ИСТИНА

Volcanism is a unique factor of suspended sediment yield formation in Kamchatka. Volcanic eruptions are the constant source of friable volcanic deposits such as ash, pyroclastic deposits in river basins. They influence on variability of suspended sediment yield characteristics (such as suspended sediment concentration, suspended sediment flux, specific suspended sediment yield and grain-size of suspended sediments) in diurnal, seasonal and long-term spatial-temporal scales. The main goal of this research is the study of volcanic activity impact on suspended sediment yield characteristics variability in different spatial-temporal scales. The study is based on sediment discharge monitoring in Kamchatka rivers under the influence of volcanic eruptions. It also includes fieldwork data in 2003 – 2012 in selected rivers draining the flanks of active volcanoes. The main factors of suspended sediment yield formation in rivers of volcanic regions are water flow, catchment area and distribution of friable volcanic deposits. Regions of modern volcanic activity in Kamchatka are characterized by maximum values of potential soil loss, mean annual suspended sediment concentrations and specific suspended sediment yield. Volcanic eruptions have substantial influence on suspended sediment flux of rivers and can lead to its increase up five-fold after eruptions. Seasonal fluctuations of suspended sediment yield characteristics depend on water regime. Diurnal variability of these characteristics in rivers draining flanks of active volcanoes is defined by snow melt and precipitation. Water regime of rivers is characterized by periodic extinction of surface flow and significant underflow because of high infiltration rates into friable volcanic deposits there.