Model Estimation of Land-Use Effects on Water Levels of Northern Prairie Wetlands

Abstract

Wetlands of the Prairie Pothole Region exist in a matrix of grassland dominated by intensive pastoral and cultivation agriculture. Recent conservation management has emphasized the conversion of cultivated farmland and degraded pastures to intact grassland to improve upland nesting habitat. The consequences of changes in land-use cover that alter watershed processes have not been evaluated relative to their effect on the water budgets and vegetation dynamics of associated wetlands. We simulated the effect of upland agricultural practices on the water budget and vegetation of a semipermanent prairie wetland by modifying a previously published mathematical model (WETSIM). Watershed cover/land-use practices were categorized as unmanaged grassland (native grass, smooth brome), managed grassland (moderately heavily grazed, prescribed burned), cultivated crops (row crop, small grain), and alfalfa hayland. Model simulations showed that differing rates of evapotranspiration and runoff associated with different upland plant-cover categories in the surrounding catchment produced differences in wetland water budgets and linked ecological dynamics. Wetland water levels were highest and vegetation the most dynamic under the managed-grassland simulations, while water levels were the lowest and vegetation the least dynamic under the unmanaged-grassland simulations. The modeling results suggest that unmanaged grassland, often planted for waterfowl nesting, may produce the least favorable wetland conditions for birds, especially in drier regions of the Prairie Pothole Region. These results stand as hypotheses that urgently need to be verified with empirical data.

Land use and wetland drainage affect water levels and dynamics of remaining wetlands

“…2007) increases in agricultural commodity prices (Gleason et al 2008(Gleason et al , 2011. We expected that crops or soil tillage would affect wetland hydrology (Euliss and Mushet 1996, Voldseth et al 2007). Accordingly, we estimated agricultural land use during the historical era ; using the earliest year in which ;1-m cell size photos for the entire catchment were available) and multiple times during the current era (2003/2004, 2009, and 2010).…”

Simulating the water budget of a Prairie Potholes complex from LiDAR and hydrological models in North Dakota, USA

“…First, the water table was not tracked below the wetland bottom in our study; this may reduce model performance, especially for small wetlands that have more labile water change and dry out more frequently than large wetlands (Voldseth et al 2007). Second, different soil and vegetation at the fringe of standing water and in the upland have different evapotranspiration rates (LaBaugh et al 1998).…”

“…Fourth, in our hydrological modelling, the spilling point location, the inter-wetland connectivity, the maximum storage capacity (V max ) and the relationship between volume (V ) and ponded area (PA) were all applied to this model; however, these data were not perfect and bias did exist, as discussed by Huang et al (2011a). Fifth, snow distribution is not spatially homogeneous due to grass trap or wind blowing (Voldseth et al 2007, Fang et al 2010; however, we assumed a spatially-homogeneous snow distribution in our model. Finally, land cover and land use changed between 1980 and 2009, resulting in the change of curve number; however, we only used static NLCD 2001 land cover classes in our study.…”

“…The PPR wetland landscape complexes are ecologically and economically important for providing ecosystem goods and services (Swanson et al 2003, Voldseth et al 2007, Johnson et al 2010. For prairie wetlands management, it is important to model the hydrological processes and understand how the amount of surface water stored in wetland complexes changes over time (LaBaugh et al 1998).…”

“…Semi-permanent wetlands were the only water regime considered in several models (Poiani and Johnson 1991, Poiani et al 1996, Johnson et al 2005; therefore, the significant water loss from small wetlands through shallow groundwater was not considered. For example, different versions (1.0, 2.0, 3.2) of WETSIM were developed for hydrology and vegetation dynamics for a single-basin and semi-permanent wetlands (Poiani and Johnson 1991, Poiani et al 1995, Carroll et al 2005, Voldseth et al 2007). Other wetland types, such as temporary wetlands, were not well addressed (e.g.…”