A Comprehensive Review of Existing Floodwall Technologies: UHPFRC Material Advances and Performance Modelling

Abstract

Floods are among the most frequent and destructive natural hazards, causing significant socio-economic losses worldwide. This paper presents a comprehensive review of floodwall technologies, focusing on the integration of ultra-high-performance fibre-reinforced concrete (UHPFRC) to enhance structural and hydraulic performance. Flood protection systems are categorized into permanent, demountable, and temporary, and are evaluated based on parameters such as activation time, seepage resistance, and lifecycle cost. This review examines key structural applications, including floodwall barriers, wave-energy floaters, and retaining walls, in which UHPFRC provides significant advantages such as reduced material consumption, improved impact resistance, and increased durability in harsh environmental conditions. Additionally, recent advancements in floodwall systems are critically assessed through experimental investigations, numerical modelling, and hydraulic performance under varied loading and flow conditions. The analysis reveals that while UHPFRC systems can reduce material volumes by up to 73% and carbon emissions by 49% compared to conventional reinforced concrete, their adoption is currently limited by a lack of dedicated design standards. Based on a synthesis of peer-reviewed studies (2010–2026), findings indicate that autonomous, buoyancy-driven UHPFRC barriers offer the highest reliability in high-risk zones, whereas manual modular systems remain limited by human-factor vulnerabilities during rapid deployment. Critical research gaps are identified—specifically the need for standardized constitutive models for UHPFRC in hydrostatic environments and extensive long-term field validation—to support the transition toward resilient, smart urban flood defence infrastructure.

1. Introduction

Floods remain among the most common and destructive natural disasters worldwide, presenting substantial risks to human safety, essential infrastructure, and ecological systems [1,2,3,4,5]. Historical data indicate an increase in flood frequency and severity, driven by climate change-induced rainfall patterns, sea-level rise, and rapid urbanization [6,7,8]. Floods may result from intense rainfall, rapid snowmelt, tropical storms, or failures of dams and levees. These events often occur suddenly, with limited warning time [9,10,11,12]. Population growth in flood-prone zones and the degradation of natural drainage systems make communities more susceptible to damage [13,14,15,16]. Comprehensive flood risk assessments can help reduce potential impacts by safeguarding communities and infrastructure [17,18]. Developing effective flood mitigation strategies, therefore, requires a holistic, multidisciplinary approach that integrates technical, environmental, and socio-economic dimensions [5,6,7,8,9,10,11,12,13,14,15,16,17,18,19]. Floodwalls are key components of engineered flood mitigation systems, strategically designed and implemented to reduce or prevent the entry of floodwaters into vulnerable areas [20]. Their implementation aims to safeguard lives, ecosystems, and critical infrastructure [21]. Unlike conventional flood control systems such as levees and dams, floodwalls provide robust, long-term protection capable of withstanding significant hydrostatic and hydrodynamic pressures [22,23,24,25]. Recent floodwalls are typically constructed from reinforced concrete (RC), masonry, or steel sheet piles [23,26,27,28,29]. However, traditional concrete structures are inherently vulnerable in hydraulic environments. These include cracking, high-water permeability, and progressive deterioration from cyclic freeze–thaw exposure and chemical ingress. These factors increase maintenance requirements and ultimately shorten the service life of flood barrier infrastructure [30,31]. To address these limitations, ultra-high-performance fibre-reinforced concrete (UHPFRC) has emerged as a transformative material in civil engineering [32,33]. UHPFRC exhibits exceptional compressive strength (often exceeding 150 MPa), high tensile ductility, extremely low permeability, and outstanding resistance to environmental degradation [34,35,36,37,38]. These characteristics make it an ideal material for flood protection structures exposed to harsh hydraulic environments [39]. UHPFRC has been used in a range of infrastructure projects, including bridge decks, high-rise buildings, seismic-resistant structures, and marine applications, where superior mechanical properties and durability are essential [40]. Despite its potential, the application of UHPFRC in floodwalls remains an emerging field, with limited comprehensive reviews available. This study provides a comprehensive review of current floodwall technologies, with particular emphasis on the effectiveness of UHPFRC in improving structural and hydraulic performance. The review synthesizes recent advancements in floodwall systems, focusing on structural optimization, hydraulic efficiency, and numerical modelling. The findings demonstrate the viability of UHPFRC for flood defence infrastructure and underscore its potential to advance climate-resilient urban engineering.

2. Review Methodology

This section outlines the systematic approach employed to conduct the comprehensive review of existing floodwall technologies, with a particular focus on the application of UHPFRC in floodwalls. The literature search was systematically conducted across major engineering and materials science databases, including Scopus, Science Direct, Web of Science (WoS), and Google Scholar. A combination of keywords and Boolean operators was used to refine the search:

• (“Floodwall” OR “Flood Barrier” OR “Flood Protection System”) AND (“Self-Closing Flood Barrier” OR “Passive Flood Protection”) AND (“Deployment Mechanism” OR “Activation System”)
• (“UHPFRC” OR “UHPC” OR “Ultra-High-Performance Concrete”) AND (“Structural Performance” OR “Hydraulic Behaviour” OR “Finite Element Analysis”)
• (“Ultra-High-Performance Concrete” OR “UHPC”) AND (“Marine Structures” OR “Structural Applications”)

The search included peer-reviewed journal articles, conference proceedings, and authoritative technical reports published primarily between 2010 and 2026, supplemented by seminal pre-2010 studies foundational to UHPFRC development and traditional flood barrier design. After initial retrieval, duplicate records were removed, and the remaining literature underwent a two-stage screening process. First, titles and abstracts were evaluated against predefined inclusion criteria: (i) direct relevance to floodwall/flood barrier systems, material composition, or hydraulic–structural interaction; (ii) empirical, experimental, or numerical investigation of barrier performance; and (iii) explicit discussion of UHPFRC mechanical properties, durability, or structural integration. Studies focusing exclusively on policy, economics, or non-engineered flood mitigation strategies were excluded. A full-text assessment was subsequently conducted to verify methodological relevance, data relevance, and alignment with the review’s engineering focus.

The final body of literature was organized thematically to provide a logical progression from system classification to material innovation, application, and analytical modelling. This classification informs the structure of the manuscript: Section 2 and Section 3 categorize flood protection systems by deployment mechanism and technological maturity; Section 4 and Section 5 synthesize UHPFRC material advances, durability characteristics, and their integration into flood defence infrastructure; Section 6 evaluates structural optimization, hydraulic performance, seepage control, and numerical modelling approaches, concluding with an assessment of smart technology integration. Relevant data on material properties, structural performance metrics, and modelling parameters were extracted and synthesised to facilitate comparative analysis and critical evaluation throughout the review.

3. Types of Flood Protection Systems

Flood protection measures are generally categorised into three primary types: temporary, demountable, and permanent [41,42]. Each category presents specific advantages and limitations, largely determined by its operational mechanisms, deployment requirements, and adaptability to site-specific conditions. This section provides a critical overview of these systems, discussing their fundamental mechanisms, relative effectiveness, and common challenges.

3.1. Temporary and Demountable Systems

A temporary flood protection system functions effectively only once the barrier is fully assembled; this assembly must be completed before floodwaters reach the minimum safe level provided by permanent defences [42,43]. The suitability of such a system depends on situational requirements and site-specific conditions. During flood events, temporary barriers are transported to affected areas and assembled on site, then disassembled and returned to storage once the event has subsided. However, most temporary barriers require a properly prepared bedding surface to minimise seepage, which can significantly increase setup time. Designing site-specific temporary systems can streamline installation and reduce these preparation requirements [44,45]. A demountable flood protection system operates effectively only when the barrier is properly secured in position. The barrier must be installed and closed before the water level reaches the minimum permanent protection threshold [42,43]. These systems are partially movable, consisting of a permanent foundation combined with a removable protection wall. Demountable barriers offer faster installation times than temporary systems and cause less environmental disturbance than permanent structures. While temporary barriers are flexible, cost-effective, and easy to store, they often exhibit high seepage rates. In contrast, demountable systems provide superior watertight integrity but are typically more expensive and less adaptable than fully mobile flood protection solutions [21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45]. Figure 1 illustrates several types of temporary and demountable flood protection systems [42].

3.2. Permanent Systems

A permanent flood protection system is fully installed and requires no activation during flood events to obstruct flood pathways [41,42]. These systems generally do not require routine maintenance or operational interventions to maintain functionality or to regulate water levels within the associated watercourse [42]. Consequently, permanent flood protection is considered the most technically reliable, providing uninterrupted protection up to its specific design standard [46]. Compared to temporary and demountable systems, permanent barriers offer superior seepage resistance and structural stability owing to their integration with fixed foundations and subsurface barriers [46]. Furthermore, they are independent of mechanical or manual activation, significantly reducing the likelihood of failure during emergency situations. However, these advantages involve several trade-offs. Permanent barriers are capital-intensive, visually intrusive, and often unsuitable for locations where flooding occurs infrequently. Their rigid construction also limits future adaptability, modifying these structures to accommodate higher flood levels typically requires major reconstruction [42,43,44,45]. A comparative analysis of the three principal types of flood protection systems is presented in

Table 1. Comparison of flood protection systems.

Aspect	Permanent Barriers	Temporary Barriers	Demountable Systems
Activation	Always in place (no operation needed).	Requires manual setup before flood.	Partially pre-installed; components assembled.
Seepage Control	Excellent (with cut-off walls).	Poor to moderate.	Moderate to good (depends on seal quality).
Flexibility	Fixed installation.	Highly flexible and mobile.	Moderate; less adaptable than temporary systems.
Cost	High (capital-intensive).	Low to moderate.	Moderate to high.
Visual Impact	High (obstructive in urban settings).	Minimal (stored when not in use).	Varies based on design.
Maintenance Needs	Regular inspections; passive in floods.	Minimal maintenance but requires readiness checks.	Combination of passive and active upkeep.
Adaptability to New Risk	Difficult and expensive.	Easy to adjust or upgrade.	Moderate; reconfiguration possible but limited.

, highlighting their relative performance in terms of activation, seepage control, adaptability, and operational requirements.

4. Advanced Floodwall Technologies

4.1. Mobile Floodwall Barrier

As depicted in Figure 2, the mobile floodwall system consists of lightweight extruded aluminium profiles, including supporting posts and dam beams. It is designed for rapid assembly in response to flood warnings and can be disassembled for storage during non-flood periods. Supporting posts are anchored to base plates embedded in a permanent ground beam; the use of a compressible base or ground seal eliminates the requirement for a ground rail, enabling more efficient deployment [47]. Mobile flood protection measures offer a solution that satisfies two key requirements: ensuring safety during flooding while preserving uninterrupted access to floodplains under normal conditions. Additionally, these portable structures serve as emergency resources in vulnerable low-lying areas and can strengthen permanent infrastructure during severe weather events. However, a primary drawback of the mobile flood solutions is the high volume of panels required, particularly for projects covering extended distances. In such cases, deployment becomes highly labour-intensive, and considerable storage space is necessary to safely house and protect the panels when not in use. A study conducted by [48] identified several further limitations, noting that these systems are more expensive than permanent barriers, require pre-deployment inspections and repairs, and are restricted in height due to regulatory constraints. The study also reported that sudden failures may occur as a result of poor design, improper installation, or excessive loading—risks that are magnified during rushed emergency deployments. Beyond these logistical and economic constraints, two technical challenges are particularly critical when implementing mobile systems. The first concerns the installation accuracy of anchor plates, which are essential for assembling the system and transmitting structural forces. These plates are typically anchored in reinforced concrete plinths to secure the columns. The second challenge involves seepage control and overall system safety, both of which remain central issues in practical applications and ongoing research.

4.2. Passive Flood Barriers

A broader review of passive flood protection systems was presented in the Strategies for Flood Risk Reduction for Vulnerable Coastal Populations Around Barnegat Bay [49]. The study identified two additional systems: automatic floodgates and the self-closing flood barrier (SCFB). Automatic floodgates are passive systems that seal vulnerable openings during flood events without requiring external power or manual activation, making them suitable for residential, commercial, and industrial infrastructure. The SCFB, originally developed in the Netherlands and commercialised in the late 1990s, provides an alternative flood protection solution in locations where permanent structures are impractical. The barrier is installed below ground level within a steel or concrete trough and remains concealed until activation. When floodwaters enter the trough, hydraulic pressure causes the barrier to rise automatically. Upon reaching its maximum height, the structure forms a strong, impermeable seal to prevent water intrusion. This system addresses significant limitations of conventional temporary solutions, such as flood doors or off-site floodgates, which depend on advance warning and manual deployment. The SCFB is available in multiple lengths, with basins fabricated from high-density polyethylene, concrete, or stainless steel. Key advantages include fully autonomous operation during power outages, low maintenance requirements, a service life of up to 100 years, and immediate activation. Furthermore, this design permits unrestricted site access until the arrival of floodwaters [44]. Munyaneza et al., 2013 [50] demonstrated the practical effectiveness of the SCFB as a flood control measure in the Nyabugogo wetland, highlighting its ability to respond to flooding events without electricity. Despite these advantages, some limitations persist. The dual-chamber design required for operation increases installation costs and restricts application to sites with sufficient subsurface clearance to accommodate the system’s infrastructure. Furthermore, the SCFB is primarily suited to inland flood events, as it cannot effectively compensate for fluctuations in tidal or coastal water levels. Figure 3 illustrates the operational sequence of this system.

Table 2. Comparative summary of advanced floodwall technologies.

Criteria	Self-Closing Flood Barrier (SCFB)	Mobile Floodwall
Origin country used	Netherlands (HYFLO, since 1998).	Slovakia (Danube River project).
Deployment Type	Permanent, passive hydro-mechanical activation.	Demountable, manually installed.
Activation Mechanism	Hydrostatic pressure from floodwater.	Manual setup during flood alerts.
Installation	Embedded at site; no need for setup during flooding.	Requires rapid installation prior to flood.
Operation Dependence	Fully automatic; no external energy or sensors.	Requires trained personnel and repair kits.
Response Time	Immediate upon water rise.	Delayed; dependent on readiness and coordination.
Maintenance Needs	Low; periodic inspection and cleaning post-flood.	High; inspection, repair, and preparedness checks.
Structural Height Limitation	Up to 1.0 m.	Limited by regulatory constraints; typically, lower than permanent structures.
Adaptability to Site Geometry	Limited to locations allowing embedded systems.	More flexible; suitable for urban areas lacking permanent space.
Durability & Lifespan	Proven long-term performance (Meppel, Antwerp cases).	Prone to failure under poor design or rushed setup.
Risk Under Sudden Flooding	Low (self-activating).	High (delays, improper installation risk).
Post-Flood Requirements	Cleaning, basic maintenance.	Full disassembly, inspection, and storage.
Cost Implication	Lower lifecycle cost; no personnel/training needed for operation.	High recurring costs (repair kits, staff, storage, training).

provides a comparative overview of both advanced systems, highlighting distinctions in deployment mechanisms, operational requirements, adaptability, and lifecycle costs. The SCFB and mobile floodwall exemplify a core trade-off between passive reliability and spatial flexibility. The SCFB is a permanent, hydro-mechanically activated system that delivers immediate, autonomous protection with low lifecycle costs and minimal human intervention, making it suitable for high-risk areas prone to sudden flooding. Conversely, the mobile floodwall offers enhanced adaptability to complex urban geometries without necessitating a permanent installation. This system, however, introduces considerable operational risk due to its dependence on manual deployment, trained personnel, and elevated recurring storage and maintenance costs. Finally, while the SCFB exhibits superior fail-safe durability, the mobile floodwall provides a flexible but logistically intensive option for sites where permanent structural integration is impractical.

5. Ultra High-Performance Fibre-Reinforced Concrete

5.1. Definition and Historical Development of UHPFRC

Ultra-high-performance fibre-reinforced concrete (UHPFRC) is an advanced cementitious composite characterised by ultra-high compressive strength, often exceeding 140 MPa, enhanced tensile strength, exceptional durability, and improved ductility due to the incorporation of steel fibres [51,52]. UHPFRC demonstrates superior mechanical properties, particularly in tensile strength, which is substantially greater than that of conventional concrete [53,54]. Its tensile behaviour is marked by strain hardening, which enhances both ductility and energy absorption capacity [55,56]. The direct tensile strength of UHPFRC typically ranges from 7 to 10 MPa, depending on mixture design and fibre content [57]. The material exhibits a dense microstructure and low porosity, conferring resistance to chemical attack, freeze–thaw cycles, and environmental degradation [58]. UHPFRC integrates strategies from self-compacting concrete (SCC), fibre-reinforced concrete (FRC), and high-performance concrete (HPC) [59]. Its composition includes high-quality ordinary cement, silica fume, sand, quartz powder, superplasticisers, minimal water, and, in some cases, supplementary cementitious materials.

Table 3. Typical constituents of UHPFRC (Kg/m³) [60].

Components	Weight Range
Cement	800–1500
Fine sand	1000–1800
Silica fume	125–275
Crushed quartz	180–350
Steel fibres	118–390
Superplasticizer	15–60
Water	120–200

presents the typical ranges of UHPFRC mix constituents [60].

Extensive research has been conducted over the past few decades in concrete technology to achieve higher performance. In the 1980s, superplasticisers (SP) were introduced to reduce the water-to-binder (w/b) ratio to as low as 0.3. The use of high dosages of silica fume and SP further decreased the w/b ratio to 0.16. Optimal grain size distribution enabled the achievement of compressive strengths up to 280 MPa, accompanied by reduced porosity and enhanced durability. These technological advancements, together with the application of low-porosity materials, led to the development of ultra-high-performance concretes. With the addition of steel fibres in the late 1980s, the ductility of the matrix improved [61,62]. In the mid-1990s, Richard and Cheyrezy [63] first introduced the concept of and mixing sequence for reactive powder concrete (RPC), which was the forerunner of UHPFRC. Their research optimized granular particle sizing using packing density theory and applied thermal treatments at 90 °C and 400 °C under pressure to achieve exceptional matrix strength. Additionally, short steel fibres (13 mm in length and 0.15 mm in diameter) were incorporated at volume fractions ranging from 1.5% to 3% to improve the toughness of the cementitious matrix. The resulting RPC exhibited compressive strengths of 200–800 MPa and fracture energy values of up to 40 kJ/m² [64].

5.2. Durability and Environmental Effects of UHPFRC

UHPFRC exhibits exceptional durability due to its highly compact microstructure, low porosity, and optimized particle packing density. These characteristics provide superior resistance to aggressive environmental conditions, exceeding the performance of both conventional and standard high-performance (HPC) concrete formulations [65,66]. Durability assessments primarily focus on water permeability, the corrosion resistance of steel reinforcement, and freeze–thaw endurance. The following sections provide a concise evaluation of UHPFRC durability with respect to these critical parameters.

5.2.1. Water Permeability

Permeability denotes the capacity of fluids to penetrate and migrate through a concrete matrix. Elevated permeability facilitates the ingress of harmful chemical agents, such as chloride ions, which can initiate corrosion of embedded steel reinforcement or fibres. Key factors influencing concrete include the water-to-binder (W/B) ratio, the incorporation of supplementary cementitious materials (SCMs), and the distribution and interconnectivity of pores [67]. UHPFRC typically exhibits a permeability coefficient of approximately 0.0005 at 98 days—nearly one order of magnitude lower than conventional concrete (0.0015 at 98 days) [68]. This significant reduction is a direct result of the highly refined, discontinuous pore structure within a homogeneous and dense matrix. During hydration, the formation of C–S–H gel progressively obstructs connected pores, increasing the tortuosity of the capillary network and continuously reducing the permeability coefficient.

5.2.2. Corrosion Resistance

UHPFRC exhibits high corrosion resistance due to its inherent impermeability to water and chloride ions. Wille et al. (2011) [69,70] reported that adequately cured specimens exposed to aggressive environmental conditions exhibit minimal corrosion activity over prolonged periods. Although microcracks may develop, their extremely fine width (typically less than 0.05 mm) restricts significant chloride migration to steel reinforcement. Comparative research by Ghafari et al. (2015) [71] using accelerated corrosion tests indicated that the time to crack initiation in UHPFRC was more than twice that of HPC. Furthermore, the corrosion rate of embedded steel reinforcement in UHPFRC was found to be negligible (0.01 μm/year), remaining significantly below the accepted damage threshold of 1 μm/year.

5.2.3. Freeze–Thaw Resistance

Freeze–thaw cycles are a primary cause of degradation in conventional concrete structures. Water within capillary pores expands volumetrically by approximately 9% upon freezing, generating tensile stresses that initiate microcracking [72]. This often leads to surface scaling, spalling, and joint deterioration, such as D-cracking [71,72,73]. In contrast, experimental studies demonstrate that UHPFRC exhibits exceptional freeze–thaw durability. Its impermeable matrix and significantly reduced capillary porosity—driven by dense particle packing and silica fume addition—effectively eliminate the interconnectivity required for water penetration [72]. Consequently, Liu et al. (2020) [73] reported no observable degradation in UHPFRC specimens even after 600 freeze–thaw cycles, whereas conventional concrete often fails well before reaching such limits.

6. Applications of UHPFRC in Floodwall Protection

UHPFRC has transitioned from laboratory research to widespread commercial application, driven by its exceptional mechanical properties and structural versatility. Its high compressive and tensile strengths, coupled with superior ductility and low permeability, enable the construction of slender, lightweight, and geometrically complex structures—such as long-span bridges, thin-shell façades—that are not feasible with conventional concrete [74]. These characteristics lead to reduced self-weight, more efficient construction methodologies, and enhanced long-term service life [75].

6.1. Innovative Flood Barrier Systems

Several innovative projects have demonstrated the efficacy of UHPFRC in flood protection.

6.1.1. Telescopic Smart Wall System (SWS)

Jorge Mario Cueto Baiz, 2016 [76] developed a telescopic, extendable/retractable “smart wall” using fibre-reinforced concrete (FRC) designed to resist hydraulic forces and retract when inactive. By utilising PVA-fibre reinforcement, the study achieved ultra-thin cross-sectional thicknesses of just 0.75 in. (19 mm) while maintaining high tensile ductility. This slender profile limited individual segment weight to approximately 160 lbs (72 Kg), enabling a 0.5 retracted-to-deployed ratio that minimizes excavation costs, storage requirements, and urban disruption. A key innovation of this system is that the material’s self-weight activates the interlocking mechanism at telescopic joints, ensuring efficient lateral load transfer during deployment without the need for complex external hydraulic or mechanical systems. Furthermore, the fibre-bridging effect imparts pronounced strain-hardening behaviour and substantial deformation capacity (up to 7% drift). This allows the barrier to absorb multidirectional hydrostatic, hydrodynamic, and debris-impact loads without brittle failure, representing a significant resilience gain over conventional concrete.

6.1.2. Self-Floating Barrier

Maryamh & Glock, 2020 [77] introduced a self-floating, autonomous flood barrier utilising a concrete sandwich structure with polystyrene cores and ultra-high-performance fibre-reinforced concrete (UHPFRC) cover layers as illustrated in Figure 4a. This buoyancy-driven barrier automatically rises as water levels rise and returns to its passive position by gravity as floodwaters recede. The matrix is reinforced with 2 vol% steel fibres, eliminating the need for traditional rebar. Experimental validation demonstrated that the system withstands hydrostatic pressures up to a 100 cm water head and urban traffic loads. The barrier achieves a fracture load of 200 kN with approximately 0.5 mm plastic deflection after cyclic loading. A specially engineered, watertight concrete pivot joint connects the rotating barrier to the stationary foundation, ensuring reliable mechanical operation and long-term sealing. The use of UHPFRC significantly reduces self-weight and excavation depth while maintaining robust load-bearing capacity under both static hydrostatic pressure and cyclic traffic loads. Furthermore, the dense, discontinuous pore structure and fibre-reinforcement network of UHPFRC mitigate crack propagation, ensuring long-term watertight integrity and resistance to freeze–thaw degradation and chloride ingress. The mechanical versatility of UHPFRC enables the creation of monolithic concrete hinges, eliminating the need for corrosion-prone metallic components and thereby enhancing structural reliability and reducing lifecycle maintenance. The combination of low density and high tensile ductility enables fully autonomous, buoyancy-driven deployment without external power or manual intervention. The robust surface finish remains safely trafficable during non-flood conditions.

6.2. Marine and Infrastructure Resilience

6.2.1. Wave Energy and Marine Durability

Hi-Con A/S, 2011 [78] employed ultra-high-performance concrete (UHPC) in wave-energy floaters, highlighting its significant potential for cost-effective, durable marine applications. The study attributes UHPC’s exceptional durability to its extremely low porosity, which confers resistance to chloride intrusion, chemical attack, and surface erosion. This dense matrix eliminates the need for protective coatings and substantially reduces lifecycle maintenance for water-exposed infrastructure. The report further confirms that UHPC exhibits superior fatigue resistance under repetitive cyclic loading, a critical requirement for flood barriers exposed to dynamic hydrostatic pressures, wave impacts, and seasonal freeze–thaw cycles. Material optimisation trials indicate that strategic fibre selection can enhance flexural strength by up to 46%. This improvement allows a 15% reduction in wall thickness while maintaining equivalent load-bearing capacity, resulting in lighter, more material-efficient designs. The field validation of a full-scale UHPC prototype subjected to harsh marine conditions for nearly four years demonstrated no structural degradation, water ingress, or performance loss, even during severe winter and ice exposure (Figure 4b). These results underscore UHPC’s long-term service reliability in demanding environments.

6.2.2. Structural and Environmental Optimization

Dahabreh & Hassan, 2015 [26] evaluated the structural integrity of floodwall defences using steel fibre-reinforced concrete (SFRC). Their findings indicate that incorporating SFRC into floodwall construction enhances structural, economic, and environmental performance compared to traditional reinforced concrete. The use of steel fibres as discrete reinforcement substantially increases the tensile strength and crack resistance of concrete, which is especially important at construction joints where the wall meets the base, as these locations are susceptible to high stress and leakage. Additionally, the adoption of SFRC supports the implementation of automated construction methods, such as slip-forming, by reducing reliance on manual rebar placement. This shift expedites construction timelines and decreases lifecycle costs. From a sustainability standpoint, minimising conventional steel reinforcement reduces the structure’s embodied carbon footprint. This approach aligns hydraulic engineering practices with contemporary carbon-reduction requirements while upholding stringent safety standards under hydrostatic loading.

6.3. Field Validation and Sustainability

6.3.1. Monsoon Drainage

Further evidence of UHPFRC’s capacity to withstand demanding loads is demonstrated by [79], who employed the material in a 90 m-long retaining wall for a monsoon drainage project in Ipoh, Malaysia. This wall successfully withstood soil backfills up to 1.5 m and an applied surcharge load of 25 kPa—a performance level 66% above the specified strength requirement. Exceeding design specifications by a substantial margin without failure demonstrates the reliability of ultra-high-performance fibre-reinforced concrete (UHPFRC) for critical infrastructure exposed to unpredictable environmental loading. This practical application highlights the material’s structural reserve capacity, offering an additional safety margin that conventional reinforced concrete cannot achieve without significantly increasing thickness and reinforcement.

6.3.2. Retaining Cantilever Walls

Nematollahi et al. (2014) [80] assessed the structural behaviour and environmental performance of precast UHPFRC cantilever retaining walls (Figure 4c), demonstrating their viability as sustainable and reliable alternatives to conventional reinforced concrete (RC) systems. By combining analytical modelling with full-scale experimental testing, this study quantified the efficiency gains associated with ultra-high-performance fibre-reinforced concrete (UHPFRC). The findings demonstrate that a UHPFRC retaining wall uses 73% less material than a conventional reinforced concrete (RC) wall. This reduction in material volume results in improved environmental performance across all major indices: the UHPFRC solution requires substantially less embodied energy, generates 49% fewer CO₂ emissions, and achieves a 43% reduction in 100-year global warming potential (GWP). These results illustrate how innovative UHPFRC design can advance sustainable construction by separating structural performance from high material consumption. Such improvements directly facilitate the adoption of UHPFRC in modular floodwall systems, where rapid deployment and a reduced carbon footprint are increasingly prioritised.

Collectively, these diverse applications underscore UHPFRC’s potential as the premier material for flood protection infrastructure where strength, long-term durability, and sustainable design are paramount.

Figure 4. Innovative UHPFRC structural solutions for flood defence and coastal applications [76,77,78,79].

Figure 4. Innovative UHPFRC structural solutions for flood defence and coastal applications [76,77,78,79].

The following

Table 4. Advantages of UHPFRC application in floodwall systems.

Criteria	Material Technology	Structural & Mechanical Significance	Primary Technical Gain	Environmental & Economic Advantage
Self-Floating Barrier	UHPFRC sandwich panels (integrated foam core)	Enables monolithic concrete pivot joints, replacing corrosion-prone metal hinges with fatigue-resistant material hinges.	Strain-hardening behaviour ensures watertight integrity and crack control even under peak hydrostatic pressure.	Reduces maintenance frequency via a dense, non-porous microstructure that resists chloride and chemical ingress.
Smart Floodwall (SWS)	PVA-FRC (Polyvinyl alcohol fibre matrix)	Facilitates ultra-thin cross-sections (19mm), drastically reducing segment weight for rapid vertical deployment.	Provides high-drift ductility (up to 7%), allowing telescopic segments to absorb debris impacts without brittle failure.	Minimises urban disruption and excavation costs by enabling a reduced footprint and storage-to-deployment.
UHPC Wave Float	Compact reinforced composite (CRC/UHPC)	Offers exceptional fatigue resistance, maintaining structural integrity under constant, high-cycle dynamic wave oscillation.	Ensures zero structural degradation in harsh marine environments, eliminating the requirements for synthetic anti-corrosion coatings.	Delivers a 77% cost savings compared to fibreglass alternatives while providing vastly superior service longevity.
SFRC Floodwall Defence	Steel fibre reinforced (SFRC)	Enhances construction joint capacity, specifically increasing the failure load at the critical wall-to-base interface.	Utilizes fibre-bridging to control differential shrinkage and significantly increase post-cracking residual strength.	Optimizes sustainability by minimising rebar dependency, thereby lowering the total embodied carbon of the barrier.
UHPFRC Cantilever Wall	Precast UHPFRC	Decouples structural performance from high material volume; allows for significantly slimmer profiles than traditional RC	73% reduction in material volume; high compressive and tensile strength eliminates the need for bulky shear reinforcement.	49% reduction in CO2 emissions and 43% lower global warming potential (GWP) over a 100-year cycle

summarises the technical advantages and functional significance of UHPFRC and SFRC across floodwall applications.

7. Structural and Hydraulic Performance Modelling of Floodwalls

7.1. Structural Optimization and Geometry

The structural investigation by Jeong et al., 2014 [81] demonstrates that applying buoyancy preflexion to floating bodies facilitates a critical mechanical transition from sagging to hogging behaviour, thereby optimising structural capacity. Conventional floating structures often sag under live loads, resulting in undesirable tensile stress on the bottom slab. In contrast, the buoyancy preflexion technique intentionally induces a hogging moment to pre-compress the bottom plate. Experimental tests on a 5400 × 1200 × 375 mm steel floating body show that maintaining compressive stress significantly enhances load-bearing capacity and allows for a reduced cross-sectional height. Aligning the structural geometry with the bending moment diagram (BMD) achieves substantial material efficiency and weight reduction while upholding safety standards.

Mugesh et al. (2015) [28] proposed an SCFB utilising an aluminium-based configuration designed to provide a passive, high-performance defence against extreme flooding as depicted in Figure 5. By opting for aluminium over conventional steel alternatives, the system achieves significant advantages in weight reduction, natural corrosion resistance, and cost-effectiveness during prefabrication. The barrier operates entirely without manual intervention or a power source, using the buoyancy of rising floodwaters to deploy, which enhances operational safety and reduces labour requirements. Structurally, the wall incorporates a 4–8 mm thick polyester component reinforced with laminated strips and a Kevlar-protected polyurethane core to ensure it can withstand hydrostatic pressures exceeding ten times the peak flood height. Furthermore, the system is designed for urban compatibility, remaining recessed and invisible at ground level when not in use to preserve local aesthetics and accessibility. While the study highlights the system as an environmentally compatible and economically feasible investment, it notes that further in situ testing is essential to validate performance under real-world flood conditions.

7.2. Hydraulic Performance and Fluid–Structure Interaction

7.2.1. Hydrostatic and Hydrodynamic Loading

Understanding the interaction between floodwaters and structural components is critical for ensuring the safety and reliability of flood defence systems. Al-Shukur et al., 2017 [22] investigated the structural optimization of floodwalls using parametric numerical modelling within the ANSYS 11.0/APDL environment. By varying wall height and thickness, the study evaluated structural responses under hydrodynamic loading, assessing safety through internal stress distributions and stability factors. The research demonstrated that while gravity-type floodwalls maintain integrity at increased heights, the required optimum cross-sectional area increases significantly to satisfy safety constraints. The modelling framework was validated using a case study from Kaoshu Village, Taiwan, confirming the software’s proficiency in simulating complex wall–water–foundation interactions. Ultimately, the study identified a specific sectional profile (Section 2) that achieved an optimal balance between structural stability and economic feasibility, highlighting ANSYS/APDL as a robust tool for the design of flood barrier systems. Building upon this concept, Petru et al., (2018) [23] investigated the development of lightweight flood-protection panels specifically designed to shield building apertures—such as doors and windows —against both hydrostatic and hydrodynamic loading. The design prioritized ease of handling, cost efficiency, and rapid installation, and was validated through numerical simulations and flexural stress analyses. To optimize the strength-to-weight ratio, the researchers examined Glass Fibre-Reinforced Composite (GFRC) boards with thicknesses of 1.5 mm, 2 mm, and 3 mm. The findings indicated that a minimum fibre volume fraction of 35% and a thickness of 3 mm were critical to ensuring sufficient stiffness and impact toughness under dynamic loading conditions. Experimental validation in a water-channel test further confirmed that these composite panels, when integrated with rubber sealing components, effectively resisted extreme deformations without structural failure (Figure 6).

Gupta et al., (2020) [41] analysed and designed a temporary, removable flood protection structure intended for application on weirs or canals. The proposed model comprises a steel frame and modular fibre sheets joined by bolts and adhesive. The primary objectives are to increase the temporary height or storage capacity of existing hydraulic structures for flash flood management and to provide a portable system that can be rapidly assembled during emergency flood events. Structural performance was evaluated through three experimental cases in a flume as shown in Figure 7. In Case 1, a steel frame covered with a plastic sheet and lacking base support was found to be unstable, with a high risk of overturning as hydraulic pressure increased and significant side leakage due to inadequate packing. In Case 2, a smaller frame covered with a higher-quality fibre sheet experienced leakage through bolt holes; however, the reduced height and improved material quality prevented overturning. In Case 3, a steel frame with fibre sheets and added base support, combined with well-packed side frames and sealed bolt holes, effectively prevented both overturning and leakage. The authors concluded that the provision of base support and adequate sealing are critical for structural stability. They proposed that the system can serve two main functions: enhancing weir capacity when anchored to the crest or acting as a standalone barrier for urban protection when anchored to the pavement.

Supar et al., 2024 [82] developed and tested a semi-automatic flood door barrier prototype to enhance the flood resilience of residential buildings in Malaysia. The system employs a modular design with a polystyrene core for buoyancy and structural support, reinforced with nylon PVC tarpaulin vinyl to enhance water resistance and durability. The barrier features a sealing rubber mechanism and springs to ensure a watertight fit and adaptability to fluctuating water levels. This study identifies several key technical and economic attributes of the barrier: (1) Cost effectiveness, as the prototype was constructed with a total material cost of approximately 71.55 RM, suggesting affordability for individual homeowners; (2) ease of deployment, since the temporary flood barrier (TFB) can be retrofitted onto existing structures or incorporated into new designs, offering immediate protection with minimal manual intervention; (3) performance stability, demonstrated by laboratory water testing, which confirmed the barrier’s ability to resist hydrostatic pressure with minimal seepage and to maintain structural integrity without evidence of failure or leakage; and (4) scalability, facilitated by the use of widely available industrial materials such as wire covers for the U-structure and silicone sealants, enabling straightforward assembly and potential for large-scale implementation. The study concludes that, although the barrier represents a practical and proactive defence strategy capable of reducing insurance costs and increasing property value, its limitations must be acknowledged. It may not provide complete protection against extremely severe flooding events, and the authors recommend integrating such barriers into a comprehensive flood management strategy that also incorporates early warning systems and ecological considerations.

Panior et al., 2025 [83] proposed a modular, self-activated flood barrier for urban and coastal protection, utilising a buoyancy-driven mechanism that deploys autonomously at a water depth of 0.065 m (Figure 8). Constructed from Polyethylene Terephthalate (PET), the system is lightweight and corrosion-resistant, with static stress of 4.19 MPa remaining well below PET’s 54.4 MPa yield limit, providing a safety factor of 6–9. However, the absence of dynamic or field-testing limits the generalisability of these findings. Practical concerns include high installation costs, restricted immobility and debris accumulation within the barrier holder, alongside the UV sensitivity of the polymer, which may lead to biodegradation over time. Consequently, the authors recommend future studies involving full-scale field trials, environmental durability assessments, and performance evaluation under complex, combined loading conditions to validate long-term operational reliability.

7.2.2. Seepage Control

Seepage control remains a central issue in both practical applications. Chen et al., (2018) [47] conducted a comprehensive evaluation of a mobile flood protection system using experimental testing in a specialised prototype facility. The study examined the mechanical reliability and hydraulic performance of the assembly to inform urban flood defence strategies. Three critical performance areas were identified: (1) anchor plate installation: two construction techniques were compared, direct installation (pouring concrete after fixing anchor plates) and the reserved slot method (installing plates into pre-formed slots). Although both methods met functional standards, direct installation was recommended due to its superior structural integrity and safer stress distribution. (2) Leakage characteristics: water impounding tests demonstrated that leakage rates change exponentially with water height, rather than following a linear trend. A significant increase in seepage occurred when water levels exceeded 1.5 m, reaching approximately 300 L/h at 1.7 m. (3) Structural stress and failure: post-loading tests (up to 100 kN) indicated that the aluminium posts and steel bars remained in an elastic state, while the surrounding concrete entered a plastic stage at approximately 25 kN. System failure typically originated from the concrete on the sides of the anchor plates and propagated toward the water-facing side. The study concluded that mobile floodwalls provide an efficient and aesthetically favourable alternative to traditional barriers, contingent upon rigorous quality control of the concrete foundation around the anchor plates. Haaland & Walderhaug, 2016 [46] addressed the lack of affordable flood protection for homeowners by developing a consumer-oriented, rigid-flexible hybrid barrier system using a front-loaded design methodology. The researchers employed a custom Excel-based Knowledge-Capturing System and an Arduino-controlled gasket test rig to determine that PVC canvas elements can provide the full stabilising moment of a rigid plate when attached at a height of 24 mm. Additionally, thicker gaskets were found to significantly reduce seepage on irregular ground. While the study established the feasibility of three core concepts—Tetrics, Caterpillar, and FlexiFront—the findings are indicative rather than statistically validated due to reliance on single-instance testing and expert judgement. Therefore, future industrialisation will require rigorous structural modelling of wave and debris impacts, long-term assessments of material durability against ultraviolet exposure and fatigue, and broader validation on diverse foundations to ensure operational reliability for end-users.

7.3. Numerical Modelling and Simulation Techniques

7.3.1. Finite Element Analysis (FEA)

Finite Element Method (FEM) simulation software performs both linear and nonlinear analyses. It provides a comprehensive library of materials and elements, enabling the modelling of a wide range of common engineering problems [84]. Petrů et al., 2017 [24] present a comprehensive framework for validating the performance of mobile flood barriers using integrated experimental and numerical approaches. The researchers subjected floating logs to barriers in both artificial channels (1–4 m/s) and real riverbed conditions with reservoir-released tidal waves, employing contactless laser sensors, accelerometers, and high-speed cameras to obtain precise deformation and velocity measurements. These experimental results served as benchmarks for Abaqus-based numerical simulations utilising a simplified CAD model, which effectively replicated hydrodynamic waveforms and accurately predicted structural responses. Although physical experiments were limited to 1 m/s, the validated model enabled reliable extrapolation to higher tidal wave velocities of up to 3.5 m/s, at which barrier deformation reached approximately 7 mm. This study marks a significant advancement in the field: whereas traditional Finite Element Method (FEM) analyses emphasise material stress and mechanical failure, the integration of Fluid–Structure Interaction (FSI) enables numerical simulations to serve as efficient, cost-effective alternatives to large-scale physical testing, thereby ensuring that lightweight, substructure-free barriers satisfy stringent structural reliability and stability standards.

7.3.2. Computational Fluid Dynamics (CFD)

CFD is used to simulate water flow patterns and pressures on structures [85,86]. Rahul et al., (2020) [25] developed a passive Self-Operating Flood Barrier (SOFB) to safeguard critical infrastructure at Cochin International Airport, such as the runway and solar power plants, from severe flood damage. As illustrated in Figure 9, the system utilises a hydrostatic mechanism whereby rising floodwaters enter an inlet pipe, fill a ground-level basin, and elevate an internal float wall to establish a watertight seal with a support block. ANSYS Workbench simulations comparing Foam Board and Gator Board indicated that Foam Board exhibited lower maximum deformation (4.5258 mm) and reduced equivalent stress, while Gator Board achieved a higher fatigue life of 8 cycles and enhanced moisture resistance due to its resin-infused wood fibre casing. Although the design automates flood defence, the study notes that manual pumping remains necessary to drain the basin and retract the barrier after water levels subside.

Chu et al., 2021 [87] employed Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) to assess the mechanical and hydrodynamic characteristics of three-dimensional marine floats. They developed a numerical model of a hollow sphere with a 280 mm diameter and a 5 mm shell thickness to replicate fishing conditions. The findings demonstrated that increasing the float diameter results in higher drag force and a higher buoyancy-to-drag ratio, while the reflux and vortex regions behind the float are substantially reduced. The study also observed that the float’s structural “ears” generate asymmetric fluid pressure. Additionally, although drag force rises with flow velocity for all sizes, the buoyancy-to-drag ratio decreases. For structural integrity under 5 m/s impact loads, various materials were compared, and Polyamide (PA) was identified as the most suitable material for extending service life, owing to its superior impact resistance and lower elastic strain peaks relative to PVC.

7.4. Integration with Smart Technologies

Future developments must prioritize smart monitoring and climate adaptability. Muñoz-Caballero et al., 2022 [88] presented the Smart Flood Barrier (SFB), an autonomous flood-prevention system for residential buildings situated on sloped streets. The SFB employs high-precision Von Karman sensors to detect rising water levels and communicates with a Siemens S7-1200 programmable logic controller (PLC) to activate high-torque servomotors. These servomotors elevate a vertical aluminium barrier from an underground pit and deploy hinged lintels to redirect water flow toward the street. A pneumatic compressor inflates a perimetric butyl rubber chamber once the barrier reaches its maximum height, ensuring a hermetic seal and establishing a protected “dry zone”. The system integrates information and communication technology (ICT) tools, including SolidWorks and TIA Portal, and supports real-time remote monitoring through a smartphone or internal human–machine interface (HMI). This design offers a low-energy, environmentally sustainable alternative to manual or hydraulic flood barriers. With an estimated implementation cost of USD 8000, the SFB supports Sustainable Development Goal 13 by improving urban resilience and safeguarding both material and sentimental assets from flood damage. Ardani et al., 2023 [14] propose an integrated flood mitigation solution that merges mechanical engineering with Internet of Things (IoT) technology for residential entryways as illustrated in Figure 10. Utilising the Kano model and Quality Function Deployment (QFD) to address local needs, the authors designed a 27.8 kg steel barrier featuring a key-operated extension mechanism that can be installed in 60 s. Structural validation through Finite Element Analysis confirmed the barrier’s ability to withstand water levels up to 60 cm. The system includes an ESP8266-based IoT module that delivers early warning alerts via WhatsApp and supports real-time water level monitoring through the Blynk application. Priced at IDR 1,941,000, the design provides affordable protection and digital monitoring for residents in flood-prone regions such as Baleendah, Indonesia.

7.5. Evaluation of Database

Table 5. Unified cross-comparison framework of flood protection systems.

Flood Barrier Type	Autonomous (SOFB/SAFB)	Smart/IoT Systems (SFB/IoT-Based)	Manual/Modular Systems (Hybrid/Anti-Flood Board)	Permanent/Structural Systems (Gravity Floodwall)
Primary Materials	Aluminium, PET/Kevlar, polyurethane	Steel/aluminium frames	GFRC boards, polystyrene cores/PVC canvas.	SFRC/RC (concrete)
Activation mechanism	Hydrostatic buoyancy-driven activation	Semi-automatic: servomotors/pneumatics (active)	Manual assembly/key-operated	Fixed/cast-in-place
Response Time	Instant Buoyancy-driven as floodwaters rise.	Rapid Remote activation via smartphone/PLC.	Variable (30–60 min)	N/A (always active)
Seepage Control	Excellent (rubber/inflatable seals)	High (pneumatic gaskets)	Moderate (leakage risk at seals)	Superior (foundation cut-offs)
Debris Impact sensitivity	High protection (shielded lids)	Moderate (sensor vulnerability)	Moderate (canvas puncture risk)	Very high (impact toughness)
Durability/Lifespan	High (~100 years)	Moderate (electronic lifespan)	Moderate (polymer UV fatigue)	Very high (~100 years)
Maintenance Burden	Basin/seal cleaning & UV checks	Sensor calibration & motor lube	Seal & joint maintenance	Low (crack monitoring)
Design & Analysis Methodology	ANSYS/scale modelling	SolidWorks/AutoCAD	Abaqus CEL/experimental	ANSYS/APDL
Critical Failure Modes & Limitations	Seal wear/basin drainage	Power failure/sensor error	Seepage depth/canvas tear	Overturning/visual impact
Aesthetic/Visual Impact	Low (sub-surface)	Low to moderate (Integrated)	Low (removable)	High (permanent barrier)
Post-Flood Recovery	Excellent (auto-drainage)	Good (remote status)	Good (clean & reuse)	Excellent (passive)
Typical Applications	Critical infrastructure/urban areas	Residential buildings/sloped streets	Weirs/door apertures	Riverbanks/coastal

presents a synthesis of findings from 11 peer-reviewed studies that compare eight distinct flood barrier systems. The analysis reveals a technological progression from traditional, material-intensive concrete structures to lightweight, sensor-integrated, and autonomously activated solutions. Each system exhibits specific trade-offs regarding structural integrity, operational efficiency, technological sophistication, and urban integration.

The transition from manual to autonomous and smart systems represents a significant shift in the reliability of flood deployment, moving from human-dependent variables to mechanical or digital certainties. Autonomous barriers, such as SOFB and SAFB, are engineered to enhance operational reliability by utilising hydrostatic buoyancy and zero-cost activation, thereby eliminating the potential for human error. In contrast, smart and Internet of Things (IoT) systems offer advanced capabilities, including remote programmable logic controller (PLC) or mobile interfaces. However, these systems introduce technological vulnerabilities, such as susceptibility to power outages, network latency, and sensor drift, which passive systems do not face. Manual and modular systems are the least reliable in critical scenarios; while they are cost-efficient, they are constrained by a human-factor bottleneck. Assembly times of 30 to 60 min pose a significant risk of failure if personnel are unavailable or inadequately trained. Permanent gravity walls provide the highest baseline reliability due to their passive readiness, yet they lack the hydraulic and architectural adaptability required for dynamic urban environments.

A critical evaluation of material science within these systems demonstrates a pronounced trade-off between longevity and environmental impact. Permanent reinforced concrete (SFRC/RC) and aluminium-based autonomous systems provide design lives exceeding one hundred years; however, their substantial initial capital costs and high embodied carbon increasingly conflict with sustainable construction requirements. In contrast, composite and polymer-based solutions (GFRC, PET/Kevlar, PVC) emphasise lightweight portability and cost-effective deployment but exhibit a notable durability deficit. These materials are vulnerable to ultraviolet-induced fatigue and polymer biodegradation, necessitating more frequent inspection cycles. Additionally, smart/IoT systems introduce distinct maintenance challenges. Unlike the low-maintenance characteristics of concrete, these systems require specialised electronic maintenance and sensor calibration, resulting in ongoing lifecycle costs that may offset their initial benefits.

Hydraulic efficacy most clearly reveals the engineering limitations of temporary systems, particularly in relation to the “Scaling Paradox.” Manual and hybrid systems perform adequately at shallow depths; however, empirical evidence indicates that seepage rates increase exponentially when water levels exceed 1.5 m, primarily due to seal deformation under pressure. In contrast, autonomous and permanent systems overcome this limitation by using foundation cut-offs and high-performance rubber interfaces to achieve superior sealing. Impact toughness also demonstrates a distinct hierarchy: permanent structures and autonomous systems with shielded lids are engineered for high-velocity debris tolerance, while IoT-enabled and polymer-based systems are more structurally vulnerable. In these advanced systems, sensor exposure and fabric puncture risks constitute “single-point-of-failure” modes that may compromise the entire barrier’s integrity during dynamic flood events.

Selecting between these technologies involves balancing structural robustness with urban integration. Municipal applications increasingly emphasise the “sub-surface invisibility” of autonomous and smart systems, which maintain the aesthetic and spatial continuity of urban environments. While permanent floodwalls provide superior structural capacity, they create enduring visual and social barriers that are often considered unacceptable in heritage or high-value landscape contexts. Furthermore, post-flood recovery processes highlight the operational efficiency of autonomous designs; features such as auto-drainage and remote diagnostics significantly reduce the labour required for cleaning and reassembly compared to manual modular boards. This analysis indicates that although advanced materials such as ultra-high-performance concrete (UHPC) enable extreme slenderness, the shift toward smart infrastructure requires a thorough reassessment of operational resilience to both hydraulic and digital failure modes.

8. Conclusions

This paper provides a comprehensive review of current flood protection technologies and highlights the significant impact of UHPFRC on the development of floodwall applications. The principal conclusions are summarized below:

• Life-cycle analysis shows that while permanent systems require a high capital investment, temporary and demountable alternatives incur substantial operational costs.
• Self-closing flood barriers (SCFBs) provide lightweight, fully autonomous flood protection; however, additional field validation is needed.
• UHPFRC achieves a 73% reduction in material volume and a 49% decrease in CO₂ emissions compared to conventional reinforced concrete.
• The integration of steel fibres enhances compressive strength and tensile ductility, enabling structures to withstand extreme hydrostatic and impact loads without experiencing brittle failure.
• The dense microstructure resists corrosion and chloride ingress, enabling advanced applications such as monolithic concrete hinges, telescopic smart walls, and buoyancy-driven systems (SOFB/SAFB).
• Autonomous systems enable immediate, zero-power activation, thereby eliminating the 30-to-60-min deployment delays and human-factor vulnerabilities associated with manual or hybrid barriers.

However, widespread adoption remains limited due to reliance on laboratory-scale data, increased seepage beyond 1.5 m in depth resulting from seal deformation, and the absence of dedicated design codes. Future research should emphasize full-scale field monitoring, debris-impact analysis, and the development of standardized constitutive models to facilitate the transition of UHPFRC-enhanced barriers from experimental prototypes to resilient, climate-adaptive infrastructure.