Hydrologic response of an alpine watershed: Application of a meteorological wireless sensor network to understand streamflow generation

Abstract

A field measurement campaign was conducted from June to October 2009 in a 20 km2 catchment of the Swiss Alps with a wireless network of 12 weather stations and river discharge monitoring. The objective was to investigate the spatial variability of meteorological forcing and to assess its impact on streamflow generation. The analysis of the runoff dynamics highlighted the important contribution of snowmelt from spring to early summer. During the entire experimental period, the streamflow discharge was dominated by base flow contributions with temporal variations due to occasional rainfall‐runoff events and a regular contribution from glacier melt. Given the importance of snow and ice melt runoff in this catchment, patterns of near‐surface air temperatures were studied in detail. Statistical data analyses revealed that meteorological variables inside the watershed exhibit spatial variability. Air temperatures were influenced by topographic effects such as slope, aspect, and elevation. Rainfall was found to be spatially variable inside the catchment. The impact of this variability on streamflow generation was assessed using a lumped degree‐day model. Despite the variability within the watershed, the streamflow discharge could be described using the lumped model. The novelty of this work mainly consists in quantifying spatial variability for a small watershed and showing to which extent this is important. When the focus is on aggregated outputs, such as streamflow discharge, average values of meteorological forcing can be adequately used. On the contrary, when the focus is on distributed fields such as evaporation or soil moisture, their estimate can benefit from distributed measurements.

Improving the degree-day method for sub-daily melt simulations with physically-based diurnal variations

“…The mean positioning of the groups is different where the southeast facing group is more south-faci ng than the southwest facing group [64]. In effect, incoming shortwave radiation values were recorded to be approximately 8 W m À2 higher for the southeast facing group througho ut the 5 month field experiment and, the groups, separated by approximat ely 1 km, do not show well correlate d temperature lapse rates.…”

“…2. For further technical details on measuring devices used, refer to the work of Nadeau et al [44] and Simoni et al [64].…”

“…The stage-discharge curve was obtained with the salt dilution method [64]. The resulting discharge profile can be seen in Fig.…”

“…3. Analysis of the discharge from this dataset was originally conducted by [64], where the contributions of glacier melt, snowmelt, rainfall-runoff and baseflow to the discharge time series were detailed. Once the baseflow is subtracted, snowmelt composes approximat ely 85% of the remaining discharge volume, whereas glacier melt comprise s less than 10%.…”

Soil Moisture & Snow Properties Determination with GNSS in Alpine Environments: Challenges, Status, and Perspectives

“…For example, a multi-year field campaign in Val Ferret (VS) in the Swiss Alps uses such a network (Sensorscope) currently consisting of 25 stations distributed over the catchment, measuring relevant meteorological parameters such as rainfall; wind speed and direction; temperature; incoming shortwave radiation and surface temperature of the soil [120]. Soil moisture, soil matric potential, and soil temperatures are also measured at 21 of the stations, using decagon 5TM and ECTM (soil moisture based on dielectric constant) sensors, and MPS1 (matric potential) sensors at 20 and 40 cm below the surface.…”