Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2006
Forfattere
Stein TurtumøygardSammendrag
Bruk av WebGIS avløp som metode for oppfølging av spredt avløp i Aksjon Jærsvassdrag.
Sammendrag
In order to investigate the influence of biological growth on flow and transport patterns in horizontal subsurface flow constructed wetlands, bromide tracer experiments were conducted in two 3m long tanks. The tanks were filled with light weight aggregates and shell sand, respectively. The hydraulic conductivity, drainable porosity and dispersivity of the two filter mediawere determined before and after biological growth. The obtained breakthrough curves of bromide tracer showed that biological growth caused a pronounced reduction in drainable porosity, mainly for shell sand, whereas its effect on saturated hydraulic conductivity was negligible. The spatial distribution of the bromide after biological growth in the two filter media showed that the flow occurred preferentially along certain paths. However, in the light"weight aggregates filter medium, biological growth with possible clogging effects seems to reduce the efficiency of some preferential flow paths, increase the retention time, and hence, improves the system treatment efficiency. This study showed that selecting a filter medium including coarse fractions to some extent can mitigate the potential negative effects of bioclogging.
Sammendrag
Hydrology in the northern hemisphere is greatly affected by permafrost and seasonally frozen soils. In areas of permafrost only the top layer of the ground, as well as various thawed structures in the permafrost layer, are active from a hydrological point of view. Water supply is a big challenge in areas with permafrost. Changes in mechanical properties caused by changes in permafrost have also received much attention. Frozen ground near the surface will influence the distribution of melt-water and rain to run-off or infiltration. Changes in englacier and subglacier hydrology are important indicators of global warming. In this chapter examples of different geophysical methods applicable for charcterising flow and transport in cold regions are described. Case-studies carried out in Svalbard, Russia, Norway and Switzerland are presented. The examples relate to: leakages below frozen dams using electromagnetic (EM) soundings; EM soundings of saline permafrost and anomalous polarization; saltwater injection into permafrost zone; infiltration and solute transport in a partially frozen soil monitored by surface tomographic electrical resistivity techniques; drainage conditions beneath a glacier. The case studies presented (as well as examples from the literature) illustrate that most common geophysical methods are applicable in cold regions but may face problems with grounding or calibration of measurements with respect to hydrological meaningful properties such as water contents, etc. Temperature and phase change affect geophysical properties, and in combination with changes in solute concentration or changes in water content, the interpretation is made more complicated. Combining different geophysical and conventional methods may help to solve this problem.
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Mål Studenten skal ha innsikt i kvantitative metoder for å beskrive egenskaper av grunnvann inklusiv strømning av vann og spredning av forurensinger. Kvantitativ analyse av transport av vann og løste stoffer i porøse medier under mettede forhold. Kunnskapen er viktig i forbindelse med effektvurdering av menneskelig inngrep i grunnvannsystemer.Bruk av kvantitative metoder, inklusiv storskala grunnvannsmodeller som predikeringsverktøy. Å kunne vurdere risiko for irreversible endringer i grunnvannsressurser både når det gjelder kvantitet og kvalitet som en følge av menneskelig inngrep er viktig for en god ressursforvaltning. Rent grunnvann er en viktig naturressurs. Innhold 1. Forelesninger teori 2. Regneøvelser 3. Innleveringsoppgaver (teller for sluttkarakter) 4. Innføring i bruk av modellen MODFLOW 5. Innleveringsoppgaver MODFLOW (skal innleveres og godkjennes)
Forfattere
T.H. Bakken L. Erikstad Helen French V. Bakkestuen Sigrun Kværnø J.R. Selvik S-E. Sloreid T. TjomslandSammendrag
Det er ikke registrert sammendrag
Forfattere
Tor Haakon Bakken Lars Erikstad Helen French Vegar Bakkestuen Sigrun Kværnø John Rune Selvik Svein-Erik Sloreid Tjorulv TjomslandSammendrag
Det er ikke registrert sammendrag
Sammendrag
During snowmelt Oslo airport has on repeated occations experienced the formation of large meltwater ponds due to impermeable ice forming below the snowcover. The airport is situated on a large glacial outwash plane with coarse sandy gravely sediments, hence the area normaly has a high infiltration capacity. Focussed infiltration can cause fast transport of contaminants to the groundwater, hence improved understanding of the processes determining where and how the focussed infiltration takes place is important. Previously the melting process has been monitored successfully on a small scale (4 m2) using a two dimensional grid of permanently installed electrodes (French and Binley, 2004). In the present work snowmelt infiltration was monitored by time-lapse measurements of electrical resistivity using grounded electrodes on 4 and 20 m2 plots and a capacitively coupled resistivity system (Ohmmapper, Geometrics) on a larger scale. While the smaller scale systems provide 3D images the capacitively coupled system was used to monitor changes in two dimensional vertical sections in a retention pond adjacent to one of the runways. The area covered by 4 lines was 170 m by 340 m. The initial data were collected late in the spring (2006) during the final stages of the snowmelt. The lines were repeated later in the year when the soil profile was dryer. The lines show good consistency in the description of the general geology of the subsurface and the time-lapse changes describe the infiltration pattern that occurred during snowmelt and subsequent drainage. The surveys provide useful information about the differences in spatial distribution of snowmelt infiltration at different scales. And there are good indications that capacitively coupled resistivity surveys can be used to describe infiltration processes at relatively large spacio-temporal scales. References French, H. and A. Binley, 2004, Snowmelt infiltration: monitoring temporal and spatial variability using time-lapse geophysics, J. Hydrology, 297, 174-186
Sammendrag
During snowmelt Oslo airport has on repeated occations experienced the formation of large meltwater ponds due to impermeable ice forming below the snowcover. The airport is situated on a large glacial outwash plane with coarse sandy gravely sediments, hence the area normaly has a high infiltration capacity. Focussed infiltration can cause fast transport of contaminants to the groundwater, hence improved understanding of the processes determining where and how the focussed infiltration takes place is important. Previously the melting process has been monitored successfully on a small scale (4 m2) using a two dimensional grid of permanently installed electrodes (French and Binley, 2004). In the present work snowmelt infiltration was monitored by time-lapse measurements of electrical resistivity using grounded electrodes on 4 and 20 m2 plots and a capacitively coupled resistivity system (Ohmmapper, Geometrics) on a larger scale. While the smaller scale systems provide 3D images the capacitively coupled system was used to monitor changes in two dimensional vertical sections in a retention pond adjacent to one of the runways. The area covered by 4 lines was 170 m by 340 m. The initial data were collected late in the spring (2006) during the final stages of the snowmelt. The lines were repeated later in the year when the soil profile was dryer. The lines show good consistency in the description of the general geology of the subsurface and the time-lapse changes describe the infiltration pattern that occurred during snowmelt and subsequent drainage. The surveys provide useful information about the differences in spatial distribution of snowmelt infiltration at different scales. And there are good indications that capacitively coupled resistivity surveys can be used to describe infiltration processes at relatively large spacio-temporal scales. References French, H. and A. Binley, 2004, Snowmelt infiltration: monitoring temporal and spatial variability using time-lapse geophysics, J. Hydrology, 297, 174-186
Sammendrag
Det er ikke registrert sammendrag