Towards a large scale modelling of wetlands water dynamics in northern basins.

English Abstract:

Understanding the hydrological behaviour of low topography, wetland-dominated sub-arctic areas is one major issue towards the improvement of large scale hydrological models. These damp organic soils cover a large extent of Northern America and have a considerable impact on the rainfall-runoff response of a catchment. Moreover their strong interactions with the lower atmosphere and the carbon cycle make of these areas a noteworthy component of the regional climate system. In the framework of the Changing Cold Regions Network (CCRN), this study aims at providing a model for wetland water dynamics that can be used for large scale applications. The modelling system is made of two main components : a) the simulation of surface runoff using the Modélisation Environmentale Communautaire – Surface and Hydrology (MESH) land surface model driven with several gridded atmospheric datasets and b) the routing of surface runoff using the WATROUTE channel scheme. As a preliminary study, we focus on two small representative study basins in Northern Canada : Scotty Creek in the lower Liard River valley of the Northwest Territories and Baker Creek which is located just a few kilometers north of Yellowknife. Both areas present characteristic landscapes dominated by a series of peat plateaus, channel fens, small lakes and bogs. The challenge of the wetland model is to represent the hydrological functioning of these different types of landscape units and their interactions using rather simple numerical formulations that can be later extended to larger basins such as the Mackenzie river basin. The performance of the model will be assessed using in-situ discharge datasets.