Periodic Reporting for period 1 - InSPiRED (Improving Subsidence PREdictions in Delta systems)
Periodo di rendicontazione: 2020-07-01 al 2021-12-31
Almost 500 million people live in river deltas, which host among the most important areas for economic activities and global food production on the planet. Relative sea-level rise in delta systems is predominantly caused by land subsidence and accelerating subsidence rates threaten the future existence of these low-lying landforms, including their inhabitants, environment and economy.
Reliable projections of future RSLR are urgently needed to prospect the fate of sinking delta systems but their creation was hampered by our inability to accurately resolve delayed subsidence. This causes uncertainties in subsidence rate projections potentially much larger than climate-change driven rates of sea-level rise.
The InSPiRED (Improving Subsidence PREdictions in Delta systems) MSCA-IF enabled dr. Philip Minderhoud (hereafter: Fellow) to move to the University of Padova in Italy to work in the group of Prof. Pietro Teatini within the Department of Civil, Environmental and Architectural Engineering (DICEA). In the InSPiRED project the Fellow and the research group at DICEA aimed to improve our ability to quantify delayed subsidence by upgrading a novel, physics-based numerical simulator and to develop an integrated approach to create numerical models and simulate relative sea-level rise (rSLR) projections for sinking coastal-deltaic areas. These projections then aid local delta policymakers to create effective management strategies. The approach was designed for different temporal and spatial scales, ranging from decennial to millennial and from a single marsh to an entire delta, respectively, in three major delta systems, the Po, Mississippi, and Mekong deltas. In addition, the project team also engaged in field experiments in the lagoon of Venice (northern Po Delta) which added valuable field data to calibrate and validate modelling results. During the project a number of successful communication and exploitation activities were undertaken, both communicating the scientific work within the science community and general public, and presenting policy reports to policymakers, translating the science to policy. The planned two-way knowledge exchanged turned out to be very effective. It resulted in the creation of large number of new interdisciplinary research topics and new joint research projects between Prof. Teatini and the Fellow.
These advancements facilitate the design of effective management strategies for local delta policymakers. The approach is designed for different temporal and spatial scales, ranging from decennial to millennial and from a single marsh to an entire delta, respectively, in three major delta systems, the Po, Mississippi, and Mekong deltas. The research has lead to new insights on the present and future evolution of coastal-deltaic environmental settings and enables the improvement of RSLR projections, thus filling a vital knowledge gap for delta policymakers. The research findings have been disseminated to the research community and communicated through public engagement.
Reliable projections of future RSLR are urgently needed to prospect the fate of sinking delta systems but their creation was hampered by our inability to accurately resolve delayed subsidence. This causes uncertainties in subsidence rate projections potentially much larger than climate-change driven rates of sea-level rise.
The InSPiRED (Improving Subsidence PREdictions in Delta systems) MSCA-IF enabled dr. Philip Minderhoud (hereafter: Fellow) to move to the University of Padova in Italy to work in the group of Prof. Pietro Teatini within the Department of Civil, Environmental and Architectural Engineering (DICEA). In the InSPiRED project the Fellow and the research group at DICEA aimed to improve our ability to quantify delayed subsidence by upgrading a novel, physics-based numerical simulator and to develop an integrated approach to create numerical models and simulate relative sea-level rise (rSLR) projections for sinking coastal-deltaic areas. These projections then aid local delta policymakers to create effective management strategies. The approach was designed for different temporal and spatial scales, ranging from decennial to millennial and from a single marsh to an entire delta, respectively, in three major delta systems, the Po, Mississippi, and Mekong deltas. In addition, the project team also engaged in field experiments in the lagoon of Venice (northern Po Delta) which added valuable field data to calibrate and validate modelling results. During the project a number of successful communication and exploitation activities were undertaken, both communicating the scientific work within the science community and general public, and presenting policy reports to policymakers, translating the science to policy. The planned two-way knowledge exchanged turned out to be very effective. It resulted in the creation of large number of new interdisciplinary research topics and new joint research projects between Prof. Teatini and the Fellow.
These advancements facilitate the design of effective management strategies for local delta policymakers. The approach is designed for different temporal and spatial scales, ranging from decennial to millennial and from a single marsh to an entire delta, respectively, in three major delta systems, the Po, Mississippi, and Mekong deltas. The research has lead to new insights on the present and future evolution of coastal-deltaic environmental settings and enables the improvement of RSLR projections, thus filling a vital knowledge gap for delta policymakers. The research findings have been disseminated to the research community and communicated through public engagement.
The Fellow has successfully joined the research group (RG) of Prof. Teatini in the ongoing development of the NATSUB-2D code. This has resulted in upgrading the NATSUB-2D code to a 3D domain NATSUB3D. The Fellow designed three realistic geomorphological testcases on which the new 3D modelling code was successfully tested and showcased. A scientific peer-reviewed paper on the 3D model code consequently was published in the Journal of Geophysical Research: Earth Surface (Xotta et al., 2022) by the Fellow and the research group. The NATSUB3D code have been published open access in an online repository as part of the journal publication. In parallel efforts the Fellow and the RG worked to implement the computation of time-depended compression (i.e. strain-based) into the NATSUB3D code as planned in the proposal which will be ready for submission in 2023.
The Fellow together with the RG performed field experiments in salt marshes on the Lagoon of Venice (Northern Po Delta) in which we have directly measured the primary compression and creep at different locations. And a first paper on the field experiments has been published (Zoccarato et al., 2022). A second paper is in preparation, to be finalized in 2023.
To test and showcase the new NATSUB3D code three model cases were created for the three spatial and temporal scales: a single salt marsh (resembling the Po delta case), the infilling of an abandoned river arm (i.e. oxbow lake) (resembling the Mississippi River), and a prograding delta lobe including beach ridges (resembling part of the Mekong delta). The cases are included in the published paper (Xotta et al,. 2022) and all three models are published in an open-access repository.
The project advanced the understanding and predictive capacity for future land subsidence, and consequent elevation, for each of the three focus delta at different spatio-temporal scales, depending on the application of advanced models. In the Venice lagoon (Northern Po Delta) the in-situ measurements of compaction in combination with a 1D modelling provided projections of future salt marsh elevation and their capacity to keep up with SLR. In the Mississippi delta the 1D modelling of the Subsidence Supersite provides a future outlook of potential natural compaction, and enables to assess the net elevation gain of the planned sediment diversion in the delta. In the Mekong delta the 3D modelling of the Holocene delta created insight in contemporary natural compaction rates and evaluate their contribution to the total subsidence experienced in the delta system.
The Fellow together with the RG performed field experiments in salt marshes on the Lagoon of Venice (Northern Po Delta) in which we have directly measured the primary compression and creep at different locations. And a first paper on the field experiments has been published (Zoccarato et al., 2022). A second paper is in preparation, to be finalized in 2023.
To test and showcase the new NATSUB3D code three model cases were created for the three spatial and temporal scales: a single salt marsh (resembling the Po delta case), the infilling of an abandoned river arm (i.e. oxbow lake) (resembling the Mississippi River), and a prograding delta lobe including beach ridges (resembling part of the Mekong delta). The cases are included in the published paper (Xotta et al,. 2022) and all three models are published in an open-access repository.
The project advanced the understanding and predictive capacity for future land subsidence, and consequent elevation, for each of the three focus delta at different spatio-temporal scales, depending on the application of advanced models. In the Venice lagoon (Northern Po Delta) the in-situ measurements of compaction in combination with a 1D modelling provided projections of future salt marsh elevation and their capacity to keep up with SLR. In the Mississippi delta the 1D modelling of the Subsidence Supersite provides a future outlook of potential natural compaction, and enables to assess the net elevation gain of the planned sediment diversion in the delta. In the Mekong delta the 3D modelling of the Holocene delta created insight in contemporary natural compaction rates and evaluate their contribution to the total subsidence experienced in the delta system.
Key scientific advancements in the InSPiRED project are the following:
a) novel concept:
• deltas are “living” landforms. To accurately project the future and support sustainable management, aimed at preserving their shape, environmental richness, agricultural productivity, and liveability for millions inhabitants, we will look into past, as the depositional history has a strong imprint on future evolution;
• including the essential geomechanical process of creep in assessments of elevation evolution at delta scale.
b) novel methodology: upgrading the state-of-the-art NATSUB-2D numerical model to 3D and from stress-based to strain-based creates an entirely novel tool allows for the first time:
• to simulate dynamic delayed subsidence including creep as result of viscous behaviour in relation to deltaic paleo-evolution and ongoing sedimentation, demonstrated at three different spatial and temporal scales;
• to analyse the interaction between potential mitigation (e.g. sediment diversions) or adaptation (e.g. dykes for flood protection) measures and dynamic delayed compression, and test their effectiveness.
The InSPiRED project ledd to new insights on delta evolution by increasing the scientific understanding on viscous behaviour of soft soils in coastal-deltaic environmental settings. The improve projections of RSLR for the three focus deltas provide new, valuable information for delta policymakers and the newly developed approach paves the way for similar assessments in other sinking deltas and coastal regions in the world. These new insights will fill a vital knowledge gap for the delta policy-makers and we expect this to lead to improved future delta management in the focus deltas, by way of example, in the short term and coastal-deltaic areas worldwide in the longer term.
a) novel concept:
• deltas are “living” landforms. To accurately project the future and support sustainable management, aimed at preserving their shape, environmental richness, agricultural productivity, and liveability for millions inhabitants, we will look into past, as the depositional history has a strong imprint on future evolution;
• including the essential geomechanical process of creep in assessments of elevation evolution at delta scale.
b) novel methodology: upgrading the state-of-the-art NATSUB-2D numerical model to 3D and from stress-based to strain-based creates an entirely novel tool allows for the first time:
• to simulate dynamic delayed subsidence including creep as result of viscous behaviour in relation to deltaic paleo-evolution and ongoing sedimentation, demonstrated at three different spatial and temporal scales;
• to analyse the interaction between potential mitigation (e.g. sediment diversions) or adaptation (e.g. dykes for flood protection) measures and dynamic delayed compression, and test their effectiveness.
The InSPiRED project ledd to new insights on delta evolution by increasing the scientific understanding on viscous behaviour of soft soils in coastal-deltaic environmental settings. The improve projections of RSLR for the three focus deltas provide new, valuable information for delta policymakers and the newly developed approach paves the way for similar assessments in other sinking deltas and coastal regions in the world. These new insights will fill a vital knowledge gap for the delta policy-makers and we expect this to lead to improved future delta management in the focus deltas, by way of example, in the short term and coastal-deltaic areas worldwide in the longer term.