Case study · Rice farming · Po Valley
Securing a 20,000 m² headwater basin for a rice irrigation consortium in Vercellese
A Vercellese irrigation consortium (Piedmont) operated a 20,000 m² storage basin feeding 350 ha of Balilla and Carnaroli rice. With Po water tension and a reference evaporation rate of 1,000 mm/year, the technical office quantified passive losses before deploying modular Hexprotect AQUA floating covers.
- 20,000 m²
- Headwater basin surface area
- 1,000 mm/year
- Reference evaporation E_ref (ARPAE, Vercellese)
- 20,000 m³/year
- Gross loss V = (S × E_ref) / 1,000
- 17,600 m³/year
- Secured volume V × η (η = 0.88 conservative)
Consortium context
Irrigation consortium grouping 42 farms and 350 ha of Balilla and Carnaroli rice in Vercelli province. The 20,000 m² headwater basin, fed by winter withdrawals from the Sesia and network top-up, regulates volumes before spring field flooding and summer support. In 2024–2025, falling Po flows and basin authority restrictions made every cubic metre stored off-paddy strategic for holding the crop calendar.
Initial diagnosis
Pre-cover water balance: V = (20,000 × 1,000) / 1,000 = 20,000 m³/year evaporated from open water. At an estimated water cost of €0.12/m³ (consortium fees and pumping), passive loss exceeded €2,400/year — excluding spring flooding delay risk if the headwater basin missed target volume. Surface algae and turbidity increased quality control operations before routing to fields.
Solution deployed
Hexprotect AQUA PEHD hexagonal modules deployed by direct pour on a shallow basin (1.8 m average depth), without structural supports or embankment modification. Modular cover adapts to large horizontal surfaces typical of rice headwater basins. Deployment completed in two weeks during winter off-season, without interrupting the distribution network.
Measurable results
With conservative η = 0.88, secured volume reaches 17,600 m³/year — 88% of gross loss intercepted passively, with zero energy use. That volume matches support needed to secure flooding for over 70 ha in a year of moderate water tension. Water-mass thermal stability also reduced surface temperature swings, valued during the emergence phase.
Lessons for rice farming
In the Po Valley, evaporation on headwater basins is often the first leak in the annual balance — before infiltration or overflow losses. An on-site audit refines E_ref (wind, shading, depth) and η (80–96%). This Vercellese profile applies to rice basins in Lombardy (Pavia, Mantua) and Emilia-Romagna where E_ref ranges between 900 and 1,100 mm/year.
Frequently asked questions about this case
Do you cover flooded paddies?
No. Hexprotect AQUA is never installed on inundated crop plots, where photosynthesis is essential. We work only on storage basins, regulation reservoirs and supply canals upstream of the paddies.
Is the cover compatible with a shallow basin?
Yes. Hexprotect AQUA modules float on the surface and adapt to low-depth basins typical of rice reservoirs. An on-site audit validates geometry, maintenance access and withdrawal points.
Why η = 0.88 instead of 0.96?
0.88 is Hydropreserve's conservative coefficient for Europe (80–96% range depending on wind and geometry). 0.96 reflects the maximum measured under extreme arid conditions (Nevada 2024, AWTT / Hexprotect AQUA reference).
What is the source for E_ref = 1,000 mm/year?
Consistent with ARPAE references for Vercellese and the 900–1,100 mm/year range on the rice farming culture page. An on-site audit refines the value for actual basin exposure.
Calculation: V = (S × E_ref) / 1,000. Secured volume = V × η with η = 0.88 (conservative coefficient). Representative profile based on a typical Po Valley rice consortium — figures to be validated by on-site audit. See Methodology for the full protocol.