| 1. |
- Irannezhad, Masoud, 1983, et al.
(författare)
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Long-term variability and trends in annual snowfall/total precipitation ratio in Finland and the role of atmospheric circulation patterns
- 2017
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Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X. ; 143, s. 23-31
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Tidskriftsartikel (refereegranskat)abstract
- This study evaluated variabilities and trends in annual snowfall to total precipitation (S/P) ratio at Sodankyla, Kajaani and Kaisaniemi weather stations in northern, central and southern Finland during 1909-2008. Annual S/ P ratio was estimated using daily precipitation and temperature records as input to a calibrated and validated temperature-index snowmelt model developed to simulate snowpack accumulation and melt processes in Finland. Factors controlling variations in annual S/P ratio and their relationships with large-scale atmospheric circulation patterns (ACPs) were also studied. The results show that there were significant declines in annual S/P ratio during 1909-2008, which were principally attributable to century-long decreasing trends in annual snowfall (S) in Finland. These reductions in annual S were predominantly controlled by both annual rainfall (R) and snowfall-day temperature (ST) in the south, annual ST in the centre, and annual R in the north. However, dividing the 100-year study period into an early (1909-1958) and late (1959-2008) periods revealed non-linear trend behaviours in annual S and consequently annual S/P ratio during 1909-2008. The Arctic Oscillation, East Atlantic, East Atlantic/West Russia and Scandinavia patterns were the most influential ACPs for annual S variability.
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| 2. |
- Klove, B., et al.
(författare)
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A study of K variability and its effect on solute transport in subsurface-flow sand filters by measurement and modelling
- 2005
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Ingår i: Journal of Environmental Science and Health. Part A. - 1093-4529 .- 1532-4117. ; 40:07-jun, s. 1123-1132
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Tidskriftsartikel (refereegranskat)abstract
- Hydraulics of subsurface flow filters (SSF) was studied by measurement of soil hydraulic conductivity (K) variation and performing tracer tests in two SSF filters consisting of 1-4 mm Ca rich sand (shell sand). Soil samples were carefully taken at several locations in Filter I. A tracer experiment was conducted in the undisturbed Filter II using KI. The measured K variability in Filer I was used to analyze the variations in tracer breakthrough. The spatially distribution of K was obtained by fitting a variogram to observed data and interpolation using Kriging. The tracer residence probability density function (PDF) was determined by modelling the tracer movement with a 3-D groundwater model. The observed and simulated tracer arrival was compared for cases with constant K, constant K and dispersion (D), and for spatially variable K and dispersion. The results show that groundwater models were well suited to simulate solute movement in the SSF system studied. An almost perfect fit to observed tracer PDF was obtained when variable K and dispersion was included in the model. This indicates that information on K variability and dispersion is important for studying solute movement in SSF constructed wetlands.
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| 3. |
- Klove, B., et al.
(författare)
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Runoff generation in a plough-drained cutover fen in Central Finland
- 1999
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Ingår i: Journal of Hydrology. - 0022-1694. ; 218:3-4, s. 157-168
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Tidskriftsartikel (refereegranskat)abstract
- The hydrology of a cutover fen was studied from May to October in 1995 and 1996. Rainfall equivalent depths were measured every 15 min and stream runoff was continuously monitored. Water table depths were measured bi-weekly during 1995 and continuously during 1996. Storm runoff was separated into different components; rain falling directly into channels and rapid groundwater response based on a contributing area method and on different electrical conductivities of rain-, ground- and streamwater. The results show three sources of storm runoff from cutover fens. Frequent small runoff peaks were caused by rain falling directly into channels. The amount of quick runoff increased when rain fell on wet soil, resulting in intermediate sized runoff peaks generated by rapid groundwater response. The largest runoff values were observed after prolonged rainfall when water from the upper part of the catchment flooded the fen. (C) 1999 Elsevier Science B.V. All rights reserved.
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