Figure 5. Map of maximum saturation (\(F_{\text{satmx}}\)) and wetland
storage capacity (\(W_{\text{cap}}\)) in the Prairie Pothole Region,
derived from the Global Inundation Extent from Multiple Satellites
(GIEMS) product and MERIT 90-m DEM, respectively.
The high \(F_{\text{satmx}}\) regions are located in the Northeast part
of the domain, near Lake Winnipeg in Manitoba and the Red River Valley.
These regions also correspond with the low \(W_{\text{cap}}\) regions.
Two 13-year offline Noah-MP simulations were conducted: one with the
default setting and one with the new wetland scheme. The 13-year average
surface water balance (surface runoff and ET) and energy balance
(sensible heat and latent heat) are shown in Figure 6. Figure 6a shows
substantial wetland water storage availability – more than 200 mm
average over the summer months, in the north domain and in the
southeastern PPR in the Red River valley. In the central and western
PPR, wetland storage is generally less than 100 mm, with some deeper
storage in large water bodies surrounding lakes and rivers.
The surface water and energy balance in the PPR are greatly altered by
the presence of surface wetlands and the differences between WS and DEF
simulation follow their spatial distribution. The presence of surface
wetlands generally holds inflow water from rain and snowmelt, reducing
surface runoff while increasing evaporation by about
100~200 mm in summer months. The water in the saturated
fraction of the grid cell creates an open water surface, reducing
(increasing) the sensible (latent) heat fluxes by about
0~50 W/m2 in summer months. These impacts on surface
energy and water compensate for each other, and the presence of open
water storage may induce potential feedback to the atmosphere through
land-atmosphere interactions, which we will discuss in next section.