Anticipated impacts of climate change on 21st century Maumee River discharge and nutrient loads

Abstract

Climate change holds great potential to affect the Lake Erie ecosystem by altering the timing and magnitude of precipitationdriven river discharge and nutrient runoff in its highly agricultural watershed.Using the SWAThydrologic model and an ensemble of global climate models, we predicted Maumee River (Ohio) discharge during the 21 st centuryunder two Intergovernmental Panel on Climate Change (IPCC) greenhouse gas emissions scenarios: RCP4.5 (mid-range, moderate reductions) and RCP8.5 (high, "business as usual"). Annual dischargewas projected to increaseunder both scenarios, both in the near-century (RCP4.5=6.5%; RCP8.5=2.0%) and latecentury (RCP4.5=9.2%; RCP8.5=15.9%), owing to increased precipitation and reduced plant stomatal conductance.Holding fertilizer application rates at baseline levels, we found that reduced winter surface runoff and increased plant phosphorus (P) uptake led to a respective decrease in annual total P (TP)runoff in the near-century (RCP4.5=-4.3%;RCP8.5=-6.6%) and by the late-century(RCP4.5=-14.6%; RCP8.5=-7.8%). Likewise, soluble reactive P (SRP)runoff was predicted to decrease under both scenarios in the near-century (RCP4.5=-0.5%; RCP8.5=-3.5%) and by the late-century (RCP4.5=-11.8%; RCP8.5=-8.6%). By contrast, when fertilizer application was modeled to increase at the same rate as plant P uptake, TP loadingincreased4.0% (0.9%) in the near-century and 9.9% (24.6%) by the late-century and SRP loading increased 10.5% (6.1%) in the near-century and 26.7% (42.0%) by the late-century under RCP4.5 (RCP8.5).Our findings suggest that changes in agricultural practices (e.g., fertilization rates) will be key determinants of Maumee Riverdischarge during the 21 st century.

Quantifying the Impacts of Climate Change on Streamflow Dynamics of Two Major Rivers of the Northern Lake Erie Basin in Canada

“…Interestingly, for both emission scenarios and in both future periods, spring (March-May) precipitation was projected to increase, on average (up to +55%). Our results were comparable to those reported in similar Canadian watersheds [26,[54][55][56]; including by Rahman et al [57] in the Ruscom River basin, and in the watersheds around the Great Lake basins, such as those reported by Cousino et al [58] and Culbertson et al [12] in the Maumee River basin, by Bosch et al [11] in four basins draining to Lake Erie from the USA, by Li et al [14] in the Grand River basin, and by Samantha et al [59] in the Western Lake Erie basin, among others. Figure 6.…”

“…As also observed in two stations of the Grand River basin, streamflow in the early spring months (March and April) was projected to decrease consistently (up to −43%), irrespective of the emission scenario and the future period. Similarly, summer and autumn streamflow were also projected to decrease, on average, which was in line with the conclusions of Culbertson et al and Verma et al [12,13] in the Maumee River basin, Cherkauer and Sinha [9] in six watersheds of Lake Michigan, and Chien et al [63] in four watersheds of midwestern US.…”

“…In general, there was a clear shift of spring snowmelt toward the late winter months or the early spring months. Additionally, decreases in the average summer streamflow were noted, which corresponded to the observations made in similar cold climate regions [26,[54][55][56]61,62] including those in the Great Lake basin [11][12][13][14]57,58].…”

“…The increasing trend in temperature was expected to continue until July. The temperature, however, was expected to decrease in the autumn months, contrary to most of the studies conducted in surrounding basins [11,12,14,57,58].…”

“…However, because we achieved "very good" streamflow results at multiple locations, it is fair to assume that these two important components (green water flow or green water storage) were well simulated when using a physically-based model such as the SWAT. the Great Lake basins, such as those reported by Cousino et al [58] and Culbertson et al [12] in the Maumee River basin, by Bosch et al [11] in four basins draining to Lake Erie from the USA, by Li et al [14] in the Grand River basin, and by Samantha et al [59] in the Western Lake Erie basin, among others. As observed for precipitation, there existed marked spatial and temporal variabilities in the projected mean temperature.…”