Multi-variable evaluation of hydrological model predictions for a headwater basin in the Canadian Rocky Mountains

Abstract

Abstract.One of the purposes of the Cold Regions Hydrological Modelling platform (CRHM) is to diagnose inadequacies in the understanding of the hydrological cycle and its simulation. A physically based hydrological model including a full suite of snow and cold regions hydrology processes as well as warm season, hillslope and groundwater hydrology was developed in CRHM for application in the Marmot Creek Research Basin (∼ 9.4 km 2 ), located in the Front Ranges of the Canadian Rocky Mountains. Parameters were selected from digital elevation model, forest, soil, and geological maps, and from the results of many cold regions hydrology studies in the region and elsewhere. Non-calibrated simulations were conducted for six hydrological years during the period 2005-2011 and were compared with detailed field observations of several hydrological cycle components. The results showed good model performance for snow accumulation and snowmelt compared to the field observations for four seasons during the period 2007-2011, with a small bias and normalised root mean square difference (NRMSD) ranging from 40 to 42 % for the subalpine conifer forests and from 31 to 67 % for the alpine tundra and treeline larch forest environments. Overestimation or underestimation of the peak SWE ranged from 1.6 to 29 %. Simulations matched well with the observed unfrozen moisture fluctuation in the top soil layer at a lodgepole pine site during the period 2006-2011, with a NRMSD ranging from 17 to 39 %, but with consistent overestimation of 7 to 34 %. Evaluations of seasonal streamflow during the period 2006-2011 revealed that the model generally predicted well compared to observations at the basin scale, with a NRMSD of 60 % and small model bias (1 %), while at the sub-basin scale NRMSDs were larger, ranging from 72 to 76 %, though overestimation or underestimation for the cumulative seasonal discharge was within 29 %. Timing of discharge was better predicted at the Marmot Creek basin outlet, having a Nash-Sutcliffe efficiency (NSE) of 0.58 compared to the outlets of the sub-basins where NSE ranged from 0.2 to 0.28. The Pearson product-moment correlation coefficient of 0.15 and 0.17 for comparisons between the simulated groundwater storage and observed groundwater level fluctuation at two wells indicate weak but positive correlations. The model results are encouraging for uncalibrated prediction and indicate research priorities to improve simulations of snow accumulation at treeline, groundwater dynamics, and small-scale runoff generation processes in this environment. The study shows that improved hydrological cycle model prediction can be derived from improved hydrological understanding and therefore is a model that can be applied for prediction in ungauged basins.

Bias corrections of precipitation measurements across experimental sites in different ecoclimatic regions of western Canada

“…The mountains range in elevation from 1600 to 2800 m, and typical mountain environments include montane and subalpine forest cover, alpine tundra, and talus/rock at higher elevation. The climate is characterized by cool, wet summers and long, cold winters; monthly mean air temperature ranges from −10.7 • C in January to 11.7 • C in July (Pomeroy et al, 2012;Fang et al, 2013;Harder et al, 2015). There is a significant difference in the annual precipitation from 638 mm at the valley bottom to 1100 mm at higher elevations (Storr, 1967).…”

“…Depending on site characteristics and environment, gauge performance can vary widely. Results from numerous studies show that gauge type and collection method significantly affect measurement precision and accuracy (Emerson and Macek-Rowland, 1990;Yang et al, 1999). Although all precipitation measurements are prone to bias, the measurement biases are most serious in cold regions due to high snowfall percentage Yang et al, 1998Yang et al, , 1999.…”

Marmot Creek Experimental Watershed Study

“…The Cold Regions Hydrological Model (CRHM) was developed using these and other studies in Marmot Creek and used to describe the hydrology of the basin using physically based calculations of blowing and intercepted snow, snow sublimation, melt, infiltration into frozen soils, evaporation and soil physics representations Fang et al 2013). Perturbations of the model showed that forest disturbance impacts on snowpack were much greater than on streamflow because of the desynchronization of melt caused by forest removal in Marmot Creek .…”

“…However, pine beetle kill of lodgepole pine had an insignificant impact on streamflow because it occurs at low elevations where precipitation is low and runoff generation is small. The most recent hydrological model can simulate the snowpack, soil moisture, groundwater and streamflow in Marmot Creek without calibration of parameters due to its reliance on the large number of scientific findings in the basin over 50 years (Fang et al 2013).…”

Runoff generation in mountain catchments: long-term hydrological monitoring in the Rio Vauz Catchment, Italy

“…The Marmot Creek catchment is currently instrumented with several permanent meteorological stations at different elevations, groundwater wells and stream gauges. Research focuses on mountain snow processes (snow accumulation and snowmelt), hydro-climatic trends and hydrological modelling (Pomeroy et al, 2012;Fang et al, 2013). Research projects in the Wolf Creek catchment (Yukon, Canada) were initiated in 1992 and include studies on water balance, hillslope runoff processes and runoff generation in permafrost areas by means of environmental tracers (Carey and Woo, 2001;Carey and Quinton, 2005).…”