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Vannplanter ved Hvaler
Soil and Water Sciences
Vannplanter ved Hvaler
The soil and water system plays a key role in the hydrological cycle, which all ecosystems depend on. Processes such as infiltration, evapo-transpiration, runoff, contaminant transport, gas diffusion and erosion are highly dependent on climatic conditions, especially freeze and thaw conditions. Field monitoring has given valuable information on variation in runoff, drainage water, particle and nutrient losses. Such studies, however, can only be regarded as black box studies.
Snow depth is a strong regulator of soil freezing and infiltration capacity. Monitoring variability and hanges in snowcover both on the soil surface and in a forest system is a major challenge, and there is a need for better techniques.

Development of these techniques do however require the appropriate scale and a controlled environment. Shallow or absent snow cover results in lower soil temperatures, more extensive soil freezing, increased freeze-thaw cycling and lower infiltration. Due to variable snow and ice cover, infiltration during snowmelt often occurs as focused recharge. These processes have so far been studied in the field and fundamental mechanisms occurring at the soil surface should still be described. In general, effects of partially frozen soil on flow rates, flow channelling and partitioning of water to infiltration and surface runoff has received little attention. Ice expansion in soil pores during freezing affects soil hydraulic properties and susceptibility to particle detachment and transport by raindrop impact and water flow (stability).

The negative effect of frequent freeze-thaw cycles on aggregate stability and shear strength has been documented. These processes are also extremely important with respect to construction engineering and for slope stability (land slides). A facility where these processes can be studied in a soil/water and plant system in combination with rain simulators and controlled slopes is nonexistant to our knowledge. Data on seasonal variations in hydraulic properties and differences between soil types are lacking for Norwegian conditions. Climate change may lead to altered number of freeze-thaw cycles during winter. A combination of changed precipitation, temperatures, snow conditions and more frequent extreme events, may change runoff and erosion. These interactions need to be properly addressed in order to evaluate possible effects of climate change.

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