taking into account

9. Water supply • The components are: collecting from the source, treatment, storage and distribution; • The rational use of water requires good management; • The main challenges are : the development of indicators of efficiency by the regulators, reduction of the losses in the network, control of the quality of the water sources, development of water reuse 1–improved water is a generic term of the water delivered without population contamination. It is no the same as “safe”, which is based on some specific indicators; 2 – water supply is understood as the water for the population; 3 – Waste disposal is understood as the disposal of the waste in a network or in the soil. It does not mean the treatment of the waste.

10. Conditions • Lack of management and economical capacity of the countries are the main causes of the limited investments and services. • There are many vulnerable regions where about 460 millions (8% of total population) are vulnerable or very often have lack of water supply and • about 25% of the total are going to the same condition. • The main indicators are: the population covered (as mentioned above), per capita consume rate and losses in the water supply network

11. Sanitation • The main components are: sewers networks which collects the sewage; Treatment Plant and disposal; • The networks can be: • combined: when sewage and stormwater flows in the same conduit. It is the scenario of old tows areas and regions the connections are so high that it is impossible to separate • Two networks : sewage network and stormwater network independents. Usually the flow of stormwater is some magnitud larger than from sewage. • The main difficulties is when there are too many sewage flowing in the stormwater and when sewer network receives storm flow. It generate a highly inefficient system.

12. Networks Combined Separate networks

13. R. Janeiro – Rio Viegas S. Paulo Nova Friburgo - Córrego Cônego Sewage in the drainage Source: eng. Orsini

14. Impact of lack of sewage treatment in the rivers São Paulo Porto Alegre

15. Water Supply and Sanitation • Lack of investments • Bad design & management: networks without house connections; inefficient operation and maintenance; • Lack of efficient indicators for management • Lack of regulation of public services and weak management in the private services. • contamination of water sources • Large amount of water lost in the networks • Limited maintenance • Improve de management • Improve de reuse of the water

16. Stormwater and Flood management • Flood Plains : there are natural floods when the river flow through the flood plains, floodind its banks. • Stormwater : flow through urban surfaces. The hydrologic cycle is changed, increasing its peak flow due to impervious areas and the increasing the pipes, channels and increase the flow velocity. Belo Horizonte

17. Flood Plains • It is a natural process of a flood seasons when the river floods its banks. Its varies from year to year based in its risk; • The main causes of the impacts are related to the occupation of the flood plains during the dry season or low flood season; • Usually who occupy the risk area suffer the direct impact • Usually there are not urban regulation or zonning for floods risk. Without knowing the risk the population construct in the risk area; • When there is regulation part of the population occupy this area wait for support during flood season; • The impacts are: economic and social lossses, deseases and contamination of water

18. Stormwaters Belo Horizonte - Brazil • Increase in the peak flow and flood frequency due to impervious areas and pipes and channels; • Increase of the solids in the rivers because of the unprotected surfaces and waste from the population ; • Decrease of the water quality because of polution of washing urban surfaces. • Deseases related to water in the floods such as leptospirose Usually who produce the impact does not suffer from it

19. IMPERVIOUS AREAS

20. Solids Total solids = Sediments + Waste • Sediments = increases with unprotect surfaces and increase in the velocity of flow • Waste = increase with the lack of services and education. Fase I – high increase in sediments and low waste when the city is in development Fase II – decreases the sediments yield and increases the solid waste after the population moves to the area

21. Fonte

22. Sediments evolution

23. Solid Waste Solid waste SW = Tc + Tli + Td Tc = colected Tli = from cleanning Td = stormwater When the first two terms are not developed or are not efficient the last term increases, leaving for the environment

24. Population in risk areas

25. Stormwater quality • Important load for the rivers • Organics such as BOD, N, P,etc • metals: Plumb, Copper, etc; • High load in the beginning of the flood when the former days were dry

26. Characteristic • Most of the load comes in the first 25 – 30 mm of the storm • Concentration of the peak occur in the beginning of the hydrograph. • Usually rivers could have a critical conditions during dry period because of the load of point source such as domestic sewage and another critical conditions at the flood due to stormwater pollution, poluthogram C Q hidrograph t C = concentration (mg/l) Q = flow (m3/s) Load = C. Q (Kg/Tempo)

27. Comparation

28. Stages

29. Contamination Cycle • supply from upstream • Efluent downstream • Transference of impact to downstreamn users; • It will be always someone upstream and another downstream • This generate the cycle of impacts

30. Questions • What are the main sources of urban water? When are they used and under what conditions? • What are the main causes of contamination of water sources? • What is the difference between river flooding and flooding caused by urbanization? • What causes the problems of these types of flooding? • What is the difference between the pollution loads of urban drainage and sewage effluent? • Why is the flow higher in an urban watershed than in rural conditions? • Analyse the causal chain in the deterioration of water quality in rivers downstream of cities. • Since the impacts of flooding and water quality are caused by urbanization, what are we doing about it today? what strategies could be adopted to avoid them?

31. Conclusions • Managing floods requires an integrated view in the city, taking into account urban developments and all aspects of urban waters; • The institutional aspects are necessary in order to have a sustainable management; • Usually the low cost solutions are the best but usually are more politically difficult to implement • The public participation is the fundamental • This is a process in many steps.