Special Issue "Recent Progress in Research on River Deltas"

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Hydrology".

Deadline for manuscript submissions: closed (31 August 2019).

Special Issue Editors

Prof. Dr. Y. Jun Xu
E-Mail Website
Guest Editor
School of Renewable Natural Resources, Louisiana State University, Baton Rouge, LA 70803, USA
Interests: surface hydrology; water quality; hydrologic and biogeochemical processes and modeling; sediment and nutrient transport; land use and climate change effects on water resources and biogeochemical cycles; isotopic tracer techniques; and GIS/Remote Sensing applications in surface hydrology
Special Issues and Collections in MDPI journals
Prof. Dr. Nina S.-N. Lam
E-Mail Website
Guest Editor
Department of Environmental Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
Special Issues and Collections in MDPI journals
Prof. Dr. Kam-biu Liu
E-Mail Website
Guest Editor
Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
Interests: Paleoecology; paleoclimatology; extreme events; storm deposits; paleotempestology; coastal environmental changes; lake sediments; wetlands; biogeography
Special Issues and Collections in MDPI journals
Prof. Dr. Zhongyuan Chen
E-Mail Website
Guest Editor
The State Kay Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China

Special Issue Information

Dear Colleagues,

We invite you to submit your latest study findings demonstrating progress in River Delta Research. The world’s river deltas are densely populated and vital to global food security, commerce, energy production, and industrial development. Many of these deltaic regions are rapidly sinking into the sea due to a number of natural and anthropogenic factors, including disconnection of rivers with their floodplains, reduced sediment input, river engineering, coastal land subsidence, and sea level rise. Over the past decades, the world’s river deltas have experienced rapid population increase and urbanization. The anthropogenic activities have interfered with delta-forming processes and, in return, the altered deltaic forming processes are affecting humans, presenting a dynamically coupled natural–human system. As global sea level continues to rise, eroding and drowning coastal shorelines, the world’s river deltas face the continuing threat to their sustainability. However, these regions are ill-prepared to face the future challenges and satisfy the needs of their inhabitants. This Special Issue aims at bringing together the latest research on the world’s river deltas as a complex dynamic system between the natural and human environments. We encourage submissions based on field, modeling, and synthetic studies concerning deltaic geomorphology, sediment transport, hydrology, spatial organization, population dynamics, social, economics, and policy making in the vulnerable deltas. We especially encourage papers that address the world’s major river deltas and stimulate critical thinking pertinent to finding practical solutions.

Prof. Dr. Y. Jun Xu
Prof. Dr. Nina S.-N. Lam
Prof. Dr. Kam-biu Liu
Prof. Dr. Zhongyuan Chen
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Water is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • River deltas
  • Deltaic processes
  • Estuarine hydrodynamics
  • Riverine sediment transport
  • Estuarine sedimentation
  • Estuarine channel and delta morphology
  • Modeling delta progradation and recession
  • Deltaic and estuarine ecosystems
  • Disturbance mechanisms and extreme events (storms, tsunamis, floods)
  • Delta evolution in geologic timescale
  • Delta resilience and stability
  • Saltwater intrusion
  • Coupled Nature-Human deltaic systems
  • The social, economic, and policy dimensions
  • Deltaic land use land cover change
  • Deltaic data and modeling infrastructure
  • Science-practice translation and communication

Published Papers (6 papers)

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Research

Open AccessArticle
Decadal-Scale Variations of Thalweg Morphology and Riffle–Pool Sequences in Response to Flow Regulation in the Lowermost Mississippi River
Water 2019, 11(6), 1175; https://doi.org/10.3390/w11061175 - 05 Jun 2019
Abstract
The lowermost Mississippi River (LMR) is one of the largest deltaic systems in North America and one of the heavily human-manipulated fluvial river systems. Historic hydrographic surveys from the mid-1900s to the early 2010s were used to document the thalweg morphology adjustments, as [...] Read more.
The lowermost Mississippi River (LMR) is one of the largest deltaic systems in North America and one of the heavily human-manipulated fluvial river systems. Historic hydrographic surveys from the mid-1900s to the early 2010s were used to document the thalweg morphology adjustments, as well as the riffle–pool sequences. Extensive aggradation was observed during 1950s to 1960s, as the Atchafalaya River was enlarging before the completion of the Old River Control Structure (ORCS). Following the completion of the ORCS, reductions in sediment input to the LMR resulted in net degradation of the thalweg profile patterns since the mid-1960s except for the 1992–2004 period. Different flood events that supplied sediment might be the cause of upstream aggradation from 1963–1975 and net aggradation along the entire reach from 1992–2004. Furthermore, the change pattern of thalweg profiles appear to be controlled by backwater effects, as well as the Bonnet Carré spillway opening. Results from riffle–pool sequences reveal that the averaging Ws ratios (length to channel width) are 6–7, similar to numerous previous studies. Temporal variations of the same riffles and pools reveal that aggradation and degradation might be heavily controlled by similar factors to the thalweg variations (i.e., sediment supply, backwater effects). In sum, this study examines decadal-scale geomorphic responses in a low-lying large river system subject to different human interventions, as well as natural flood events. Future management strategies of this and similar river systems should consider recent riverbed changes in dredging, sediment management, and river engineering. Full article
(This article belongs to the Special Issue Recent Progress in Research on River Deltas)
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Open AccessArticle
Hurricanes as a Major Driver of Coastal Erosion in the Mississippi River Delta: A Multi-Decadal Analysis of Shoreline Retreat Rates at Bay Champagne, Louisiana (USA)
Water 2018, 10(10), 1480; https://doi.org/10.3390/w10101480 - 19 Oct 2018
Abstract
The Louisiana shoreline is rapidly retreating as a result of factors such as sea-level rise and land subsidence. The northern Gulf of Mexico coast is also a hotspot for hurricane landfalls, and several major storms have impacted this region in the past few [...] Read more.
The Louisiana shoreline is rapidly retreating as a result of factors such as sea-level rise and land subsidence. The northern Gulf of Mexico coast is also a hotspot for hurricane landfalls, and several major storms have impacted this region in the past few decades. A section of the Louisiana (USA) coast that has one of the highest rates of shoreline retreat in North America is the Caminada-Moreau headland, located south of New Orleans. Bay Champagne is a coastal lake within the headland that provides a unique opportunity to investigate shoreline retreat and the coastal effects of hurricanes. In order to examine the influence of hurricanes on the rate of shoreline retreat, 35 years (1983–2018) of Landsat imagery was analyzed. During that period of time, the shoreline has retreated 292 m. The overall rate of shoreline retreat, prior to a beach re-nourishment project completed in 2014, was over 12 m per year. A period of high hurricane frequency (1998–2013) corresponds to an increased average shoreline retreat rate of >21 m per year. Coastal features created by multiple hurricanes that have impacted this site have persisted for several years. Bay Champagne has lost 48% of its surface area over the last 35 years as a result of long-term shoreline retreat. If shoreline retreat continues at the average rate, it is expected that Bay Champagne will disappear completely within the next 40 years. Full article
(This article belongs to the Special Issue Recent Progress in Research on River Deltas)
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Open AccessArticle
Forces Driving the Morphological Evolution of a Mud-Capped Dredge Pit, Northern Gulf of Mexico
Water 2018, 10(8), 1001; https://doi.org/10.3390/w10081001 - 28 Jul 2018
Cited by 3
Abstract
Sandy sediments preserved as paleo-channel fill on the inner shelf, some of which are overlain by modern muds, have been mined for barrier island restoration along the northern Gulf of Mexico. These mined areas have been termed “mud-capped” dredge pits. The processes governing [...] Read more.
Sandy sediments preserved as paleo-channel fill on the inner shelf, some of which are overlain by modern muds, have been mined for barrier island restoration along the northern Gulf of Mexico. These mined areas have been termed “mud-capped” dredge pits. The processes governing the morphological evolution of the pits are poorly constrained due to limited observational data. Physical oceanographic (e.g., currents and waves) and sedimentary data were collected at Sandy Point dredge pit offshore Plaquemines Parish, Louisiana in summer 2015. Currents outside the pit flowed southward and/or southeastward at speeds of 8–20 cm/s, while currents inside the pit had speeds less than 2 cm/s with no clear dominant direction. Wave heights detected inside the pit were less than 0.4 m. A high turbidity layer with suspended sediment concentration around 4 g/L was observed above the pit floor, and its thickness was ~0.5 m. With observational data as input, three 2–D numerical models were employed to predict pit morphological responses, including pit infilling, margin erosion and slope change. The model results suggest that resuspension events were rare on the seafloor adjacent to the pit under summer fair weather conditions. Modeled pit margin erosion was very limited. With little resuspension of seafloor sediment locally, weak margin erosion and stable pit walls, the dominant process governing pit evolution was infilling sourced by the deposition of suspended sediments from the Mississippi River plume. Full article
(This article belongs to the Special Issue Recent Progress in Research on River Deltas)
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Open AccessArticle
Estuarine Turbidity Maxima and Variations of Aggregate Parameters in the Cam-Nam Trieu Estuary, North Vietnam, in Early Wet Season
Water 2018, 10(1), 68; https://doi.org/10.3390/w10010068 - 13 Jan 2018
Cited by 5
Abstract
This study aims at exploring the characteristic parameters of the Estuarine Turbidity Maxima (ETM) and at investigating their tidal variations within the Cam-Nam Trieu estuary (North Vietnam) during the early wet season. Six longitudinal river transects were performed at spring tide. Two types [...] Read more.
This study aims at exploring the characteristic parameters of the Estuarine Turbidity Maxima (ETM) and at investigating their tidal variations within the Cam-Nam Trieu estuary (North Vietnam) during the early wet season. Six longitudinal river transects were performed at spring tide. Two types of ETM were observed: an upper well mixed ETM with high Suspended Particulate Matter (SPM) concentrations up to the surface at low salinity (0.11 to <1 psu), and a lower ETM confined in a bottom layer over stratified waters at salinities between ~1 psu and 15 psu. Their length depended on the longitudinal salinity gradient and was highest at low tide than at high tide. D50 of the flocs varied between 35 and 90 μm, their excess of density between 60 and 300 kg m−3 and their settling velocity ranged from 0.07 to 0.55 mm s−1 with values between 0.12 and 0.40 mm s−1 in the core of ETMs. The average fractal dimension of flocs was estimated to vary between 1.93 (at high tide) to 2.04 (at low tide). Full article
(This article belongs to the Special Issue Recent Progress in Research on River Deltas)
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Open AccessArticle
Seasonal Water Exchanges between China’s Poyang Lake and Its Saucer-Shaped Depressions on River Deltas
Water 2017, 9(11), 884; https://doi.org/10.3390/w9110884 - 12 Nov 2017
Cited by 5
Abstract
The saucer-shaped depressions located at the river deltas of Poyang Lake are typical floodplain shallow sub-lakes subject to river-lake connection or isolation. The hydrological connectivity between these depressions and the main lake has a major influence on the hydrologic function and ecological integrity [...] Read more.
The saucer-shaped depressions located at the river deltas of Poyang Lake are typical floodplain shallow sub-lakes subject to river-lake connection or isolation. The hydrological connectivity between these depressions and the main lake has a major influence on the hydrologic function and ecological integrity of the lake-floodplain and associated wetland habitats. This study explored the water level fluctuations and water exchange processes between the Poyang Lake and three typical saucer-shaped depressions, using a 30-min temporal resolution of water level observations during 2015–2016. Our results showed that the water level correlation and hydrological connectivity between the main lake and its depressions displayed a strong seasonal and spatial signal. Temporally, the rainfall significantly influences the seasonality and frequency of water level fluctuations both in the main lake and the depressions. The correlation coefficient of the water level ordered from high to low occurred during the high-water period, the rising-water period, the falling-water period and the low-water period, respectively. Spatially, depressions with a shorter connection duration to the main lake are located at higher local elevation and at larger geographical distance from the main lake. Finally, we also discussed the implications of these findings and possible factors that could have caused these particular water regime characteristics and water exchange processes. Full article
(This article belongs to the Special Issue Recent Progress in Research on River Deltas)
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Open AccessFeature PaperArticle
Bedload and Suspended Load Transport in the 140-km Reach Downstream of the Mississippi River Avulsion to the Atchafalaya River
Water 2017, 9(9), 716; https://doi.org/10.3390/w9090716 - 18 Sep 2017
Cited by 9
Abstract
The Mississippi River Delta has been continuously losing land since the 1930s due to several factors, chief of which is the reduced sediment supply. A few recent studies have estimated individual components of short-term sediment transport, i.e., bedload and suspended load, separately for [...] Read more.
The Mississippi River Delta has been continuously losing land since the 1930s due to several factors, chief of which is the reduced sediment supply. A few recent studies have estimated individual components of short-term sediment transport, i.e., bedload and suspended load, separately for some locations along the Lowermost Mississippi River (LmMR, commonly considered as the last 500-km reach of the Mississippi River before entering the Gulf of Mexico). However, the combined effects of both components on the long-term sediment supply along the river reach are still unclear. One of the major obstacles here hindering our understanding is that it is difficult and impractical to accurately measure bedloads in large alluvial rivers, such as the Mississippi. In this study, we estimated bedloads of three medium grain sizes (D50 = 0.125, 0.25 and 0.5 mm) for three locations along the uppermost 140-km reach of the LmMR: Tarbert Landing (TBL) at river kilometer (rk) 493, St Francisville (St F) at rk 419, and Baton Rouge (BTR) at rk 367.5 during 2004–2015. We also estimated suspended loads at St F during 1978–2015 and at BTR during 2004–2015 in order to discern the interactive relationship between bedloads and suspended loads. We found gradually increasing bedloads for all the three medium grain sizes from TBL (83, 41.5 and 20.75 million tons (MT), respectively) to BTR (96, 48 and 24 MT). We also found that suspended loads at TBL (reported previously) were significantly higher than those at St F and BTR during corresponding overlapping periods. Bedloads increased almost linearly with suspended loads, river discharge and river stage at the upstream locations (TBL and St F); however, such a relationship was not evident downstream at BTR. The total sediment load (bedload + suspended sediment load) was substantially higher at TBL (931 MT), while lower and nearly equal at other two downstream locations (550 MT at St F and 544 MT at BTR) during 2004–2010 (the matching period of availability of both loads). These findings indicate that the uppermost 20–25 km LmMR reach (covering TBL) has potentially entrapped substantial suspended load over the last three to four decades, while bedload transport prevails in the lower reach (covering St F and BTR). We suggest that future sediment management in the river should seek engineering solutions for moving trapped coarse sediments downstream towards the coast for the Mississippi River Delta restoration Full article
(This article belongs to the Special Issue Recent Progress in Research on River Deltas)
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