Catchment Hydrology during Winter and Spring and the Link to Soil Erosion: A Case Study in Norway

Torsten Starkloff,Jannes Stolte,Rudi Hessel,Coen Ritsema

doi:10.3390/hydrology4010015

Torsten Starkloff, Jannes Stolte + Show 2 more

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https://doi.org/10.3390/hydrology4010015

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Abstract

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.

Highlights

In the Nordic countries, soil erosion rates in winter and early spring can exceed those occurring during other seasons of the year
Field measurements covering three winter periods (2013, 2014 and 2015) were carried out, with the aim of improving overall understanding of how soil hydraulic properties behave during winter and affect surface runoff caused by snowmelt and rain and how these processes are linked to soil erosion
Field observations carried out during three winters in a catchment in southern Norway showed how soil hydraulic properties changed due to freezing-thawing, affecting surface runoff caused by snowmelt and rain, and how these processes are linked to soil erosion

Summary

Introduction

In the Nordic countries, soil erosion rates in winter and early spring can exceed those occurring during other seasons of the year. A large number of laboratory studies has investigated different processes occurring in soils during freezing and thawing. Edwards and Burney [3] showed that soil freezing and thawing can significantly increase soil erosivity. They concluded that only plant cover is effective in reducing soil losses due to rain and overland flow on frozen ground. E.g., Ban et al [4], have shown that water flows much faster over a frozen slope than over a thawed slope. Watanabe et al [5] found that the speed of snowmelt and/or rain infiltration into frozen soils is largely dependent on initial water content, frost depth and temperature of the soil.

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