The economic case for re-using sediment from the Tuyamuyun Hydropower Complex

Vanja Westerberg

Vanja is an environmental economist and number cruncher extraordinaire. She has 15 years of professional experience in applied research and consultancy work.

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Posted on: 13 May 2023
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Time frame: August 2022 - March 2023

Challenge

The Tuyamuyun Hydro Complex (THC) is a system of four interconnected reservoirs and a series of canals on the lower Amu Darya River, bordering Uzbekistan and Turkmenistan. Its primary purpose is to provide water for irrigation schemes in Uzbekistan and Turkmenistan. The complex also provides water for industrial and municipal uses and has a 150 MW power station.

Reservoirs, including the THC, are typically built with a design life of fifty years – the time it takes to pay-off capital equipment costs. As a result, sedimentation volume is estimated over this period, and the lowest dam outlets are set above the dead storage, so as to not infringe on active storage during that period. Without consideration to sediment management costs, this kind of design defers future sediment management to another generation than those that built the dam (Randle and Boyd 2018).
The construction of the THC was completed 40 years ago in 1983 and today, the sediment management problem is very real. With 1.5 billion m3 of sediments trapped in the main channel (Ruslovoe) reservoir, the total storage loss is estimated at 63% of total initial storage volume. Projections in Ikramova (2021) suggest that the Ruslovoe reservoir will be entirely lost by 2040 with no further action, whilst the hydropower facility will cease to operate much earlier (Giri 2022b, personal communications). 

At the same time, there is an imminent supply crisis of sediment materials, especially sand, referred to as the unrecognized hero of our development, used for roads, buildings, infrastructure, land reclamation, electronics, glass etc. Gravel and sand account for the largest volume of solid material extracted globally with demand set to increase by over 300% across lower- and middle-income regions by 2060.

Action

From an economic perspective, sediments in reservoirs can therefore considered as resources that are ‘out of place’. A financial feasibility assessment was therefore undertaken by Altus Impact to assess the case for using dredged sediments from the THC. The analysis demonstrates that there is ample scope for recovering the investment, operation and maintenance costs, from sales revenues of dredged sediments associated under a first maintenance dredging phase.

Impact

The technical feasibility assessment preceding this report (Siri 2022), demonstrates that maintenance dredging is a crucial starting point for addressing the problems of the THC and a requirement for minimising potential disaster risks.  This experience could serve as a pilot for a much larger reservoir storage recovery program that would help safeguard water, energy and food security, enhance disaster resilience and provide a sustainably supply of raw materials for the construction industry within the Amu Darya watershed. . There is consequently an important opportunity to capitalise on sediments that are currently trapped in the THC reservoirs, and use this bankable component of sediment re-use to help finance the dredging and processing of sediments.

.As such, the value of the sediments can be unlocked by simultaneously targeting the case for extending the lifetime of the hydropower complex, and using them to fill a supply gap of sustainably sourced raw materials for the construction industry. Moreover, by ensuring adequate pricing of key reservoir services – irrigation water and electricity – the effective operation and maintenance of the facility may also be secured in time.

There is ample scope to start cost-recovery efforts and develop fruitful Public Private Partnerships to turn unwanted sediments into economic resources, while financing the preservation of the reservoir function for food, water and energy security.

Further project context and documents may be found here:

EUROPEAN UNION SUPPORTS WATER RESERVOIR SEDIMENTATION TREATMENT EFFORTS IN CENTRAL ASIA.

The economic case for re-using sediment from the Tuyamuyun Hydropower Complex: https://www.water-energy-food.org//fr/resources/publication-meeting-the-demands-of-the-construction-industry-the-economic-case-for-re-using-sediment-from-the-tuyamuyun-hydropower-complex

Related presentation: https://altusimpact.com/wp-content/uploads/2022/10/22.10.2022a-The-case-for-re-use-of-sediment-econ-of-sediment-management.pdf