Flood Risk Guayaquil Final Report A critical analysis on inundations Augustus-November 2016 Team: Supervisors: J.G. Stenfert 4098366 Dr. ir. E. Mosselman TU Delft, Deltares R.M. Rubaij Bouman 4169603 Dr. ir. M. Arias Hidalgo ESPOL{FICT R.C. Tutein Nolthenius 4155807 Ir. J. van Overeem TU Delft S. Joosten 4174070 Preface This report concludes our multidisciplinary project written as a part of the master program Hy- draulic Engineering at Delft University of Technology (TU Delft). The project took place between August and November 2016 in the city of Guayaquil, Ecuador. The project has been written under the supervision of the department of Hydraulic Engineering at the TU Delft, the faculty 'Ingenieria en Ciencias de la Tierra' at Escuela Superior Politecnica del Litoral (espol) and Deltares. For three months we have had the opportunity to experience the lifestyle and culture of Ecuador. In the first place we want to thank the people who directly enabled us to start the project in Guayaquil. Pri- marily, we thank dr. ir. Erik Mosselman for both his help with the organisation of the project from the Netherlands and the supervision during our stay in Guayaquil. Secondly, we greatly thank our supervisor and host dr. ir. Mijail Arias Hidalgo. Without his help we would not have been able to execute the project the way we did. We acknowledge him for his great hospitality, the excursions to show us the culture of his country, translating during several interviews and of course his academic supervision during the project. Furthermore, we would like to thank ir. Jan van Overeem for his help during the preparations of the project and his overall supervision. We would also like to thank ir. Anke Becker and dr. Arthur van Dam from Deltares in their support using the Delft3D Flexible Mesh software. Finally, we would like thank our dear friend and project-associate Ren´e van Meerkerk who at the very last moment had to decide not to join us to Guayaquil. He has made a big effort during the preparations of the project and we certainly missed him here in Guayaquil. Guayaquil, November 2016. Joost Stenfert Roland Rubaij Bouman Raoul Tutein Nolthenius Stan Joosten i Abstract Despite several researches about the hydrological and hydrodynamic system of the Guayas region, elementary insight of the total system was lacking. Therefore, the purpose of this study was to create a general overview regarding floods. Besides, basic solutions are proposed for preparing Guayaquil against floods which might be present in the future. From August till November the project team researched this topic by starting with a thorough analysis of the hydrological and hydrodynamic system and thereby interviewing many stakeholders within Guayaquil. Afterwards, several solutions concerning different major problems within the system have been conceived and relative effects have been modelled in Delft3D-FM and ArcGIS. Several possible measures are proposed to challenge the rising sea level and more severe weather conditions which might be present in the future. Relative changes concerning implementing mea- sures are modelled and discussed. Idem, existing articles on the estuary system are reviewed. It can be concluded that an integral solution is required on measures against current flood problems. To protect the entire city against floods, governmental institutions must share knowledge and ideas. In addition, only a combination of a solution for better drainage and improved flood defences will prepare Guayaquil for more extreme weather events. iii Contents List of Figures vii List of Tables ix 1 Introduction 1 2 Approach and Methodology 3 2.1 System analysis . 3 2.2 GIS modelling . 3 2.3 Hydrodynamic modelling . 3 2.3.1 Boundary conditions . 3 2.3.2 Modelling situations . 4 2.4 Stakeholder analysis . 4 2.5 Formulation of design conditions . 5 2.6 Identification and evaluation of possible measures . 5 3 Results 7 3.1 System analysis . 7 3.1.1 Literature review . 7 3.1.2 Data analysis . 13 3.2 GIS modelling . 14 3.3 Hydrodynamic modelling . 15 3.3.1 Amplification of tide . 15 3.3.2 Influence of river discharges . 15 3.3.3 Influence of Sea Level Rise . 16 3.4 Stakeholder analysis . 17 3.5 Formulation of design conditions . 18 3.5.1 Design water level . 18 3.5.2 Design discharge . 19 3.5.3 Design precipitation . 19 3.6 Identification and evaluation of possible measures . 20 3.6.1 Measures considering stormwater system . 20 3.6.2 Measures considering flood defence . 23 3.6.3 Evaluation . 28 4 Discussion 29 5 Conclusions and recommendations 33 v 5.1 Conclusions . 33 5.1.1 Required measures . 33 5.1.2 Future measures . 33 5.2 Recommendations . 34 Bibliography 35 A System analysis 39 B Model outcomes 49 C Stakeholder analysis 53 D Design conditions 57 E Possible measures 63 F Article reviews 67 vi List of Figures 2.3.1 Map of Delft3D-FM model . 4 3.1.1 Urbanization of Guayaquil [Jimenez and Matamoros, 2009] . 7 3.1.2 Overview of the estuary [Google, 2016a] . 7 3.1.3 Averaged monthly precipitation in Guayaquil . 9 3.1.4 Sea Level Rise in Latin America cities [Miller, 2009] . 11 3.1.5 Discharge Quevedo river during the El Ni~nophenomena [Xinqiang et al., 2015] . 11 3.1.6 Simplified intrusion scheme [Pietrzak, 2016] . 12 3.1.7 Sketch of the effect of a narrower channel . 13 3.1.8 Average monthly discharge Guayas river between 1988 and 2012 . 13 3.1.9 Water levels Guayaquil in river Guayas . 14 3.2.1 Flooded areas due to sea level rise . 14 3.3.1 Tidal amplification within estuary . 15 3.3.2 Influence on water levels due to different discharges . 15 3.3.3 Tidal asymmetry due to sea level rise . 16 3.3.4 Influence in water levels due to different scenarios . 16 3.6.1 Possible storage area in Guayaquil [Draftlogic, 2016] . 21 3.6.2 Possible storage area within the sea branches [Draftlogic, 2016] . 22 3.6.3 Use of a check valve . 22 3.6.4 Example of permeable asphalt [TARMAC, 2016] . 23 3.6.5 Example of green tiles [Grass Concrete Ltd., 2016] . 23 3.6.6 Position of levees and barriers [Google, 2016a] . 24 3.6.7 Possible barrier locations in the river Guayas [Google, 2016b] . 25 3.6.8 Possible location of barrier 2 [Google, 2016b] . 25 3.6.9 Modelled time series at Guayaquil using a discharge with a return period of 100 years . 26 3.6.10Modelled time series at Guayaquil using a discharge with a return period of 200 years . 26 3.6.11Effect on the main channel [Drawing by E. Mosselman, in Havinga, 2014] . 28 3.6.12Potential location of a bypass [Google, 2016b] . 28 3.6.13Side channel effects further downstream . 28 A.1.1Tide during observation [Mobile Geographics, 2016] . 39 A.1.2Field observations 09-09-2016 . 40 A.1.3Field observations 2-10-2016 . 40 A.1 Elevation of Guayaquil provided by Interagua . 41 A.1 Wind direction and speed [Su´arezChangu´an,2010] . 42 A.1 Stormwater system in Guayaquil provided with Interagua . 43 A.1 Cartoon of the El Ni~nophenomenon . 44 vii A.2 Effected zones by El Ni~nophenomenon 1982-1983 [Xinqiang et al., 2015] . 45 A.3 Effected zones by El Ni~nophenomenon 1997-1998 [Xinqiang et al., 2015] . 46 B.1 Influence of dam on water level in sea branch . 50 B.2 Water levels at Guayaquil . 50 B.1 Tidal current velocity over a tidal cycle (1) [Barrera Crespo, 2016] . 51 B.2 Tidal current velocity over a tidal cycle (2) [Barrera Crespo, 2016] . 51 D.1 Water levels Guayaquil in river Guayas . 59 D.2 Filtered water levels Guayaquil in river Guayas . 59 D.3 The Gumbel exceedance graph of water level . 60 D.1 Frequency curve discharge . 61 D.1 Frequency curve precipitation . 61 D.2 idf analysis [emapag-ep - Interagua, 2016] . 62 E.1 Considered city area [Draftlogic, 2016] . 63 E.1 Floating house [Cherry Mortgages, 2016] . 65 E.1 Inlet of the high water channel Veessen-Wapenveld [Dutchwatersector, 2013] . 65 E.2 Overview of the high water channel Veessen-Wapenveld [Dutchwatersector, 2013] . 65 F.1 Part of 20 cities with highest loss in 2050, assuming sea level rise of 20 cm and main- taining flood probability [Hallegatte et al., 2013] . 68 F.1 Basin area of Guayas river [Twin2Go, 2016] . 68 F.2 Closure of barrier proposed by cispdr [Xinqiang et al., 2015] . 70 viii List of Tables 3.5.1 Return period of 24 hours storm . 19 3.6.1 Evaluation/Summary table of possible measures . 28 D.1.1Reference projects storm surge barriers . 57 D.1.2Probability of Exceedance for different design lives and return periods . 58 D.1.3Design requirements for different components in a flood defence system . 58 D.2.1Discharges at different return periods [Xinqiang et al., 2015] . 60 D.3.1Return period of 24 hours storm [emapag-ep - Interagua, 2016] . 61 ix 1 Introduction Due to climate change more severe weather conditions might be present in the future in large parts of the world [IPCC, 2013][Cai et al., 2014]. In Ecuador, Guayaquil urbanized rapidly without proper planning. Therefore, the city.