Hydrometric monitoring of the River Virkisá

Helen Bonsor undertakes sampling of river water

Andrew Black performs a stream gauge of the upper reaches of the Virkisá

Virkisjökull-Falljökull foreland and proglacial lake area

A team from BGS and the University of Dundee has been studying the Virkisjökull-Falljökull glacier's main outflow river, the Virkisá, since 2012, as part of ongoing research and monitoring at the BGS glacier observatory in south east Iceland.

Why measure the River Virkisá?

As it is the only major surface drainage from the glacier and its valley, the Virkisá is an ideal site to measure the total surface discharge resulting from both precipitation inputs to the catchment in terms of rain and snowfall, and the melting of the glacier ice.

Our findings have real-world importance for areas where large numbers of people rely on water from glaciated areas. Countries such as India and Nepal are at least partially dependent on water from glacial catchments for domestic, agricultural and industrial uses. The evolution of these water supplies and their future security are of critical importance to millions as the Earth's climate continues to change, and our glaciers diminish.

The challenges

Long term monitoring of glacial rivers is extremely difficult, due to a combination of factors.

Highly variable discharge resulting from daily and seasonal ice and snow melt and heavy precipitation typical of mountainous areas means that river levels vary constantly from extremely low flows in the cold, dry periods of the winter, to extreme flows during storms, the spring thaw and in hot weather. This has the knock-on effect of creating very changeable channel conditions, with high bedload (sediment) transport and movement of the channel course sometimes on a daily basis.

Very low temperatures during the winter lead to freezing of the river, reducing overall flow, but with ice on the surface giving 'false' readings of water height.

As a result there are few studies globally that reliably record water balance from glaciated catchments.This challenge has been tackled head on by Dr Andrew Black, a leading hydrologist and hydrometrist from the University of Dundee.

Collaboration with the University of Dundee

BGS has benefitted from Andrew's expertise in projects across the UK, and he is a key part of the Iceland project team. He has designed a sensor network at the Virkisá, incorporating two stream gauge sensors (water level) and a water surface velocity radar sensor. These are supplemented by two cameras giving a visual indication of river conditions.

In order to calibrate these sensor readings and to develop the all-important rating curve Andrew, with the help of various BGS staff members and Dundee MSc and PhD students, has manually gauged the river during all seasons and weather over the last three years, often wading waist deep in the chilly waters.

In this way we have been able to determine the seasonal and annual discharge from the catchment, which we can relate to precipitation and temperature data from our weather stations, and to our measurements of ice melting from the glacier. By incorporating the data from our groundwater borehole network, we are able to make very good estimates of total water output from the catchment and see how these vary as a result of seasonal or longer climate variation.

Contact

Contact Jez Everest for further information.