While the sun is shining today Marlborough is waterlogged, with soils holding more water than is usual for this time of year, making ponding and surface flooding slow to disappear.

Council hydrologist Val Wadsworth says soils are struggling to cope with further rain because soils are already saturated from heavy rains in February, and regular rainfall since then.

“After a dry October, November and December, we had above-average rainfall in January, and then 180 millimetres in February. March and April were above average as well, May was 15 per cent above average, June was below, but we’ve already had 48mm in July.”

Usually, evapotranspiration reduces moisture levels but that hasn’t happened so much this year because of the regular rainfall.

Soil moisture levels are quite full and it “doesn’t take much” to cause large amounts of runoff, he says.

Anecdotally, there are some changes to groundwater caused by the 2016 earthquake, which are expected to come back to previous levels eventually, but Val says the biggest cause of the runoff experienced around Marlborough is the high soil moisture levels.

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