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Development of E-rules of Intra-annual Flow Regulation in the Amu Darya River Basin

Client: Ministry of Innovative Development of Uzbekistan

Executing organization: SIC ICWC, partner: BWO Amu Darya, Institute of Geographic Sciences and Natural Resources Research of the Chinese Academy of Sciences.

Implementation period: 2021-2022

Project objective: Developing e-rules of intra-annual flow regulation in the Amu Darya River basin, including:

1. Modeling the flow of the Amu Darya River and its tributaries: current level (2020), perspective (2035) modeling the annual flow and the intra-annual flow, determination of a share of the glacial component in the river runoff;

2. Estimation of the required water intake from the Amu Darya River and its tributaries for various water consumers: current level (2020), perspective (2035) assessment of crop water requirements, taking into account the impact of climate change; assessment of water requirements of non-agricultural sectors, including Afghanistan, and determination of water needs of the Aral Sea;

3. Studying the components of the rivers water balance and development of a dynamic model of the Amu Darya river flow transformation development of the relationships for calculation of the components of the water balance and the dynamic model.

Outputs:

The research activities 2021 were undertaken in the following areas:

1. The quantitative assessment of natural water resources of the Amu Darya River was made and the share of the glacial component in the river runoff was determined; the series of the annual river flow and its intra-annual distribution were simulated for 2020-2035;



2. The assessment of consumption of water in transboundary rivers of the Amu Darya basin was made, environmental flow requirements were determined and needed water supply to South Aral region (Amu Darya delta) and Large Aral Sea was estimated based for the condition of stabilization of its water regime;

3. The studies were carried out and relationships for river water balance components were derived. Based on these relationships, the model and algorithms of planning water distribution and flow regulation by reservoirs, as well as the model of operational management that allows correcting the initial plan of water distribution and flow regulation by reservoirs were developed; the dynamic model and the algorithm for calculation of daily river hydrograph transformation in space and time were developed. The existing approaches to calculation of morphometric relationships of the Amu Darya River were analyzed, they were tested and compared with morphometric relationships derived from processing of satellite images covering the middle and lower reaches of the Amu Darya River. Additionally, water losses in the Amu Darya river and reservoirs of Tuyamuyun Hydroscheme were assessed using the data from the past research. The river course was divided into balancing sites, where formation of seepage flow is characteristic, for instance, in the river reach from Kerki gauging station to Ilchik gauging station the river forms, through seepage, the underflow, which in the next reach from Ilchik gauging station to Darganata gauging station is discharged into the river (inverse seepage). The seepage flow in the form of water losses from reservoirs of Tuyamuyun Hydroscheme is formed only under high water level (large quantities of water) in the reservoirs. There are no seepage losses when storage is below the dead level. Testing of the dynamic model will be done in early 2022 as scheduled by the work plan.

4. The following additional sub-tasks were fulfilled: i) analysis of the current performance of BWO Amu Darya and its territorial division in part of planning and operational management of water resources in the Amu Darya basin; ii) requirements of BWO Amu Darya for the development of the Amu Darya River water management e-rules were determined; iii) developed structure and composition of water management e-rules for the Amu Darya River.



The completed research and analysis of BWOs operations show that, at present, water allocation by BWO Amu Darya can be characterized as conflict-free and shows reasonably good agreement between planned and actual water supply from the Amu Darya River to the countries as a whole, by season in average or wet years. Management problems occur in particularly dry years, when the lower reaches are disadvantaged against the middle reaches. It is especially important to draw correctly the river water balance by river reach and the TMHS reservoir balance for such periods of time.

The work done allowed us to determine more precisely the components of river water balance in the middle and lower reaches of the Amu Darya and of TMHS reservoir balance. The test calculations show that drawing the Amu Darya river water balance with account of the studied components of river water balance improve the accuracy of planning water distribution and flow regulation in the Amu Darya basin. Discrepancies in the actual water balance decrease substantially. The analysis of river water losses derived from the proposed algorithms leads to some important conclusions on admissible discrepancies of river water balance.