Editorial: Advances in Environmental Hydraulics

1. Introduction

Water-related challenges represent one of the most pressing global concerns of the 21st century. Environmental hydraulics describes the study of flow behavior, hydrodynamic processes, and their environmental implications; it has emerged as a critical field for addressing sustainable water management, ecosystem preservation, and adaptive engineering solutions in the face of climate change. This Special Issue on “Advances in Environmental Hydraulics” provides an international platform for disseminating cutting-edge research and innovative engineering applications that combines theoretical foundations with practical, field-based implementations.

The scope of environmental hydraulics encompasses a diverse range of water-related problems, including sustainable management practices that optimize resource utilization, eco-hydraulic engineering solutions that restore aquatic ecosystem functions, and innovative flood management and energy nexus considerations. Modern environmental hydraulics increasingly emphasizes the integration of computational modeling with experimental validation and field observations, recognizing that complex water systems require multidisciplinary approaches that link hydrology, ecology, engineering, and socioeconomic considerations [1].

2. Context and Motivation

Contemporary water systems face unprecedented pressures from multiple directions. For instance, climate change alters precipitation patterns and hydrological cycles, demanding adaptive management strategies and improved predictive capabilities [Contribution 1]. Urbanization results in concentrated population and infrastructure in water-dependent regions, intensifying competition for the limited freshwater resources and escalating flood risks. Agricultural intensification, which depends critically on irrigation systems, consumes substantial volumes of water while simultaneously requiring a sustainable management approach to preserve water quality and ecosystem health [2]. Additionally, the nexus between water management and energy production—particularly in hydropower systems—introduces complex trade-offs between energy generation, environmental sustainability, and system efficiency.

These converging challenges necessitate integrated solutions that transcend traditional disciplinary boundaries. Environmental hydraulics provides the theoretical and practical framework for developing such solutions, incorporating the following factors:

• Advanced computational methods for flow simulation and prediction, including computational fluid dynamics (CFD), large eddy simulations (LES), and machine learning approaches;
• Field-based experimental investigations that validate proposed models and provide ground-truth data for understanding real-world flow behavior and hydrodynamic processes;
• Eco-hydraulic engineering solutions that restore ecological functions while maintaining water infrastructure performance;
• Innovative design approaches that enhance system efficiency, resilience, and environmental compatibility;
• Monitoring and management strategies that support adaptive water resource governance in response to climate variability.

3. Contributions Included in This Topic

This Special Issue comprises 15 peer-reviewed papers that exemplify the breadth and depth of contemporary environmental hydraulics research. The contributions span multiple dimensions of the field and are outlined in the following.

3.1. Climate Change and Hydrological Adaptation

The impacts of climate change on water systems represent a central challenge for environmental hydraulics. Katip and Anwar [Contribution 1] employed feed-forward neural networks to simulate climate-based hydrological changes at Doğancı Dam in Turkey, demonstrating the application of machine learning in predictive modeling under non-stationary climate conditions. Similarly, research on environmental flow assessment in the Yen River Basin (Vietnam) illustrated holistic approaches integrating hydrological, ecological, and management considerations to support adaptive water governance in the face of climate uncertainty [Contribution 2].

3.2. Advanced Hydraulic Modeling and Simulation

Computational approaches form the foundation of modern environmental hydraulics. There are multiple contributions advancing modeling capabilities: Liu et al. [Contribution 3] applied a hydrodynamic simulation (MIKE21) to elucidate the mechanisms governing pollutant transport in coastal waters, while numerical investigations into the optimal placement of portable fishways demonstrated the application of computational methods to enhancing ecosystem connectivity in agricultural drainage systems [Contribution 4]. Zöschg [Contribution 5] employed large eddy simulations to quantify head losses through trash racks at hydropower installations, providing actionable information for improving energy efficiency in renewable energy systems. Weijermars and Afagwu [Contribution 6] developed analytical solutions for pressure transient behavior in bounded and unbounded reservoirs, advancing fundamental theory for both groundwater and petroleum systems.

3.3. Eco-Hydraulic Engineering and Ecosystem Restoration

In the field of environmental hydraulics, the restoration and maintenance of aquatic ecosystem functions is increasingly emphasized. Calluaud et al. [Contribution 7] investigated flow conditions and fish passage efficiency in vertical slot fishways through detailed behavioral observations, providing empirical guidance for optimizing fish migration corridors. Research on hydraulic roughness in mountain headwater streams [Contribution 8] contributed to the understanding of natural flow–habitat relationships essential for stream restoration and ecosystem-based management. Zhang et al. [Contribution 9] characterized vegetation resistance in muddy water flows, building fundamental knowledge for modeling ecosystem–water interactions in engineered and natural systems.

3.4. Innovation in Hydraulic Systems Design

Contemporary hydraulic challenges demand innovative design solutions. The study on using friction groups for hydraulic parameter estimation [Contribution 10] provided practical tools for solving pressure drop, flow, and diameter estimation problems in piping and open-channel systems. Research on capillary barrier design and water storage capacity [Contribution 11] addressed subsurface water management relevant to both agricultural and environmental engineering applications. Studies on scour protection around bridge piers [Contribution 12] exemplified the application of hydraulic engineering to critical infrastructure resilience and safety.

3.5. Energy–Water Nexus

The relationship between water management and energy production remains central to sustainable development. Research on water consumption rates in cascade hydropower stations [Contribution 13] demonstrated systematic approaches to optimizing energy generation efficiency while considering water availability constraints. Investigations into flood discharge characteristics at high-altitude dam projects [Contribution 14] addressed the safety and operational challenges emerging from climate variability and topographic extremes, illustrating the complexity of integrating water security with energy production in vulnerable environments.

3.6. Nonlinear Wave Dynamics and Shallow Water Hydraulics

Fundamental advances in the understanding of wave generation and propagation in shallow water environments [Contribution 15] provided theoretical foundations that are applicable to coastal engineering, tsunami modeling, and river dynamics. These contributions bridge academic theory and practical applications in hazard mitigation and infrastructure design.

4. Overarching Themes and Future Perspectives

Several overarching themes emerge from these contributions:

Integration of modeling approaches: Effective solutions require combining computational modeling (CFD, machine learning, analytical solutions) with experimental validation and field observation. No single approach captures the full complexity of environmental hydraulic systems.

Climate adaptation and resilience: Climate change fundamentally alters hydrological patterns, necessitating adaptive management strategies informed by predictive modeling, long-term monitoring, and flexible system design.

Ecosystem–infrastructure coupling: Modern environmental hydraulics recognizes that engineered water systems and natural ecosystems are inextricably linked. Solutions must optimize functionality across both domains.

Efficiency and sustainability imperatives: Whether addressing energy generation, agricultural water use, or pollutant transport, contemporary hydraulic engineering emphasizes resource optimization and environmental protection as complementary rather than competing objectives.

Interdisciplinary knowledge integration: Environmental hydraulics problems require expertise from a variety of disciplines, including civil engineering, environmental science, ecology, economics, and data science, necessitating genuinely collaborative research approaches.

5. Concluding Remarks

This Special Issue demonstrates that environmental hydraulics remains a vibrant, evolving discipline that is increasingly central to global sustainability challenges. The research presented illustrates how contemporary hydraulic science combines theoretical rigor with practical applicability, sophisticated computational methods with empirical validation, and engineering innovation with ecological awareness.

The field faces continuing evolution driven by climate change impacts, urbanization pressures, agricultural transformation, and technological advancement. The future of this field must focus on emerging opportunities, such as the enhanced integration of artificial intelligence and machine learning for adaptive water management, development of nature-based solutions combining ecological and hydraulic principles, and improved connections between local hydraulic studies and global water security frameworks.

This topic represents a snapshot of current progress; future contributions will undoubtedly expand the field’s capability to address increasingly complex water challenges in an uncertain environmental future.