Suspended load in the Aktru River and peculiarities of its regime over the last 50 years

Mountain rivers with glacier-derived nourishment bring an appreciable quantity of water-borne dust - stream load. The principal supplier of fragmentary materials is glaciers. The glacier attrites the foot of massive materials to the smallest rates - less than a thousandth of a millimeter. At the same time the stream load has larger items - river gravel and granule round stone. However, despite a significant mountain rivers' turbidity regular water observation of this phenomenon is not realized in every region of our country. Water observation was realized at the hydrometeostation Aktru for a month by a standard instrument - the bathometer. Water measurement was made at the same time. The records of water measurement were fixed by the logger Valdai. The water rate was obtained daily by a hydromet-ric current meter for the period of 14 to 23 of July. Diurnal variations of water depend on the solar altitude - the max is at 2.00-4.00 p.m. when the sun is at zenith. At this time the bulk of water reaches the section line of the measurements. The min of the water level is at 8 а.m. At night the ablation reduces to a minimum. The water level decreases. The abrupt jump of turbidity on July 14, 2012 is considered separately. On this day at 4 p.m. the turbidity of 27500 g/m was registered. For reference, in 1962 the max level of turbidity was 6820 g/m, in 1958 - 1560 g/m, in 1957 - 1487 g/m. Yet, I.M. Kolushkina, V.V. Vasilyev, I.K. Kovalev marked that the 1962 turbidity was anomalously high. It happened because of the extended rain period on July 13-14. At the same time earth falls and mudflows moved down from the flanks of the mountain the dome of the three lakes. The max turbidity of glacial origin was 5181 g/m. The flood of the airborne hirst of 2012 with 16.4 kg/s is greater than that of 1962 with 8.99 kg/s. The max of water turbidity was on July 14, 2012 with 357 kg/s. The measurements were made in the upper zone of the Aktru River at different times of the day. Altogether, the max turbidity of the Small Aktru in 2012 was 1824 g/m in 1962 it was 4582 g/m on August 1. Another part of observations in 2012 was sediment gradation analysis. The selection of samples was realized at the different levels of spring flood including but not limited to July 14. The results of the grain-size analysis indicate that sediments are mainly (30% to 60%) composed of particles with the size of 0.5 to 0.1 mm. The composition of the sediments of July 14 is different. The particles are 0.1-0.05 mm.

Keywords

Authors

References