Modelling the hydrological interactions between a fissured granite aquifer and a valley mire in the Massif Central, France

Abstract. We developed a high-resolution MIKE SHE/MIKE 11 model of 231.3 ha headwater catchment in the granitic uplands French Massif Central to estimate contribution groundwater upwelling water balance Dauges mire, an acidic valley mire international importance for nature conservation. estimated that from underlying weathered granite formations – mostly approximately 55 m deep fissured zone provides 27.1 % total long-term inflows mire. This increases 37.2 September when are small. Overland boundary inflow accounts average 40.2 inflows. However, most this originates seepage through mineral soils along margins or small non-channelised valleys upslope A sensitivity analysis showed performance terms simulation levels was sensitive parameters describing and rather than overlying peat layer. Variation partitioning demonstrated important factor driving simulated monthly table depth within Sustained maintains close at ground level year. As result, precipitation overland quickly leave wetland as saturation-excess runoff. There agreement between observed distribution habitats areas where rate larger zero September. Our results demonstrate that, contrary assumed hydrology hard-rock regions, can be quantitatively functionally critical element mires catchments. These have legal management implications.