Sedimentology and Clast Orientation of Deposits Produced by Glacial-Lake Outburst Floods in the Mount Everest Region, Nepal

Abstract

Climatic wanning during the last 100 to 150 years has caused many alpine glaciers to thin and retreat (Grove, 1990; O’Connor and Costa, 1993; Evans and Clague, 1994). This glacial downwasting has disturbed geomorphic systems in mountainous environments, increasing the risk of geologic and hydrologic hazards such as glacial-lake outburst floods, landslides, and glacier avalanches (O’Connor and Costa, 1993; Evans and Clague, 1994). Glacial-lake outbursts are perhaps the most devastating of these processes because they can travel tens to hundreds of kilometers downstream dramatically modifying channel morphology and, in some cases, causing loss of human life and destruction of property. The devastating effects of glacial-lake outburst floods have been documented in the Andes (Lliboutry et al., 1977), Himalayas (Hewitt, 1982; Fushimi et al., 1985; Ives, 1986; Vuichard and Zimmermann, 1986, 1987), Canadian Rockies (Clarke, 1982; Blown and Church, 1985; Desloges and Church, 1992; Evans and Clague, 1994), Swiss Alps (Haeberli, 1983; Haeberli et al., 1989), and Cascades (O’Connor et al., in press).