Luis Leonardo González Jiménez; CE, MSc - PowerPoint Presentation

Luis Leonardo González Jiménez; CE, MScJorge Enrique Saénz Samper; CE INCIDENCE OF THE NEW BRIDGE CONSTRUCTION OVER THE MAGDALENA RIVER IN BARRANQUILLA (COLOMBIA) ON THE HYDRAULIC CONDITIONS Pittsburgh, USA, 18-21 September 2017 “SMART RIVERS 2017”

19-09-2017 “SMART RIVERS 2017”INTRODUCTION The objective of the study was evaluating the influence of the new bridge construction on the river hydraulics near the crossing. New bridge is located parallel to the existing one. - Existing bridge: piles arranged in pairs with 2.5m diameter each and 5m diameter for the central piers. - New bridge: span of 380m between central piers, each one supported on a dice with piles of 2.8m diameter.

Main Topics Analyzed19-09-2017 “SMART RIVERS 2017” 1- Water levels at Canchera School 2- Hydraulics and scouring at the New Bridge 3- Pasadena Channel Hydraulics4- Ahuyama Branch Hydraulics

Location 19-09-2017“SMART RIVERS 2017” CARIBBEAN SEA PACIFIC OCEAN Barranquilla Barranquilla MAGDALENA RIVER Location New Bridge N New Bridge Piles Barranquilla To San Marta Existing Bridge Rondón Island MAGDALENA RIVER

Magdalena River General Characteristics 19-09-2017 “SMART RIVERS 2017”Width of the Magdalena River on site: 1150 mMean Annual Discharge :7200 m3/s Distance to Caribbean Sea: 21 kmManning’s n Main channel : 0.024 - Manning’s n Island and banks: 0.035

1- Water levels at Canchera School 19-09-2017“SMART RIVERS 2017” Canchera School MAGDALENA RIVER Existing Bridge New Bridge Piles 500 m aprox N

1- Water levels at Canchera School 19-09-2017 “SMART RIVERS 2017” Based on the topographic information and the hydraulic modeling, water levels that can be reached by the river and affected property were stablished. Magdalena River Location current Bridge and New Bridge Aprox 500 m Hydraulic Profiles Site closest to Canchera School

1- Water levels at Canchera School 19-09-2017“SMART RIVERS 2017” For the construction of the Canchera School, a period return period of 50 years was considered. Return Period(Years)Water Level (msnm)Protection Level (msnm) 5 1.98 2.13 10 2.21 2.36 20 2.402.55502.612.761002.752.90 It was recommended to raise the terrain level to a height of 2 masl . T he first floor should start at 2.75 masl .

2- Pasadena channel hydraulics 19-09-2017“SMART RIVERS 2017” N CHANNEL PASADENA MAGDALENA RIVER BARRANQUILLA

2- Pasadena Channel hydraulics 19-09-2017“SMART RIVERS 2017” According to the topography of the area, the channel projected for the Channel Pasadena in the sector where the camp is located is hydraulically studied. This included hydrology, channel layout and cross-sections.Hydraulic Modeling - HECRAS - Design flow - Tr 50 years: 10.8 m3/s corresponding to 54 ha Boundary Conditions: Levels in the Magdalena river at the place of channel delivery and variation of water levels by tide effect. Manning’s n: 0.015, corresponding to concreteSlopes: 0.12% and 0.64%

2- Pasadena channel hydraulics 19-09-2017 “SMART RIVERS 2017” Channel bottom is below the natural terrain as a result of the interference with existing pipes and cross section changes. T he possibility of a hydraulic jump for a period of Tr = 50 years and a minimum level in the Magdalena river was considered. Although improbable, it will happen in the lined section of the channel and will be submerged by the water level of the Magdalena River.

3- Hydraulic Evaluation and Scouring at the New Bridge 19-09-2017 “SMART RIVERS 2017” Analysis were conducted to study the behavior of the river at the project site during the construction of the new bridge. This condition is considered the most critical during the next 3 years and which will be at the same time the following structures: Piles of the existing b ridge Piles of the new b ridge Four temporary jetties for construction of the new bridge

3- Hydraulic Evaluation and Scouring at the New Bridge 19-09-2017 “SMART RIVERS 2017” Rondón Island Barranquilla Magdalena River Palermo Rondón Island 380 m Temporary jetties for construction of the new Bridge Piles of the existing b ridge Piles of the New Bridge N

3- Hydraulic Evaluation and Scouring at the New Bridge 19-09-2017 “SMART RIVERS 2017” Piles of the existing bridge = 30 piles Piles of the new bridge = 54 piles, 2.0m diam + 20 Piles, 2.8m Four temporary jetties during construction 2*(54 + 75)= 258 piles, 0,90m diam .

3- Hydraulic Evaluation and Scouring at the New Bridge 19-09-2017 “SMART RIVERS 2017” Hydraulic Modeling New bridge Existing b ridge Jetty Jetty Jetty Jetty Magdalena River

3- Hydraulic Evaluation and Scouring of the New Bridge 19-09-2017 “SMART RIVERS 2017” Model Results Return Period (years) Flow (m 3 /s ) Water level (masl) Existing bridge Scenario Scenario during construction Future scenario only with the New bridge Original design (2014 ) Jesyca (2015) Original design (2014 ) 2 11 819 1.63 1.64 1.63 5 13 790 2.08 2.11 2.09 10 14 800 2.32 2.35 2.33 20 15 619 2.52 2.55 2.53 50 16 521 2.74 2.77 2.75 100 17 111 2.89 2.92 2.89 500 18 279 3.18 3.21 3.18 1000 18 717 3.29 3.32 3.29

3- Hydraulic Evaluation and Scouring at the New Bridge 19-09-2017 “SMART RIVERS 2017” It can be concluded that the effect of the piles during construction on the hydraulic behavior of the Magdalena River, is minimal and does not imply any complication from the point of view of changes in the water levels or the average velocities in the central channel or the banks.

3- Hydraulic Evaluation and Scouring of the New Bridge 19-09-2017 “SMART RIVERS 2017” General scour was estimated by the Lischtvan-Lebediev formulation. Local scour by the formulations in HEC-18 for a composite pile. According to the total estimated scour, the final profile theoretically exceeds the coral rock boundary. Since it is a competent stratum, the scour is limited to rock level. Longitudinal profile main channel Maximun water level 3.13 masl - Average water level 1.69 masl Scour estimated assuming sandy bed Coral rock Shallow fill Alluvial filling Alluvial - Lacustrine filling Residual Soil 1 Residual Soil 2

4- Ahuyama branch hydraulics 19-09-2017 “SMART RIVERS 2017” MAGDALENA RIVER N BARRANQUILLA CAÑO AHUYAMA Existing dyke NEW BRIDGE PILES

4- Ahuyama branch hydraulics 19-09-2017 “SMART RIVERS 2017” Another aspect to determine the effect of the area is the influence of the tributaries that reach the Magdalena River, in this case the Caño Ahuyama. Evaluation of Tr=100 year discharge was analized in respect of the existing dyke. Two scenarios were analized : -The first one contemplates high levels in the Magdalena river that generate flow towards the Ahuyama branch, - The second one when the Ahuyama branch flows to the Magdalena river because of the runoff from the urban zone.

4- Ahuyama branch hydraulics 19-09-2017 “SMART RIVERS 2017” Scenario - 1 Flow DIrection Projected Piles Projected Piles CAÑO AHUYAMA 2.92 masl 2.87 masl Dyke Projection MAGDALENA RIVER Q=20 m3/s Projected Piles Flow Direction MAGDALENA RIVER

4- Ahuyama branch hydraulics 19-09-2017 “SMART RIVERS 2017” Q=20 m3/sScenario - 2 The most critical condition to evaluate the water levels next to the Ahuyama branch is the Scenario 2. As for the effect of the piles on the Ahuyama branch, this is minimal with over elevations of only 1cm.It is recommended that the existing dyke be raised up to 3.5 masl along its entire length (300 m). Tr 2 añosTr 25 años Q=98.4 m 3 /s Flow Direction MAGDALENA RIVER CAÑO AHUYAMA Projected piles Projected piles 3.13 masl 3.43 masl Q=55.05 m 3 /s 2.92 masl Dyke Projection   MAGDALENA R IVER Projected piles Flow Direction Q=55.05 m 3 /s Q=98.4 m 3 /s

CONCLUSIONS 19-09-2017 “SMART RIVERS 2017” The evaluations performed for each of the mentioned scenarios were carried out using a free computational tool in 1 dimension (HEC-RAS). This software was sufficient to estimate levels and affectations in the study areas.The determination of flood levels for the Canchera School, allowed to have the respective levels from which the new area to be built was projected and thus to avoid damages of floods. In the same way, the modeling made it possible to dimension hydraulic structures such as the Pasadena channel and the dyke along the Ahuyama channel in the right bank. The incidence of the New Bridge in the hydraulic conditions of the area, does not generate a considerable affectation in the water levels and the speeds in the sector in spite of flowing through 362 piles. This is due that most of the piles are in zones near to the banks, where the speeds are smaller than those registered in the center of the main channel.The scour is limited by the coral rock, which is approximately 10 m below the natural bed.

19-09-2017 “SMART RIVERS 2017” Source : Giovanny Escudero – El Heraldo 16 de Noviembre de 2016