Research project description
Influence of snow water equivalent and soil freezing conditions on springtime hydrology in agricultural field derived from combined synthetic aperture radar data, field observations and hydrological modeling
Introduction
There is a pressing need in southern Quebec to improve the short-term (days) and long-term (weeks to months) forecast of springtime floods. As a large fraction (60-80%) of springtime flood volumes originates from snowmelt, monitoring the snow water equivalent (SWE - the total amount of water held in the snowpack) is key to better anticipate the severity of springtime floods. In addition, soil freezing in the fall and early winter can restrict the infiltration of meltwater and rain into the soil during snowmelt, promoting surface runoff and larger floods. SWE, and even more soil freezing observations, are spare, both over time and space. The high spatial resolution (22 m) and small revisit time (6 days) of the Sentinel 1 satellite (European Space Agency) opens new opportunities to monitor snow and soil freezing conditions in cold regions, and to use these data to improve hydrological forecasts mostly during spring snowmelt season.
Objectives
This project will investigate the possibility of using SAR images to map SWE and ground freezing conditions in southern Quebec, Canada, to improve the simulation of spring flooding
Specific objectives are to:
Develop a temporal frozen soil change detection approach using Copernicus Sentinel-1 constellation (two satellites: 1A and 1B) backscattering coefficient (σ0).
Produce SWE and SD retrieval algorithms from the cross-polarization ratio throughout winter in open areas.
Develop simple approaches to assimilate SWE and frozen soil maps into a hydrological model to improve stream flow simulations in spring in southern Québec.
Study Sites
The case study of the project is located in the agricultural regions of southern Quebec, mainly in the municipalities of Sainte-Marthe and Saint-Maurice. The study sites will be instrumented and monitored to properly represent the heterogeneous characteristics of soil temperature (Tsoil) in an agricultural field.
Material and methods
Soil temperature, snow depth, and SWE measurements for data calibration will be collected simultaneously with Sentinel-1 SAR satellite acquisitions. The near-surface temperature (5 cm) will be monitored using the installation of soil temperature microbloggers at the site in Fall 2020. Snow depth and SWE measurements will be measured several times throughout winter at these sites using snow pits and coring.
As part of this research, not only frozen soil and SWE algorithms will be developed and validated in southern farmlands of Quebec, but also in northern agricultural areas with higher latitudes.
Research Site Coordinates
