New Suspended Sand Concentration Model for Breaking Waves

Process-based morphodynamic modelling suites (as well as other process-based models) are often considered to be inefficient and unsuitable for simulating medium- to long-term morphodynamics due to the various theoretical (e.g. robustness of sediment transport models) and practical (e.g. computational costs) limitations. In particular, a lack of knowledge of sediment transport processes and how they relate to hydrodynamics makes the application of short-term models to long-term coastal evolution challenging. Even the state-of-the-art coastal area modelling suites (such as Delft3D and MIKE21) consist of relatively simple physics, relying instead on numerous semi-empirical parameterizations, which are often poorly supported by measured data and/or physical process understanding. In particular, suspended sediment transport in the highly turbulent surf zone is poorly modelled under breaking wave conditions. Six existing suspended sand concentration (SSC) models were critically evaluated against four high-resolution datasets with field-scale breaking waves and co-located velocity and concentration measurements over multiple cross-shore zones (shoaling, breaking and inner-surf zones). A new improved concentration model was proposed based on a novel empirical relationship observed between local water depth and reference concentration, as well as latest process understanding and insights

Corrigendum to “Suspended sand concentration models under breaking waves: Evaluation of new and existing formulations” [Marine Geology 426 (2020) 106197]

Refers to: Lim, G., Jayaratne, R. and Shibayama, T. 2020. Suspended sand concentration models under breaking waves: Evaluation of new and existing formulations. Marine Geology. 246 (Art. 106197). https://doi.org/10.1016/j.margeo.2020.10619

Suspended sand concentration models under breaking waves: Evaluation of new and existing formulations

A total of 7 reference concentration (C₀) models (6 existing and 1 newly proposed) were validated against 119 test cases from 4 recently published datasets collected under the LIP, CROSSTEX, SandT-Pro and SINBAD experimental studies. These models were evaluated for performance in different cross-shore regions: the shoaling zone, breaking (outer surf) zone and inner surf zone, under regular and irregular breaking wave conditions. In almost all existing C₀ models, substantial under-prediction was found particularly around the wave plunging point (point at which breaking wave plunges and surface generated turbulent kinetic energy, TKE, is injected into the water column) where strong localised increases in C₀ were observed. This strong increase in concentration was attributed to the large-scale breaking-generated turbulent vortices invading the wave bottom boundary layer (WBBL) and entraining dense clouds of sediment near the plunging point. Models that were directly or indirectly driven by local wave climate such as the local wave height (H), breaker height (Hb) or local water depth (d), were found to perform quite poorly in the breaking region under regular and irregular plunging breaker waves. Formulations that related C₀ to the sand pickup rate (i.e. depending on exerted bed shear exceeding critical bed shear for entrainment) were adept in regions unaffected by external breaking-induced TKE (e.g. the shoaling zone) but could not account for the high levels of concentration observed at the plunging point. This is because these formulations were based on the implicit assumption that sediment entrainment is only induced by the local TKE generated by bed shear; not taking surface-generated breaking-induced TKE into account. This assumption was addressed in more recent studies, by including breaking-induced TKE into sediment pickup rate or reference concentration formulations. Though latest studies have shown promising relationships between near-bed TKE (kb) and reference concentration/sediment pickup, such formulations also face inherent limitations. These formulations are highly dependent on the accuracy of measured or modelled kb and are also sensitive to the magnitude of k. For example, the magnitude of measured kb was found to vary by a factor of 1.1–1.3 between regular and irregular wave conditions, with kb being smaller under irregular wave conditions. This resulted in varied performance between datasets in kb-driven reference concentration formulations. The Froude-scaled TKE produced smaller deviations in magnitude of TKE between datasets, suggesting that it may be a more suitable driving parameter for reference concentration models than kb. A new reference concentration model, L19, was empirically derived from an inverse relationship observed between d and C₀, and from the roller energy dissipation rate. The newly proposed L19 model shows good agreement with measured C₀ (with RMSE ranging between 0.36 and 1.79 kg/m³ over the different datasets) in regular and irregular wave conditions, even at the plunging point where concentration is highest. The modified concentration profile [C(z)] equation also performs well, generally capturing the vertical concentration profile accurately throughout the whole water column

Building Foundation Instability Induced by Tsunami Scour

Understanding the role of tsunami-induced scour in building foundation instability can allow for the proper design of buildings located in areas prone to tsunami events. The process of tsunami scour around building foundations reduces the bearing capacity of the soil to support loading, lateral resistance and loss of soil- foundation friction (i.e. piles). Scour can cause loss of material around a foundation, due to increased pore pressure within the soil and removal of the soil during the tsunami, resulting in reduced bearing capacity of the soil (Macabuag et al., 2018). During the 2004 Indian Ocean Tsunami and the 2011 Great East Japan Earthquake and Tsunami, three similar failure modes of building foundations were experienced, namely overturning, sliding and bearing (scour) failure (Macabuag et al., 2018). According to Wright (2015), shallow foundations such as strip, slab or pad are vulnerable to erosion of surrounding soil causing scour during a tsunami. The present paper discusses the application of the scour depth predictive model of Nicholas et al. (2016) and the development of a Relative Risk Index for future design of building foundations accounting for tsunamis

Modeling of Berm Formation and Erosion at the Southern Coast of the Caspian Sea

Cross-shore beach profile data from field measurements performed at six locations on the southern coast of the Caspian Sea are used to investigate bathymetry change due to various wave conditions. Beach profile measurements are analyzed and subsequently compared with the results of a berm formation and erosion model. The model comprises distinct empirical sediment transport equations for predicting the cross-shore sediment transport rate under various wave conditions. To yield a berm formation and erosion model, empirical cross-shore sediment transport equations are combined with the mass conservation equation. Simulations results obtained from the model compared well with the measurements, proving the capability of the model in simulating berm formation and erosion evolution

Modelling of Krakatoa Tsunami Wave Propagation and Community Engagement Based on SWOT Analysis in Southern Lampung, Indonesia

The eruption of Krakatoa which occurred on the 22 December 2018 caused an avalanche from the Gunung Anak Krakatau (GAK) body into the sea, causing a tsunami in the Sunda Strait. The tsunami affected Lampung (Sumatra) and Banten (Java) provinces in Indonesia. Based on the field observations made by Takabatake et al. (2019) in the southern part of Lampung, it was identified that there were severely damaged areas in Lampung; i.e. East Way Muli, Central Way Muli, and Kunjir villages. A numerical model was developed to simulate past and future tsunami wave propagation scenarios. In addition, the strategic planning technique of SWOT analysis was carried out in order to make recommendations for the resilience of local coastal communities for future tsunami events in Southern Lampung

Novel analytical techniques for improved decision making Implications for consumers and institutions

Information availability plays a key role in determining the choices of consumers, firms and governments.However, externalities associated with most commodities represent information failure leading toincorrect decisions. The emerging scientific advances nevertheless have produced several new analyticaltechniques that could guide towards better decisions. The objective of the paper is to review theexisting Iiterature on such analytical techniques and assess the appl icabi lity of such tools within the SriLankan context.Literature in environmental management and economics related disciplines revealed that availabilityof techniques such as Life cycle assessment (LCA) and food mile analysis for consumer productswhile institution or firm level decision making could be guided by tools such as management costaccounting and sustainable chain managementLCA has often been used in evaluating environmental performances of different food production andfood packaging options, waste management and transport options. The information of such analyseshas been made available through product standards such as ISO 14040. Food mile is an indicator oftransport costs offood items which could provide important guidelines for transport policy, internationaltrade and product related environmental information for consumeThe review elaborates on range of examples of application of such techniques over a wide range ofconsumer goods and services, institutions. The review reveals that although there seem to be sufficientanalytical techniques available worldwide, the applicability of such tools within Sri Lanka has beenvery sparse. LCA studies are only limited to two products and the ISO standards have not beenattempted yet. The study also highlights the need to improve the relevant data bases which wouldenable the rapid application of these tools and guide the decision maker towards sustainable directions.

ESTIMATION OF LOCAL RECREATIONAL VALUE OF HAKGALA BOTANIC GARDEN

The Botanical garden at Hakgala is one of the oldest ex-situ conservation areas in SriLanka. It is a unique environmental asset, nationally as well as globally, due to itsconservation, recreation, historical, cultural, educational and other values.A study was carried out in the Hakgala botanic garden to estimate its local recreationalvalue. The economic approach used to estimate the recreational value was the travel costmethod. The travel cost approach is a way to value unpriced goods. The surroundingareas were divided into concentric zones of increasing distance, which representedincreasing levels of travel cost. A survey of users was conducted at the Hakgala garden todetermine zone of origin, visitation rates, travel costs, and various socio economiccharacteristics. The data generated were used to regress visitation rates, the total travelcost and urban population fraction of each zone. With respect to multiple trips, the costcomponent was differentiated based on distances to particular destinations traveled.Demand curve based on visitation rates, was constructed using these data to estimate theconsumer surplus, or benefits, from the site.Estimated minimum total cost experienced by the visitors at the current entrance fee (Rs.20.00) was Rs.6,943,520. When this amount is subtracted from the total consumersurplus (total welfare) of Rs.228,493,714 the estimated consumer surplus is Rs.221,550,194. This figure can be used to demonstrate the contribution of a botanicalgarden to the economy and to attract more funds to develop infrastructural facilitiesinside the garden from the government allocations.

Validation of serum cytokines as potential biomarkers in acute dengue infection

Objectives: Serum IL-10, Macrophage inhibitory factor (MIF) and interferons have been found to be associated with fatal dengue. We set out to investigate the possibility of using these cytokine as biomarkers to predict severe dengue. Methods: Serum IL-10 levels were determined by quantitative ELISA in 215 adult patients with confirmed acute dengue infection (ADI). Serum IFNα and IFNγ levels were done in 79 patients. Serial recording of clinical features and laboratory investigations were done to determine clinical disease severity. Results: 33 (17.46%) patients were classified as severe dengue (SD). Serum IL-10 levels were significantly higher (p=0.0034) in patients with SD (median= 121.9, range= 24.98 to 3271 pg/ml) when compared to those with non SD (median= 78.28, range= 7.18 to 1343 pg/ml). In the 29 patients with paired serum samples, serum IL-10 levels rose in all 6 patients with SD whereas in 20/23 patients with non SD, serum IL-10 levels fell in the critical phase.  Although serum MIF values were higher in patients with SD (mean 70774, SD± 59874 pg/ml) when compared to those with non SD (mean 45362, SD± 26891 pg/ml), this was not statistically significant. The IFNγ levels were significantly higher (p=0.038) in patients with shock (median= 77.55, range= 18.21 to 468.4 pg/ml) when compared to those who did not develop shock (median= 35.25, range= 4.050 to 733.1 pg/ml). Conclusion: Serum IL-10 levels appear to be associated with SD. It would be crucial to investigate the possible role of this cytokine in the pathogenesis of SD

Counseling Update: A Flexible Monitoring Method for the Client and Practitioner

Recent years have seen a number of articles questioning both the utility and practicality of single-case designs. The authors propose a flexible monitoring method for practice evaluation. The proposed method is presented as a dynamic model, one that utilizes the existing evaluative procedures of the practitioner. This flexible method is proposed within the general outlines of developmental research. It is proposed as a method designed to lead practitioners toward an empirical model of practice. Some case examples are provided to substantiate the utility and value of the model.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68429/2/10.1177_104973159300300203.pd