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Final Report

NASA Award Number: NNX12AD28G

Global-scale assessment of threatened river delta systems: Evaluation of connections between the continental land mass and ocean

through integrated remote sensing and process modeling.

City University of New York City College of New York; CUNY Advanced Science Research Center Co-investigators: Charles J. Vörösmarty, Kyle McDonald, Balazs M. Fekete, Hansong Tang, Deborah Balk, Irina Gladkova, Michael Grossberg Research Scientist: Zachary D. Tessler PhD Students: Hannah Aizenman, Kat Jensen Undergraduate Student: Sean Thatcher

University of Colorado CSDMS, INSTAAR, Univ. of Colorado Award Number: PZ07124 Co-investigator: James P.M. Syvitski Research Scientist: Albert J. Kettner PhD Student: Stephanie Higgins Undergraduate Student: Josh Russell

1. Project overview With population growth, development, and the specter of climate change-- sea level rise and changes in storm and flood surge exposure-- coastal wetland systems increasingly will become a major focal point of concern with respect to human vulnerability and sustainable development. The urgent need to study and develop a capacity to forecast the changing character of these linked geophysical-social systems serves as the chief impetus for our study. River deltas, in particular, are an important focal point for the impacts of humans on both terrestrial land mass and coastal zone systems, due to their position at the interface of these two major functional components of the Earth system. This project seeks to forward an integrated modeling and remote sensing system to assess their vulnerabilities by combining geophysical and social science perspectives. Our work is motivated by a major research challenge in the Earth system science: to identify, quantify, and understand how natural and human-dominated factors change freshwater discharge and riverborne sedimentary connections between the landmass and coastal ocean.

The overarching project science goal was “To analyze how the strength and variability of land-to-ocean links, as defined by riverine sediment fluxes, local anthropogenic activities and ocean processes, produce impacts on coastal delta systems, today and into the future.”

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Science objectives were developed to address major research activities necessary to meet the project’s science goal. These included (1) Identify Global Patterns of Coastal Delta Syndromes, (2) Better Understand the Contemporary Dynamics of Coastal Delta Systems, (3) Map Vulnerabilities and Exposure of Deltas to Threat, and (4) Future Forecasts of Changing Deltas.

Below we highlight key research results associated with each of these four science objectives. In total, the project resulted in the publication of 23 peer-reviewed journal articles or book chapters (with 2 additional articles currently in review), 46 research presentations at scientific conferences, meetings, and workshops, and the convening of 3 workshops and conference sessions.

2. Key Results – Objective 1: Identify Global Patterns of Coastal Delta Syndromes

a. Coupled hydrology-sediment models Earlier work by co-PI Syvitski developed a global, empirical basin-outlet sediment flux model (BQART). This model integrates averaged upstream basin properties, including area, relief, and lithology, as well as human variables of population and GDP. This model was previously incorporated into WBMplus, a spatially distributed water balance and river routing model developed by the CUNY team, as WBMsed, producing a long-term average sediment flux scaled, in a stochastic manner, to modeled daily river discharge, by treating each grid cell as the outlet of an independent upstream basin. Recent work has incorporated WBMsed into the main WBMplus model.

Several improvements to the codebase have enabled the sediment flux calculations to be run in a threaded mode, reducing run time and enabling higher resolution runs at 6 arc minutes (lat/long). Options have also been added to the model to enable separation of the human impacts in the BQART code, allowing for disturbed and pristine condition comparison experiments. These experiments are being incorporated in the integrated land and coastal river delta data bank and the fingerprinting system.

Additional improvements include a floodplain routine designed to simulate spatially and temporally variable storage of overbank floodwater. The absence of such mechanism in the model resulted in a river system that is overly responsive to runoff. Secondly, we ran the model

Figure 1:Water discharge time series for the Mekong River (observed versus predicted).

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for a 50 year period (1960 – 2010) on a global (6 arc-minute resolution) scale to calculate yearly trends at pixel scale as well as continental averages. Temporal changes in riverine sediment flux and freshwater are quantified applying a normalized departure analysis technique. The applied precipitation dataset constitutes the "Full" product from the Global Precipitation Climate Center GPCC, refined temporally to a daily resolution by applying the NCEP reanalysis product. For flow routing the HydroSHEDS was used. All datasets are available to the research team on the CSDMS High Performance Computer Cluster. Preliminary results indicate that the WBMsed

Figure 2: Southeast Asia riverine normalized departure-from-mean for year 1971 for: (top) sediment flux overlaying a lithology factor map, derived according to Syvitski and Milliman (2007), and (bottom) water discharge overlaying the precipitation-normalized departure-from-mean. The images compare annual precipitation of 1971 with the 50-year mean precipitation (1960-2010).

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simulations are very well able to simulate monthly water discharge to the deltas of interest (see for example Figure 1).

Due to scarcity of observational data we are not yet able to validate the WBMsed sediment load simulations for the deltas of interest (Figure 2). However, six gauging stations in the U.S. with sufficiently high temporal sampling frequencies were used in model validation. Gauging station information for these sites were obtained from the USGS `Water Data for the Nation' website, which provides daily suspended sediment flux and water discharge for the period 1997 – 2007. Our evaluation indicates that the WBMsed v.2.0 model simulates the monthly and yearly trend of sediment flux well but slightly overestimates suspended sediment load (see Cohen et al., 2013).

b. Retrospective landcover change assessment The rapid growth of the populations and economies in populated delta regions has resulted in areas of large-scale land cover change. Development – agricultural, industrial, or urban – is known to displace flood-retention areas such as wetlands, forest, shrub, and bare lands. A study of the Mekong and Chao Phraya deltas was done to compare the patterns of land-use change that have occurred using historical Landsat imagery.

Three Landsat images, from similar seasons in each year, were selected from Landsat 5 TM [L5] and Landsat 7 ETM+ [L7] for each study area (Figure 3) and processed through the USGS LEDAPS system. The atmospherically corrected bands 1-5 and 7, along with two indices – the widely used normalized difference vegetation index (NDVI) and the normalized difference water index (NDWI) – were used as inputs for supervised classification. Each image was classified into five land cover classes: water (open water, flooded vegetation, aquaculture), sparse vegetation (shrub, grassland, senescing crops), dense vegetation (forest, peak healthy agriculture), built environment (concrete, asphalt, aluminum, etc), and bare land, using the maximum likelihood algorithm. Secondary data sources, such as aerial photographs, GoogleEarth and land cover maps from MODIS and GlobCover, were referred to when assigning training pixels for each land cover. More generalized classes are used because of the lack of detailed ground truth data. RGB composites of the Landsat imagery and the derived land cover classification maps are illustrated in Figure 5 (Mekong) and Figure 5 (Chao Phraya).

Mekong 04-06-1989[L5] 04-09-1996[L5] 04-05-2003[L7]

Figure 3: Study areas: Mekong and Chao Phraya deltas. Image acquisition dates listed.

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Figure 5: Mekong delta Landsat imagery (A) “true color” composite RGB channels 3,2,1 (B) false-color composite RGB channels 5,4,2 (C) classified image results from 1989, 1996, and 2003.

Figure 5: Chao Phraya delta Landsat imagery (A) “true color” composite RGB channels 3,2,1 (B) false-color composite RGB channels 5,4,2 (C) classified image results from 1994, 1999, and 2004.

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In the Mekong Delta we observed a decrease in bare area, increase in built environment and slight growth in overall vegetation. Agricultural areas were expanded in areas initially occupied by bare area by the building of embankments, dikes, and sluice gates in the late 1990s, according to census reports. Expansion of waterbodies can be potentially attributed to aquaculture ponds for fish and shrimp production. The built environment represents a much larger proportion of the scene over the Chao Phraya delta – which also had substantial urban expansion from 1994 to 2004.

c. Global typology of delta environmental change We have constructed an environmental typology of deltas based on a global database of major drivers of environmental change. Anthropogenic drivers of change are located upstream, within, and offshore of deltas. From the upstream basin we consider reservoir sediment retention, impervious surface area, wetland disconnectivity, and population density. From the coastal delta we include population density, wetland disconnectivity, impervious surface area, groundwater depletion, and oil and gas extraction. Sea-level rise is included from the offshore domain. These drivers were estimated for 48 deltas using globally-available remote sensing data and model output, allowing for globally-consistent data and meaningful comparisons between delta systems. We utilized several statistical clustering algorithms to develop the typology, which resulted in eight distinct clusters of deltas that shared common drivers of environmental change (Figure 6). This work was published as part of a special issue on deltas in Sustainability Science (Tessler et al., 2016).

Figure 6: (A) Global distribution of distinct types of delta environmental change. (B) Distribution of environmental drivers for each delta within each cluster.

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3. Key Results – Objective 2: Better Understand the Contemporary Dynamics of Coastal Delta Systems a. High resolution, high-fidelity simulation of swash zone hydrodynamics When a wave propagates from a surf zone to a swash zone, its hydrodynamics are very complicated and accompanied by a large amount of sediment transport. These zones are hydrodynamically active regions with the clear changes in coastal dynamics and morphology. The hydrodynamics of swash zones play a vital role in determining sediment transport and coastal evolution. This work developed a numerical model using a fully three-dimensional, incompressible, two-phase flow Navier-Stokes solver, in conjunction with a high-resolution VOF method to capture the interface between air and water phases. With the developed model, a systematical simulation has been made on uprush and backwash generated by surge bores. Analyses have been made on the computed spatial and temporal evolution of free-surface, instantaneous flow fields, maximal bed shear stress collapsing bores, and uprush and backwash processes. The results from the analyses reveal that the flow dynamics is complicated after the bores breaks, and the proposed model can well capture the structure characteristics of sheet flows, which are better simulated than previous results. All these findings are beneficial to understanding the pattern of sediment transport and coastal evolution in swash zones. See Jiang et al. (2013).

b. Simulation of coupled wave-current-morphology system Coastal flow involves surface wave propagation, current circulation, and seabed evolution, and its prediction remains challenging when they strongly interact with each other, especially during extreme events such as tsunamis and storm surges. We developed a fully coupled method to simulate motion of wave-current-seabed systems and associated multiphysics phenomena. The wave action equation, the shallow water equations, and the Exner equation are respectively used for wave, current, and seabed morphology, and the discretization is based on a second-order, flux-limiter, finite difference scheme previously developed for current-seabed systems. The proposed method is tested with analytical solutions, laboratory measurements, and numerical solutions obtained with other schemes. Its advantages are demonstrated in capturing interplay among wave, current, and seabed; it has the capability of first-order upwind schemes to suppress artificial oscillations as well as the accuracy of second-order schemes in resolving flow structures. The coupled modeling system has been applied a dam-break flow over a movable bed, a wave-driven flow over a sand dune, etc., presenting insight on how seabed morphology evolves in time under action of currents and surface waves. See Wang et al. (2013).

c. Improvement and Downscaling of Delta Inundation Mapping The Surface Water Microwave Product Series (SWAMPS) is a global time series of inundated area fraction (fw) that is derived from passive and active microwave data (SSM/I, ERS, QuikSCAT, ASCAT) developed as part of a NASA MEaSUREs project. The most recent version of this product extends from 1992 to Figure 8: Flowchart of SWAMPS downscaling process.

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2013, allowing large-scale assessment of hydrological baselines, dynamics, and trends at 25km resolution. We have applied a physical downscaling algorithm to reduce the spatial resolution to ~100m. (Figure 8). Topography from the Shuttle Radar Topography Mission (SRTM) digital elevation model, stream networks from HydroSHEDS, and a permanent water cover mask derived from Landsat are combined compute a static, relative “floodability” ranking representing the likelihood of flooding at each grid point relative to those in the surrounding area. We are currently working on developing this framework.

We had planned to use radar data from the NASA Soil Moisture Active Passive (SMAP) satellite to generate high resolution, operational surface water maps with frequent revisit intervals. With the failure of the SMAP radar, we are assessing other potential data sources for future use in higher resolution products, including Sentinel radar data. We plan to modify the inundation retrieval algorithms we developed using simulated SMAP data from Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) for use with other existing and future radar data sources. A multi-scale analysis of these datasets and SWAMPS (at 25km resolution and downscaled) will assess the trade-offs between spatial resolution, temporal coverage and product fidelity.

4. Key Results – Objective 3: Map Vulnerabilities and Exposure of Deltas to Threats

a. InSAR-derived subsidence maps of target deltas Interferometric Synthetic Aperture Radar (InSAR)-derived subsidence maps of the target deltas are a significant product of this project and are a key tool for assessing heterogeneities in space and time. We have documented significant (> 12 cm/y) land subsidence at aquaculture facilities along the coast of the Yellow River Delta in China. Significantly, this work was the first to achieve direct measurements of aquaculture-induced land subsidence by any technique. Aquaculture facilities dominate large portions of most Asian megadeltas, but wet, muddy conditions have previously made both remote and in situ measurements challenging. This article has been published in Geophysical Research Letters (Higgins et al., 2013) (Figure 9), and the

Figure 9: Example InSAR measurements over an aquaculture facility in the Yellow River Delta, China, showing a subsidence bowl in map view (top) and cross-section (bottom) over four years. Subsidence rates are as high as 30 cm/y at this subsidence “hot spot,” the largest on the delta. From Higgins et al., [GRL 2013].

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results have garnered significant attention; this work was featured by a descriptive article in Nature (http://www.nature.com/news/fish-farms-cause-relative-sea-level-rise-1.13569) and widely reported by both national and international radio, online and print news outlets. Three presentations were made about this work at scientific conferences.

Over a second target delta, InSAR analysis was completed for a >10,000 km2 portion of the Ganges-Brahmaputra Delta, Bangladesh. This work has been published and in Journal of Geophysical Research (Higgins et al., 2014). The study reconstructs subsidence rates in the most populous portion of the Ganges-Brahmaputra delta at a high spatial resolution of 90 m. Land subsidence of 0 to > 10 mm/y is seen in the capital city of Dhaka, likely related to groundwater extraction with rates corresponding to local variations in shallow subsurface sediment properties (Figure 10). Outside of the city, where abstraction is still high, rates vary from 0 to > 18 mm/y. Lowest rates appear primarily in Pleistocene clays and the highest rates in Holocene marshy clays and peat. Results demonstrate that subsidence in this delta is primarily controlled by local stratigraphy, with rates varying by more than an order of magnitude depending on soil properties.

These high-resolution subsidence maps provide important case-studies against which to test the global-scale fingerprinting method under development in this project. In the Ganges Delta, for instance, it is a combination of variable stratigraphy and local groundwater extraction rates that determine which parts of the delta experience subsidence rates of up to 2 cm/y. Even within the

Figure 10: (a) InSAR-derived subsidence over the city of Dhaka, Bangladesh, 2007-2011. Boundaries are rivers bordering the city. (b) NEHRP soil classification, from stiffest (D1, blue) to loosest (E, red). Strong spatial correspondence suggests that groundwater extraction in the city is driving compaction of the loosest soils, while stiffer and older soils are stable despite rapid drawdown. From Higgins et al., [submitted, 2014].

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city of Dhaka, where groundwater extraction is uniformly high, local stratigraphy controls compaction rates and therefore determines the change in elevation driven by human activities.

A review of the benefits and limitations of InSAR as a technique for generating subsidence maps in rural coastal settings was published in Hydrogeology Journal (Higgins, 2016). This work aims to guide future research by providing direct processing chain improvements for InSAR analysis in these challenging settings.

b. Geophysical, Anthropogenic, and Social drivers of delta risk We have successfully constructed a global delta risk outlook index based on the global-scale environmental change dataset developed in Objective 1, and have utilized this index for ranking and comparison of global deltas-at-risk. Our risk outlook index, an estimate of how risk, or expected loss, is increasing relative to other deltas, is constructed from three sub-indexes: an index of relative sea level rise and wetland loss, which results in increased population exposure to flood events; an index of hazardous event magnitude and frequency; and an index of vulnerability, assessing the relative damage caused by exposure to flooding conditions. Together, these risk components define a risk-space, shown in Figure 11. These results highlight the impact of social vulnerability on risk. Deltas in wealthy nations, particularly the Han, Mississippi, and Rhine, have substantially reduced risk due to investments in risk-reducing technologies such as storm surge barriers and levees, as well as a greater capacity to respond to hazardous events.

Figure 11: Risk trends for deltas worldwide. (A) Phase diagram of contemporary risk assessment results, showing the three component proxy indices used to estimate per-capita R'. Color density represents a delta’s overall risk trend. Quadrant III deltas have predominantly low R', whereas quadrant II deltas have high R'. (B) Estimates of the relative rate of change in risk, or risk trend, for each delta due to increasing exposure associated with RSLR. The Krishna and Ganges-Brahmaputra deltas, despite being only moderately susceptible to short-term hazardous events, are increasingly at risk because of high rates of RSLR and high socioeconomic vulnerability.

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The deltas with the greatest expected increases in risk due to relative sea level rise are the Krishna and Ganges. These estimates are in a per-capita sense, when considering risk aggregated across populations, the Ganges is by far the most at-risk, with both the second-highest risk outlook and more than twice the population of the second-most populous delta, the Nile. We also identify several deltas where their high vulnerability strongly exacerbates already high-risk conditions. A given increase GDP or government effectiveness, resulting in reduced vulnerability, would have the largest effect on risk-reduction in the Limpopo, Irrawaddy, and Krishna deltas.

We also construct a future scenario of large-scale changes in social vulnerability to hazardous events to explore the consequences for delta risk. Several developed deltas have substantially reduced risk when contemporary vulnerability is considered, including the Han, Mississippi, Rhine, Tone, and Yangtze deltas. The vulnerability estimate here is an index constructed from total delta GDP, per-capita GDP, and a Government Effectiveness indicator, intended to reflect the amount of harm resulting from flood exposure in a given delta community. The GDP indicators reflect how deltas populations protect themselves: at the delta-scale through engineering projects such as storm-surge barriers, pumping stations, and levees; and at the individual scale through safer housing and protective investments. The government effectiveness indicator expresses the role local and regional governments play in directing GDP toward better hazard preparedness.

However, it has been suggested in the literature that deltas and other environments that depend on external energy and financial inputs are less sustainable than self-reliant systems, particularly

Figure 12: Current and future investment impacts on risk-trend rankings. (A) Contemporary risk trend when considering only the anthropogenic and geophysical setting of each delta. (B) When also considering relative vulnerability, which is low for deltas that can make risk-reducing investments, the overall contemporary risk trend changes, in many cases dramatically. The Mississippi and Rhine deltas show substantially reduced risk. (C) Current risk- reduction strategies become more expensive and less sustainable in a more energy-constrained future scenario (14). In the long term, deltas that today are protected by substantial compensating infrastructure are likely to see their risk profiles approach those in (A).

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in light of potentially higher energy costs in a fossil-fuel-constrained future. For comparison with contemporary delta vulnerability, we construct a future vulnerability index by reducing the weight given to the GDP indicators, reflecting higher costs. This adjusts each delta in the risk-space, with high-GDP/low-vulnerability deltas such as the Mississippi and Rhine experiencing the most change. This identifies delta systems most at-risk for future increases in flood-related expected loss. Figure 12 shows the risk ranking for each delta system under three scenarios: A) Contemporary estimates of risk rank due only to geophysical hazards and anthropogenically-accelerated relative sea level rise; B) Contemporary estimates of risk rank when considering the effect of risk-reduction investments and reduced vulnerability; and C) Future estimate of risk rank with discounted investment effects. While contemporary risk trends are greatest in deltas in Southeast and East Asia, largest future risk-rank changes are estimated in the Mississippi, Rhine, Han, and Tone, highlighting the dependence of these high-hazard, high-exposure deltas on their low vulnerability, which may not be the case in the future. This work has been published in Science (Tessler et al., 2015), was featured with a companion Perspectives article (Building land with a rising sea, Temmerman and Kirwan, 2015, Science), and received substantial press coverage (e.g., https://www.washingtonpost.com/news/energy-environment/wp/2015/08/06/the-global-threat-to-river-deltas-and-the-people-who-live-on-them/). We have made the results and data publicly available at www.globaldeltarisk.net.

5. Key Results – Objective 4: Future Forecasts of Changing Deltas a. Future delta scenarios and forecasts of relative sea-level rise In addition to delta risk and vulnerability forecasts based on future social and economic scenarios described above and published in Tessler et al., (2015), we have also developed and analyzed the impact of several geophysical and anthropogenic scenarios on relative sea-level rise rates in deltas. We modeled ongoing development and scenarios of future water resource management and hydropower infrastructure in upstream river basins to explore impacts on sediment fluxes. Changes in sediment fluxes were used to estimate rates of relative sea-level rise through a sediment mass balance model in the delta.

Sediment fluxes were estimating using the BQART sediment flux model and the WBMplus river discharge model. Dam and reservoir effects on sediment fluxes to the coastal zone were estimated with a basin-wide sediment retention model based on the increase in mean water residence time by water storage in reservoirs.

We developed and tested four main scenarios of the future, and a further three minor modifications to the baseline scenario used to bracket uncertainty ranges for delta sediment retention rates, a key geophysical process. The main scenarios represented baseline conditions, pristine (non-anthropogenic) conditions, and two scenarios of potential future development of dam and reservoir infrastructure. Heuristic algorithms for future dam placement were developed based on river network topology and digital elevation models.

Model results show that contemporary sediment fluxes, anthropogenic drivers of land subsidence, and sea-level rise result in relative sea-level rise rates in deltas that average 6.8 mm/year (Figure 13). Should potential future impoundment of river basins be realized to the same degree as the heavily impounded Mississippi River basin, an extreme case, relative sea-level rise rates would increase by less than 1 mm/year on average across all deltas in the study,

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though particular delta systems including the Magdalena, Orinoco, and Indus show greater sensitivity with RSLR rates increasing up to 4 mm/year. Assessment of impacts of planned and under-construction dams on relative sea-level rise rates suggests increases on the order of 1 mm/year in deltas with new upstream construction. Sediment fluxes may be reduced by up to 60% in the Danube and 21% in the Ganges-Brahmaputra-Meghna if all currently planned dams are constructed. Reduced sediment retention on deltas due to increased river channelization and management has a larger impact, increasing RSLR on average by nearly 2 mm/year. This work is currently in review for publication in Geomorphology.

6. Outreach a. Science On a Sphere Model output examples are made available to a larger public in collaboration with the NSF funded CSDMS project, by presenting simulations on Science On a Sphere (SOS). SOS, developed by NOAA, is a spherical display system approximately 6 feet in diameter, which can present “movies” of animated Earth system dynamics. We have developed animations, lesson material and running exhibit ‘fact slides’ for two Science On a Sphere (SOS) animations of models, used for this NASA study: a) Global Wave Dynamics (WAVEWATCH III®), and b) Global River Runoff, with special focus on (Water Balance Model-WBMsed). The development of the early prototypes of the animations and lesson material has been in close cooperation with the education and outreach team of the Fiske Planetarium at the University of Colorado and NOAA SOS technicians. The evaluated lesson material and animations are made available as datasets through the SOS animation library and is available to 33 million people who see Science On a Sphere® every year worldwide. See also: http://sos.noaa.gov/Datasets/.

Figure 13: RSLR rate distributions across three scenarios: Scon, Srpot, and Slow. (A) Comparison of RSLR rates for the three scenarios. (B) Increases in RSLR rate over the baseline contemporary scenario, Scon. Note reduction in vertical scale of inset.

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b. Undergraduate mentorship through RESESS (Univ. of Colorado) and CSURP (CUNY) In summer 2014, University of Colorado Boulder researcher Stephanie Higgins mentored an undergraduate through the Research Experiences in Solid Earth Science for Students (RESESS) Program. RESESS is an NSF-funded undergraduate internship and support program based at UNAVCO in Boulder, Colorado. Each summer, RESESS accepts 10 student interns who are members of a group that is historically underrepresented in the Earth sciences. Josh Russell, the CU group’s student, completed an 11-week research project and was mentored in the preparation of a research paper, graduate school and fellowship applications, and a presentation at the annual meeting of the AGU in December 2014.

Similarly, CUNY researcher Zachary Tessler mentored an undergraduate student during summer 2016 through the CUNY Summer Undergraduate Research Program (CSURP). CSURP is a highly selective program that supports approximately 20 undergraduate students as they conduct hands-on research projects in CUNY labs during the summer. Sean Thatcher worked on analysis of remote sensing imagery of the Mekong Delta during his 11-week summer research project after his junior year. He will be entering graduate school during the fall of 2017.

c. Undergraduate data visualization research As part of a course taught by Co-I Grossberg, City College of New York undergraduate students Andrew Fitzgerald, Ian McBride, and Ebenezer Reyes developed a web-based data visualization project utilizing surface inundation, precipitation, river discharge, and wave energy datasets in the Mekong and Ganges-Brahmaputra River Deltas. The student website is still in the development stage and not yet publicly available, but a screenshot is of one component of the site is presented in Figure 14. The goal of the site is to provide an interactive exploration of surface inundation time-series and spatial patterns in the two deltas, highlighting patterns and anomalies.

Figure 14. Example screenshot from student-developed interactive data visualization website.

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7. Publications (23 published, 2 in review) 1. Allison, M, B Yuill, T Törnqvist, F Amelung, T Dixon, G Erkens, R Stuurman, G Milne, M

Steckler, J Syvitski, P Teatini, 2016, Coastal subsidence: global risks and research priorities, EOS Transactions 97, 13 July 2016.

2. Brakenridge G.R., J.P.M. Syvitski, E. Niebuhr, I. Overeem, S.A. Higgins, A.J. Kettner, L. Prades 2017, Design with nature: Causation and avoidance of catastrophic flooding, Myanmar. Earth-Science Reviews 165: 81–109.

3. Brondizio ES, Foufoula-Georgiou E, Szabo S, Vogt N, Sebesvari Z, Renaud FG, Newton A, Anthony E, Mansur AV, Matthews Z, Hetrick S, Costa SM, Tessler ZD, Tejedor A, Longjas A, 2016. Catalyzing action towards the sustainability of deltas. Current Opinion in Environmental Sustainability, 19, 182-194. doi: 10.1016/j.cosust.2016.05.001.

4. Cohen, S., Kettner, A.J., and Syvitski, J.P.M., (2014), Global Suspended Sediment and Water Discharge Dynamics Between 1960-2010: Continental trends and intra-basin sensitivity. Global and Planetary Change 115: 44-58. DOI: 10.1016/j.gloplacha.2014.01.011

5. Day, JW, J Agboola, Z Chen, C D’Elia, DL Forbes, L Giosan, P Kemp, C Kuenzer, RR Lane, R Ramachandran, J Syvitski, A Yañez-Arancibia, 2016, Approaches to Defining Deltaic Sustainability in the 21st Century. Coastal and Shelf Science 183B: 275–291.

6. Ehsani N, Fekete BM, Vörösmarty CJ, and Tessler ZD, 2015. A neural network based general reservoir operation scheme. Stochastic Environmental Research and Risk Assessment. doi:10.1007/s00477-015-1147-9.

7. Gao, J.H., Jia, J., Kettner, A.J., Xing, F., Wang, Y.P., Li, J., Bai, F., Zou, X., and Gao, S. Reservoir-induced changes to fluvial fluxes and their downstream impacts on sedimentary processes: The Changjiang (Yangtze) River, China (2015). Quaternary International. DOI: 10.1016/j.quaint.2015.03.015.

8. Giosan, L., Syvitski, J., Constantinescu, S., and Day, J. (2014), Protect the world’s deltas, Nature 516: 31-33.

9. Hajra R, Szabo S, Tessler Z, Ghosh T, Matthews Z, Foufoula-Georgiou E. (2016). Unravelling the association between the impacts of natural hazards and household poverty: evidence from the Indian Sundarban delta. Sustainability Science, doi: 10.1007/s11625-016-0420-2.

10. Higgins, S., Overeem, I., Steckler, M. S., Syvitski, J. P.M., Akhter, S. H., and Seeber, L., (2014), InSAR measurements of compaction and subsidence in the Ganges-Brahmaputra Delta, Bangladesh. Journal of Geophysical Research – Earth Surface 119: 1768-1781.

11. Higgins, S., Overeem, I., Tanaka, A. & Syvitski, J.P.M., (2013), Land subsidence at Aquaculture Facilities in the Yellow River Delta, China, Geophys. Res. Lett. 40(15), 3898-3902.

12. Jiang, C. B., B. Deng, S. X. Hu, H. S. Tang, Numerical investigation of swash zone hydrodynamics. Science China Technological Sciences. 56(2013), 3093-3103

13. Overeem, I., Kettner, A.J., and Syvitski, J.P.M., 2013. Impacts of Humans on River Fluxes and Morphology, In: Editor-in-Chief: John F. Shroder, Treatise on Geomorphology, Volume 9: Fluvial Geomorphology, Academic Press, San Diego, Pages 828-842.

14. Schroeder R, McDonald KC, Chapman B, Jensen K, Podest E, Tessler ZD, Bohn TJ, Zimmermann R, 2015. Development and Evaluation of a Multi-Year Fractional Surface Water Data Set Derived from Active/Passive Microwave Remote Sensing Data. Remote Sensing, 7, 16688-16732. doi:10.3390/rs71215843.

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15. Sebesvari Z, Renaud FG, Hass S, Tessler ZD, Kloos J, Szabo S, Vogt N, Tejedor A, Brondizio E, Kuenzer C, 2016. A review of vulnerability indicators for deltaic social-ecological systems. Sustainability Science. doi: 10.1007/s11625-016-0366-4.

16. Syvitski, J.P.M., Cohen, S., Kettner, A.J., and Brakenridge, G.R., (2014), How important and Different are Tropical Rivers? – An overview. Geomorphology 227: 5-17. DOI: 10.1016/j.geomorph.2014.02.029

17. Syvitski, J.P.M., Kettner, A.J., Overeem, I., Giosan, L., Brakenridge, G.R., Hannon, M., and Bilham, R., (2014), Anthropocence metamorphosis of the Indus Delta and lower floodplain. Anthropocene 3: 24-35.

18. Szabo S, Brondizio E, Hetrick S, Renaud FG, Nicholls RJ, Matthews Z, Tessler ZD, Tejedor A, Sebesvari Z, Foufoula-Georgiou E, Costa S, Dearing JA. (2016). Population dynamics, delta vulnerability and environmental change: Comparison of the Mekong, Ganges-Brahmaputra and Amazon delta regions. Sustainability Science. doi: 10.1007/s11625-016-0372-6.

19. Tang, H.S., Chien, S. I-Jy, Temimi, M., Ke, Q., Zhao, L.H., Blain, C.A., Kraatz, S. Vulnerability of population and transportation systems at east bank of Delaware Bay to coastal flooding in climate change conditions. Natural Hazards, 69(2013), 141-163.

20. Tessler ZD, Vörörsmarty CJ, Overeem I, Syvitski JPM, in review. A model of water and sediment balance as determinants of relative sea-level rise in contemporary and future deltas. Geomorphology.

21. Tessler ZD, Vörösmarty CJ, Grossberg M, Gladkova I, Aizenman H, 2016. A global empirical typology of anthropogenic drivers of environmental change in deltas. Sustainability Science. doi: 10.1007/s11625-016-0357-5.

22. Tessler ZD, Vörösmarty CJ, Grossberg M, Gladkova I, Aizenman H, Syvitski JPM, Foufoula-Georgiou E., 2015. Profiling Risk and Sustainability in Coastal Deltas of the World. Science 349 (6248) 638-643. doi:10.1126/science.aab3574.

23. Wang HJ, N Bi, S Li, P Yuan, A Wang, X Wu, Y Saito, Z Yang, Z Yu, S Liu, Syvitski, JPM, in press, Dam-orientated Water Sediment Regulation Scheme of the Yellow River, China: A review and perspective. Earth Science Reviews.

24. Wang, J. Y., H. S. Tang, and H. W. Fang, A strongly coupled method to simulate wave, current, and morphology system, Comm. Nonlinear Sciences & Numerical Simulations, 18 (2013) 1694–1709.

25. Xing, F, Syvitski, JP, AJ Kettner, EA Meselhe, JH Atkinson, A Khadka, in review, Morphodynamic Impacts of Hurricanes on the Wax Lake Delta, Louisiana, Elementa.

8. Convened Workshops and Conferences (3) 1. Conference Session: Deltas in Times of Change: Scientific Advances in Support of Socio-

Ecological Resilience. AGU Fall Meeting 2014, San Francisco, CA, December 2014. 2. Workshop: Science-to-Action: Aligning science with stakeholder and community needs in

the Mekong Delta system. Deltas in Times of Climate Change II Conference, Rotterdam, The Netherlands, 24-26 September, 2014.

3. Conference Session: Deltas and sea-level rise: geological and social-ecological perspectives. AGU Fall Meeting 2016, San Francisco, CA, December 13, 2016.

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9. Presentations (46) 1. Ashton, A.D., Nienhuis, J., Ortiz, A.C., Trueba, J.L., Giosan, L., Kettner, A.J., Xing, F.,

December, 9-13th, 2013. Effects of marine reworking and sea-level rise on deltas of the 21st century, AGU, San Francisco, CA, USA.

2. Cohen, S., Kettner, A.J., and Syvitski, J.P.M., December 17-21, 2012. Spatio-temporal dynamics in riverine sediment and water discharge between 1960-2010 based on the WBMsed v.2.0 Distributed Global Model. Frontiers in Computational Physics conference, Boulder, CO, USA.

3. Cohen, S., Kettner, A.J., Syvitski, J.P.M., and Yamazaki, D., Global-scale simulation of river-floodplain water and sediment exchange within a riverine modeling framework. AGU, San Francisco, CA, USA, 15-19 Dec. 2014.

4. Cohen, S., Kettner, A.J., Syvitski, J.P.M., April 14-17, 2013. Human and climate impact on global riverine water and sediment fluxes - a distributed analysis. American Geophysical Union (AGU Meeting of the Americas), Cancun, Mexico.

5. Cohen, S., Kettner, A.J., Syvitski, J.P.M., December, 3-7, 2012. A distributed analysis of Humans impact on global sediment dynamics. AGU, San Francisco, CA, USA.

6. Cohen, S., Kettner, A.J., Syvitski, J.P.M., December, 9-13th, 2013. Anthropogenic effects on global riverine sediment and water discharge - a spatially explicit analysis, AGU, San Francisco, CA, USA.

7. Cohen, S., Kettner, A.J., Syvitski, J.P.M., Spatially and Temporally Explicit Prediction of Sediment, Nutrients and Water Discharge in Global Rivers. AAG, Tampa, Florida, USA, 8-12, Apr. 2014.

8. Foufoula-Georgiou E, Tessler ZD (presenting author), Brondizio E, Overeem I, Renaud F, Sebesvari Z, Nicholls RJ, Anthony E. Catalyzing action towards the sustainability of deltas: deltas as integrated socio-ecological systems and sentinels of regional and global change. AGU Fall Meeting, San Francisco, CA, December 14, 2016.

9. Higgins, S. & Syvitski, J. P. M., (2013), Land Subsidence at Aquaculture Facilities in the Yellow River Delta, China, 1st Annual Workshop on Coastal Subsidence, New Orleans, LA, Nov 19 – 21, 2013.

10. Higgins, S., Measuring land subsidence at the coastal zone, 39th Annual Natural Hazards Research and Applications Workshop, Broomfield, CO, 22-25 Jun. 2014.

11. Higgins, S., Overeem, I., & Syvitski, J. P.M., (2013), Fish Farms and the Sinking Delta, Community Surface Dynamics Modeling System (CSDMS) 2.0: Moving Forward, Boulder, CO, Mar 23 – 25, 2013.

12. Higgins, S., Overeem, I., and Syvitski, J.P.M., July 2012. Land Subsidence in the Yellow River Delta, China: Results from Interferometric Synthetic Aperture Radar (InSAR). IEEE International Geoscience and Remote Sensing Symposium (IGARSS-2012), Munich, Germany.

13. Higgins, S., Overeem, I., Syvitski, J.P.M., Steckler, M., Seeber, N. A., and Akhter, H., InSAR measurements of compaction and subsidence in the Ganges-Brahmaputra Delta, Bangladesh, CSDMS 2014 annual meeting, Uncertainty and Sensitivity in Surface Dynamics Modeling, Boulder Colorado, USA, May 20-22, 2014.

14. Higgins, S., Overeem, I., Syvitski, J.P.M., Steckler, M., Seeber, N. A., and Akhter, H., Monitoring delta subsidence with Interferometric Synthetic Aperture Radar (InSAR), GC21D-0574, 2014 Fall Meeting, AGU, San Francisco, Calif., 15-19 Dec. 2014.

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15. Higgins, S., Overeem, I., Tanaka, A., & Syvitski, J. P. M., (2013), Land Subsidence at Aquaculture Facilities in the Yellow River Delta, China, Annual Meeting of the American Geological Society (AGU), San Francisco, CA, Dec 9 – 12, 2013.

16. Jensen K, McDonald KC, Schroeder R, Tessler ZD. Bridging the past with today’s microwaves remote sensing: A case study of long term inundation patterns in the Mekong River Delta. AGU Fall Meeting, San Francisco, CA, December 18, 2015.

17. Kettner, A.J., August 28-30th, 2013. Advances in simulating fluvial sediment transport at basin-scale. Stratodynamics, Nagasaki, Japan.

18. Kettner, A.J., Syvitski, J.P.M., Overeem, I., and Brakenridge, G.R., December 3-7, 2012. Human induced flooding of the Indus River in 2010: How it changed the landscape. San Francisco, CA, USA.

19. Kettner, A.J., Syvitski, J.P.M., Overeem, I., Brakenridge, G.R., December 9-13th, 2013. Fluvial geomorphological changes of the Indus River due to human failure, AGU, San Francisco, CA, USA.

20. McDonald, K., Chapman, B., Schroeder, R., Azarderakhsh, M., Podest, E., Moghaddam, M., Whitcomb, J., Hess, L., Kimball, J. (2013) Assembly and Assessment of ASCAT Scatterometer Data for Continuing Global Vegetation State Monitoring: Comparison with SeaWinds-on-QuikSCAT and Vegetation Response to Seasonal Drought, 2013 NASA Terrestrial Ecology Science Team Meeting, Scripps Seaside Forum, La Jolla, CA, USA.

21. Overeem, I., and Kettner, A.J., Sedimentation patterns in Fluvio-Deltaic systems. Nanjing University, Nanjing, China, 14 Oct. 2014.

22. Overeem, I., Higgins, S.A., Syvitski, J.P.M., Kettner, A.J., and Brakenridge, G.R., The Impacts of Armoring our Deltas: mapping and modeling large-scale deltaplain aggradation. AGU, San Francisco, CA, USA., 15-19 Dec. 2014.

23. Overeem, I., Rogers, K., and Higgins, S., 2012. 'The Ganges Delta Balance'. November, 2012. Oral presentation at BANGLAPIRE MEETING 2012, VanderBIlt University, Nashville TN.

24. Rogers, K.G., Overeem, I., Higgins, S., Gilligan, J., and Syvitski, J.P.M., 2013. Farming Practices and Anthropogenic Delta Dynamics, Proceedings of IAHS-IAPSO- IASPEI Assembly, Gothenburg, Sweden.

25. Schroeder, R., McDonald, K.C., Azarderakhsh, M., Steiner, N., Dunbar, R.S., Zimmermann, R., Küppers, M. December 9-13th, 2013. ASCAT MetOp-A Backscatter Observations over the Global Land Surface: Application to Monitoring Recent Trends in Lake and Wetland Extent and to Monitoring Crop Growth over the United States, AGU, San Francisco, CA, USA.

26. Slayback, D., Policelli, F.S., Brakenridge, G.R., Tokay, M.M., Smith, M.M., Kettner, A.J., December 9-13th, 2013. Global, Daily, Near Real-Time Satellite-based Flood Monitoring and Product Dissemination, AGU, San Francisco, CA, USA.

27. Syvitski, J.P.M. & Higgins, S.A., Subsidence and Relative Sea-level Rise in Threatened Deltas, H31L-01, 2014 Fall Meeting, AGU, San Francisco, Calif., 15-19 Dec. 2014.

28. Syvitski, J.P.M., Coastal Subsidence, 2014 Science Workshop, UNAVCO, Boulder CO, 4-6 Mar. 2014.

29. Syvitski, J.P.M., Cohen, S., Kettner, A.J., Brakenridge, G.R., December 9-13th, 2013. New Possibilities in Global Hydrology and Sediment Transport, AGU, San Francisco, CA, USA.

30. Syvitski, J.P.M., Rivers of the Anthropocene, Rivers of the Anthropocene, Indiana University-Purdue University, Indianapolis (IUPUI), 23-25 Jan. 2014.

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31. Syvitski, J.P.M., The Global Water Cycle in the World of the Anthropocene, 7th Int’l Scientific Conference on the Global Energy and Water Cycle, The Hague, The Netherlands, 14-18 Jul. 2014.

32. Syvitski, J.P.M., The Peril of Deltas: India and elsewhere - Welcome to the Anthropocene, IGBP Symposium, Bangalore India, 07 Apr. 2014.

33. Tessler Z.D., Vörösmarty C.J., Cohen S., and Tang H. River network uncertainty and morphodynamics in the Mekong Delta: Model validation and sensitivity to fluvial flux distribution. AGU Fall Meeting, San Francisco, CA, December 2014.

34. Tessler Z.D., Vörösmarty C.J., Foufoula-Georgiou E., and Ebtehaj A.M.. Spatial and temporal patterns of rainfall and inundation in the Amazon, Ganges, and Mekong Deltas. Deltas in Times of Climate Change II, Rotterdam, The Netherlands, September 25, 2014.

35. Tessler ZD, Vörösmarty CJ, Grossberg M, Gladkova I, Aizenmann H, Syvitski J, Foufoula-Georgiou E. From relative sea level rise to coastal risk: Estimating contemporary and future flood risk in deltas. CSDMS Annual Meeting, Boulder, CO, May 19, 2016.

36. Tessler ZD, Vörösmarty CJ, Grossberg M, Gladkova I, Aizenmann H, Syvitski J, Foufoula-Georgiou E. The geophysical, anthropogenic, and social dimensions of delta risk: Estimating contemporary and future risks at the global scale. AGU Fall Meeting, San Francisco, CA, December 17, 2015.

37. Tessler ZD, Vörösmarty CJ. Sea-Level Rise and Land Subsidence in Deltas: Estimating Future Flood Risk Through Integrated Natural and Human System Modeling. AGU Fall Meeting, San Francisco, CA, December 13, 2016.

38. Tessler ZD. Assessing risk and vulnerability in global deltas. ESPA Deltas – Sustainable Development Goals in Deltas Workshop, London, UK. November 23, 2016.

39. Tessler ZD. The Geophysical, Anthropogenic, and Social Dimensions of Coastal Risk: Assessment of Change in Populated River Deltas. New York City College of Technology Scholar on Campus Geophysics Lecture Series. New York, NY, February 28, 2017.

40. Tessler, Z.D., Vörösmarty, C.J. A global deltas typology of environmental stress and its relation to terrestrial hydrology, AGU Fall Meeting, San Francisco, CA, December 9-13, 2013.

41. Tessler, Z.D., Vörösmarty, C.J., June 5-6, 2013. Environmental stress and relative sea level rise in river delta systems, NOAA-CREST Symposium: Climate and Extreme Weather Impacts on Urban Coastal Communities, New York, NY, USA.

42. Tessler, Z.T., and Vörösmarty, C.J. Empirical estimates of the dominant environmental forcings on the relative sea level change of river delta systems. AGU Fall Meeting, San Francisco, CA, December 3-7, 2012.

43. Vörösmarty, C.J, Foufoula-Georgiou, E., Tessler, Z.D., Overeem, I. January 9, 2014. Environmental CrossRoads and a New Global DELTAS Sustainability Initiative. Deltares, Rotterdam, The Netherlands.

44. Vörösmarty, C.J. November 2012. River deltas: From local challenges to global syndrome. Invited Speaker. First CREST Mini-Conference, The City College of New York, New York, NY.

45. Vörösmarty, C.J. October 2012. River deltas: From local challenges to global syndrome.” Plenary Speaker. 7th Biennial Bay – Delta Science Conference, Sacramento Convention Center, Sacramento, CA.

46. Xing, F., Kettner, A.J., Syvitski, J.P.M., and Atkinson, J., Hydrodynamics and morphological changes of the Wax Lake Delta (WLD) during Hurricane Rita, 2005, CSDMS 2014 annual

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meeting, Uncertainty and Sensitivity in Surface Dynamics Modeling, Boulder Colorado, USA, May 20-22, 2014.