应用LGR液态水同位素分析仪在北部水源集中区域监测土壤类型与植被覆盖类型对水的存储和传输的影响

Josie Geris,^1* Doerthe Tetzlaff,¹ Jeffrey McDonnell^1,2 and Chris Soulsby¹

¹ Northern Rivers Institute, School of Geosciences, University of Aberdeen, Scotland, UK

² Global Institute for Water Security, National Hydrology Research Centre, University of Saskatchewan, Saskatoon, Canada

 

Abstract:

Soil water storage and stable isotopes dynamics were investigated in dominant soil–vegetation assemblages of a wet northern headwater catchment (3.2 km2) with limited seasonality in precipitation. We determined the relative influence of soil and vegetation cover on storage and transmission processes. Forested and non-forested sites were compared, on poorly drained histosols in riparian zones and freely draining podzols on steeper hillslopes. Results showed that soil properties exert a much stronger influence than vegetation on water storage dynamics and fluxes, both at the plot and catchment scale. This is mainly linked to the overall energy-limited climate, restricting evaporation, in conjunction with high soil water storage capacities. Threshold behaviour in runoff responses at the catchment scale was associated with differences in soil water storage and transmission dynamics of different hydropedological units. Linear input–output relationships occurred when runoff was generated predominantly from the permanently wet riparian histosols, which show only small dynamic storage changes. In contrast, nonlinear runoff generation was related to transient periods of high soil wetness on the hillslopes. During drier conditions, more marked differences in soil water dynamics related to vegetation properties emerged, in terms of evaporation and impacts on temporarily increasing dynamic storage potential. Overall, our results suggest that soil type and their influence on runoff generation are dominant over vegetation effects in wet, northern headwater catchments with low seasonality in precipitation. Potential increase of subsurface storage by tree cover (e.g. for flood management) will therefore be spatially distributed throughout the landscape and limited to rare and extreme dry conditions. Copyright © 2014 John Wiley & Sons, Ltd.

 

KEY WORDS：hydropedology; isotopes; water storage; soils; land cover; vegetation