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This study presents a dataset on long-term multidisciplinary glaciological, hydrological, and meteorological observations and isotope sampling in a sparsely monitored alpine zone of the North Caucasus in the Djankuat research basin. The Djankuat glacier, which is the largest in the basin, was chosen as representative of the central North Caucasus during the International Hydrological Decade and is one of 30 "reference" glaciers in the world that have annual mass balance series longer than 50 years (Zemp et al., 2009). The dataset features a comprehensive set of observations from 2007 to 2017 and contains yearly measurements of snow depth and density; measurements of dynamics of snow and ice melting; measurements of water runoff, conductivity, turbidity, temperature, δ18O , δ D at the main gauging station (844 samples in total) with an hourly or sub-daily time step depending on the parameter; data on δ18O and δ2H sampling of liquid precipitation, snow, ice, firn, and groundwater in different parts of the watershed taken regularly during melting season (485 samples in total); measurements of precipitation amount, air temperature, relative humidity, shortwave incoming and reflected radiation, longwave downward and upward radiation, atmospheric pressure, and wind speed and direction – measured at several automatic weather stations within the basin with 15 min to 1 h time steps; gradient meteorological measurements to estimate turbulent fluxes of heat and moisture, measuring three components of wind speed at a frequency of 10 Hz to estimate the impulse of turbulent fluxes of sensible and latent heat over the glacier surface by the eddy covariance method. Data were collected during the ablation period (June–September). The observations were halted in winter. The dataset is available from PANGAEA (10.1594/PANGAEA.894807, Rets et al., 2018a) and will be further updated. The dataset can be useful for developing and verifying hydrological, glaciological, and meteorological models for alpine areas, to study the impact of climate change on hydrology of mountain regions using isotopic and hydrochemical approaches in hydrology. As the dataset includes the measurements of hydrometeorological and glaciological variables during the catastrophic proglacial lake outburst in the neighboring Bashkara valley in September 2017, it is a valuable contribution to study lake outbursts. [ABSTRACT FROM AUTHOR]

During the night of September 1, 2017, a disastrous debris flood occurred in the valleys Adylsu and Baksan (Mt. Elbrus area, Kabardino-Balkaria Republic, Russia). There were three casualties. More than 3.4 km of the highways were destroyed and damaged. About 8000 local people and tourists were blocked without transportation, power supply and telephone connection. There was no gas supply in six settlements. According to the official data the cost of the emergency and reparation works amounted to 10 mln EUR.The debris flood was caused by the outburst of the Bashkara glacier lake. The burst has been triggered by abnormal rainfall in combination with strong overmoistening of a loose material. The volume of the liquid phase of the flow was about 1 million m3, volume of solid phase entrained along flow path was about 0.35-0.5 million m3. We also note that similar amount of rain has been registered 3 times since 2008, but moraine dam was stable. Besides rainstorm lowering of the Bashkara glacier surface disturbed dam stability and amplify effect of rain.The Bashkara glacier lakes have been monitored since 1999, repeated bathymetric surveys were performed using echo-sounder, water level was measured automatically by different gauges. The geophysical survey was performed on the Bashkara glacier snout. An automatic weather station is located at the distance of 500 m from Bashkara Lake. Increase of outburst probability and hazard has been reported in many studies. Numerical simulation of potential GLOF has been realized in FLO-2D software and reflects situation which observed ten years ago. Considering that lake has been dammed by moraine dam and glacier snout it was proposed that lake will drain through englacial channels.According to field data gathered immediately after event, the real outburst scenario was differed from the proposed one. Moraine dam was destroyed by erosion and flow travelled through glacier surface. The availability of detailed data on the Bashkara GLOF allowed us to perform the debris flow simulation. High resolution DEMs before and after event were generated from SPOT-6 and Pleiades stereo pairs, consequently. RAMMS:DEBRISFLOW and STREAM-2D software were used for simulation. According to the modelling, we assumed the mudflow was the water-stone type, had speeds of up to 6 m/s on average and density about 1450 kg/m3. Modelled flow velocity, depth and inundation area correlate well with observed values, but the results from RAMMS software were better than from FLO-2D and STREAM-2D. RAMMS is more suitable for the modelled conditions, since it takes into account the slope steepness, turbulence and flow viscosity in mountains. The other models, originally developed for water flows in plains, require more careful calibration and cannot fully take into account mountain conditions.We thank Russian Foundation for Basic Research, project 18-05-00520 for funding. [ABSTRACT FROM AUTHOR]