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.
2017
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Forfattere
Nicholas Clarke Wenche Dramstad Wendy Fjellstad Jørn-Frode Nordbakken Hilde Karine Wam Tonje Økland Holger LangeSammendrag
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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.
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The nature of subsurface flow depends largely on hydraulic conductivity of the vadoze zone, the permeability of the underlying bedrock, the existence of soil layers differing in hydraulic properties and macropore content, soil depth and slope angle. Quantification of flow pathways on forested hillslopes is essential to understand the hydrological dynamics and solute transport patterns. Acrisols, with their argic Bt horizons, are challenging in this respect. To increase the understanding of flow pathways of water and the short-term variability of the soil moisture patterns in Acrisols, a field study was conducted on a forested hillslope in the Tie Shan Ping (TSP) watershed, 25 km northeast of Chongqing city, PR China. This catchment is covered by mixed secondary forest dominated by Masson pine (Pinus Massoniana). The soil's Ksat reduced significantly at the interface between the AB and Bt horizons (2.6E-05 versus 1.2E-06 m s−1). This led to that the flow volume generated in the Bt horizon was of little quantitative importance compared to that in the AB horizon. There was a marked decrease in porosity between the O/A horizon and the AB horizon, with a further decrease deeper in the mineral subsoil. Especially the content of pores >300 µm were higher in the AB horizon (14.3%) compared to the Bt horizon (6.5%). This explains the difference in Ksat values. Our study shows that Bt horizons have limited water transport capability, forcing part of the infiltrated rainwater as interflow through the OA and AB horizons. The topsoil thus responds quickly to rainfall events, causing frequent cycles of saturation and aeration of soil pores
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Climate change is expected to alter average temperature and precipitation values and to increase the variability of precipitation events, which may lead to even more intense and frequent water hazards. Water hazards engineering is the branch of engineering concerned with the application of scientific and engineering principles for protection of human populations from the effects of water hazards; protection of environments, both local and global, from the potentially deleterious effects of water hazards; and improvement of environmental quality for mitigating the negative effects of water hazards. An integrated approach of water hazards engineering based on mapping, nature-based and technical solutions will constitute a feasible solution in the process of adapting to challenges generated by climate changes worldwide. This paper will debate this concept also providing some examples from several European countries.