1. Introduction
Understanding water in the twenty-first century requires acknowledging that it can no longer be analysed from a single disciplinary perspective. The tensions between availability, demand, quality, ecosystem value, and governance compel the construction of bridges between hydrology, economics, ecology, and the social sciences. This Special Issue assembles ten studies which, despite their diverse geographical settings, converge in demonstrating that hydro-economic models are now an essential component for translating the complexity of water resources into informed and sustainable decisions.
One of the most striking commonalities across the contributions is the renewed appreciation of water as a provider of ecosystem services. The proposal to measure the Gross Ecosystem Product of the Lishui wetlands at finer spatial scales (contribution 1)—capable of capturing local nuances lost in macro-approaches—aligns with studies estimating the willingness to pay for river beaches in the Peruvian Amazon (contribution 3) and for natural pools in Sri Lanka (contribution 5). All of these studies reach the same conclusion: aquatic ecosystems generate tangible and intangible benefits that are seldom fully reflected in planning processes. By giving voice to the social and recreational value of water, these investigations broaden the focus beyond conventional uses and show how incorporating social preferences can strengthen water management.
Water also underpins critical economic activities whose vulnerability often remains invisible until quantified. The study on low-flow episodes in the Elbe River (contribution 2) reveals that a recurrent hydrological phenomenon can directly affect freight and tourist navigation, disrupting entire logistical chains. At the other end of the water cycle, the techno-economic assessment of advanced technologies to remove emerging contaminants (contribution 8) demonstrates that water quality conditions both the sanitary feasibility and the economic viability of wastewater treatment systems. The historical analysis of the Spanish desalination industry (contribution 4) illustrates how a strategic sector can evolve, innovate, and withstand regulatory and market changes when supported by an appropriate incentive structure. Taken together, these studies underscore that water security is inseparable from economic security.
2. Overview of the Contributions to This Special Issue
The Special Issue also underscores the importance of institutional models and economic incentives in water management. The analysis of the La Marina Baja Water Consortium (contribution 6) shows how cooperation among municipalities sustained the tourism-driven development of Benidorm under conditions of acute water stress, anticipating governance arrangements that have since become essential in many Mediterranean regions. Likewise, the collaborative model for agricultural water-rights trading (contribution 7) highlights how price reforms and uncertainty influence users’ willingness to exchange resources, shaping the system’s efficiency and equity. Both studies converge on the same lesson: governance and rules matter as much as the physical availability of water.
A systemic perspective is especially evident in the study analysing the five northwestern provinces of China (contribution 9), where coordination among economic, hydrological, and ecological dimensions is not merely a theoretical aspiration but a structural necessity. The integrated methodology proposed by the authors offers a valuable tool for regions simultaneously facing scarcity, environmental degradation, and uneven development.
Completing the picture, the bibliometric review on household water conservation behaviours (contribution 10) reminds us that no institutional or technological strategy can be effective without a deep understanding of people’s habits, psychological barriers, and motivations. Ultimately, sustainability is also determined within households.
3. Conclusions
Read collectively, these ten papers trace a coherent narrative: sustainable water management is only possible when ecological knowledge, economic evaluation, technological innovation, governance, and social behaviour are aligned. None of these dimensions is sufficient on its own; all, however, reinforce one another when integrated through rigorous models that connect the local with the global, the scientific with the political, and the environmental with the economic.
This Special Issue is therefore more than a collection of studies: it is an invitation to understand water as a complex, interdependent, and profoundly human system.
Author Contributions
Conceptualization, B.M.; methodology, B.M.; validation, B.M.; formal analysis, B.M.; resources, B.M.; data curation, B.M.; writing—original draft preparation, B.M.; writing—review and editing, B.M.; visualization, B.M.; supervision, J.M.; project administration, J.M.; funding acquisition, J.M. All authors have read and agreed to the published version of the manuscript.
Funding
This research was partially supported by Vice-Rectorate for Research and Knowledge Transfer of the University of Alicante, by the Water Chair of the University of Alicante-Diputación de Alicante, by the University Institute of Water and Environmental Sciences of the University of Alicante, and by the CDTI through the project “Sustainability, water and agriculture in the 21st century, SOS-AGUA-XXI” (Science and Innovation Missions 2021, Recovery, Transformation and Resilience Plan, NextGenerationEU) and the R&D&I project “Resilience and public policies in the evolution of Spanish industry, 1950–2019” (PID2022-138464NB-I00), funded by MCIN/AEI/10.13039/501100011033 and by ERDF A way of doing Europe.
Conflicts of Interest
The authors declare no conflicts of interest.
List of Contributions
- Zhu, Z.; Wu, K.; Zhou, S.; Wang, Z.; Chen, W. Multi-Scale Gross Ecosystem Product (GEP) Valuation for Wetland Ecosystems: A Case Study of Lishui City. Water 2024, 16, 3554. https://doi.org/10.3390/w16243554.
- Folkens, L.; Bachmann, D.; Satzinger, U.; Schneider, P. The Hydro-Economic Modeling of Low-Flow Events on the Middle Elbe: Assessing Socio-Economic Impacts on River Navigation. Water 2024, 16, 3497. https://doi.org/10.3390/w16233497.
- Alarcon-Aguirre, G.; Del Águila Romero, Y.; Vela-Dafonseca, M.; Zevallos Pollito, P.A.; Rodriguez Achata, L.; Ramos Enciso, D.; Cardozo Soarez, J.; Diaz Revoredo, J.L.; Canahuire-Robles, R.; Garate-Quispe, J. Valuation of Ecosystem Services of Fluvial Beaches in the Southeastern Peruvian Amazon. Water 2024, 16, 3474. https://doi.org/10.3390/w16233474.
- Montano, B. Historical Analysis of Resilience in Spanish Desalination Companies: Period 1980–2024. Water 2024, 16, 3318. https://doi.org/10.3390/w16223318.
- Udugama, M.; Alhafi Alotaibi, B.; Navoda, M.; Najim, M.M.M.; Udayanga, L.; Traore, A. Willingness-to-Pay for Blue Ecosystem Services of Natural Pools in Sri Lanka: A Discrete Choice Experiment. Water 2024, 16, 2437. https://doi.org/10.3390/w16172437.
- Sánchez-Pérez, C.; López-Ortiz, M.-I.; Fernández-Aracil, P. La Marina Baja Water Consortium (1950–1978): Hydro-Economic Model of Water Governance behind Tourism Development in Benidorm (Spain). Water 2024, 16, 1832. https://doi.org/10.3390/w16131832.
- Song, L.; Wang, H.; Ding, L. Multi-Dimensional Collaborative Optimization Model for Agricultural Water Rights Based on Water Price Reform under Changing Environment. Water 2024, 16, 1262. https://doi.org/10.3390/w16091262.
- Fabregat, V.; Pagán, J.M. Technical–Economic Feasibility of a New Method of Adsorbent Materials and Advanced Oxidation Techniques to Remove Emerging Pollutants in Treated Wastewater. Water 2024, 16, 814. https://doi.org/10.3390/w16060814.
- Shi, J.; Yang, H.; Wang, F.; Sun, D.; Run, Y. Comprehensive Evaluation and Coupled Coordinated Development Study of Water–Economic–Ecological Systems in the Five Northwestern Provinces of China. Water 2023, 15, 4260. https://doi.org/10.3390/w15244260.
- Sanchez, C.; Rodriguez-Sanchez, C.; Sancho-Esper, F. Barriers and Motivators of Household Water-Conservation Behavior: A Bibliometric and Systematic Literature Review. Water 2023, 15, 4114. https://doi.org/10.3390/w15234114.
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