Modeling Soil Moisture From Real Time Weather Data.

The Versatile Soil Moisture Budget (VSMB) is a model used to estimate soil moisture levels at various depths in the soil profile. The current version of the model simulates solar radiation and uses the Priestley-Taylor equation to estimate evapotranspiration which are important inputs in the model. Access to direct solar radiation data from pyranometers and the improved estimation of evapotranspiration using the Penman-Monteith (FAO 56) method is expected to significantly improve the coefficient of correlation between modelled and observed soil moisture. The Steven’s hydraprobe was used to establish a network of soil moisture monitoring sites in central and eastern Manitoba, Canada.  The purpose was to test soil moisture models and adapt them for use with input from weather stations reporting rainfall, air temperature, humidity, wind speed and solar radiation in real-time.  Prior to their deployment, in the field, each hydraprobe was tested using a laboratory calibration technique to ensure that they perform uniformly under controlled conditions. At each soil moisture monitoring site, four hydraprobes were installed to monitor moisture levels at 4 depths (5, 20, 50 and 100 cm).  Volumetric soil moisture, neutron moisture meter and PR-2 probe readings at specified times at the same depths were used to verify the soil moisture readings from the hydraprobes. The modelled results from the VSMB will be tested with soil moisture output from these calibrated hydraprobes.

Keywords: VSMB, model, hydraprobes, soil moisture, calibration, evapotranspiration.