TR(BR)-153 : Development of a weighing type snow water equivalent sensor

Abstract

The estimation of water resources from the snow bound regions requires continuous monitoring of several hydro-meteorological parameters at remote locations. Limited accessibility of these sites inhibits regular maintenance of such instruments, especially if these are of manual operating types (e.g. non-recording or daily/weekly recording types). Subzero temperatures, high precipitation and strong winds are additional factors which prevent continuous operation of such manual instruments. Under extreme conditions, therefore, robust instrumentation, with a fair degree of assured automated operation, is required.

Although snow plays a vital role in our lives as a primary source of the water supply in India, so far the country lacks a coordinated effort for obtaining accurate, reliable and timely information on the extent and water content of the mountain snowpack. To a limited extent, manual snow surveys have been conducted to access this vital resource. Under a few bi-lateral or collaborative projects, some automated instruments were also deployed at a few selected sites. Due to various operational problems, these automated instruments could not be sustained for long. Since, in the Indian context, maintenance problems are generally associated with imported equipment, it is necessary that equipment with indigenous expertise and technology are developed within the country.

In order to cater to this long felt need, the National Institute of Hydrology initiated the development of automated, yet simple, instruments for measurement of the snow water equivalent (SWE). The basic idea was to develop the sensors with indigenously available components and use a versatile, and readily available, data logger along with the other required components (e.g. battery, solar panel) for in-situ SWE measurements. With about two years of efforts, the Institute has been able to develop a prototype of an automated instrument for SWE measurements.

The SWE instrument comprise a weighing platform with strain gauge based load cell, a Campbell Scientific data logger (CR10), a PT107 thermistor temperature probe, SPV supported battery pack and suitable enclosure for housing the electronics. After conducting an extensive laboratory testing, the prototype instrument was first installed at a site near Chilla Top (Jammu & Kashmir) in the winter of 1993-94 and later at Kaddukhal (Garhwal Himalayas, U.P.) in the winter of 1994-95. After initial problems with the battery, the instrument was successfully tested during the winter of 1995-96 near Dhanaulti in Garhwal Himalayas. In this report, development of the snow gauge and preliminary results of the testing are reported.