The effect of flow impedance on deposition of Cryptosporidium parvum oocysts with or without a vetiver buffer strip

Cryptosporidium parvum oocysts can be transported in overland flow from faecal deposits of grazing animals causing potential water contamination problems. Deposition of oocysts can occur when overland flow encounters vegetative buffers and its transport capacity is decreased in the upslope backwater region. Deposition of oocysts was investigated using a large rainfall simulator, with and without a vetiver buffer strip. Oocysts-spiked slurries were applied to two contrasting soils and the resultant oocyst/sediment depositions from the flow were compared. The buffers substantially reduced suspended sediment loads from the two soils and increased the oocyst concentration in the soil with >99% of the deposited oocysts measured upslope of the buffer.