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ORIGINAL RESEARCH ARTICLE
Environmental flow assessment in the Chirchik River Basin using multi-method hydrological indicators
Nodir Abdushakhidov1,2,3 ,
Zhenhong Wang1,2,3* ,
Madhab Rijal1,2,3,4 ,
Maksud Abbaskhanov5 ,
Tamara Akhmedova6 ,
Ilkhom Ruziyev7 ,
Adil Muzaffarov8 ,
Bakhodirjon Usmonov9
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1 School of Water and Environment, Chang’an University, Xi’an, Shaanxi , China
2 Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of the Ministry of Education, Chang’an University, Xi’an, Shaanxi , China
3 Key Laboratory of Eco-hydrology and Water Security in Arid and Semi-arid Regions of Ministry of Water Resources, Chang’an University, Xi’an, Shaanxi , China
4 Central Department of Hydropower Engineering, Graduate School of Engineering, Mid-West University, Surkhet, Karnali Province , Nepal
5 Directorate for the Construction of New Tashkent City under the Cabinet of Ministers, Tashkent , Uzbekistan
6 Hydrometeorological Research Institute, Tashkent , Uzbekistan
7 Tashkent Institute of Irrigation and Agricultural Mechanization Engineers National Research University, Tashkent , Uzbekistan
8 Andijan Institute of Agriculture and Agrotechnologies, Andijan, Andijan Region , Uzbekistan
9 Faculty of International Educational Programs, Tashkent State Transport University, Tashkent , Uzbekistan
AJWEP, 026320218 https://doi.org/10.36922/AJWEP026320218
Received: 6 August 2026 | Revised: 17 September 2026 | Accepted: 23 September 2026 | Published online: 13 October 2026
© 2026 by the Author(s). This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution 4.0 International License ( https://creativecommons.org/licenses/by/4.0/ )
Abstract
Environmental flow assessment is increasingly important for maintaining riverine ecosystems amid climate variability, reservoir regulation, and rising water demand. However, information on environmental flow requirements remains limited for regulated river basins in Central Asia, including the Chirchik River Basin in Uzbekistan. This study aims to estimate and compare environmental flow requirements at three hydrological stations—Chinaz, Ugam, and G’azalkent—using long-term monthly discharge data from 1971 to 2020. Seven hydrological methods were applied: Tennant, Tessman, average annual flow, flow duration curve, dynamic mean flow, median flow, and flushing-flow assessment. Trend analysis was conducted using the Mann–Kendall test to examine station-wise environmental flow gradients across the basin. The results showed substantial differences among the stations: mean annual flows were 80.4, 23.1, and 227.7 m3/s at Chinaz, Ugam, and G’azalkent, respectively. The Tessman method yielded seasonal environmental flow ranges of 30.4–63.3 m3/s, 8.6–22.8 m3/s, and 91.1–147.1 m3/s, respectively. The findings indicate that fixed-percentage methods underestimate seasonal ecological requirements, especially in reaches affected by snowmelt and flow regulation. Seasonal and station-specific environmental flow rules are recommended to support sustainable basin management.
Keywords
Environmental flow assessment
Hydrological methods
Tessman method
Chirchik River
Flushing flow
Funding
None.
Conflict of interest
The authors declare no conflict of interest.
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