In 1972-1978, the Kazakh Research Hydrometeorological Institute (KazNIGMI) for the first time in the world conducted experiments on the artificial reproduction of debris flows on a natural scale.
The purpose of these experiments was to identify the mechanisms and conditions that determine the main characteristics of the debris flow (flow rate and volume), as well as debris-flow mass (density, viscosity and plasticity).
In 1968, the specialized design bureau (SKB) of the Kazgeofizpribor plant received an order from KazNIGMI for the development of devices for debris flows characteristics measurements. Under the leadership of Dr. B.S. Stepanov (head of the Bureau of the SKB of the Kazgeofizpribor plant), devices for non-contact measurement of debris flows characteristics and methods for measuring the debris-flow mass density and discharge of water flow and debris flow in the mountain rivers were developed. All devices and measurement methods had the copyright certificates of the USSR.
The experiments were conducted under the guidance of Dr. Yu.B. Vinogradov (head of the Debris flow department of KazNIGMI) and with his direct participation in the upper reaches of the Chemolgan River. During the experiments, measurements were carried out by employees of the SKB of the Kazgeofizpribor plant under the leadership of B.S. Stepanov.
As a result of experiments, it was found for the first time that:
1) The interaction of a water flow with debris can lead to the formation of a debris flow with a density of debris-flow mass of more than 2400 kg/m3 (previously it was assumed that the density could not exceed 1690 kg/m3);
2) The average speed of movement of the solid component and the water component of debris flow are equal (previously it was assumed that the velocity of the water component exceeds the velocity of the solid component);
3) The solid component of the debris flow moves due to its own potential energy (and is not transported by the water component, as previously thought);
4) With the density of the solid component equal to 2650 kg/m3, the threshold density of the debris flow below which it should be classified as a suspended stream (flood transporting sediments) is 1452 kg/m3.
These experiments have made a major contribution to the worldwide debris flow study.
A scientific documentary film about these experiments can be viewed here: https://www.youtube.com/watch?v=rlYNHqqGjPo.