Ice-penetrating radar and kinematic GPS observations from Subglacial Lake Whillans (SLW), West Antarctica, reveal a shallow lake that is confined by steep basal topographic features. Radar imaging of ...SLW, although indicating wet basal conditions, is consistent with a water column depth of only ~6m or less during the near low-stand state at the time of the survey. Kinematic GPS profiles reveal that SLW is generally defined by a ~15m surface depression centered at S 84.237° W 153.614°. This point coincides with the area of lowest hydropotential in the lake basin and also the largest surface elevation range in ICESat data. Therefore this location appears to be an opportune site for subglacial access drilling of this active subglacial lake. A distinct basal topographic ridge on the grid south side of the basin is coincident with a strong contrast in relative basal reflectivity (~6dB), which we interpret as the lake boundary. Mapped hydropotential (calculated assuming hydrostatic equilibrium) shows that water enters the lake from the upstream direction and drains downstream. We hypothesize that a lake-level rise of ~5m plus flexural effects is sufficient to overtop a drainage divide. Thus SLW acts as a temporary storage basin for water beneath Whillans Ice Stream.
► Radar and GPS surveys geophysically characterize a dynamic subglacial lake. ► Subglacial lakes store and release transient water flow impacting ice dynamics. ► A depression in hydropotential coincides with the greatest surface elevation change. ► Ice flexural effects may play a key role in lake drainage. ► Water flux during filling (or draining) is modest (∼10m3/s).
Firn thickness across the NE Greenland Ice Stream is a function of accumulated strain, with thinner firn in the high‐strain margins of the ice stream. We present a novel technique for extracting firn ...density from previously collected seismic reflection profiles and apply this technique across both shear margins of NE Greenland Ice Stream. Firn is up to 30 m thinner in the vicinity of the ice stream shear margins. Snow accumulation rates across the ice stream were calculated from airborne ice‐penetrating radar data, calibrated with ground‐based firn density measurements from a shallow core. We find that accumulation is ~20% higher in the shear margins compared to the surroundings. The higher density firn adjacent to shear margins is due to high along‐flow stresses that accelerate firn densification and develops despite the higher accumulation rate favoring lower density. These firn density variations influence subglacial hydropotential by changing the ice surface slope and overburden pressure and may influence subglacial water flow. These results demonstrate the importance of high‐resolution firn surveys in studies of shear‐margin dynamics.
The evaluation of ecosystem services is a method of estimating the value of the natural capital of a defined territory. This article examined the approaches to an evaluation of ecosystem services as ...a method of an ecological-economic evaluation of the efficiency of hydropower projects.
The paper presents the results of a study of the structure of Russia's hydropower potential, which is estimated at ~2900 bln kWh of electricity generation per year. The hydropower potential of Russia ...is 9% of the global potential and is the 2nd in the world in terms of volume. The potential has been developed by 20%. Preliminarily, the distribution of hydropower resources across the territory of Russia is sharply uneven: 80% is in Siberia and the Far East, 20% is in the European part of the country. One of the conditions for the prospective development of the Russian hydropower potential is to obtain data on its current structure and the degree of development of the potential in the regions, and in the interregional and technologically isolated power systems in Russia. Also, such a structure is necessary for various types of hydroelectric power plants. The numerical of such results are given in the work.
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