Winter hydrology and soil erosion processes in an agricultural catchment in Norway

In regions with a Nordic climate, soil erosion rates in winter and early spring can exceed those occurring during other seasons of the year. In this context, this study was initiated to improve our understanding of the interaction between agricultural soils and occurring winter conditions. The main objective was to better understand how hydrological processes in a catchment are influenced by snow, ice, and freeze-thaw cycles of soils, leading to runoff and soil erosion in winter and spring conditions. For this purpose, detailed spatially and temporally distributed measurements and observations in a small catchment in Norway were executed during three consecutive winter/spring periods. During the winter/spring periods of 2013-2014, 2014-2015 and 2015-2016, soil water content, soil temperature, and snow cover properties were measured. In addition, numerous soil samples were taken to determine the soil hydraulic characteristics of the investigated soils and to quantify the changes in their macropore networks due to freeze-thaw events, using X-ray imaging. With the collected data and deduced process understanding, it was possible to model and quantify the spatial and temporal development of snow packs. Furthermore, the field observations revealed how the interaction of tillage, state of the soils and snow cover at a certain time can lead to none or extensive surface runoff and soil erosion. Integrating acquired data, observations and process knowledge facilitated advances in simulating and quantifying surface runoff and soil erosion rates across the catchment under investigation. The models applied and the maps and output derived are crucial elements for presenting current state and problems in the catchment to stakeholders (such as farmers), providing a starting point for discussing ways to prevent and reduce further runoff and erosion. For model calibration and validation, including interpretation of modelling results, good knowledge of the area and availability of detailed data are essential, especially when processes such as freezing-thawing of soils and ice layer and snow-pack dynamics have to be considered also. In order to reduce runoff and soil erosion during winter and snowmelt conditions in the future, more targeted research is required in order to address the full range of existing knowledge gaps in this field, as identified in this particular study also.</p

Combining FDR and ERT for monitoring soil moisture and temperature patterns in undulating terrain in south-eastern Norway

The occurrence of freeze–thaw cycles modifies water infiltration processes and surface runoff generation. Related processes are complex and are not yet fully investigated at field scale. While local weather conditions and soil management practices are the most important factors in both runoff generation and surface erosion processes, local terrain heterogeneities may significantly influence soil erosion processes in catchments with undulating terrain. This paper presents a field-based investigation of spatial and temporal heterogeneities in subsurface soil moisture and soil temperature associated with freezing, thawing, and snowmelt infiltration. The field setup consists of a combination of traditional point measurements performed with frequency domain reflectometry (FDR) and electrical resistivity tomography (ERT). The transect was approximately 70 m long and spanned an entire depression with a north-facing slope (average slope of 11.5%) and a south-facing slope (average slope of 9.7%). The whole depression was entirely covered with stubble. Observed resistivity patterns correspond well to the measured soil moisture patterns. During the observation period, the north facing slope froze earlier and deeper compared with the south facing slope. Freeze–thaw cycles were less pronounced in the north-facing slope than in the south-facing slope. There were also differences in soil temperature and soil moisture patterns between lower and upper parts of the monitored depression. These indicate that initiation and development of runoff related processes, and consequently soil erosion, in regions with freeze–thaw cycles may differ significantly depending on local terrain characteristics. Consequently, it indicates that spatial terrain heterogeneities, especially slope aspects, may be important when studying soil erosion processes, water flow and nutrient leaching in lowlands where patchy snowpacks and dynamic freeze–thaw cycles are predominating.publishedVersio

Kjelle avrenningsforsøk. Årsrapport 2016–2017 for jordarbeidingsforsøk på lav erosjonsrisiko

Redusert og endret jordarbeiding har vært et av de viktigste tiltakene mot erosjon og tap av næringsstoffer fra jordbruksarealer siden begynnelsen på 1990-tallet. Redusert jordarbeiding betyr bare harving i stedet for pløying, mens endret jordarbeiding betyr pløying om våren i stedet for høsten. Avrenningsforsøk som startet på 1980-tallet viser stor effekten av redusert og endret jordarbeiding på erosjon og næringsstofftap på forholdsvis bratte jordbruksarealer. Det eksisterer derimot kun få undersøkelser av jordarbeidingseffekter på arealer med liten helling, på tross av at slike arealer utgjør størsteparten av jordbruksarealene der det dyrkes korn.....publishedVersio

Lokal tiltaksplan for Rakkestadelva

I denne rapporten er det fremstilt resultater fra beregninger av erosjon og fosforavrenning fra jordbruksarealer i nedbørfeltet til Rakkestadelva. I tillegg er det laget et kart som kan brukes som utgangspunkt for å vurdere risiko for fure-erosjon. Enkle, empiriske modeller er brukt for å framskaffe estimater for tilførsler under dagens drift (2016) og for ulike scenarier. Slike resultater er forbundet med en rekke usikkerheter, og det anbefales at man fokuserer på relative forskjeller mellom områder og ulike driftsformer, heller enn på absolutte nivåer for jord- og fosfortap. ..

Lokal tiltaksplan for Rakkestadelva

I denne rapporten er det fremstilt resultater fra beregninger av erosjon og fosforavrenning fra jordbruksarealer i nedbørfeltet til Rakkestadelva. I tillegg er det laget et kart som kan brukes som utgangspunkt for å vurdere risiko for fure-erosjon. Enkle, empiriske modeller er brukt for å framskaffe estimater for tilførsler under dagens drift (2016) og for ulike scenarier. Slike resultater er forbundet med en rekke usikkerheter, og det anbefales at man fokuserer på relative forskjeller mellom områder og ulike driftsformer, heller enn på absolutte nivåer for jord- og fosfortap. ...publishedVersio

Flomtiltak i landbruksområder

Klimaet forventes å bli våtere, varmere og villere. Faren for økt avrenning, flom og jorderosjon vil øke, med påfølgende fare for høyere tilførsler av næringsstoff fra landbruket til vannforekomster. Det finnes mange undersøkelser og publikasjoner om overvannstiltak, og basert på denne informasjonen presenterer vi her en oversikt over tiltak som har til formål å holde vannet lengst mulig i nedbørfeltet, både i skogen og i typiske jordbruksområder, og som er egnet til bruk i Norge. Vi indikerer viktigste virkemåte av tiltakene: «forsink og fordrøy» (F) og/eller «fang og infiltrer

Combining FDR and ERT for monitoring soil moisture and temperature patterns in undulating terrain in south-eastern Norway

The occurrence of freeze–thaw cycles modifies water infiltration processes and surface runoff generation. Related processes are complex and are not yet fully investigated at field scale. While local weather conditions and soil management practices are the most important factors in both runoff generation and surface erosion processes, local terrain heterogeneities may significantly influence soil erosion processes in catchments with undulating terrain. This paper presents a field-based investigation of spatial and temporal heterogeneities in subsurface soil moisture and soil temperature associated with freezing, thawing, and snowmelt infiltration. The field setup consists of a combination of traditional point measurements performed with frequency domain reflectometry (FDR) and electrical resistivity tomography (ERT). The transect was approximately 70 m long and spanned an entire depression with a north-facing slope (average slope of 11.5%) and a south-facing slope (average slope of 9.7%). The whole depression was entirely covered with stubble. Observed resistivity patterns correspond well to the measured soil moisture patterns. During the observation period, the north facing slope froze earlier and deeper compared with the south facing slope. Freeze–thaw cycles were less pronounced in the north-facing slope than in the south-facing slope. There were also differences in soil temperature and soil moisture patterns between lower and upper parts of the monitored depression. These indicate that initiation and development of runoff related processes, and consequently soil erosion, in regions with freeze–thaw cycles may differ significantly depending on local terrain characteristics. Consequently, it indicates that spatial terrain heterogeneities, especially slope aspects, may be important when studying soil erosion processes, water flow and nutrient leaching in lowlands where patchy snowpacks and dynamic freeze–thaw cycles are predominating

Catchment hydrology during winter and spring and the link to soil erosion: A case study in Norway

<p>In the Nordic countries, soil erosion rates in winter and early spring can exceed those at other times of the year. In particular, snowmelt, combined with rain and soil frost, leads to severe soil erosion, even, e.g., in low risk areas in Norway. In southern Norway, previous attempts to predict soil erosion during winter and spring have not been very accurate owing to a lack of catchment-based data, resulting in a poor understanding of hydrological processes during winter. Therefore, a field study was carried out over three consecutive winters (2013, 2014 and 2015) to gather relevant data. In parallel, the development of the snow cover, soil temperature and ice content during these three winters was simulated with the Simultaneous Heat and Water (SHAW) model for two different soils (sand, clay). The field observations carried out in winter revealed high complexity and diversity in the hydrological processes occurring in the catchment. Major soil erosion was caused by a small rain event on frozen ground before snow cover was established, while snowmelt played no significant role in terms of soil erosion in the study period. Four factors that determine the extent of runoff and erosion were of particular importance: (1) soil water content at freezing; (2) whether soil is frozen or unfrozen at a particular moment; (3) the state of the snow pack; and (4) tillage practices prior to winter. SHAW performed well in this application and proved that it is a valuable tool for investigating and simulating snow cover development, soil temperature and extent of freezing in soil profiles.</p

Catchment hydrology during winter and spring and the link to soil erosion: A case study in Norway

In the Nordic countries, soil erosion rates in winter and early spring can exceed those at other times of the year. In particular, snowmelt, combined with rain and soil frost, leads to severe soil erosion, even, e.g., in low risk areas in Norway. In southern Norway, previous attempts to predict soil erosion during winter and spring have not been very accurate owing to a lack of catchment-based data, resulting in a poor understanding of hydrological processes during winter. Therefore, a field study was carried out over three consecutive winters (2013, 2014 and 2015) to gather relevant data. In parallel, the development of the snow cover, soil temperature and ice content during these three winters was simulated with the Simultaneous Heat and Water (SHAW) model for two different soils (sand, clay). The field observations carried out in winter revealed high complexity and diversity in the hydrological processes occurring in the catchment. Major soil erosion was caused by a small rain event on frozen ground before snow cover was established, while snowmelt played no significant role in terms of soil erosion in the study period. Four factors that determine the extent of runoff and erosion were of particular importance: (1) soil water content at freezing; (2) whether soil is frozen or unfrozen at a particular moment; (3) the state of the snow pack; and (4) tillage practices prior to winter. SHAW performed well in this application and proved that it is a valuable tool for investigating and simulating snow cover development, soil temperature and extent of freezing in soil profiles.</p