This project was delivered with the JBA Group for the World Bank which involved the assessment and development of actions for flood mitigation in two urban areas in Burundi, Africa.

The project included hydrology, hydraulic modelling, urban drainage, risk modelling, water resources and disaster risk management, where we worked in partnership with a technical committee in Burundi to collect data and develop modelling systems for decision making. Our assessment and modelling focussed on Lake Tanganyika, and the impacts on rising lake levels on local communities within Bujumbura and Gatumba. Here regional flood risk has been exacerbated by rising water levels in the lake which has been coupled with recent extreme rainfall. The Flood Hazard Assessment produced estimates of inundation hazards which were used to consider the social and economic losses from a given event, based on local demographic and infrastructural data. It has supported a strategic investment plan, which provides different strategies for intervention for Disaster Risk Reduction, with management reports disseminated back to the World Bank team and Government of Burundi.

This week (April 2023) we have seen Tropical Cyclone Ilsa intensifying rapidly as it begins final approach to Western Australia’s Pilbara region.

With traditional cyclone insurance unavailable for many areas in northern Australia, we’ve put the spotlight on the use of Parametric Insurance as a disaster resilience tool. This is a type of policy that provides coverage based on a predetermined set of parameters, which for cyclone impacts is a wind speed threshold. So unlike traditional insurance policies that typically require on-ground assessment to understand the extent of damage, a parametric insurance policy aims to pay out automatically when the agreed-upon parameters are met.

Redicova (www.redicova.com.au) is a leading example of parametric cyclone insurance in Australia, where cover is triggered when the BoM records a severe tropical cyclone (Category 3 or higher) at the insured location. Its development has been due to the ongoing efforts of Managing Director Karen Hardy, who after experiencing the financial hardship caused to her community following a severe tropical cyclone, founded Redicova to offer a new approach for any exposed communities within northern Australia.

JBP has been working with Karen on the Redicova product since 2020, which uses our real-time monitoring system developed using Delft-FEWS. Here we access gridded forecasts, high-detail forecasts, operational best cyclone track datasets, and Automatic Weather Station data, with the system tracking the “Very Destructive” wind threshold of 118 km/hr.

If you are interested in learning more about our extreme weather forecasting systems visit our website (www.jbpacific.com.au) or contact Dan Rodger on: info@jbpacific.com.au.

Our team has been undertaking coastal and marine inspections at the Historic Sugar Wharf in Port Douglas, Queensland.

Our work included inspections to identify localised failures, uneven crossfall, material defects, joint condition, material deterioration, delamination, pile and concrete failures. This is combined with our review of coastal processes, tide and current assessments and wave loadings to complete the structural assessment.

If you are interested in learning more about our coastal and marine services please visit our website (www.jbpacific.com.au) or contact Brian Lam on: info@jbpacific.com.au

Alex Maskell has been down in Rockingham looking at the coastal processes within Warnbro Sound. Thanks to Tim Clee (Rockingham City Council) for the tour of the Sound, pointing out the important features such as the Tern Island Sandbar and discussing the ongoing management challenges.

This is an area that has experienced a very unique coastal change over the recent decades. It is a region exposed to ongoing tidal action, wave processes, storm surges, longshore drift, erosion and deposition. The Tern Island Sandbar itself is very dynamic, which is a long, narrow sandbar that extends from the shore out into the Sound. Over time it has experienced a change in direction, originally extending south-westerly, but now shifting to a southern-easterly orientation from the coast. We have used the Geoscience Australia’s DEA (Digital Earth Australia) Coastlines dataset to track its movement over time, which uses remote sensing to map the location and shape of the coastline. You can see the changes in the animation below, spanning the 1980s-present.

If you are interested in learning more about our services or working with us on a project, please visit our website (www.jbpacific.com.au) or contact Alexandra on: alexandra.maskell@jbpacific.com.au

This week our coastal modellers Alex Maskell and Mike Thomson have hit the road from Perth, Western Australia. Heading south from our office, they have been busy looking at the beaches between Perth and Bunbury, as Alex explains.

“Heading off for my first field work in Australia since returning from Scotland, the first thing that struck me was how much nicer it is without wearing a raincoat! For Mike, the biggest shock (apart from the lack of humidity compared to Brisbane) was that the ocean was to the west.

Living close to the water was a huge drawcard when I started the Western Australia office, and I’m not the only one – there is an ever-growing number of communities lining the west coast. Our first stop took us all the way down to Bunbury where we were able to try out some of our field tools. After first debating the size of sand grains on Back Beach, Mike, never leaving home without his American dime, took a SandSnap to settle the tie break (he won) and also became the first WA contributor to this fantastic collaborative project. Tools like SandSnap are great for quick analysis, which uses a deep learning neural network (~ AI) to calculate a full particle size distribution. This information then helps us model sand movement caused by the tides and waves, and allows us to predict how the coast will change under extreme events. SandSnap is actually run as aa collaborative citizen-science project that is building a world-wide database of beach sand grain sizes, so for anyone wanting to learn more, look here: https://sandsnap-erdcchl.hub.arcgis.com/

We ventured around Back Beach and Bunbury Port looking at all the coastal protection structures comparing and contrasting between the UK and Queensland. There is plenty of areas where we want to setup either a wave model or an XBeach model (using our new sand data) to help understand exactly what’s happening….which I will share next week”.
If you are interested in learning more about our services or working with us on a project, please visit our website (www.jbpacific.com.au) or contact Alexandra on: alexandra.maskell@jbpacific.com.au

Extreme weather events are becoming more frequent and more severe around the world, causing devastating damage to homes, infrastructure, and lives. This has led to an increased demand for engineering solutions that can withstand these extreme weather conditions. In response to this growing need, JBPacific (JBP) is proud to announce the opening of its new office in Perth, Western Australia. The new office will serve as a hub for our operations on the west coast , providing cutting-edge solutions to help protect communities from extreme weather events.

Dr Alexandra Maskell, who will be leading the Perth office is excited about the venture: “Perth is an ideal location for JBP’s new office, with Western Australia facing ongoing and increasing challenges from extreme weather. Western Australia is home to coastal communities, a thriving engineering industry, with a wealth of talented professionals who will help us achieve our mission of building extreme weather and climate resilience”

Our work will focus on detailed numerical modelling for extreme weather events;

• coastal erosion
• storm surges
• storms
• flooding
• cyclones
• wave impacts
• changes to tidal currents
• climate change impacts.

This information can be used by local or state government agencies, transport operators, asset managers and disaster managers to undertake risk assessments, climate resilience planning, design/construction, or develop new early warning systems. We look forward to bringing our latest technology and numerical modelling techniques to Perth, and collaborating with other industry and academic partners.

If you are interested in learning more about our services or working with us on a project, please visit our website (www.jbpacific.com.au) or contact Alexandra on: alexandra.maskell@jbpacific.com.au

Our team undertakes coastal and marine assessments that consider how waves enter and interact with harbours, breakwaters, and other structures.  This work is important to understand wave behaviour within constructed harbours and to estimate wave conditions at vessel berths, which can be affected by wave propagation, shoaling, diffraction and reflection processes. 

We commonly use XBeach, an open-source numerical model originally developed to simulate hydrodynamic and morpho dynamic processes on sandy coasts.  Throughout the model development, it has increasingly been upgraded to simulate complex structures, and validated against analytical, laboratory and field test cases.  The model now includes:

• Short wave transformation (refraction, shoaling and breaking).
• Long wave (infragravity wave) transformation (generation, propagation, and dissipation).
• Non-hydrostatic wave diffraction.
• Wave-induced setup and unsteady currents.
• Over wash and inundation.

A big benefit of the XBeach model is that it is Open Source, free to download and comes with a great following through the community website.  Give it a go via this link:  https://oss.deltares.nl/web/xbeach/

Midge Point is a small coastal community in central Queensland that was hit by the Category 4 Cyclone “Debbie” in 2017. The resulting erosion was extreme, with the majority of beach swept away, and the township flooded from the associated storm tide. JBP undertook concept and detailed designs for a new beach nourishment, buried seawall constructed of geotextile sand containers (GSC), and dune revegetation. The sand and dune revegetation is designed to maintain coastal and ecological processes, with the GSC seawall providing a backstop defence against cyclonic erosion, with a 50-year standard of protection and 20 year design life before replacement is needed.

The new 3.6-metre buried seawall is made from 2000 GSC units, each holding 2.5m3 of sand with a weight of four tonnes. The associated nourishment will cover the full residential 900-metre shoreline, with 26,000m3 of sand imported to restore and raise the frontal dune. While the nourished beach will evolve with ongoing shoreline processes and erode over time, the sand is designed to offer increased protection from erosion and storm tides as it absorbs and spreads the waves’ energy in a storm. By including revegetation along the dune, grasses can capture wind-blown sand before it leaves the beach, with roots helping to stabilise the rear dune. The designs were approved by the State Government and recovery works supported under the Natural Disaster Relief and Recovery Arrangements.

JBPs work included the following tasks

• Concept design and numerical modelling
• Detailed design calculation for the GSC wall
• Detailed design for sand nourishment
• Safety in Design report
• Technical Specification

Nature-based coastal resilience measures are being increasingly recommended to stabilise shorelines and protect against coastal inundation. These measures include Nature Based Solutions/ Adaptation (NbS/NbA), Working With Nature (WWN), Soft Engineering, and bio-engineering. These are gaining interest for applications as a substitute for – or in conjunction with – standard coastal protection, due to their co-benefits in habitat creation, increases to social amenity, flood mitigation and climate change adaptation. However, there are limited case studies on the effectiveness of NbS, and a lack of design guidelines for their implementation. Furthermore, a number of technical and planning barriers exist when progressing nature-based approaches from the planning phase to on-ground works. This project has focussed on bridging this gap through new Pilot Projects.

A Living Shoreline Pilot Project has been subject to engineering and ecological design in Moreton Bay, Australia. This project has been developed to identify the challenges, opportunities and risks involved in implementing a coastal protection scheme incorporating NbS. This project is designed to be a Council-led and State Government-supported pilot study to validate the assumptions made within initial assessments. It has been implemented for two sites currently experiencing erosion and coastal inundation hazards.

STUDY SITES

The sites are located at Three Paddocks Park, Birkdale, and Oyster Point Park, Cleveland, QLD. Both are located within Moreton Bay and are offered protection from ocean swell by surrounding islands. However, persistent wind-generated wave conditions have led to ongoing coastal erosion and the development of an erosion scarp approximately 1m high at each. Moreton Bay has a meso-scale tidal range, spanning around 2m during spring tides. Under extreme conditions the study areas can experience a coastal storm surge leading to total sea levels around 1m above the HAT. Additionally, under Queensland State Planning Policies, the areas are considered to be subject to additional sea level rise increases of 0.8m by 2100.

The study has the capacity for multiple approaches to be designed, implemented and evaluated. The ‘textbook’ NbS options investigated during the design process included artificial reefs, mangrove establishment, living seawalls, piling and logjams, oyster reefs, bank regrading and revegetation. Each option has been progressively investigated – subject to a design process, certification and planning checks – with the most suitable option incorporated into the final designs. During this process, the study considered the following:
• If a typical engineering design procedure is suited to the implementation of NbS
• If a standard of protection can be applied to the design
• If there is a need for engineering certification, given the design’s role as an erosion protection scheme
• The planning requirements for the designs
• How ‘textbook’ unit-rates compare to detailed construction cost estimates
• Community response to the new design approach

NEW RESEARCH INTO THE EFFECT OF MANGROVES ON REDUCING WAVE IMPACTS
In addition to developing new concept designs, this project has undertaken testing of the protection offered by mangrove forests. Mangroves will reduce wave heights, which can increase the resilience of a coastline or watercourse. This could benefit areas experiencing residual coastal waves, wind-generated waves over wide waterbodies or boat wash. The degree of wave height reduction will depend on the width of the forest, the mangrove tree morphology, water depth, topography, and the incoming wave height. Waves will be more effected by the density of the mangrove forest during high water levels, and the characteristics of aerial roots during low water levels. Both will directly reduce wave energy, in addition to reducing wind speeds over the water surface, and consequent bank erosion.

The XBeach coastal wave and erosion model has been used to assess the level of protection offered by varying widths and density of mangrove forests. It is an open-source numerical model that can simulate the effects of wave dampening through submerged and semi-submerged vegetation such as mangroves and parametrises plant density (N), height (ah), stem diameter (bv), and drag coefficient (Cd). The model was calibrated against field testing conducted by Bao (2011) and Mazda et al (2006) which showed the wave height reduction when passing through mangrove forests can be between 40% and 80% over 100m, with the XBeach model showing around 55% reduction. The new modelling also shows a lower density forest will have a reduction in effectiveness (wave reduction rate drops to 40%) and conversely a healthy mangrove forest with doubled density will reduce incoming waves more than 70%.

An island-wide flood risk assessment targeting seven potential sites for renewable hydrogen power sites. The project applied new spatial analysis using the JBA Pacific Island Flood Maps, considering Q20 and Q100 flood inundation.