Aquaculture Sciences

Aquaculture Sciences

Determining the environmental water rights to preserve key habitats of commercial fish using ecohydraulic modeling and habitat simulation, Case Study: Chalus River

Document Type : Original Article

Authors
Edris Taghvaye Salimi
Vahid Gholami
Department of Range and Watershed Management, Faculty of Natural Resources, University of Guilan, Iran.
Abstract
Providing environmental water requirements for rivers supporting commercial fish species is essential for sustaining valuable aquatic stocks and maintaining the integrity of associated ecosystems, particularly in basins experiencing increasing water abstraction pressures. The Chalusroud river, one of the most important rivers discharging into the southern Caspian Sea, provides critical habitats for economically valuable species such as Caspian Kutum (Rutilus frisii) and rainbow trout (Oncorhynchus mykiss), but has experienced a noticeable decline in base flow in recent years. The objective of this study was to determine an optimal ecological flow regime for conserving key habitats of commercial fish species using an integrated ecohydraulic approach. To this end, five widely used and advanced environmental flow assessment methods were comparatively applied, including hydrological methods (Tennant, flow duration curve, and aquatic base flow) and ecohydraulic methods (wetted perimeter and the Physical Habitat Simulation model, PHABSIM). The analysis was based on 45 years of hydrological data combined with detailed field surveys conducted across 12 river reaches. The results indicated that simple hydrological methods, yielding environmental flow estimates ranging from 0.34 to 15.13 cubic meters per second (cms), lack sufficient ecological resolution to effectively protect fish habitats. The wetted perimeter method produced a wide range of flow requirements (1.7 to 8.77 cms), highlighting the strong dependence of environmental flow needs on channel morphology. In contrast, PHABSIM provided the most ecologically robust results by identifying a dynamic, species-specific flow regime. For example, maintaining at least 85% of suitable spawning habitat for Caspian white fish requires a discharge of approximately 5.7 cms in downstream reaches. The mean environmental flow estimated by PHABSIM for the entire river was approximately 4.8 cms. Overall, the findings demonstrate that environmental water requirements cannot be represented by a single fixed discharge, but rather constitute a flow regime that varies with species and life stage. The combined application of PHABSIM and the wetted perimeter method is therefore recommended as a scientifically sound and practical framework for determining ecological water allocations in rivers with high fisheries value. The results further indicate that current river flows during several seasons, particularly summer, fall below the minimum ecological thresholds required to sustain commercial fish habitats, underscoring the urgent need to revise water allocation strategies toward ecosystem-based and integrated water resources management.
Keywords
Environmental water requirements
PHABSIM
commercial fish habitats
Caspian Kutum
ecological flow regime
environmental water rights
Chalusroud River
Subjects
امینی م.، شکوهی ع. 1393. حل تحلیلی تعیین نقطه شکست نمودار محیط تر شده – دبی در روش هیدرولیکی تعیین حداقل جریان زیست محیطی. نشریه علمی هیدرولیک، 9(1): 43-27.
زرعکانی م.، شکوهی ع. 1393. تعیین جریان لازم برای حفظ مورفولوژی بستر رودخانه و مقایسه چهار روش تعیین جریان زیست‌محیطی مبتنی بر هیدرولوژی و هیدرولیک جریان. کنفرانس ملی علوم و مهندسی محیط‌زیست، اهواز، 28 بهمن 1393.
شکوهی ع.، هانگ ی. 1390. استفاده از مشخصه‌های مرفولوژیکی در رودخانه‌های دایمی برای تعیین حداقل نیاز آبی محیط اکولوژیکی. محیط‌شناسی، 37(58): 128-117.
قاسمی ع.، ولی‏نسب ت.، محمدپور، م. ۱۴۰۱. ارزیابی جریان زیست‌محیطی رودخانه با روش‌های هیدرولوژیک و اکوهیدرولوژیک به‌منظور حفاظت از اکوسیستم‌ آبی و آبزیان. مجله علمی شیلات ایران، 31(4): 119-107.
Akhtar M.P., Roy L.B., Vishwakarma, K.M. 2020. Assessment of agricultural potential of a river command using geo-spatial techniques: a case study of Himalayan river project in Northern India. Applied Water Science 10(3), 81-92.
Anthoni C., Githinji S., Kisternam T. 2018. The impact of water on health and ill-health in a sub-Saharan African wetland: exploring both sides of the coin. Science of the Total Environment 624, 1411-1420.
Arthington A.H. 1998. Comparative evaluation of environmental flow assessment techniques: review of holistic methodologies. Land and Water Resources Research and Development Corporation, Occasional paper no. 26/98, Canberra, Australia, 149 p.
Arthington A.H., Zalucki J.M. 1998. Comparative evaluation of environmental flow assessment techniques: review of methods. Land and Water Resources Research and Development Corporation, Occasional paper no. 27/98, Canberra, Australia, 54 p.
Brooks R.P. 1997. Improving habitat suitability index models. Wildlife Society Bulletin 25(1), 163-167.
Cao F., Lu Y., Dong S., Li X. 2020. Evaluation of natural support capacity of water resources using principal component analysis method: a case study of Fuyang district. Applied Water Science 10, 192.
Cui M, Zhou J.X., Huang B. 2012. Benefit evaluation of wetlands resource with different modes of protection and utilization in the Dongting Lake region. In: The 18th Biennial conference of international society for ecological modelling. Procedia Environmental Sciences 13, 2-17.
Esmaeili H.R., Sayyadzadeh G., Eagderi S., Abbasi K. 2018. Checklist of freshwater fishes of Iran. FishTaxa 3(3), 1–95.
Gholami V., Booij M.J., Tehrani E.N., Hadian M.A. 2018. Spatial soil erosion estimation using an artificial neural network (ANN) and field plot data. Catena 163, 210-218.
Gordon N.D., McMahon T.A., Finlayson B.L., Gippel C.J., Nathan R.J. 2004. Stream hydrology: an introduction for ecologists. 2nd edition, John Wiley and Sons, 448 p.
Groffman P., Baron J., Blett T., Gold A., Goodman I., Gunderson L., Levinson B., Palmer M., Paerl H., Peterson G., LeRoy P.N., Rejesk D., Reynolds J., Turner M., Weathers K., Wiens J. 2006. Ecological thresholds: the key to successful environmental management or an important concept with no practical application?. Ecosystem 9(1), 1-13.
Dyson M., Bergkamp G., Scanlon J. 2008. Flow-The essentials of environmental flows. 2nd edition, IUCN, Gland, Switzerland, 134 p.
Sajedipour S., Zarei H., Oryan S. 2017. Estimation of environmental water requirements via an ecological approach: a case study of Bakhtegan Lake Iran. Ecological Engineering 100, 24-255.
Sarhadi A., Soltani S. 2013. Determination of water requirements of the Gavkhuni wetland, Iran: a hydrological approach. Journal of Arid Environments 98, 27-40.
Seifi F., Janbaz Ghobadi G.R. 2017. The role of ecotourism potentials in ecological and environmental sustainable development of Miankaleh Protected Region. Open Journal of Geology 7(4), 478-487.
Shaeri Karimi S., Yasi M., Eslamian S. 2012. Use of hydrological methods for assessment of environmental flow in a river reaches. International Journal of Environmental Science and Technology 9, 549-558.
Shah D., Panchal M., Sanghvi A., Chavda H., Sha M. 2020. Holistic review on geosolar hybrid desalination system for sustainable development. Applied Water Science 10, 155.
Tehrani E.N., Sahour H., Booij M.J. 2018. Trend analysis of hydro-climatic variables in the north of Iran. Theoretical and Applied Climatology 136, 85-97.
Tennant D.L. 1976. Instream flow regimens for fish, wildlife, recreation and related environmental resources. Fisheries 4(1), 6-10.
Tharme R.E. 2003. A global perspective on environmental flow assessment: emerging trends in the development and application of environmental flow methodologies for rivers. River Research and Applications 19, 397-441.
Vogel R.M., Fennessey N.M. 1994. Flow-duration curves. I: New interpretation and confidence intervals. Journal of Water Resources Planning and Management 120(4), 485-504.
Yang W. 2011. A multi objective optimization approach to allocate environmental flows to the artificially restored wetlands of China’s yellow river delta. Ecological Modelling 222(2), 261-267.
Ye Z., Li W., Chen Y., Qiu J., Aji D. 2017. Investigation of the safety threshold of eco-environmental water demands for the Boston Lake wetlands, western China. Quaternary International 440(B), 130-136.
Aquaculture Sciences
Volume 13, Issue 2
October 2025
Pages 135-148