1. Public Investment in Infrastructure to Reducing Flood Disaster Risk in the District of Bab El Oued in Algiers (Algeria) NATIONAL DELEGATION FOR MAJOR RISKS (NDMR) Author: DIRECTORATE OF WATER RESOURCES (PROVINCE OF ALGIERS) Presenter: DJILLALI BENOUAR dbenouar@gmail.com Third UN World Conference on Disaster Risk Reduction (WCDRR) Sendai (Japan), 14-18 March 2015

2. Historically, this area has experienced abnormally high rainfall events, but that of 2001 (260 mm), is by far the highest: 134 mm 31.10.1911 : 134 mm 101 mm 21.09.1934 : 101 mm 129 mm 11.11.1935 : 129 mm 35 mm 02.04.1954 : 135 mm On 9 th and 10 th of November 2001, a violent torrential rains hit the province of Algiers and particularly Bouzaréah zone with a total of 260 mm (260 liters per square meter) in 18 hours "stations Bouzaréah and Cap Caxine). Of the normal, November does not exceed 96 mm. At the height of the phenomenon, the rainfall had a duration of 1h:30, combined with a significant swell with wave heights of 6 to 8m. November 10 th, 2001 Bab El Oued flood, mud and debris flow

3. ALGIERS FLOOD AND MUDFLOW 10 NOVEMBER 2001 CAUSED 776 HUMAN LIVES LOST, 350 INJURED, 126 MISSING, 1800 HOUSING UNITS SUFFERED DAMAGE, 1500 FAMILIES MADE HOMELESS, 56 SCHOOLS, SCORES OF BRIDGES, ROADS, PUBLIC WORKS WERE DAMAGED. MORE THAN 1.40 MILLION M3 (UP TO 10 M THICK) OF MUD IN THE STREET OF BAB EL OUED, MORE THAN 350 VEHICULES (CARS, TRUCKS AND BUSES) WITH PASSENGERS BURIED UNDER DEBRIS FLOW AND MUD. MAIN SEWERS AND DRAINAGE SYSTEMS WERE COMPLETELY CLOGGED, SIGNIFICANT DAMAGE TO WATER, ELECTRICITY, GAS AND TELECOMMUNICATIONS NETWORKS. THE PRELIMINARY DIRECT COST U.S.$ 250. 000 000.

4. Bab El Oued Flood of November 10 th, 2001 DAMAGE

7. Main Catchments

8. 8 Flood hazard Map

9. 9 The following measures were implemented to the Oueds (rivers in Arabic) as flood risk reduction by: Clearing out, Recalibration and reprofiling, Placing the gabion, Enlargement of beds, Achieving reception structures, realization of settling ponds, etc.

10. Oued des Oiseaux Oued Z’GHARA Oued Bou Amar Oued Frah Oued Beau Sejour Oued Sidi kebir Oued cimetière ouhounouzene Oued grand rocher Oued Boukikaz Oued les Aures Oued Ajel el Afroun Oued Bainem Oued Schbot Oued Miramar Floods of November 2001

11. Oued Z’ghara Oued Bou Amar Collecteur oued M’Kacel Oued Frah Oued des Oiseaux Oued Sidi El- Kebir

12. Project of Duplicating the collector Oued M’kacel

13. 9 km 2 Barranès Scotto Nadal and Jaubert Sidi Medjbar And Frais Vallon DUPLICATION OF THE COLLECTOR OUED M’KACEL Catchement of Oued Koriche Most Affected

14. DUPLICATION OF THE COLLECTOR OUED M’KACEL Civil Engineering Works

15. DUPLICATION OF THE COLLECTOR OUED M’KACEL high flow rate (63 m 3 /s) Protection of works against the erosion  effluent limitation speeds from 5 m/s to 7 m/s) ► Limitation slope of the collector between 0,5% and 0,8%), except for the first section (slope= 6%) ► Waterfall well (vortex and bearings) Constraints integrate into the hydraulic study 1) Hydraulic constraints MAIN PROJECT CONSTRAINTS except for the first section

16. DUPLICATION OF THE COLLECTOR OUED M’KACEL Few sites available for locations of wells and construction facilities Reduced space, sinuous course Depth of wells > 50 m, conducted in the rocks Use of explosives prohibited and traffic restrictions Protection against the swell of the sea discharge structure PROJECT CONSTRAINTS 2) Constructive and environmental constraints

17. DUPLICATION OF THE COLLECTOR OUED M’KACEL +220 NGA +97 NGA +51 NGA +4 NGA 27 m 33 m 43 m 20 m 2500 m 800 m 1050 m Average depth of water line = 30 à 55 m Accumulated height of the fall wells = 50 m Accumulated height of the connection wells = 115 m The project

18. DUPLICATION OF THE COLLECTOR OUED M’KACEL Waterfall Well à vortex JAUBERTHelicalEntonnement Wellvortex Chamber of dissipation 24 m 53 m DN 4000 Ø 15 m

19. DUPLICATION OF THE COLLECTOR OUED M’KACEL Ouvrage Jaubert 44m Wellvortex WaterfallWell InterceptionRoomDN2000 InterceptionRoomOvoide

20. DUPLICATION OF THE COLLECTOR OUED M’KACEL CE Work Scotto Nadal Tunnel InterceptionRoom Grit removal Room Waterfallbearings JunctionGalery AccessChimneys M’kacelexisting 23m

21. DUPLICATION OF THE COLLECTOR OUED M’KACEL Testing on reduced models (2006)

22. DUPLICATION OF THE COLLECTOR OUED M’KACEL Le Collecteur Cadre Aval Civil Engineering works Open Sky

23. Le rejet en mer DUPLICATION OF THE COLLECTOR OUED M’KACEL Civil engineering works

24. DUPLICATION OF THE COLLECTOR OUED M’KACEL Le terrassement des puits Civil engineering works of wells

25. La réalisation du tunnel DUPLICATION OF THE COLLECTOR OUED M’KACEL Le tunnelier Yasmine Descente du tunnelier Vue du tronçon amont 75 m 45 m Le train suiveur et le train de marinage The Collector

26. DUPLICATION OF THE COLLECTOR OUED M’KACEL Civil Engineering works of a connecting tunnel

27. Civil Engineering Works of Wells and Junctions DUPLICATION OF THE COLLECTOR OUED M’KACEL

28. Civil engineering works

29. Junction Chambers DUPLICATION OF THE COLLECTOR OUED M’KACEL

30. Civil engineering vortex well works DUPLICATION OF THE COLLECTOR OUED M’KACEL Frais Vallon Vortex Wall BarranèsEntonnement Tangential Tangential

31. Civil engineering vortex well works DUPLICATION OF THE COLLECTOR OUED M’KACELJaubert Vortex Well BarranèsaccessChimnies

32. DUPLICATION OF THE COLLECTOR OUED M’KACEL Civil engineering vortex well works

33. Structures: Excavation (m3) Concrete (m3) Steel (T) Tunnel 83 000 28 000 2 000 Civil Engineering Works Civil Engineering Works 55 000 13 000 1 780 DUPLICATION OF THE COLLECTOR OUED M’KACEL Quantities realized

34. In the wake of this disaster, the Algerian Government allocated, for disaster flood reduction strategy across the whole Algeria, a total budget of US $ 3.6 Billion. The total cost of the duplication of the Collector Oued M’kacel was US $ 74 million.

35. BAB EL OUED BUILT BACK BETTER

36. Thank you very much for your attention dbenouar@gmail.com