Simulation of soil water content on a small reclaimed watershed in northern Alberta using the Root Zone Water Quality Model (RZWQM)

A study was conducted at Syncrude Canada Ltd., Alberta, to evaluate the simulation of soil volumetric water content from the reclaimed slopes of the Southwest Sand Storage Facility using the Root Zone Water Quality Model (RZWQM). Soil water content measurements were conducted every 2 wk using a neutron moisture meter in 2001 (dry year) and 2002 (wet year). Two types of calibration and evaluation were performed: first, calibration using 2001 weather data (dry year) and evaluation using 2002 weather data (wet year) (herein referred to as method 1); second, calibration using 2002 weather data (wet year) and evaluation using 2001 weather data (dry year) herein referred to as (method 2). Results from the method I calibration for each tube indicated modeling efficiencies (EF) between -0.27 and 0.90, coefficients of determination (r(2)) between 0.13 and 0.97, and deviation (D, as %) of simulated from measured values of less than 5%. The model evaluation by tube location following method I calibration indicated EF values between -3.80 and 0.56, whereas r(2) values ranged between 0.08 and 0.82. Although five out of eight tubes had D values > 5%, all except for one tube had D values < 20%. Method 2 calibration results for each tube indicated EF values of -0.34 to 0.85, r(2) values of 0.07 to 0.85 and all D values < 5%. Results of the method 2 model evaluation by tube location indicated EF values of -10.15 to 0.75 (overall EF = -0.84), r(2) values of 0.04 to 0.96 (overall r(2) = 0.39) and D values of 2.6 to 48.6% (overall D = 19.8). Method 2 model evaluation results indicated EF values of -1.69, -3.85 and -0.01, for depths of 15, 25 and 35 cm, respectively. The D values were 27, 20 and 13%, respectively. Graphical displays indicated that during the evaluation process, the model generally tended to slightly under-estimate the wetter moisture conditions, regardless of whether data for a wet year or a dry year were used during the calibration process.