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Vädrets betydelse för snöavsmältningen i Tarfaladalen

Finnander, Maj-Lena (1989) In Lunds universitets Naturgeografiska institution - Seminarieuppsatser
Dept of Physical Geography and Ecosystem Science
Abstract
In order to study the influence of the weather on the snowmelt in the Tarfala Valley, a survey of the runoff from the snow in the valley, was performed in May and June 1988, at the Tarfala Research Station. The aim of the survey was to find a simple numerical model that corresponds well to the runoff from the snow and to identify reasons for deviating runoff in different places.
The survey was based on daily stake readings of snowdepth and several density measurements in four profiles with different exposure towards the sun. The waterequivalent each day for all the stakes was calculated and used for estimating the daily runoff. The density was assumed to be proportional to the snowdepth and to change linearly between the days of density... (More)
In order to study the influence of the weather on the snowmelt in the Tarfala Valley, a survey of the runoff from the snow in the valley, was performed in May and June 1988, at the Tarfala Research Station. The aim of the survey was to find a simple numerical model that corresponds well to the runoff from the snow and to identify reasons for deviating runoff in different places.
The survey was based on daily stake readings of snowdepth and several density measurements in four profiles with different exposure towards the sun. The waterequivalent each day for all the stakes was calculated and used for estimating the daily runoff. The density was assumed to be proportional to the snowdepth and to change linearly between the days of density measurements. The calculated runoff was compared with the data registered by the datalogger belonging to the station.
Diagrams and correlations were made between the calculated runoff and the meteorological parameters, to determine whether any of the parameters could be used for estimating the runoff. The runoff values for each profile and for each stake were compared to each other, to study the influence of snowdepth and of exposure towards the sun on runoff.
The importance of the different meteorological parameters was difficult to estimate, as measurements of the humidity of the atmosphere were lacking from the data. The average daily temperature shows a fairly high correlation with runoff (0.89). Use of the degree-day method according to Male & Gray (1981) did not increase the correlation, and was rather timewasting. The constant can be used as the degree-day factor, if the daily mean temperature is assumed to be proportional to the runoff. Tests with regression analysis gave the coefficient 4.55 mm/°C and day, and a constant of 3.27 mm/day. As the constant is fairly high, the runoff will be too low, if the constant is not considered in the calculations. The degree-day melting factor does however vary during the melting season, primarily due to the changing albedo of the snow, and should also be calibrated every melting season.
To make statistical evaluations it was considered necessary to estimate the runoff every day during the field period, even though there was a risk that the errors in the measurements would exceed the calculated runoff variations. A longer measurement period would make it possible to estimate the runoff every four to eight days, which would give a more reliable result. (Less)
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author
Finnander, Maj-Lena
supervisor
organization
year
type
M2 - Bachelor Degree
subject
keywords
geografi, naturgeografi, snöavsmältning, Tarfaladalen
publication/series
Lunds universitets Naturgeografiska institution - Seminarieuppsatser
report number
14
language
Swedish
id
2173232
date added to LUP
2011-10-11 10:24:25
date last changed
2011-10-11 10:24:25
@misc{2173232,
  abstract     = {In order to study the influence of the weather on the snowmelt in the Tarfala Valley, a survey of the runoff from the snow in the valley, was performed in May and June 1988, at the Tarfala Research Station. The aim of the survey was to find a simple numerical model that corresponds well to the runoff from the snow and to identify reasons for deviating runoff in different places.
The survey was based on daily stake readings of snowdepth and several density measurements in four profiles with different exposure towards the sun. The waterequivalent each day for all the stakes was calculated and used for estimating the daily runoff. The density was assumed to be proportional to the snowdepth and to change linearly between the days of density measurements. The calculated runoff was compared with the data registered by the datalogger belonging to the station.
Diagrams and correlations were made between the calculated runoff and the meteorological parameters, to determine whether any of the parameters could be used for estimating the runoff. The runoff values for each profile and for each stake were compared to each other, to study the influence of snowdepth and of exposure towards the sun on runoff.
The importance of the different meteorological parameters was difficult to estimate, as measurements of the humidity of the atmosphere were lacking from the data. The average daily temperature shows a fairly high correlation with runoff (0.89). Use of the degree-day method according to Male & Gray (1981) did not increase the correlation, and was rather timewasting. The constant can be used as the degree-day factor, if the daily mean temperature is assumed to be proportional to the runoff. Tests with regression analysis gave the coefficient 4.55 mm/°C and day, and a constant of 3.27 mm/day. As the constant is fairly high, the runoff will be too low, if the constant is not considered in the calculations. The degree-day melting factor does however vary during the melting season, primarily due to the changing albedo of the snow, and should also be calibrated every melting season.
To make statistical evaluations it was considered necessary to estimate the runoff every day during the field period, even though there was a risk that the errors in the measurements would exceed the calculated runoff variations. A longer measurement period would make it possible to estimate the runoff every four to eight days, which would give a more reliable result.},
  author       = {Finnander, Maj-Lena},
  keyword      = {geografi,naturgeografi,snöavsmältning,Tarfaladalen},
  language     = {swe},
  note         = {Student Paper},
  series       = {Lunds universitets Naturgeografiska institution - Seminarieuppsatser},
  title        = {Vädrets betydelse för snöavsmältningen i Tarfaladalen},
  year         = {1989},
}