Drought impacts on Canadian prairie wetland snow hydrology

Abstract

Abstract:Droughts affect the Canadian prairies on a regular basis. The drought of 1999-2005 was the most recent one and was the most severe on record for part of the region. It was characterized by lack of precipitation, desiccation of agricultural soils, decline in groundwater tables and depletion of surface water supplies. The effects on wetlands were particularly severe, with many wetlands completely drying out. The physically based cold regions hydrological modelling (CRHM) platform was used to analyse the impacts of this recent drought on water flow to and storage within a small Canadian prairie wetland. Model simulations were conducted for a small closed basin for the drought period of 1999-2005 and the relatively wet period of [2005][2006]. The basin consists of a cultivated upland, draining into a glacially formed pothole depression with no outlet. The wetland fills the depression in wet years and is underlain by a heavy glacial till that impedes groundwater exchange. Results from the observations and model outputs showed that much lower precipitation and snow accumulation, shorter snow-covered duration, enhanced winter evaporation, and much lower discharge to the wetland from basin snowmelt runoff developed in the severe drought years of 1999-2002. As a result, there were only 14Ð9, 3Ð7, and 14Ð4 mm of snowmelt runoff for the springs of 2000, 2001, and 2002, respectively. Compared to the 68Ð2 mm of melt-water discharge in the spring of 2006, discharge to the wetland was 78, 95, and 79% less for these years. This is consistent with the observed water level in the wetland, which shows dramatic decline over this period. CRHM was used to investigate the potential impact of snow management as a tool to enhance runoff to the wetland during droughts. Model runs parameterized with suppressed vegetation in the cultivated land surrounding the wetland showed increased blowing snow transport to the wetland from an area exceeding the basin area that resulted in greater snow accumulation in and melt-water supply to the wetland.

Prediction of snowmelt derived streamflow in a wetland dominated prairie basin

“…These wetlands occasionally connect to one another during wet conditions through the "fill and spill" mechanism (van der Kamp and Hayashi, 2009). The water balance of these wetlands is influenced by redistribution of snow by wind from adjacent upland areas, precipitation, evapotranspiration, snowmelt runoff, groundwater exchange, and antecedent status of soil and depressional storage (Fang and Pomeroy, 2008;van der Kamp and Hayashi, 2009). Depending on the water balance, these wetlands vary from being shallow and seasonal to deep and permanent.…”

“…They are also valuable habitats for migratory waterfowl (Smith et al, 1964). However, hydrology of these wetlands is very sensitive to changes in air temperature, seasonal precipitation and other climatic variability (Poiani et al, 1995;Fang and Pomeroy, 2008;van der Kamp et al, 2008). Land use alteration in surrounding upland areas can produce noticeable impacts on snowpack trapped by wetland vegetation, surface runoff to wetlands, and wetland pond level Fang and Pomeroy, 2008).…”

“…However, hydrology of these wetlands is very sensitive to changes in air temperature, seasonal precipitation and other climatic variability (Poiani et al, 1995;Fang and Pomeroy, 2008;van der Kamp et al, 2008). Land use alteration in surrounding upland areas can produce noticeable impacts on snowpack trapped by wetland vegetation, surface runoff to wetlands, and wetland pond level Fang and Pomeroy, 2008). 50 to 75% of the original Prairie wetlands have been filled, levelled, and drained since European settlement (Dahl and Johnson, 1991;Gleason and Euliss, 1998), which has been implicated as a cause for downstream flooding (Rannie, 1980;Hubbard and Linder, 1986).…”

“…Hydrological modelling systems have been developed to focus on predicting water balance for large scale basins with considerable wetland storage (Vining, 2002;St. Laurent and Valeo, 2007;Wang et al, 2008), whereas physically based models integrating more cold regions hydrological processes have been assembled to simulate hydrological processes for the individual closed wetland basins (Su et al, 2000;Pomeroy et al, 2007b;Fang and Pomeroy, 2008). In light of the hydrological and ecological importance of prairie wetlands, the objectives of this paper are to: (1) develop a physically based hydrological model for a Canadian Prairie basin with large wetland areas; (2) derive all model parameters using field survey data, digital elevation model (DEM), satellite imageries, stream network and wetland inventory GIS data (no calibration); (3) evaluate the model performance in simulating winter snow accumulation, estimating spring soil moisture, and predicting basin streamflow.…”

Simulation of Snowmelt and Runoff Based on Component in Northwest of China

“…Simulated and measured values were compared using the model efficiency (ME) and root mean square error (RMSE) [8]. Model efficiency (ME ≤ 1) is defined as the fraction of variation in observed values explained by the model (Nash and Sutcliffe, 1970), it is an indication of model performance compared to the mean of the observations.…”