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A new method for the assessment of formation conditions of rainfall-generated mudflows is proposed. The method introduces two new criteria: minimum (critical) values of rainfall and meteorological force of rain obtained from the data of observations of rainfalls from 1953 to 2014. This is important for the early warning about the risk of mudflows and for timely taken protection measures in restdential areas and other economic obj ects situated in the zone of the possible negative impact of mudflows.

Presented are the results of studying the dynamics of changes in the chemical composition of water from the formation zone to the estuary of the Zeravshan River; also the effects are investigated of the sewage of the Anzob ore mining and processing enterprise on the water quality. It is revealed that the concentration of heavy metals in the river water is far from the maximum permissible concentration, i.e., the ore mining and processing enterprise does not affect water composition variations. It is discovered that in the river lower reaches on the territory of the Republic of Uzbekistan the river water is mainly contaminated with drain-collector and municipal waste water. The chemical analysis revealed the presence of cations and anions in the seasonal snow on the glaciers of volcanic origin in the Zeravshan River basin. According to the observational data for the period of 1998–2012, severe floods occur and mudflows causing the appreciable economic damage are formed in Panjakent and Ayni mountain areas in the Zeravshan River basin.

The main problems of the study of the meteorological regime, climate, hydrology, snow avalanches, mudflows, and glaciers are considered. It is demonstrated that the level of their exploration on the plain territory is sufficient on the whole, however, the mountain territories are poorly studied. The opening of new stations including the automatic ones and the organization of snow-route observations are required. It is necessary to carry out the preparation and publishing of new handbooks on the climate and surface water resources and to create the catalogs of glaciers, snow avalanches, and mudflows on the basis of the modern topographic maps and satellite images.

Regional peculiarities of the direction of climate-related changes in the maximum and minimum river runoff in Russia in the 20th century, frequency and duration of dangerous inundations with economic damage, floods, mudflows as well as lack of water, and low-water periods are under consideration. It is found that for the first years of the 21st century, compared to the last decade of the 20th century, frequency and duration of hazardous inundations during high waters and floods increased in the Upper Ob and Kama river basins, during high waters, in the rivers of the Far East Primorye and Sakhalin, in the Northern Caucasus, the danger induced by mudflows and rain floods increased. In the Lena and Yenisey river basins, the flood hazard was preserved in the case of ice clogging. At the same time, in the Western Siberian, Trans-Baikal, the Amur, and Kolyma basins the frequency of periods with extremely shallow water significantly increased.

Presented are the dependences that allow judging as a rough approximation about the process of accumulation of the cohesive mud mass in mudflow areas till the complete formation of a mudflow in the erosion inset of the main riverbed of a mudflow type.

A criterion ratio is proposed which allows to estimate the possibility of origination of avalanche-like motion of a mudflow with hyperconcentration of debris in a certain mudflow-bearing watercourse.

Hydraulic motion equations of the cohesive mudflow with variable discharge along the way, based on the energy principle and derived by theoretical means, are given. They can form the base for the discovery of algorithms of open hydrological problems in the field of dynamics of cohesive mudflows for both prismatic and non-prismatic channels.

In this paper, a glacial mudflow hazardous lake, Bashkara, is described. Its depth is 32 m and volume exceeds 494400 m3. Quite intensive deformations and destructive processes at the end of Bashkara glacier are noted. The lake debacle probability is consistently growing. A new way to prevent the glacial mudflow that can be caused by the lake debacle is proposed. This way supposes conducting of the uncontrolled lake discharging by digging, filling of the lake with moraine materials, formatting of the lake surrounding dam, and making a drainage outlet in this dam.