Simulating cold-region hydrology in an intensively drained agricultural watershed in Manitoba, Canada, using the Cold Regions Hydrological Model

Abstract

Abstract. Etrophication and flooding are perennial problems in agricultural watersheds of the northern Great Plains. A high proportion of annual runoff and nutrient transport occurs with snowmelt in this region. Extensive surface drainage modification, frozen soils, and frequent backwater or icedamming impacts on flow measurement represent unique challenges to accurately modelling watershed-scale hydrological processes. A physically based, non-calibrated model created using the Cold Regions Hydrological Modelling platform (CRHM) was parameterized to simulate hydrological processes within a low slope, clay soil, and intensively surface drained agricultural watershed. These characteristics are common to most tributaries of the Red River of the north. Analysis of the observed water level records for the study watershed (La Salle River) indicates that ice cover and backwater issues at time of peak flow may impact the accuracy of both modelled and measured streamflows, highlighting the value of evaluating a non-calibrated model in this environment. Simulations best matched the streamflow record in years when peak and annual discharges were equal to or above the medians of 6.7 m 3 s −1 and 1.25 ×10 7 m 3 , respectively, with an average Nash-Sutcliffe efficiency (NSE) of 0.76. Simulation of low-flow years (below the medians) was more challenging (average NSE < 0), with simulated discharge overestimated by 90 % on average. This result indicates the need for improved understanding of hydrological response in the watershed under drier conditions. Simulation during dry years was improved when infiltration was allowed prior to soil thaw, indicating the potential importance of preferential flow. Representation of in-channel dynamics and travel time under the flooded or ice-jam conditions should also receive attention in further model development efforts. Despite the complexities of the study watershed, simulations of flow for average to high-flow years and other components of the water balance were robust (snow water equivalency (SWE) and soil moisture). A sensitivity analysis of the flow routing model suggests a need for improved understanding of watershed functions under both dry and flooded conditions due to dynamic routing conditions, but overall CRHM is appropriate for simulation of hydrological processes in agricultural watersheds of the Red River. Falsifications of snow sublimation, snow transport, and infiltration to frozen soil processes in the validated base model indicate that these processes were very influential in stream discharge generation.

On the relationship between flood and contributing area

“…negative bias in simulated maximum annual streamflow of 18%. This is not uncommon for hydrological models in this landscape (e.g., Cordeiro et al, 2017). This negative bias is reflected in the flood frequency distributions (Figure 4) and is likely responsible for suppressing Nash-Sutcliffe values.…”

Shifting Hydrological Processes in a Canadian Agroforested Catchment due to a Warmer and Wetter Climate

“…Regarding runoff routing, agricultural fields were first routed to the drainage canals, and then the outflow from the drainage canals routed to the river network, while other HRUs were routed directly to the streamflow network. Similar to the method used by Cordeiro et al [102], the routing length was determined as the median distances from the centroid of each HRU to the closest drainage canal for agricultural HRUs, and as the median distances from each HRU to the streamflow network for non-agricultural HRUs.…”

Hydroclimatic controls on runoff activation in an artificially drained, near‐level vertisolic clay landscape in a Prairie climate

“…OF was activated ahead of TF and GWT during the majority of events (Figure ), and the combined examination of OF and GWT data suggest that OF was due to infiltration excess rather than saturation excess. Although the dominance of OF in the RRV had been extensively demonstrated before (Cordeiro et al, ; Dumanski et al, ; Tiessen et al, ), OF occurrence had not previously been examined in conjunction with TF and GWT on an event basis. The current study demonstrates that the activation times OF were comparable between tiled and nontiled fields, indicating that tile drains do little to delay the activation of surface runoff atop vertisolic clays in the Prairies.…”

“…High‐intensity rainfall may also activate preferential flow pathways in macroporous soils (Edwards, Shipitalo, Owens, & Dick, ; Heppell, Worrall, Burt, & Williams, ; Stone & Wilson, ), thus, allowing vertical connectivity between the surface and subsurface tiles drains: This can produce rapid TF responses and lead to the rapid mobilization of nutrients in tile drain effluent (Smith et al, ; Stillman, Haws, Govindaraju, & Rao, ; Stone & Wilson, ; Vidon & Cuadra, ). Antecedent moisture conditions (AMC) have also been identified as important drivers of runoff generation, both in the presence and in the absence of tile drains (Hardie et al, ; Macrae et al, ; Macrae, English, Schiff, & Stone, ; Vidon, Hubbard, Cuadra, & Hennessy, ), as they control effective porosity for water flow in unsaturated soil conditions as well as portion of soil volume occupied by ice formed during seasonal freezing (Cordeiro, Wilson, Vanrobaeys, Pomeroy, & Fang, ; Gray, Toth, Zhao, Pomeroy, & Granger, ). In temperate regions, runoff responses to AMC have been shown to be non‐linear in nature (Macrae et al, ) and vary temporally (Lam et al, ; Macrae et al, ; Vidon et al, ).…”

“…Although studies have been conducted on tile drainage in clay soils in other regions (e.g., King et al, ), these regions do not have cold climates such as those in the Northern Great Plains. The RRV basin is a generally flat landscape that hosts predominantly vertisolic clay soils prone to shrinking and swelling and with low‐hydraulic conductivities (Cordeiro et al, ), characterized by a subhumid climate with long and cold winters having minimal snow cover and a deep seasonal ice layer, contrasted with short, warm, and relatively dry summers (Fang et al, ; Pomeroy, Shook, Fang, & Brown, ). Runoff typically occurs as OF, and the risk of flooding on frozen, saturated soils in spring is considerable (Fang et al, ).…”