Details

Autor(en) / Beteiligte

• LEAVESLEY, GEORGE H.
• LUSBY, GREGG C.
• LICHTY, ROBERT W.

Titel

Infiltration and erosion characteristics of selected tephra deposits from the 1980 eruption of Mount St. Helens, Washington, USA

Ist Teil von

• Hydrological sciences journal, 1989-06, Vol.34 (3), p.339-353

Ort / Verlag

Wallingford: Taylor & Francis Group

Erscheinungsjahr

1989

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Infiltration and erosion characteristics of two tephra deposits from the 1980 eruption of Mount St. Helens, Washington, were evaluated using a rainfall simulator and selected process models. The deposits were a 20 cm thick silty-sandy profile in the Shultz Creek drainage and a 35 cm thick profile containing a 15-20 cm pumice-gravel layer in the Clearwater Creek drainage. At Shultz Creek, infiltration was affected by surface crusting and erosion. Steady-state infiltration rates ranged from 0.21 to 0.51 cm h −1 in September 1980, and from 0.41 to 0.71 cm h −1 in August 1981. Rill erosion countered the effects of crusting by exposing the more permeable tephra and pre-emption surface. Erosion rates in 1980 decreased rapidly with successive rainfall simulations. Erosion rates in 1981 were 65-80% less than those in 1980 and were more stable. At Clearwater Creek, surface crusting was less evident and sheet erosion was dominant. The steady-state infiltration rate in 1981 was 2.92 cm h −1 . The surface runoff volume was small but subsurface flow through the pumice gravel was substantial.