Precision Ecological Water Dispatch in the Tarim River Basin: Practices and Technical Insights

1. The Problem: Three Decades of River Dry-Up and Ecological Crisis

The Tarim River is the longest inland river in China. Since the 1970s, its lower reaches experienced continuous dry-up, accumulating to nearly 30 years. The direct consequences were a continuous decline in groundwater levels, massive degradation of natural vegetation, and accelerated desertification, pushing the basin’s ecosystem to the brink. For inland river basins in arid regions, the high-intensity artificial extraction of water resources and the spatial-temporal imbalance during river water transmission are the core causes of downstream ecological degradation. Restoring river flow and rebuilding the positive response relationship between groundwater depth and vegetation have become the primary technical challenges in basin governance.

Since 2000, basin management authorities have organized continuous ecological water delivery to the lower Tarim River. By releasing ecological water volumes, they aimed to raise downstream groundwater levels and gradually restore the riparian vegetation belt. This was not a one-off project but a systematic practice requiring long-term iteration, continuous observation, and dynamic adjustment.

2. Precision Evolution of the Water Delivery Model: From “Discharge if Available” to “Precision Control”

The core contradiction in early ecological water delivery was limited water supply against widespread demand. Extensive, concentrated discharges led to high transmission losses and uneven benefit distribution. Through years of practice, the management authorities developed a precision water delivery model during the 14th Five-Year Plan period, characterized by “dual channels, multiple time periods, long duration, and low flow.”

• Dual Channels: Utilizing the mainstream and parallel (or braided) channels for collaborative water delivery. This expands the lateral coverage of water flow, reduces concentrated transmission losses along a single channel, and provides more balanced replenishment to vegetation belts in different sections.
• Multiple Time Periods: Splitting annual water delivery into multiple stages, such as spring and summer, to match plant growth rhythms and glacial meltwater timing. For instance, spring delivery focuses on replenishing prior deficits and ensuring water supply during the vegetation greening period, while summer delivery leverages peak inflow to scale up replenishment.
• Long Duration: Extending the duration of water delivery to avoid riverbed scouring and overflow waste caused by short-term high flows, giving water sufficient time to infiltrate and recharge groundwater.
• Low Flow: Releasing water continuously at lower flow rates to improve the ecological conversion efficiency per unit of water, ensuring that transmission losses convert into groundwater recharge rather than ineffective evaporation and surface loss.

Complementing this is a “three-year rotation, full-area coverage” strategy for watering Populus euphratica (desert poplar) forests. Traditional spot-based watering easily creates localized benefits and overall imbalance. By adopting a three-year rotation cycle and applying full-area coverage to the forest distribution zones, the frequency of water replenishment is balanced across blocks in the time dimension, while spatial omissions are avoided, balancing efficiency and equity.

3. Institutional Restructuring: From “Four Sources, One Mainstream” to “Nine Sources, One Mainstream”

The effectiveness of ecological water delivery depends not only on dispatch algorithms but also on the completeness of management authority. The previous fragmented management structure across source rivers often caused inconsistent dispatch objectives between source rivers and the mainstream, along with high coordination costs for water allocation. In 2024, management decisions integrated multiple source river agencies and key reservoirs under the unified management of the basin authority. By the end of September 2024, the water resource management reform was completed, with dozens of unified units officially assuming their duties, expanding the management structure from “Four Sources, One Mainstream” to “Nine Sources, One Mainstream.”

The essence of this reform is to establish an operational mechanism of “unified planning, unified governance, unified dispatch, and unified management.” At the planning level, ecological water targets and water allocation are centrally determined; at the governance level, river channel regulation and hub construction are unified; at the dispatch level, the water delivery schedule for source rivers and the mainstream is uniformly arranged; at the management level, assessment and monitoring are centralized. For cross-regional, multi-source ecological water replenishment projects, the centralization of dispatch authority is the prerequisite for implementing precision models.

4. Engineering and Digital Support: Hydrological Hubs and Digital Twin Simulation

Engineering-side incremental supply provides the physical foundation for water delivery scale. In September 2025, the Dashixia Water Conservancy Hub began impounding water, adding approximately 3.42 billion cubic meters of annual regulation capacity for the basin’s ecological water delivery. The hub’s ability to store wet-season flows and supplement dry-season flows shifts ecological water delivery from relying on natural inflow sequences to active, adjustable, and plannable dispatch.

Digital-side support is equally critical. In July 2025, the “Digital Twin Tarim River Pilot Construction” project passed acceptance. Its typical capabilities include: building hydrodynamic models based on hydrological monitoring data to simulate water delivery processes; predicting water front arrival times, transmission infiltration volumes, and groundwater responses based on simulation results; evaluating the ecological benefits of different flow schemes before delivery; and dynamically adjusting dispatch parameters during delivery based on measured data. This closed-loop system of “forecasting, pre-acting, pre-planning, and execution” serves as the technical foundation transitioning precision water delivery from experiential judgment to computable dispatch.

5. Implementation Rhythm and Typical Annual Dispatch Example

Using the 27th ecological water delivery as an example, we can observe the phased design of the dispatch organization:

27th Ecological Water Delivery
├── Phase 1 (Spring, started 2026-03-22)
│   ├── Duration: ~15 days
│   └── Planned release: 20 million cubic meters
└── Phase 2 (Summer, started 2026-07-21)
    ├── Duration: ~3 months
    ├── Planned release: 329 million cubic meters
    └── Source river implementation (2026-08-06, Yarkant River)
        ├── Mainstream delivery: 330 million cubic meters
        └── Cross-basin replenishment: 30 million cubic meters to Populus forest area

As of the start date of the second phase, the cumulative released ecological water volume reached 10.7 billion cubic meters. This dispatch structure reveals several characteristics: spring starts with low volumes to test channel flow conditions and cover prior deficits; summer scales up delivery volumes leveraging peak inflow; at the source river level, it simultaneously handles both “mainstream delivery” and “cross-basin ecological replenishment,” reflecting a multi-objective water allocation approach. The cross-basin water transfer to the Populus forest area is essentially precision spot-replenishment via reservoir regulation and canal systems in areas difficult for river flow to reach.

6. Effectiveness Evaluation: Observable Ecological Response Indicators

The effectiveness of ecological water delivery must be verified through quantifiable indicators. Following continuous water delivery, the downstream area exhibited the following responses:

• Groundwater depth significantly decreased (levels rose), providing a stable water source for vegetation root zones along the river;
• Plant species increased from 17 to 81, with community structure trending towards complexity;
• Vegetation coverage increased from 8.35% to 11.62%;
• Bird populations grew significantly, indicating improved habitat quality.

In 2025, 2.43 billion cubic meters of floodwater were diverted to replenish Populus forests, and 1.72 billion cubic meters of ecological water were secured for ecological management at the desert edge. This water resource supports the construction of the ecological barrier around the Taklamakan Desert, which spans 3,046 kilometers and achieved closure on November 28, 2024. From a technical perspective, the value of ecological water delivery lies not merely in the water volume itself, but in transforming “passive protection” into a “vegetation self-sustaining” ecological process through stable moisture supply.

7. Summary of Practical Insights

Based on the practices above, several reusable insights for large-scale basin ecological water replenishment can be extracted:

1. Refined Dispatch Model: Expanding coverage via dual channels, matching phenology via multiple time periods, improving infiltration conversion via long duration, and reducing ineffective loss via low flow. These four elements synergize to form an efficiency-oriented water delivery strategy.
2. Cyclic Replenishment Strategy: Achieving full-area coverage via rotation cycles to balance spatial equity and temporal fairness.
3. Integrated Institutional Management: Unified planning, governance, dispatch, and management serve as the institutional prerequisite for executing precision dispatch.
4. Dual Engineering and Digital Support: Regulation hubs provide water volume flexibility, while digital twins offer simulation and rolling correction capabilities. Together, they reduce dispatch uncertainty.
5. Quantified Effectiveness Evaluation: Using observable indicators such as groundwater depth, species count, and vegetation coverage to form a closed-loop validation of dispatch schemes, creating a continuous “dispatch-observe-correct” iteration.

In 2026, a new round of the “Mother River Revival” initiative will commence, and the second phase of the 27th water delivery continues. For technical professionals engaged in basin governance, ecological hydrology, and water resource dispatch, the Tarim River Basin practices provide a complete reference sample from mechanism design to execution: unifying management to streamline the decision chain, applying precision dispatch to improve water efficiency, leveraging engineering and digital capabilities to control uncertainty, and ultimately validating engineering value through observable ecological indicators.