In a scenario where the climate crisis accelerates the decline in global water availability and more than 40% of the world’s population lives in severely stressed basins, the Guanzhong region faces increasing pressure that threatens the economic and social stability of one of China’s most dynamic industrial corridors. Each year, Shaanxi Province experiences a structural imbalance between supply and demand that intensifies with rising temperatures, irregular precipitation patterns and the progressive reduction of baseflows; while the south holds 71% of available water, the central and northern regions generate over 90% of provincial economic output with only 29% of the resource, creating a deficit reflected in aquifer overexploitation, ecological flow reduction in the Wei River and growing water vulnerability for the city of Xi’an. This tension is amplified in a regional market where industrial demand exceeds 1.2 billion m³ annually, and urban consumption grows at a rate equivalent to more than 350,000 new households per year, requiring solutions that transcend conventional infrastructure and usher in a new stage of intelligent, interconnected and resilient water management.
In this context, the Han-Wei Diversion Project and the Ziwu Water Treatment Plant emerge as a visionary intervention designed to transform water security across metropolitan Xi’an through an interbasin transfer system capable of moving up to 1.5 billion m³/year from the Han River. This infrastructure not only corrects a long-standing asymmetry but redefines regional hydrological balance through advanced multibarrier treatment, dual-membrane processes, ozonation and activated carbon, ensuring superior drinking water quality even under low temperatures and high variability in organic load. The impact is substantial: the transferred volume equals the annual consumption of over 20 million inhabitants and represents a critical input for high-tech industry, surrounding intensive agriculture and core urban services.
Located in Xi’an, within the Guanzhong–Tianshui economic belt at approximately 34.3416°N, 108.9398°E, the project is anchored in the Ziwu Plant, the most advanced treatment facility in northwest China, recognized for its final nominal capacity of 700,000 m³/day. Its purpose lies in the urgent need to secure a safe, diversified and sustainable water supply amid rising demand and the inability of traditional sources to support continued urban expansion. The infrastructure responds to a strategic national priority: guaranteeing reliable water resources to sustain regional competitiveness, protect industrial productivity and stabilize ecologically stressed mountain and lowland systems.
Its commissioning involves a broad ecosystem of actors, including the Shaanxi Provincial Government, Xi’an’s water utility, technical institutes specializing in advanced treatment systems, engineering and construction firms, and verification entities ensuring compliance with national standards and international methodologies. Interinstitutional coordination has been essential to align hydrological planning, quality control, energy efficiency and ecological restoration in the Han and Wei basins.
The connection with Water Positive strategy is evident in the project’s ability to generate verifiable volumetric benefits under the principles of intentionality, additionality and traceability. Each cubic meter supplied to the urban system comes from an alternative source that reduces pressure on previously overexploited rivers and aquifers, while physical and digital traceability ensures that origin, volume and impacts can be audited using methodologies such as VWBA. This integration ensures that the infrastructure not only supplies a growing city but also builds a water management model capable of anticipating risks, regenerating sources and contributing to the long-term environmental and economic stability of the entire region.
The project leverages a decisive technical opportunity derived from the need to improve the efficiency of the regional supply system by integrating a transfer infrastructure that compensates for the structural deficit of the Wei Basin and optimizes operational management during low‑recharge periods. The combination of interbasin transfer and advanced treatment creates a system capable of converting irregular flows into a stable drinking water supply with high standards, enabling energy savings through steady‑state operation, reducing evaporation losses and improving resilience to climatic variability. Operationally, the infrastructure can process over 1.5 billion m³ annually, stabilizing urban supply and reducing dependence on critical, heavily stressed sources.
The impact unfolds at three scales: in the short term, improved water security, immediate reduction of aquifer stress and increased responsiveness to demand peaks; in the medium term, restoration of ecological flows in the Wei River and support for industrial growth in Xi’an; and in the long term, structural transformation of the regional water system through diversified sources, reduced emissions from pumping and the adoption of clean‑energy models that lower the carbon footprint of the water cycle.
Prior to the project, the system faced significant distribution losses, heavy reliance on a single drought‑vulnerable source, limited controlled flow availability and progressive degradation of water quality downstream. Lack of adequate infrastructure to regulate interannual flows caused frequent service interruptions, disruptions to sensitive industrial operations and escalating ecological deterioration.
Exacerbating factors included aquifer overexploitation in the absence of alternative sources, capacity limitations of existing pipelines, absence of technological redundancy under extreme conditions and a regulatory framework that, until the project’s inclusion in national plans, did not consider large-scale transfer solutions. Rapid urban expansion and industrialization increased demand with no system capable of buffering hydrological variability, reinforcing the urgency of structural intervention.
Classified as grey infrastructure with digital integration under VWBA, the project adopts a hybrid technical solution combining interbasin transfer, pressurized conveyance, reservoir regulation and a multibarrier treatment train designed to operate stably under extreme temperature and organic‑load variability. The system includes controlled intake from the Han River, lined tunnels to ensure watertightness, high‑efficiency pumping stations and direct distribution to the Ziwu Plant, where water undergoes physical‑chemical pretreatment, ozonation, granular activated carbon and ultrafiltration, with nanofiltration available when inflow quality requires it.
The infrastructure treats up to 700,000 m³/day and integrates into a transfer system able to mobilize 1.5 billion m³/year, reducing withdrawals from vulnerable sources and improving the quality of water supplied to the city. The technology was chosen for its operational robustness over alternatives such as expanded local abstraction, new dams or desalination, offering lower environmental impact, greater drought resilience and improved energy efficiency.
The intervention resolves structural water shortage, degradation of the Wei River and the inability of the previous system to support industrial expansion. Its design enables flow modulation throughout the year and adaptive quality control through automated chemical dosing and membrane operation.
Quantifiable benefits include substitution of local withdrawals, improved turbidity, COD and ammonium, recovery of groundwater levels and reduced emissions from emergency pumping. Social and economic benefits include supply reliability, reduced operational risk and a more competitive environment aligned with ESG principles.
Key risks include failures in critical equipment, hydrological variability and potential contamination events at intake. Mitigation includes redundancy, by‑pass options, energy backup, continuous monitoring, shared governance and emergency protocols.
Climate resilience is ensured through modularity, dynamic flow adjustment and progressive integration of renewables, along with protocols for emerging contaminants and sudden supply disruptions.
The model is replicable in basins with similar structural imbalances, provided regulatory frameworks, coordinated governance and technical capacity are in place. Its competitiveness is supported by favorable levelized costs, high hydrological resilience and demonstrable Water Positive contributions enhanced by public‑private partnerships and technological cooperation.
The project follows a phased approach ensuring technical rigor and risk reduction. It begins with an exhaustive diagnostic establishing hydrological, quality and operational baselines through supply‑demand balances, characterization of both basins and climate‑risk assessments. Based on this, detailed design covers tunnels, pumping stations, pressurized conveyance and the multibarrier treatment train at Ziwu. Construction includes tunnel excavation and lining, installation of electromechanical equipment and assembly of all treatment units with hydraulic and energy compatibility.
Commissioning proceeds in stages with hydraulic and electrical tests, followed by treatment trials to calibrate chemicals, membranes and operational sequences. Once stable flows and quality are achieved, external audits validate performance prior to continuous operation. Maintenance routines, KPI tracking and hydrological adjustments follow.
Technologically, the system integrates controlled intake, pressurized conveyance and advanced treatment (ozone, activated carbon, ultrafiltration and nanofiltration) under a centralized SCADA with flowmeters, multiparameter sensors and IoT nodes. Chosen for drought resilience, energy efficiency and adaptive quality control, the plant delivers 700,000 m³/day with >95% membrane performance.
The baseline includes historical flow, groundwater levels, water quality and energy consumption, enabling KPIs such as transferred volumes, substituted withdrawals, potability compliance, efficiency and carbon footprint. Measurement uses online sensors, laboratory sampling and remote sensing when necessary.
Traceability is ensured via physical sectorization and a digital platform logging real‑time flow, quality and equipment status, triggering alarms and generating reports for regulators and verifiers. VWBA/WQBA validation and technical audits complement this system.
Governance defines clear roles among the technical operator, basin authorities, verifiers and municipalities. Agreements establish priority use, contingency responsibilities and transparency standards. Maintenance includes scheduled routines, critical spare management and rapid‑response protocols.
Monitoring quantifies transferred volumes, avoided extractions, quality improvements and contaminants removed, continually comparing with‑ and without‑project scenarios. Continuous improvement uses operational data to optimize processes, modernize technology and ensure long‑term benefit durability through long‑term contracts, external verification and reinvestment.
The Han‑Wei Project and Ziwu Plant form a large‑scale hydro‑infrastructure intervention designed to structurally rebalance water availability in Guanzhong, where natural supply has been insufficient to sustain demographic, urban and industrial growth. Technically, the solution is built around an interbasin transfer conveying flows from the Han to the Wei through long tunnels, pressurized conveyance and high‑efficiency pumping, terminating at Ziwu Plant, where a multibarrier treatment train, physical‑chemical pretreatment, ozonation, activated carbon, ultrafiltration and reserve nanofiltration, ensures superior drinking‑water quality even under extreme conditions. The system is sized for 700,000 m³/day at the plant and up to 1.5 billion m³/year transferred, replacing local withdrawals and restoring ecological flows and groundwater levels.
This solution is especially relevant because it addresses chronic supply‑demand imbalance, aquifer overexploitation and water‑quality deterioration in the Wei Basin. Compared to the baseline situation, where Xi’an relied on vulnerable sources and limited infrastructure, the project installs a resilient, redundant and technologically advanced supply system reducing drought exposure, stabilizing quality and improving responsiveness to demand peaks. Its suitability rests on leveraging a more robust upstream source, protecting ecological flows, integrating renewables and aligning with regional land‑use and economic planning.
Expected outcomes include replacing or replenishing ~1.5 billion m³/year, significantly improving turbidity, COD, ammonium and permanganate index, and reducing emissions linked to emergency pumping and inefficient local systems. Additional benefits include ecological restoration, biodiversity protection and public‑health improvements. Water security for agriculture and high‑tech industry strengthens employment and economic stability.
Strategically, the project aligns with Water Positive commitments by generating additional, verifiable and traceable volumetric benefits under VWBA and supporting ESG, SDG, Science Based Targets for Water and European ESRS E3 compliance. Its modular design, digital backbone and shared governance make it replicable in other structurally stressed basins in China and globally, provided institutional and social conditions for interbasin transfer and advanced‑system operation exist. Ultimately, the project signals to investors, clients and society that transitioning toward a more resilient and regenerative water economy is achievable when engineering, basin planning and climate ambition converge in a unified platform for action.
