Marie-Audray Ouellet

Subaerial sediment-water flows on hillslopes Essential research questions and classification challenges

Subaerial sediment-water flows on hillslopes have received growing attention from the scientific community in recent years. Interest in this type of geomorphic process is twofold: they constitute a major risk factor and they have generally been poorly defined in the past. Major classification schemes are considered here, with a particular interest in criteria for discriminating between various subaerial flow type processes. Identification techniques from various fields (morphometry, rheology, geomorphology, sedimentology) are reviewed. Recent accounts of flow processes as part of a continuum of processes as opposed to belonging to distinct categories are discussed. It is proposed that process identification include information drawn from various methods in order to minimize identification error, given that correct identification is essential to appropriate hazard assessment and mitigation measures.

Long-term trends in groundwater recharge and discharge in a fractured bedrock aquifer – past and future conditions

In the context of climate change, it is important to understand possible future projections and historical trends of groundwater recharge, flow, and discharge to surface reservoirs. Knowledge of a vast range of possible conditions is required to fully appreciate the variability of the hydrologic cycle and hence the long-term vulnerability of groundwater-dependent habitats. This research investigates historical trends for a groundwater–surface water interacting system that supports a fragile ecosystem in southern Quebec. A transient model was developed using MODFLOW to simulate site-wide groundwater flow for the study area. The model was used to simulate past hydrogeological conditions (1900–2010) using a new data set of available precipitation (rain and snowmelt) and temperature. This data set was used to simulate the overall groundwater budget and to determine groundwater discharge (river baseflow and spring flow) in the study area. This allows for the quantification of century-long trends in flow data, as well as the extreme maximum and minimum flows over 110 years. Recharge was variable, ranging from 41 to 197 mm/year over the study period. Lower recharge rates from 1950 to 1965 induced marked effects on spring flow. Although the trend is not statistically significant, there appears to be, for the second half of the study period (1966–2010), a tendency towards a reversal to an increase for recharge, hydraulic heads, spring flow and baseflows. A longer time series would be necessary to confirm this tendency. The simulated historical trends are compared with flow projections for future scenarios (2041–2070). The confirmation that the natural system has been subjected to a wide range of climatic conditions over the last century helps to inform about its resilience. This study highlights the utility of groundwater flow modeling using historical climate data sets to gain a better understanding of long-term trends for climate change-related hydrogeological and ecohydrological studies.

Modeling cross-scale relationships between climate, hydrology, and individual animals: generating scenarios for stream salamanders

Hybrid modelling provides a unique opportunity to study cross-scale relationships in environmental systems by linking together models of global, regional, landscape, and local-scale processes, yet the approach is rarely applied to address conservation and management questions. Here, we demonstrate how a hybrid modelling approach can be used to assess the effect of cross-scale interactions on the survival of the Allegheny Mountain Dusky Salamander (Desmognathus ochrophaeus) in response to changes in temperature and water availability induced by climate change at the northern limits of its distribution. To do so, we combine regional climate modelling with a landscape-scale integrated surface-groundwater flow model and an individual-based model of stream salamanders. On average, climate scenarios depict a warmer and wetter environment for the 2050 horizon. The increase in average annual temperature and extended hydrological activity time series in the future, combined with a better synchronization with the salamanders’ reproduction period, result in a significant increase in the long-term population viability of the salamanders. This indicates that climate change may not necessarily limit the survivability of small, stream-dwelling animals in headwater basins located in cold and humid regions. This new knowledge suggests that habitat conservation initiatives for amphibians with large latitudinal distributions in Eastern North America should be prioritized at the northern limits of their ranges to facilitate species migration and persistence in the face of climate change. This example demonstrates how hybrid models can serve as powerful tools for informing management and conservation decisions.