Dr Steven Sandi Rojas

Dr Steven Sandi Rojas

Associate Lecturer

School of Engineering

Career Summary

Biography

Steven is originally from Costa Rica, where he graduated as a Civil Engineer in 2012. Soon after, he was recruited as a junior engineer by the "Comision Nacional de Emergencias (CNE)" due to the work of his Final Graduation Project: Hydro-graph Generation from Tomas Tropical Storm to Evaluate Urban Infrastructure in the Virilla River Basin.     

In 2013, he moved to Australia to start his doctoral studies at the University of Newcastle where he obtained a Ph.D. in Environmental Engineering in 2018. The focus of his research was the development of eco-hydrological and eco-geomorphological models of coastal and freshwater wetland vegetation and to explore vegetation dynamics under scenarios of climate change. His work integrates the use of hydrodynamic flood modelling and the study of vegetation dynamics.   

In 2019, he started a position as an Associate Lecturer where he delivers the courses CIVL2040 Engineering Probabilities and CIVL3470 Contaminant Hydrogeology as well as continuing his work on wetland dynamics modelling.


Qualifications

  • PhD (Environmental Engineering), University of Newcastle
  • Bachelor of Engineering (Civil), Universidad de Costa Rica

Keywords

  • Eco-geomorphology
  • Eco-hydrology
  • Wetland Modelling

Languages

  • Spanish (Mother)
  • English (Fluent)

Fields of Research

Code Description Percentage
400513 Water resources engineering 40
410199 Climate change impacts and adaptation not elsewhere classified 30
370702 Ecohydrology 30

Professional Experience

UON Appointment

Title Organisation / Department
Associate Lecturer University of Newcastle
School of Engineering
Australia

Academic appointment

Dates Title Organisation / Department
1/4/2018 - 30/6/2019 Associate Researcher Faculty of Engineering and Built Environment - The University of Newcastle (Australia)
School of Engineering
Australia

Awards

Award

Year Award
2020 Early Career Research Excellence Award
Faculty of Engineering and Built Environment - The University of Newcastle (Australia)

Teaching

Code Course Role Duration
CIVL3410 Hydrobiological Modelling
Faculty of Engineering and Built Environment - The University of Newcastle (Australia)
Tutor 1/6/2014 - 31/12/2016
CIVL2040 Engineering Probabilities
Faculty of Engineering and Built Environment - The University of Newcastle (Australia)
Course coordinator and lecturer 1/1/2019 - 1/7/2020
CIVL2310 Fluid Mechanics
Faculty of Engineering and Built Environment - The University of Newcastle (Australia)
Tutor 1/1/2015 - 31/12/2017
ENGG2100 Engineering Risk and Uncertainty
School of Engineering, The University of Newcastle
Course Coordinator 1/1/2021 - 30/6/2021
CIVL2050 Engineering Computations and Probability
Faculty of Engineering and Built Environment - The University of Newcastle (Australia)
Tutor 1/1/2016 - 31/12/2017
CIVL4330 Hydrology
Faculty of Engineering and Built Environment - The University of Newcastle (Australia)
Tutor 1/1/2018 - 1/7/2018
SURV3650 Spatial Data Sytems and Remote Sensing
Faculty of Engineering and Built Environment - The University of Newcastle (Australia)
Lecturer 1/8/2018 - 31/12/2018
CIVL3470 Contaminant Hydrogeology
Faculty of Engineering and Built Environment - The University of Newcastle (Australia)
Course coordinator and lecturer 1/7/2019 - 31/12/2021
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Publications

For publications that are currently unpublished or in-press, details are shown in italics.


Journal article (10 outputs)

Year Citation Altmetrics Link
2021 Saintilan N, Bowen S, Maguire O, Karimi SS, Wen L, Powell M, et al., 'Resilience of trees and the vulnerability of grasslands to climate change in temperate Australian wetlands', Landscape Ecology, 36 803-814 (2021) [C1]
DOI 10.1007/s10980-020-01176-5
Citations Scopus - 1Web of Science - 1
Co-authors Jose Rodriguez, Patricia Saco
2021 Breda A, Saco PM, Sandi SG, Saintilan N, Riccardi G, Rodríguez JF, 'Accretion, retreat and transgression of coastal wetlands experiencing sea-level rise', Hydrology and Earth System Sciences, 25 769-786 (2021) [C1]

The vulnerability of coastal wetlands to future sea-level rise (SLR) has been extensively studied in recent years, and models of coastal wetland evolution have been developed to a... [more]

The vulnerability of coastal wetlands to future sea-level rise (SLR) has been extensively studied in recent years, and models of coastal wetland evolution have been developed to assess and quantify the expected impacts. Coastal wetlands respond to SLR by vertical accretion and landward migration. Wetlands accrete due to their capacity to trap sediments and to incorporate dead leaves, branches, stems and roots into the soil, and they migrate driven by the preferred inundation conditions in terms of salinity and oxygen availability. Accretion and migration strongly interact, and they both depend on water flow and sediment distribution within the wetland, so wetlands under the same external flow and sediment forcing but with different configurations will respond differently to SLR. Analyses of wetland response to SLR that do not incorporate realistic consideration of flow and sediment distribution, like the bathtub approach, are likely to result in poor estimates of wetland resilience. Here, we investigate how accretion and migration processes affect wetland response to SLR using a computational framework that includes all relevant hydrodynamic and sediment transport mechanisms that affect vegetation and landscape dynamics, and it is efficient enough computationally to allow the simulation of long time periods. Our framework incorporates two vegetation species, mangrove and saltmarsh, and accounts for the effects of natural and manmade features like inner channels, embankments and flow constrictions due to culverts. We apply our model to simplified domains that represent four different settings found in coastal wetlands, including a case of a tidal flat free from obstructions or drainage features and three other cases incorporating an inner channel, an embankment with a culvert, and a combination of inner channel, embankment and culvert. We use conditions typical of south-eastern Australia in terms of vegetation, tidal range and sediment load, but we also analyse situations with 3 times the sediment load to assess the potential of biophysical feedbacks to produce increased accretion rates. We find that all wetland settings are unable to cope with SLR and disappear by the end of the century, even for the case of increased sediment load. Wetlands with good drainage that improves tidal flushing are more resilient than wetlands with obstacles that result in tidal attenuation and can delay wetland submergence by 20 years. Results from a bathtub model reveal systematic overprediction of wetland resilience to SLR: by the end of the century, half of the wetland survives with a typical sediment load, while the entire wetland survives with increased sediment load.

DOI 10.5194/hess-25-769-2021
Citations Scopus - 1Web of Science - 1
Co-authors Patricia Saco, Jose Rodriguez
2021 Saco PM, McDonough K, Rodriguez JF, Rivera-Zayas J, Sandi Rojas S, 'The role of soils in the regulation of hazards and extreme events', Philosophical Transactions of the Royal Society B: Biological Sciences, (2021)
DOI 10.1098/rstb.2020.0178
Citations Scopus - 2Web of Science - 2
Co-authors Patricia Saco, Jose Rodriguez
2021 Sandi SG, Rodriguez JF, Saco PM, Saintilan N, Riccardi G, 'Accelerated Sea-Level Rise Limits Vegetation Capacity to Sequester Soil Carbon in Coastal Wetlands: a Study Case in South-Eastern Australia', Earth's Future, (2021)
DOI 10.1029/2020ef001901
Co-authors Jose Rodriguez, Patricia Saco
2020 Sandi SG, Saco PM, Rodriguez JF, Saintilan N, Wen L, Kuczera G, et al., 'Patch organization and resilience of dryland wetlands', Science of the Total Environment, 726 (2020) [C1]
DOI 10.1016/j.scitotenv.2020.138581
Citations Scopus - 4Web of Science - 4
Co-authors George Kuczera, Patricia Saco, Jose Rodriguez
2020 Saco PM, Rodríguez JF, Moreno-de las Heras M, Keesstra S, Azadi S, Sandi S, et al., 'Using hydrological connectivity to detect transitions and degradation thresholds: Applications to dryland systems', Catena, 186 (2020) [C1]
DOI 10.1016/j.catena.2019.104354
Citations Scopus - 26Web of Science - 26
Co-authors Patricia Saco, Jose Rodriguez
2020 Sandi SG, Rodriguez JF, Saintilan N, Wen L, Kuczera G, Riccardi G, Saco PM, 'Resilience to drought of dryland wetlands threatened by climate change', Scientific Reports, 10 (2020) [C1]
DOI 10.1038/s41598-020-70087-x
Citations Scopus - 5Web of Science - 4
Co-authors George Kuczera, Patricia Saco, Jose Rodriguez
2019 Sandi SG, Saco PM, Saintilan N, Wen L, Riccardi G, Kuczera G, et al., 'Detecting inundation thresholds for dryland wetland vulnerability', Advances in Water Resources, 128 168-182 (2019) [C1]
DOI 10.1016/j.advwatres.2019.04.016
Citations Scopus - 7Web of Science - 7
Co-authors Jose Rodriguez, George Kuczera, Patricia Saco
2018 Sandi SG, Rodríguez JF, Saintilan N, Riccardi G, Saco PM, 'Rising tides, rising gates: The complex ecogeomorphic response of coastal wetlands to sea-level rise and human interventions', Advances in Water Resources, 114 135-148 (2018) [C1]
DOI 10.1016/j.advwatres.2018.02.006
Citations Scopus - 21Web of Science - 20
Co-authors Jose Rodriguez, Patricia Saco
2017 Rodriguez JF, Saco PM, Sandi S, Saintilan N, Riccardi G, 'Potential increase in coastal wetland vulnerability to sea-level rise suggested by considering hydrodynamic attenuation effects', Nature Communications, 8 1-12 (2017) [C1]
DOI 10.1038/ncomms16094
Citations Scopus - 59Web of Science - 51
Co-authors Patricia Saco, Jose Rodriguez
Show 7 more journal articles

Conference (8 outputs)

Year Citation Altmetrics Link
2020 Sandi Rojas S, Rodriguez J, Saco P, Kuczera G, McDonough K, Wen L, et al., 'Predicting flow and vegetation status in floodplain wetlands during drought', River Flow 2020. Proceedings Of The 10th Conference On Fluvial Hydraulics, Delft, The Netherlands (2020) [E1]
DOI 10.1201/b22619
Co-authors George Kuczera, Jose Rodriguez, Patricia Saco
2019 Sandi Rojas S, Saco P, Wen L, Saintilan N, Kuczera G, Riccardi G, Jose F R, 'Predicting the resilience of dryland wetlands affected by droughts', E-proceedings of the 38th IAHR World Congress, Panama City (2019)
Co-authors Patricia Saco, Jose Rodriguez, George Kuczera
2018 Sandi SG, Saco PM, Kuczera G, Wen L, Saintilan N, Rodriguez JF, 'Predicting floodplain inundation and vegetation dynamics in arid wetlands', E3S Web of Conferences, Lyon-Villeurbanne, France (2018) [E1]
DOI 10.1051/e3sconf/20184002019
Citations Web of Science - 1
Co-authors Jose Rodriguez, Patricia Saco, George Kuczera
2016 Sandi SG, Rodriguez JF, Saco PM, Wen L, Saintilan N, 'Simulation of the vegetation state and flow regime interaction in the Macquarie Marshes', Proceedings of the International Conference on Fluvial Hydraulics RIVERFLOW 2016, Saint Louis, USA (2016) [E1]
Citations Scopus - 1Web of Science - 1
Co-authors Jose Rodriguez, Patricia Saco
2016 Sandi SG, Rodriguez JF, Saco P, Wen L, Saintilan N, 'Linking hydraulic regime characteristics to vegetation status in the Macquarie Marshes', Proceedings of the 11th International Symposium on Ecohydraulics, Melbourne, Australia (2016) [E1]
Citations Web of Science - 2
Co-authors Patricia Saco, Jose Rodriguez
2015 Sandi S, Rodriguez J, Saco P, Saintilan N, Wen L, Kuczera G, 'Development of a vegetation dynamics model for freshwater wetland assessment in the Macquarie Marshes', The Art and Science of Water - 36th Hydrology and Water Resources Symposium, HWRS 2015 (2015)

The configuration of the Macquarie Marshes is a mosaic-like collection of swamps, marshes and lagoons. The Macquarie Marshes is also one of the most ecologically important wetland... [more]

The configuration of the Macquarie Marshes is a mosaic-like collection of swamps, marshes and lagoons. The Macquarie Marshes is also one of the most ecologically important wetland systems in Australia. It contains unique plant communities that serve as a sanctuary for many species of waterbirds and other fauna such as frogs and mammals. A significant deterioration of the ecological features of the Macquarie Marshes has been recorded in the past decades. This fact is mostly attributed to reductions of the input discharges to the marshes due to water allocations for industrial, agricultural and domestic usage. Reduction of water supply translates into changes of the hydraulic regime which has a direct impact on the flood dependent vegetation species of the marshes. The complexity of the system and its ecological significance requires the use of an adequate computational tool that would allow for a realistic assessment of the site. In this paper we present initial work regarding the development of a vegetation dynamics model that can integrate vegetation establishment with time aggregated characteristics of the flow. We simulate floods on a fictional wetland by implementing a quasi-2D hydrodynamic model (VHHMM 1.0) over a rectangular cell grid. This same grid constitutes the basis for a cellular vegetation model that can calculate changes in the vegetation for each element inside the domain. The work presented here for a fictional site was developed in order to test the capability of our model to recreate consistent vegetation gradients by using deterministic transitional rules. These rules relate time aggregated characteristics of the flow such as flood period and depth of water to water requirements of different vegetation communities. We found that a well calibrated set of deterministic transitional rules based on water preferences can recreate consistent vegetation distributions; however, succession and critical conditions for succession rules will have to be defined for a specific site application. Further development of this model will result in a strategic tool for managing environmental water allocations and water sharing plans in the Macquarie Marshes.

Citations Scopus - 2
Co-authors Jose Rodriguez, Patricia Saco, George Kuczera
2015 Rodriguez JF, Seoane M, Saco, Sandi Rojas, 'A geomorphological modelling approach for landscape evolution analysis of the Macquarie Marshes, Australia', e-proceedings 36th IAHR World Congress, The Hague, The Netherlands (2015)
Co-authors Jose Rodriguez, Patricia Saco
2014 Sandi Rojas SG, Rodríguez JF, Saco P, Riccardi G, Wen L, Saintilan N, et al., 'Macquarie river floodplain flow modeling: Implications for ecogeomorphology', River Flow 2014 (2014) [E1]

This work presents preliminary results of implementing a quasi-2D hydrodynamic module (VMMHH 1.0) to simulate flows and flooding patterns throughout the Macquarie Marshes, south e... [more]

This work presents preliminary results of implementing a quasi-2D hydrodynamic module (VMMHH 1.0) to simulate flows and flooding patterns throughout the Macquarie Marshes, south east Australia, in order to assess habitat requirements. The model uses an interconnected cell scheme that solves mass conservation and uses simplified versions of the momentum equations to represent flow between cells. This model has been used before to assess geomorphological changes in large river floodplains and vegetation evolution in estuarine wetlands, showing results consistent with cases of gradual floodplain inundation following overbank flow. The simplified characteristics of the quasi-2D model allow for an adequate representation of hydrodynamic processes with similar performance of other higher dimensional models. Model results and computational times are compared with outputs from a conventional 1D/2D model (MIKE FLOOD) applied to the same domain showing that the VMMHH 1.0 is adequate for representation of floods in the Macquarie Marshes.

Citations Scopus - 2Web of Science - 2
Co-authors Patricia Saco, Jose Rodriguez
Show 5 more conferences

Other (13 outputs)

Year Citation Altmetrics Link
2020 Breda A, Saco PM, Sandi SG, Saintilan N, Riccardi G, Rodríguez JF, 'Accretion, retreat and transgression of coastal wetlands experiencing sea-level rise', (2020) [O1]
DOI 10.5194/hess-2020-439
Co-authors Jose Rodriguez, Patricia Saco
2020 Sandi Rojas S, Rodriguez J, Saco P, 'Modelled hydrodynamic and vegetation data Hunter Estuary _ Area E', . HydroShare (2020) [O1]
Co-authors Jose Rodriguez, Patricia Saco
2020 Saco P, 'Accretion, retreat and transgression of coastal wetlands experiencing sea-level rise, supplement', : Copernicus Publications (2020)
DOI 10.5194/hess-25-769-2021-supplement
Co-authors Patricia Saco
2016 Sandi Rojas S, Rodriguez JF, Saco PM, Riccardi G, Wen L, Saintilan N, 'Hydrodynamics, vegetation transition and geomorphology coevolution in a semi-arid floodplain wetland.', (2016) [O1]
Co-authors Jose Rodriguez, Patricia Saco
2015 Seoane M, Rodriguez JF, Sandi Rojas S, Saco PM, Riccardi G, Saintilan N, Wen L, 'Coevolution of hydrodynamics, vegetation and channel evolution in wetlands of a semi-arid floodplain', (2015) [O1]
Co-authors Patricia Saco, Jose Rodriguez
2015 Rodriguez JF, Sandi Rojas S, Riccardi G, Stenta H, Saco PM, 'Estuarine wetland evolution including sea-level rise and infrastructure effects.', (2015) [O1]
Co-authors Jose Rodriguez, Patricia Saco
Sandi S, Rodriguez J, Saco P, Saintilan N, Riccardi G, 'Carbon burial capacity limited by accelerated sea-level rise in coastal wetlands', [O1]
DOI 10.5194/egusphere-egu21-13953
Rodriguez J, Breda A, Saco P, Sandi S, Saintilan N, Riccardi G, 'Physical-biological interactions limit the resilience of coastal wetlands to sea level rise', [O1]
DOI 10.5194/egusphere-egu21-14219
Sandi S, Rodriguez J, Saco P, Saintilan N, Riccardi G, 'Accelerated Sea-Level Rise Limits Vegetation Capacity to Sequester Soil Carbon in Coastal Wetlands a Study Case in South-Eastern Australia', Wiley [O1]
DOI 10.1002/essoar.10507647.1
Breda A, Saco P, Rodriguez J, Sandi-Rojas S, 'Understanding the effects of dynamic sediment inputs on the prediction of coastal wetland evolution', [O1]
DOI 10.5194/egusphere-egu2020-11476
Sandi SG, Saco PM, Rodriguez JF, Moreno-de las Heras M, Azadi S, 'Hydrological Connectivity: A Useful framework to identify degradation thresholds in semiarid landscapes.', [O1]
DOI 10.5194/egusphere-egu2020-11934
Jorquera E, Breda A, Sandi Rojas S, Rodriguez JF, Saco P, 'Assessment of morphodynamic evolution and changes in a mangrove wetland under current and future climate change scenarios', [O1]
DOI 10.5194/egusphere-egu2020-619
Saco P, Moreno-de las Heras M, Rodriguez J, Sandi S, Azadi S, Quijano J, 'Applications of a hydro-geomorphic (dis)connectivity framework to study vegetation transitions in semiarid ecosystems.', [O1]
DOI 10.5194/egusphere-egu21-14057
Co-authors Juan Quijanobaron
Show 10 more others

Thesis / Dissertation (2 outputs)

Year Citation Altmetrics Link
2018 Sandi Rojas S, Modelling wetland dynamics under climatic and human pressures, The University of Newcastle (2018)
2012 Sandi Rojas S, Generación de hidrogramas de creciente de la tormenta tropical Tomás para la evaluación de la infraestructura urbana en la cuenca del Río Virilla, University of Costa Rica (2012)
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Grants and Funding

Summary

Number of grants 1
Total funding $6,448

Click on a grant title below to expand the full details for that specific grant.


20211 grants / $6,448

Research Grant$6,448

Funding body: College of Engineering, Science and Environment, University of Newcastle

Funding body College of Engineering, Science and Environment, University of Newcastle
Scheme Fellowship Accelerator Funding
Role Lead
Funding Start 2021
Funding Finish 2021
GNo
Type Of Funding Internal
Category INTE
UON N
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Research Supervision

Number of supervisions

Completed0
Current2

Current Supervision

Commenced Level of Study Research Title Program Supervisor Type
2020 PhD Improving Water Management and Security by Applying Remote Sensing Tools PhD (Environmental Eng), College of Engineering, Science and Environment, The University of Newcastle Co-Supervisor
2017 PhD Eco-Geomorphologic Modelling of Australian Sub-Humid Environments PhD (Civil Eng), College of Engineering, Science and Environment, The University of Newcastle Co-Supervisor
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Research Collaborations

The map is a representation of a researchers co-authorship with collaborators across the globe. The map displays the number of publications against a country, where there is at least one co-author based in that country. Data is sourced from the University of Newcastle research publication management system (NURO) and may not fully represent the authors complete body of work.

Country Count of Publications
Australia 18
Argentina 10
Germany 1
Spain 1
Netherlands 1
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Dr Steven Sandi Rojas

Position

Associate Lecturer
Department of Civil and Environmental Engineering
School of Engineering
College of Engineering, Science and Environment

Contact Details

Email steven.sandirojas@newcastle.edu.au
Phone (02) 49216703

Office

Room EA121
Building EA Building
Location Callaghan
University Drive
Callaghan, NSW 2308
Australia
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