Figure 1: Anh Tuấn Hương harvesting coffee at his 2.5ha farm in Thôn Cầu 2, Di Linh
This paper presents Mach Thuy Hoan, a closed-loop rainwater harvesting and circulation system designed specifically for sloped farms in Vietnam's Central Highlands. The system consists of five components: Low Heart (underground reservoir, 1,500 m³/ha), High Heart (hill-top reservoir, 150 m³/ha), Lungs (lotus pond, 100 m²), Capillaries (infiltration channels, 10 lines/ha with check dams), and Green Belt (perimeter vegetation). Operating on 100% rainwater with solar and gravity energy, the system maintains stable soil moisture 365 days/year and provides 250 days of drought resilience. Field validation at BrainFarm, Di Linh (2023-2026) during El Niño 2023-2024 (138 consecutive days without rain) showed soil moisture maintained at 65-75% field capacity at 30cm depth, compared to 25-35% in control plots. Investment cost is approximately 250 million VND per hectare with annual operating costs of 10 million VND.
I am Vũ Trường Ca (A Ca). My agricultural journey began in 2006 with farms in Long An (0.72 ha), Đồng Nai (0.13 ha), and Lâm Đồng (0.39 ha). Later, as Chairman of Kim Minh Investment Corporation, I managed a 76.8-hectare project in Đạ Tẻh, Lâm Đồng - an area with a natural stream that seemed to provide year-round water.
The prolonged El Niño drought of 2014–2016 brought devastating losses:
| Crop | Loss |
|---|---|
| Gac fruit | 2.7 hectares completely lost |
| Fruit trees | 0.6 out of 1.2 hectares severely damaged |
| Rubber trees | ~3 out of 15 hectares died |
Despite the presence of water in the stream, we couldn't control it during the dry season. I learned a hard truth:
From these losses, I began researching on-site rainwater harvesting and closed-loop circulation systems. After years of testing in Vietnam's Central Highlands, Mach Thuy Hoan was born - to help farmers achieve water autonomy, reduce crop failure risk, and ensure sustainable harvests.
The Central Highlands of Vietnam receive 1,500-2,600mm of annual rainfall, yet experience 4-6 month dry seasons exacerbated by El Niño events every 2-7 years. Traditional irrigation relies on groundwater extraction, leading to aquifer depletion and high energy costs. This paper documents a field-tested alternative: Mach Thuy Hoan, a system that captures, stores, and slowly releases rainwater through gravity-fed infiltration.
| Component | Specification | Function |
|---|---|---|
| Low Heart (Underground reservoir) | 300 m² × 5m deep = 1,500 m³ | Main rainwater storage at lowest point |
| High Heart (Hill-top reservoir) | 150 m³ (1/10 of Low Heart) | Creates gravity pressure for distribution |
| Lungs (Lotus pond) | 100 m² × 1m deep = 100 m³ | Biological filtration, oxygenation, microclimate |
| Capillaries (Forest channels) | 10 lines, check dams every 5-10m | Slow flow infiltration, subsurface moisture |
| Green Belt | Perimeter vegetation | Erosion control, biodiversity, pest management |
| Parameter | Equipment | Accuracy |
|---|---|---|
| Water flow | Sensus 420 flow meter (Germany) | ±2% |
| Soil moisture | Decagon 5TM sensors (USA) | ±3% VWC |
| Water level | Keller DCX-22 pressure sensors | ±0.1% |
| Weather | Davis Vantage Pro2 | WMO standards |
A control plot of 0.8 ha coffee (same variety, age, soil type) located 500m from BrainFarm used traditional sprinkler irrigation from a 60m deep well. Five Decagon 5TM sensors installed at 30cm depth for comparison.
Dry spell duration: 138 consecutive days without rain (December 1, 2023 - April 17, 2024)
| Parameter | Mach Thuy Hoan | Control Plot | Difference |
|---|---|---|---|
| Soil moisture at 30cm (March 2024) | 65-75% FC | 25-35% FC | +40% |
| Water consumption | 5.8 m³/day (measured) | 8-12 m³/day (estimated) | -40% |
| Coffee yield loss | <5% | 60-80% | -75% |
| Energy cost (dry season) | 2.5 million VND | 18-22 million VND | -88% |
Di Linh rainfall 2024: 1,847 mm (source: National Centre for Hydro-Meteorological Forecasting)
Catchment area: 1.5 ha, runoff coefficient: 0.5 → Calculated harvest: 13,852 m³
Actual storage: 1,480 m³ (post-construction survey) → 250 day supply at 5.8 m³/day consumption
| Item | Cost (million VND/ha) |
|---|---|
| Excavation (underground reservoir) | 80-100 |
| HDPE lining (1.0mm) + installation | 90-110 |
| Solar pump system (2HP + panels) | 30-40 |
| Piping, valves, sensors | 30-40 |
| Lotus pond, channels, planting | 20-30 |
| Total investment | 250-320 |
| Annual operating cost | 8-12 |
Figure 1: Anh Tuấn Hương harvesting coffee at his 2.5ha farm in Thôn Cầu 2, Di Linh
Figure 2: Anh Tuấn Hương at Di Linh highlands - his farm is open for visits
Mach Thuy Hoan demonstrates a viable, field-tested approach to rainwater management for sloped farms in Vietnam's Central Highlands. With 2+ years of operational data from two independent sites, the system shows consistent ability to maintain soil moisture through severe drought while reducing energy costs by 80-90% compared to traditional groundwater pumping. Key innovations include the 5-component biological design, gravity-fed distribution, and dual-layer control system. Limitations include initial investment requirements and site-specific topography needs. Future work includes third-party validation with agricultural research institutes and development of standardized implementation guides.
APA Format:
Vũ Trường Ca. (2026). Mach Thuy Hoan: Closed-loop Rainwater Circulation System for Sloped Farms in Vietnam's Central Highlands. BrainFarm, Di Linh. Retrieved from https://machthuyhoan.pro/en/case-study.html