Tristan da Cunha Weather

Mid-Summer 2007 Rainfall gets gulches flowing

Despite Tristan da Cunha's heavy rainfall (over 1600mm at sea level annually), the porous volcanic ash soils mean that most rainfall infiltrates the soil and flows as ground water to springs along the beaches (and in occasional streams on plains including the Big Watron east of The Settlement). The exceptions are areas of peat bog, especially on the lower base, which act as a sponge and release water slowly in streams, often flowing in narrow valleys known locally as 'gutters'.

During heavy rain, excess water runs off the surface and into gulches, often deep ravines on the mountain slopes. These normally dry, boulder-strewn valleys suddenly fill up with water and disgorge their loads over the edge of the cliffs as waterfalls or torrents. Occasionally these sound like a thunder storm as huge boulders (up to 20 tonnes in weight) are rolled over the cliffs by the force of the water, disgorging them onto the plains below.

This photograph taken on Tuesday 9th January by Janice Hentley shows the waterfall of Caves Gulch, and further east the cataracts of Plantation Gulch, as they disgorge their load of water, sand and stones to the outwash plain of Pigbite beyond the 1961 lava flow.