Multi-Time Scale Mangrove-Mudflat Modelling: Exploring Guyana’s Unique Dataset & Numerical Modelling

The uncertainty surrounding the impact of sea-level-rise (SLR) and storms, which threaten the coastal hinterland, heightens the need for design guidelines on mangroves adaptation and their use in coastal safety. Mangrove forests, well known as coastal ecosystem defences, attenuate the hydrodynamic forces, reduce coastal erosion and foster conditions for increased sedimentation. However, the mechanistic understanding of the feedbacks between the vegetation and the morphodynamics and, the processes which result in the long term erosion- sedimentation during extreme wave events has been limited (Horstman 2014, Best 2017).Therefore, this research seeks to quantify the bio-physical processes governing the geomorphological evolution of mangrove-mudflat systems utilizing spatially explicit observations of mangrove population dynamics with process-based modelling. For calibration purposes and increased insight into interactions between hydrodynamics, sediment dynamics and mangroves, field observations were collected along Guyana&#8217;s coast.&#160;A quadrant, 1km wide and 6km in length, was established in the mangrove-mudflat coastline at Chateau Margot. This stretch of coastline is subject to a semi-diurnal tidal regime with a maximum tidal range of 3.5m during spring tide. Using the data, we developed a 2D high-resolution depth-averaged model of the field site using Delft3D-Flexible Mesh.We coupled this model with a mangrove dynamics model capturing the development of Avicennia germinans and Laguncularia racemosa species under suitable inundation and competition regimes. With the dynamic vegetation interface linked via the Basic Model Interface (BMI) with Delft3D-FM, the initial establishment is randomized over the computation grid cells, followed by the growth, diffusion and decay of the mangroves in areas of high stresses. The coupled model simulates the geomorphological development from the interaction between the intertidal flow, waves, sediment transport and the temporal and spatial variation in the mangrove growth, drag and bio-accumulation over 100 years.&#160;A combination of 1D and 2D simulations to analyze the equilibrium behavior of the system as well to identify the mechanistic feedbacks critical for the development of stable belt widths. Waves are critical for the transport of mud into the mangrove belt during high tide. Inundation of the inner fringe occurs during spring tides, so the calm conditions allow for a heightened platform and species establishment. The channels form the major path for the tidal inflow during the lower tides, while the interior of the forest is an effective sediment sink during the higher tides.RCP SLR scenarios, liner and exponential, reinforce behavioral trends for mangrove retreat and decay, with modelled tipping points realized after 1.5m increases. Results indicate mangrove adaptability hinges on the long term sedimentation responses and system conditions to promote the establishment of belt widths exceeding 300m.

Download Full-text

Climate studies with a coupled atmosphere-upper-ocean-ice-sheet model

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1989.0074 ◽

1989 ◽

Vol 329 (1604) ◽

pp. 249-261 ◽

Cited By ~ 13

Keyword(s):

Seasonal Cycle ◽

Low Frequency ◽

Coupled Model ◽

Upper Ocean ◽

Glacial Cycle ◽

Last Interglacial ◽

The North ◽

Technical Report ◽

Averaged Model

A two-dimensional zonally averaged model has been developed for simulating the seasonal cycle of the climate of the Northern Hemisphere. The atmospheric component of the model is based on the two-level quasi-geostrophic potential vorticity system of equations. At the surface, the model has land—sea resolution and incorporates detailed snow and sea-ice mass budgets. The upper ocean is represented by an integral mixed-layer model that takes into account the meridional advection and turbulent diffusion of heat. Comparisons between the computed present-day climate and climatological data show that the model does reasonably well in simulating the seasonal cycle of the temperature field. In response to a projected CO 2 trend based on the scenario of Wuebbles et al. (DOE/ NBB-0066 Technical Report 15 (1984)), the modelled annual hemispheric mean surface temperature increases by 2 °C between 1983 and 2063. In the high latitudes, the response undergoes significant seasonal variations. The largest surface warmings occur during autumn and spring. The model is then asynchronously coupled to a model that simulates the dynamics of the Greenland, the Eurasian and the North American ice sheets in order to investigate the transient response of the climate to the long-term insolation anomalies caused by orbital perturbations. Over the last interglacial-glacial cycle, the coupled model produces continental ice-volume changes that are in general agreement with the low-frequency part of palaeoclimatic records.

Download Full-text

Prey choice and habitat use of people exploiting intertidal resources

Environmental Conservation ◽

10.1017/s0376892902000140 ◽

2002 ◽

Vol 29 (2) ◽

pp. 238-252 ◽

Cited By ~ 25

Author(s):

W.F. de Boer ◽

A.-F. Blijdenstein ◽

F. Longamane

Keyword(s):

Prey Species ◽

Prey Availability ◽

Spring Tide ◽

Dry Weight ◽

Intake Rate ◽

Mangrove Forests ◽

Prey Choice ◽

Relative Value ◽

The Mean ◽

The Impact

The impact of human exploitation depends mostly on the size of the catch and the species targeted. The value of a species is an important explanatory variable in understanding human impact. Co-management of resources should take into account these different resource values, when evaluating exploitation strategies. The prey choice and foraging behaviour of women and children searching for crabs and shells on the intertidal area at Inhaca Island, South Mozambique, were investigated using optimal foraging theory. This theoretical framework offers the possibility to understand the reasoning of an exploitation strategy and the preference for certain prey species. The number of people was registered, catches were analysed, and timing and substrate choice were recorded. The value of species was estimated using contingency tables. Women were more efficient than children, as their catch was heavier, and the mean weight/animal was larger. The density of women and their timing were positively correlated to prey availability. During neap tide, they spread their visit over more of the low water period and collected crabs by digging in the mangrove forests. No digging occurred during spring tide when a larger area was exposed, the total abundance of species increased, and more species became available. Women then switched to a second strategy, targeting swimming crabs in the tidal channel. Mean neap and spring tide catches were equal (133 g ash-free dry weight per person), but spring catches comprised significantly fewer animals per catch (42 against 123 per person), and mean animal weight was larger (5.4 against 3.0 g ash-free dry-weight per person). Diet breadth was narrower during spring tide, and decreased significantly with increased catch weight. Species with profitabilities (energy intake/handling time) lower than the mean intake rate of 0.024–0.028 g ash-free dry weight s−1 were generally excluded from the diet. The prey preference was positively related to the relative value ranks of the prey species, as measured by ranking of species by women. Women maximized the cumulative relative value ranks during spring tide, instead of total weight. Using this analysis, differences in prey choice and spatial differences in exploitation can be understood as a strategy aimed at maximizing intake and the relative value of a prey species.

Download Full-text

Spill Response that Benefits the Long-Term Recovery of Oiled Mangroves

International Oil Spill Conference Proceedings ◽

10.7901/2169-3358-2003-1-539 ◽

2003 ◽

Vol 2003 (1) ◽

pp. 539-550 ◽

Cited By ~ 1

Author(s):

Charles D. Getter ◽

Roy R. Lewis

Keyword(s):

Mangrove Forests ◽

Response Effort ◽

Short Term ◽

Habitat Creation ◽

Heavy Equipment ◽

Nearshore Environments ◽

Beneficial Response ◽

Response Method ◽

The Impact

ABSTRACT We revisited three sites in Florida and Puerto Rico that were oiled 23 to 29 years ago, analyzing them and the published literature to determine that mangroves follow a 6 to 25 year recovery cycle. We reviewed response methods and determined that the use of offshore dispersants, the booming of tidal creeks and inlets, the use of onshore sorbents, low-pressure flushing and the manual collection of oily debris provide benefits for recovery at least in the short term. Non-beneficial response efforts that have degraded mangroves include forest cutting, heavy equipment and personnel traffic, tree burning, onshore use of chemicals, and plantings in toxic soil. Perhaps the most detrimental response effort studied was the impoundment of basin forests that has resulted in long-term losses and slow recovery rates. The intertidal use of dispersants has been shown to be beneficial to mangroves, however their use has also caused damages to nearshore environments such as coral reefs. In summary, once the oil has reached sheltered mangrove forests there exist only short-term benefits from traditional response efforts. More likely there are only non-beneficial results compared to natural attenuation. We conclude that the only longterm beneficial response method appears to be a combination of non-intrusive oil collection and booming techniques in heavily oiled, sheltered areas with closely monitored natural recovery in forests more lighly oiled. This should be paired with mitigation programs involving habitat creation either in unoiled areas or in the impact zone following the attenuation of oil and removal of debris from the deteriorating forests.

Download Full-text

Study on Hydrodynamic Characteristics and Environmental Response in Shantou Offshore Area

Journal of Marine Science and Engineering ◽

10.3390/jmse9080912 ◽

2021 ◽

Vol 9 (8) ◽

pp. 912

Author(s):

Yuezhao Tang ◽

Yang Wang ◽

Enjin Zhao ◽

Jiaji Yi ◽

Kecong Feng ◽

...

Keyword(s):

Flow Field ◽

Water Level ◽

Tidal Current ◽

Sea Water ◽

High Tide ◽

Spring Tide ◽

River Estuary ◽

Tidal Range ◽

Offshore Area ◽

Tidal Constituents

As a coastal trading city in China, Shantou has complex terrain and changeable sea conditions in its coastal waters. In order to better protect the coastal engineering and social property along the coast, based on the numerical simulation method, this paper constructed a detailed hydrodynamic model of the Shantou sea area, and the measured tide elevation and tidal current were used to verify the accuracy of the model. Based on the simulation results, the tide elevation and current in the study area were analyzed, including the flood and ebb tides of astronomical spring tide, the flood and ebb tides of astronomical neap tide, the high tide, and the low tide. In order to find the main tidal constituent types in this sea, the influence of different tidal constituents on tide elevation and tidal current in the study area was analyzed. At the same time, the storm surge model of the study area was constructed, and the flow field under Typhoon “Mangkhut” in the study area was simulated by using the real recorded data. Typhoon wind fields with different recurrence periods and intensities were constructed to simulate the change in the flow field, the sea water level, and the disaster situation along the coast. The results showed that under normal sea conditions, the sea water flows from southwest to northeast at flood tide and the flow direction is opposite at ebb tide. The tidal range is large in the northwest and small in the southeast of the study area. The tides in the study area are mainly controlled by M2, S2, K1, and O1 tidal constituents, but N2, K2, P1, and Q1 tidal constituents have significant effects on the high water level. The water level caused by typhoons increases significantly along the coast of Shantou City. In the west area of the Rong River estuary, a typhoon with a lower central pressure than 910 hPa may induce a water increase of more than 2 m.

Download Full-text

A Fully Coupled Hydromechanical Model for CO2 Sequestration in Coal Seam: the Roles of Multiphase Flow and Gas Dynamic Diffusion on Fluid Transfer and Coal Behavior

Geofluids ◽

10.1155/2020/8871614 ◽

2020 ◽

Vol 2020 ◽

pp. 1-14

Author(s):

Rui Yang ◽

Weiqun Liu ◽

Tianran Ma ◽

Junhe Xie ◽

Yang Hu ◽

...

Keyword(s):

Coal Seam ◽

Multiphase Flow ◽

Coupled Model ◽

Gas Dynamic ◽

Fluid Transfer ◽

The Impact ◽

Fully Coupled ◽

Dynamic Diffusion ◽

Hydromechanical Model

CO2 sequestration in coal seam has proved to be an effective way for reducing air pollution caused by greenhouse gases. A study on the rules of fluid transfer and reliability of CO2 storage during gas injection is necessary for the engineering application. However, the clarification of multifield coupling in long-term CO2 sequestration is the difficulty to solve the aforementioned problem. Previous investigations on the coupled model for CO2 storage in coal seam were not exactly comprehensive; for example, the multiphase flow in the fracture and the nonlinear behavior of gas diffusion were generally neglected. In this paper, a new multistage pore model of the coal matrix and the corresponding dynamic diffusion model were adopted. Meanwhile, the CO2-induced coal softening and the CO2-water two-phase flow in coal fracture were also taken into account. Subsequently, all the mentioned mechanisms and interactions were embedded into the coupled hydromechanical model, and this new fully coupled model was well verified by a set of experimental data. Additionally, through the model application for long-term CO2 sequestration, we found that the stored CO2 molecules are mainly in an adsorbed state at the early injection stage, while with the continuous injection of gas, the stored CO2 molecules are mainly in a free state. Finally, the roles of multiphase flow and gas dynamic diffusion on fluid transfer and coal behavior were analyzed. The results showed that the impact of multiphase flow is principally embodied in the area adjacent to the injection well and the coal seam with lower initial water saturation is more reliable for CO2 sequestration, while the impact of gas dynamic diffusion is principally embodied in the area far away from the injection well, and it is safer for CO2 sequestration in coal seam with greater attenuation coefficient of CO2 diffusion.

Download Full-text

The Impact of Embankments on the Geomorphic and Ecological Evolution of the Deltaic Landscape of the Indo-Bangladesh Sundarbans

10.5772/intechopen.94163 ◽

2020 ◽

Author(s):

Subhamita Chaudhuri ◽

Punarbasu Chaudhuri ◽

Raktima Ghosh

Keyword(s):

18Th Century ◽

High Water ◽

Water Levels ◽

Tidal Range ◽

Mangrove Forests ◽

Fish Ponds ◽

Ecological Evolution ◽

Late 18Th Century ◽

Anthropogenic Modifications ◽

The Impact

The deltaic landscape of the Ganga-Brahmaputra delta has evolved through a complex interplay of geomorphic processes and tidal dynamics coupled with the anthropogenic modifications brought over in course of the reclamation of the islands since the late 18th century. The reclamation process was characterized by clearing lands for paddy farms and fish ponds by building a mesh of earthen embankments along creek banks to restrict saltwater intrusion. The length of the embankments in the Indian Sundarbans alone is 3638 km (World Bank, 2014) which altered the tidal inundation regimes, sediment accretion and geomorphic character of the deltaic inlets. The mean annual sedimentation rate (2.3 cm y−1) in the central Ganga-Brahmaputra delta is over two times higher than sedimentation within the natural intertidal setting of the Sundarbans (Rogers et al., 2017). The tidal range has also increased inland due to polder construc¬tion, with high water levels within the polder zone increasing as much as 1.7 cm y−1 (Pethick and Orford, 2013). Embankments have impacted on the biodiversity and physiological adaptations of mangroves within the sphere of tidal ingression, habitat fragmentation and seedling establishment. The chapter attempts to reappraise the impact of dykes on the geomorphology of the deltaic landscape and on the functionalities of mangrove forests.

Download Full-text

Evaluation of the Continuous Monitoring of Land Disturbance Algorithm for Large-Scale Mangrove Classification

Remote Sensing ◽

10.3390/rs13193978 ◽

2021 ◽

Vol 13 (19) ◽

pp. 3978

Author(s):

Katie Awty-Carroll ◽

Pete Bunting ◽

Andy Hardy ◽

Gemma Bell

Keyword(s):

Continuous Monitoring ◽

Large Scale ◽

Data Availability ◽

Mangrove Forests ◽

Mangrove Species ◽

Land Disturbance ◽

Long Term Monitoring ◽

The Impact ◽

Term Monitoring

Mangrove forests are of high biological, economic, and ecological importance globally. Growing within the intertidal zone, they are particularly vulnerable to the effects of climate change in addition to being threatened on local scales by over-exploitation and aquaculture expansion. Long-term monitoring of global mangrove populations is therefore highly important to understanding the impact of these threats. However, data availability from satellites is often limited due to cloud cover. This problem can be mitigated using a season-trend modelling approach such as Continuous Monitoring of Land Disturbance (COLD). COLD operates by using every available observation on a pixel-wise basis, removing the need for whole cloud free images. The approach can be used to better classify land cover by taking into account the underlying seasonal variability, and can also be used to extrapolate between data points to obtain more accurate long term trends. To demonstrate the utility of COLD for global mangrove monitoring, we applied it to five study sites chosen to represent a range of mangrove species, forest types, and quantities of available data. The COLD classifier was trained on the Global Mangrove Watch 2010 dataset and applied to 30 years of Landsat data for each site. By increasing the period between model updates, COLD was successfully applied to all five sites (2253 scenes) in less than four days. The method achieved an overall accuracy of 92% with a User’s accuracy of 77% and a Dice score of 0.84 for the mangrove class. The lowest User’s accuracy was for North Kalimantan (49.9%) due to confusion with mangrove palms. However, the method performed extremely well for the Niger Delta from the 2000s onwards (93.6%) despite the absence of any Landsat 5 data. Observation of trends in mangrove extent over time suggests that the method was able to accurately capture changes in extent caused by the 2014/15 mangrove die-back event in the Gulf of Carpentaria and highlighted a net loss of mangroves in the Matang Forest Reserve over the last two decades, despite ongoing management. COLD is therefore a promising methodology for global, long-term monitoring of mangrove extent and trends.

Download Full-text

Suppressed, but Not Forgotten

Swiss Journal of Psychology ◽

10.1024/1421-0185/a000033 ◽

2011 ◽

Vol 70 (1) ◽

pp. 5-11 ◽

Cited By ~ 8

Author(s):

Beat Meier ◽

Anja König ◽

Samuel Parak ◽

Katharina Henke

Keyword(s):

Memory Trace ◽

Thought Suppression ◽

Test Phase ◽

Indirect Test ◽

Final Test ◽

Test Experiment ◽

And Control ◽

Cue Words ◽

The Impact

This study investigates the impact of thought suppression over a 1-week interval. In two experiments with 80 university students each, we used the think/no-think paradigm in which participants initially learn a list of word pairs (cue-target associations). Then they were presented with some of the cue words again and should either respond with the target word or avoid thinking about it. In the final test phase, their memory for the initially learned cue-target pairs was tested. In Experiment 1, type of memory test was manipulated (i.e., direct vs. indirect). In Experiment 2, type of no-think instructions was manipulated (i.e., suppress vs. substitute). Overall, our results showed poorer memory for no-think and control items compared to think items across all experiments and conditions. Critically, however, more no-think than control items were remembered after the 1-week interval in the direct, but not in the indirect test (Experiment 1) and with thought suppression, but not thought substitution instructions (Experiment 2). We suggest that during thought suppression a brief reactivation of the learned association may lead to reconsolidation of the memory trace and hence to better retrieval of suppressed than control items in the long term.

Download Full-text