Rainfall Simulator
In 2007, the Water Research Laboratory commissioned a rainfall simulator for the investigation of surface runoff and infiltration processes under field conditions. The rainfall generator has been built to enable more rapid field testing and based around a published design to achieve size distributions and at-surface droplet velocities that are as similar as possible to natural rainfall.
Specifications of simulated rainfall:
- Variable rainfall intensities ranging from 70 mm/hr to 180 mm/hr with potential for generation of temporal patterns
- Drop size distribution similar to those of natural rainfall with near vertical impact
- Drop impact velocity at the terminal velocity of natural rainfall
- Near uniform rainfall intensity over a test area of 6 m x 6 m (36 m2)
Whilst infiltration and runoff behaviour can be estimated by a range of hydrological techniques, the simulator has been designed to obtain real runoff and infiltration data not accessible using other systems. The large test area gives it the potential to be linked to subsurface monitoring. An entire monitoring system would provide unique data regarding rainfall, runoff, soil moisture response and subsurface recharge. The rainfall simulator is transportable to multiple sites to determine spatial recharge functions across natural landscapes. This type of recharge measurement is critical to provide base-line data and independent verification of numerical groundwater flow models.
Potential applications include:
- Rainfall-runoff-infiltration determination
- Soil moisture response to rainfall events
- Water balance investigations
- Determination of cross-catchment rainfall response
- Surface and subsurface contaminant mobilisation studies
- Rainfall surface mobilisation investigations
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