Pronounced Increases in Future Soil Erosion and Sediment Deposition as Influenced by Freeze–Thaw Cycles in the Upper Mississippi River Basin

Abstract

Soil erosion and sediment deposition are relevant to multiple important ecosystem services essential for natural and human systems. The present study aims to project future soil erosion and sediment deposition in the Upper Mississippi River Basin (UMRB) using climate projections by five Global Circulation Models (GCMs) under the Representative Concentrations Pathway (RCP) 8.5 scenario. To understand the importance of freeze–thaw cycles (FTCs) for soil erosion and sediment deposition estimation with climate change, this study compared two Soil and Water Assessment Tool (SWAT) models with different representations of the FTCs, with the standard SWAT using a simple regression method and SWAT-FT employing a physically based method. Modeling results show that future climate change can pronouncedly intensify soil erosion and increase sediment deposition, and the impacts are sensitive to how FTCs are represented in the model. The standard SWAT projected an increase in soil erosion by nearly 40% by the end of the 21st century, which is much lower than the projected over 65% increase in soil erosion by SWAT-FT. For sediment deposition, the projected percent changes by the standard SWAT and SWAT-FT also deviate from each other (i.e., about 70% by the standard SWAT vs about 120% by SWAT-FT). Overall, these results demonstrate the important roles of FTCs in projecting future soil erosion and sediment deposition and underline the need to consider the effects of conservation practices on FTCs to realistically assess the effectiveness of those measures.

Spatiotemporal Variations of Dryland Vegetation Phenology Revealed by Satellite-Observed Fluorescence and Greenness across the North Australian Tropical Transect

“…The trend of global warming has aroused great interest in understanding and monitoring the dynamics of vegetation phenology under the changing climate [2]. As a valuable indicator of climate variability and ecosystem responses [1,3], accurate measurement of land surface phenology (LSP) is crucial for better explicating the land-atmosphere-energy exchange and its representation in terrestrial biosphere models [4][5][6][7].…”

Assessing the Impact of Extreme Droughts on Dryland Vegetation by Multi-Satellite Solar-Induced Chlorophyll Fluorescence

“…Traditional reflectance-based vegetation indices are widely applied to assess the effects of extreme drought on ecosystem functioning and vegetation productivity at a regional, continental, or global scale [8,[13][14][15][16][17]. Dramatic impacts of climate extremes on vegetation dynamics (as measured by EVI) with abrupt changes in phenology and productivity over southeast Australia demonstrates that semiarid ecosystems exhibit the largest sensitivity to hydro-climatic variations [18,19]. Although vegetation-index-based approaches are essential for evaluating vegetation variation under large-scale drought events, the observations they provide are not directly associated with vegetation functioning [20].…”

Using the Soil and Water Assessment Tool (SWAT) to quantify the economic value of ecosystem services

“…Most of the studies reported to calibrate and validate the hydrological processes, which are considered the foundation of the model (Arnold et al, 2012; Nair et al, 2011), most of them based on observed data from gauging stations. Only one study did not calibrate or validated any of the objective variables used in the analysis, because one of their objectives was to conduct a model performance comparison between SWAT and SWAT‐FT models (Wang et al, 2021). Regarding the rest of modeled processes, although not the most common, output variables that have not been properly calibrated are used.…”