Articles | Volume 29, issue 13
https://doi.org/10.5194/hess-29-2785-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/hess-29-2785-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| Highlight paper
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03 Jul 2025
Research article | Highlight paper |
| 03 Jul 2025
| 03 Jul 2025
Is drought protection possible without compromising flood protection? Estimating the potential dual-use benefit of small flood reservoirs in southern Germany
Institute for Water and the Environment – Hydrology, Karlsruhe Institute of Technology, 76133 Karlsruhe, Germany
Center for Disaster Management and Risk Reduction Technology (CEDIM), Karlsruhe Institute of Technology, 76133 Karlsruhe, Germany
Invited contribution by Sarah Quỳnh-Giang Ho, recipient of the EGU Natural Hazards Outstanding Student and PhD candidate Presentation Award 2023.
Uwe Ehret
Institute for Water and the Environment – Hydrology, Karlsruhe Institute of Technology, 76133 Karlsruhe, Germany
Center for Disaster Management and Risk Reduction Technology (CEDIM), Karlsruhe Institute of Technology, 76133 Karlsruhe, Germany
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Small flood reservoirs are modelled to determine whether they can still provide water for farms and low-flows under uncertain forecasts. Though forecasts did affect how much water was available, reservoirs were still able to provide water for raising river levels and for crops. At the same time, they were able to ensure that flooding conditions were maintained. This shows that such flood reservoirs could be converted into water supply reservoirs to expand water resources in a warming world.
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We propose the
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Cited articles
Acheampong, D., Balana, B. B., Nimoh, F., and Abaidoo, R. C.: Asssesing the effectiveness and impact of agricultural water management interventions: the case of small reservoirs in northern Ghana, Agr. Water Manag., 209, 163–170, https://doi.org/10.1016/j.agwat.2018.07.009, 2018.
Adams, L. E., Lund, J. R., Moyle, P. B., Quiñones, R. M., Herman, J. D., and O'Rear, T. A.: Environmental hedging: A theory and method for reconciling reservoir operations for downstream ecology and water supply, Water Resour. Res., 53, 7816–7831, https://doi.org/10.1002/2016wr020128, 2017.
Baden-Württemberg, H. R.: Strategie zur Minderung von Hochwasserrisiken in Baden-Württemberg, https://um.baden-wuerttemberg.de/fileadmin/redaktion/ (last access: 30 June 2025), 2014.
Baden-Württemberg, L. f. U.: Regionalisierte Abfluss-Kennwerte Baden-Württemberg - Mittlere Abflüsse und mittlere Niedrigwasserabflüsse [data set], https://www.lubw.baden-wuerttemberg.de/wasser/regionalisierte-abflusskennwerte (last access: 30 June 2025), 2016.
Baden-Württemberg, L. f. U.: NIZ Pegel Klassifizierung, https://www.hvz.baden-wuerttemberg.de/pdf/NIZ_Pegel_Klassifizierung.pdf (last access: 30 June 2025), 2024a.
Baden-Württemberg, L. f. U.: Hinweise zu den Wasserstands- und Aflussvorhersagen der Hochwasservorhersagezentrale der LUBW, https://www.hvz.baden-wuerttemberg.de/pdf/Hinweise-WHM-Vorhersage.pdf (last access: 30 June 2025), 2024b.
Balley, P.: An integrated real-time optimal flood and drought control operation model of a multi-purpose two-reservoir system: the Waiau River System, Dissertation, Department of Natural Resources Engineering, Lincoln University, 1997.
Beck, H. E., McVicar, T. R., Vergopolan, N., Berg, A., Lutsko, N. J., Dufour, A., Zeng, Z., Jiang, X., van Dijk, A., and Miralles, D. G.: High-resolution (1 km) Koppen-Geiger maps for 1901–2099 based on constrained CMIP6 projections, Sci. Data, 10, 724, https://doi.org/10.1038/s41597-023-02549-6, 2023.
Berhane, G., Gebreyohannes, T., Martens, K., and Walraevens, K.: Overview of micro-dam reservoirs (MDR) in Tigray (northern Ethiopia): Challenges and benefits, J. Afr. Earth Sci., 123, 210–222, https://doi.org/10.1016/j.jafrearsci.2016.07.022, 2016.
Bundesamt, U.: Niedrigwasser, Dürre und Grundwasserneubildung – Bestandsaufnahme zur gegenwärtigen Situation in Deutschland, den Klimaprojektionen und den existierenden Maßnahmen und Strategien1862-4804, 2021.
Cammalleri, C., Vogt, J., and Salamon, P.: Development of an operational low-flow index for hydrological drought monitoring over Europe, Hydrol. Sci. J., 62, 346–358, https://doi.org/10.1080/02626667.2016.1240869, 2016.
Cañón, J., González, J., and Valdés, J.: Reservoir operation and water allocation to mitigate drought effects in crops: a multilevel optimization using the Drought Frequency Index, J. Water Res. Pl., 135, 458–465, https://doi.org/10.1061/(ASCE)0733-9496(2009)135:6(458), 2009.
Casadei, S., Di Francesco, S., Giannone, F., and Pierleoni, A.: Small reservoirs for a sustainable water resources management, Adv. Geosci., 49, 165–174, https://doi.org/10.5194/adgeo-49-165-2019, 2019.
Chang, J., Guo, A., Wang, Y., Ha, Y., Zhang, R., Xue, L., and Tu, Z.: Reservoir Operations to Mitigate Drought Effects With a Hedging Policy Triggered by the Drought Prevention Limiting Water Level, Water Resour. Res., 55, 904–922, https://doi.org/10.1029/2017wr022090, 2019.
Chang, T. J., Kleopa, X. A., and Teoh, C. B.: Use of Flood-Control Reservoirs for Drought Management, J. Irrig. Drain. Eng., 121, 9 pp., 1995.
Consoli, S., Matarazzo, B., and Pappalardo, N.: Operating Rules of an Irrigation Purposes Reservoir Using Multi-Objective Optimization, Water Resour. Manag., 22, 551–564, https://doi.org/10.1007/s11269-007-9177-9, 2007.
Di Baldassarre, G., Wanders, N., AghaKouchak, A., Kuil, L., Rangecroft, S., Veldkamp, T. I. E., Garcia, M., van Oel, P. R., Breinl, K., and Van Loon, A. F.: Water shortages worsened by reservoir effects, Nat. Sustain., 1, 617–622, https://doi.org/10.1038/s41893-018-0159-0, 2018.
Draper, A. and Lund, J.: Optimal hedging and carryover storage value, J. Water Res. Plan. Manag., 130, 83–87, https://doi.org/10.1061/(ASCE)0733-9496(2004)130:1(83), 2004.
Drastig, K., Prochnow, A., Libra, J., Koch, H., and Rolinski, S.: Irrigation water demand of selected agricultural crops in Germany between 1902 and 2010, Sci. Total Environ., 569/570, 1299–1314, https://doi.org/10.1016/j.scitotenv.2016.06.206, 2016.
Erfurt, M., Skiadaresis, G., Tijdeman, E., Blauhut, V., Bauhus, J., Glaser, R., Schwarz, J., Tegel, W., and Stahl, K.: A multidisciplinary drought catalogue for southwestern Germany dating back to 1801, Nat. Hazards Earth Syst. Sci., 20, 2979–2995, https://doi.org/10.5194/nhess-20-2979-2020, 2020.
Heinzel, C., Fink, M., and Höllermann, B.: The potential of unused small-scale water reservoirs for climate change adaptation: A model- and scenario based analysis of a local water reservoir system in Thuringia, Germany, Front. Water, 4, 892834, https://doi.org/10.3389/frwa.2022.892834, 2022.
Hisdal, H., Tallaksen, L. M., Gauster, T., Bloomfield, J. P., Parry, S., Prudhomme, C., and Wanders, N.: Hydrological drought characteristics, in: Hydrological Drought, 1st Edn., Elsevier Science, 157–231, 2004.
Ho, S. Q.-G.: Reservoirs Max Benefit, Zenodo [data set and code], https://doi.org/10.5281/zenodo.12724797, 2024.
Huang, W.-C. and Chou, C.-C.: Drought early warning system in reservoir operation: Theory and practice, Water Resour. Res., 41, W11406, https://doi.org/10.1029/2004wr003830, 2005.
Hui, R., Lund, J., Zhao, J., and Zhao, T.: Optimal Pre-storm Flood Hedging Releases for a Single Reservoir, Water Resour. Manag., 30, 5113–5129, https://doi.org/10.1007/s11269-016-1472-x, 2016.
Jurik, L., Húska, D., Halászová, K., and Bandlerová, A.: Small Water Reservoirs – Sources of Water or Problems?, J. Ecol. Eng., 16, 22–28, https://doi.org/10.12911/22998993/59343, 2015.
Jurík, L., Zeleòáková, M., Kaletová, T., and Arifjanov, A.: Small Water Reservoirs: Sources of Water for Irrigation, in: Water Resources in Slovakia: Part I, The Handbook of Environmental Chemistry, 69, 115–131, https://doi.org/10.1007/698_2018_301, 2018.
Karamouz, M. and Araghinejad, S.: Drought Mitigation through Long-Term Operation of Reservoirs: Case Study, Journal of Irrigation and Drainage Engineering – ASCE, 134, https://doi.org/10.1061/(ASCE)0733-9437(2008)134:4(471), 2008.
Knight, R. R., Gain, W. S., and Wolfe, W. J.: Modelling ecological flow regime: an example from the Tennessee and Cumberland River basins, Ecohydrology, 5, 613–627, https://doi.org/10.1002/eco.246, 2011.
Knight, R. R., Murphy, J. C., Wolfe, W. J., Saylor, C. F., and Wales, A. K.: Ecological limit functions relating fish community response to hydrologic departures of the ecological flow regime in the Tennessee River basin, United States, Ecohydrology, 7, 1262–1280, https://doi.org/10.1002/eco.1460, 2013.
LARSIM-Entwicklergemeinschaft: Das Wasserhaushaltsmodell LARSIM: Modellgrundlagen und Anwendungsbeispiele, https://larsim.info/dokumentation/LARSIM-Dokumentation.pdf (last access: 30 June 2025), 2023.
Liebe, J., Andreini, M., van de Giesen, N., and Steenhuis, T.: The small reservoirs project: Research to improve water availability and economic development in rural semi-arid areas., in: The hydropolitics of Africa: A contemporary challenge, edited by: Bardouille, R., Nagel, M., and Ndulo, M., Cambridge Scholars Publishing, Necastle, UK, 325–332, ISBN 1-84718-112-0, 2007.
Liu, H., Sun, Y., Yin, X., Zhao, Y., Cai, Y., and Yang, W.: A reservoir operation method that accounts for different inflow forecast uncertainties in different hydrological periods, J. Clean. Prod., 256, 120471, https://doi.org/10.1016/j.jclepro.2020.120471, 2020.
LUBW: Arbeitshilfe zur DIN 19700 für Hochwasserrückhaltebecken in Baden-Württemberg, https://pd.lubw.de/93810 (last access: 30 June 2025), 2007.
Ludwig, K. and Bremicker, M.: The Water Balance Model LARSIM - Design, Content and Applications, Institut für Hydrologie der Universität Freiburg i. Br., https://larsim.info/fileadmin/files/Dokumentation/FSH-Bd22-Bremicker-Ludwig.pdf (last access: 30 June 2025), 2006.
Mady, B., Lehmann, P., Gorelick, S. M., and Or, D.: Distribution of small seasonal reservoirs in semi-arid regions and associated evaporative losses, Environ. Res. Commun., 2, 061002, https://doi.org/10.1088/2515-7620/ab92af, 2020.
Ministerium für Umwelt, K. u. E. B.-W.: Strategie zum Umgang mit Wassermangel in Baden-Württemberg: Erfordernisse zur Verringerung von Risiken und – Nutzungskonflikten bei Niedrigwasser und – abnehmenden Grundwasserreserven, Ministerium für Umwelt, Klima und Energiewirtschaft Baden-Württemberg, Stuttgart, https://um.baden-wuerttemberg.de/de/umwelt-natur/wasser/wasserversorgung/wassermangel (last access: 30 June 2025), 2022.
Ogilvie, A., Riaux, J., Massuel, S., Mulligan, M., Belaud, G., Le Goulven, P., and Calvez, R.: Socio-hydrological drivers of agricultural water use in small reservoirs, Agr. Water Manag., 218, 17–29, 2019.
Padiyedath Gopalan, S., Hanasaki, N., Champathong, A., and Tebakari, T.: Impact assessment of reservoir operation in the context of climate change adaptation in the Chao Phraya River basin, Hydrol. Process., 35, e14005, https://doi.org/10.1002/hyp.14005, 2020.
Qadir, M., Sharma, B. R., Bruggeman, A., Choukr-Allah, R., and Karajeh, F.: Non-conventional water resources and opportunities for water augmentation to achieve food security in water scarce countries, Agr. Water Manag., 87, 2–22, https://doi.org/10.1016/j.agwat.2006.03.018, 2007.
Salmoral, G., Rey, D., Rudd, A., de Margon, P., and Holman, I.: A Probabilistic Risk Assessment of the National Economic Impacts of Regulatory Drought Management on Irrigated Agriculture, Earth's Future, 7, 178–196, https://doi.org/10.1029/2018ef001092, 2019.
Shih, J.-S. and ReVelle, C.: Water-Supply Operations during Drought: Continuous Hedging Rule, Journal of Water Resources Planning and Management, 120, 613–629, https://doi.org/10.1061/(ASCE)0733-9496(1994)120:5(613), 1994.
Shih, J.-S. and ReVelle, C.: Water supply operations during drought: A discrete hedging rule, Eur. J. Oper. Res., 82, 163–175, https://doi.org/10.1016/0377-2217(93)E0237-R, 1995.
Tallaksen, L. M., Madsen, H., and Clausen, B.: On the definition and modelling of streamflow drought duration and deficit volume, Hydrol. Sci. J., 42, 15–33, https://doi.org/10.1080/02626669709492003, 2009.
Van Loon, A. F.: Hydrological drought explained, WIRES Water, 2, 359–392, https://doi.org/10.1002/wat2.1085, 2015.
Van Loon, A. F. and Van Lanen, H. A. J.: A process-based typology of hydrological drought, Hydrol. Earth Syst. Sci., 16, 1915–1946, https://doi.org/10.5194/hess-16-1915-2012, 2012.
Van Loon, A. F., Van Lanen, H. A., Hisdal, H., Tallaksen, L. M., Fendeková, M., Oosterwijk, J., Horvát, O., and Machlica, A.: Understanding hydrological winter drought in Europe, Global Change: Facing Risks and Threats to Water Resources, IAHS Publ., 340, 189–197, 2010.
Venot, J.-P. and Krishnan, J.: Discursive framing: Debates over small reservoirs in the rural South, Water Altern., 4, 316–324, 2011.
Venot, J.-P., Andreini, M., and Pinkstaff, C. B.: Planning and Corrupting Water Resources Development: The Case of Small Reservoirs in Ghana, Water Altern., 4, 399–423, 2011.
Venot, J.-P., Fraiture, C. D., and Nti Acheampong, E.: Revisiting dominant notions: a review of costs, performance and institutions of small reservoirs in Sub-Saharan Africa, International Water Management Institute (IWMI), Colombo, Sri Lanka, IWMI Research Report 144, 39 pp., https://doi.org/10.5337/2012.202, 2012.
Vigiak, O., Lutz, S., Mentzafou, A., Chiogna, G., Tuo, Y., Majone, B., Beck, H., de Roo, A., Malago, A., Bouraoui, F., Kumar, R., Samaniego, L., Merz, R., Gamvroudis, C., Skoulikidis, N., Nikolaidis, N. P., Bellin, A., Acuna, V., Mori, N., Ludwig, R., and Pistocchi, A.: Uncertainty of modelled flow regime for flow-ecological assessment in Southern Europe, Sci. Total Environ., 615, 1028–1047, https://doi.org/10.1016/j.scitotenv.2017.09.295, 2018.
Wisser, D., Frolking, S., Douglas, E. M., Fekete, B. M., Schumann, A. H., and Vörösmarty, C. J.: The significance of local water resources captured in small reservoirs for crop production – A global-scale analysis, J. Hydrol., 384, 264–275, https://doi.org/10.1016/j.jhydrol.2009.07.032, 2010.
Yarnell, S. M., Stein, E. D., Webb, J. A., Grantham, T., Lusardi, R. A., Zimmerman, J., Peek, R. A., Lane, B. A., Howard, J., and Sandoval-Solis, S.: A functional flows approach to selecting ecologically relevant flow metrics for environmental flow applications, River Res. Appl., 36, 318–324, https://doi.org/10.1002/rra.3575, 2020.
You, J.-Y. and Cai, X.: Hedging rule for reservoir operations: 2. A numerical model, Water Resour. Res., 44, W01416, https://doi.org/10.1029/2006wr005482, 2008a.
You, J.-Y. and Cai, X.: Hedging rule for reservoir operations: 1. A theoretical analysis, Water Resour. Res., 44, W01415, https://doi.org/10.1029/2006wr005481, 2008b.
Zhao, T., Zhao, J., Lund, J. R., and Yang, D.: Optimal Hedging Rules for Reservoir Flood Operation from Forecast Uncertainties, J. Water Res. Plan. Manag., 140, 04014041–040140411, https://doi.org/10.1061/(asce)wr.1943-5452.0000432, 2014.
Executive editor
This study addresses the highly relevant issue of dam operation around the central question if dam operation can help to alleviate both floods and droughts, and under what conditions. This study of dams in Germany is highly relevant to water management in a climate with increasing frequency and magnitude of weather extremes.
This study addresses the highly relevant issue of dam operation around the central question if...
Short summary
In this paper, we use models to demonstrate that even small flood reservoirs – which capture water to avoid floods downstream – can be repurposed to release water in drier conditions without affecting their ability to protect against floods. By capturing water and releasing it once levels are low, we show that reservoirs can greatly increase the water available in drought. Having more water available to the reservoir, however, is not necessarily better for drought protection.
In this paper, we use models to demonstrate that even small flood reservoirs – which capture...
