Projected changes in monthly baseflow across the U.S. Midwest

Abstract

Baseflow is an essential water resource because it is the groundwater discharged to streams and represents long‐term storage. Understanding its future changes is a major concern for water supply and ecosystem health. This study examines the impacts of climate and agriculture on monthly baseflow in the U.S. Midwest through the end of the 21st century. We use a statistical approach to evaluate three scenarios. The first scenario is based on downscaled and bias corrected global climate model (GCM) outputs and the representative concentration pathway (RCP) 8.5, and agriculture is held constant (and equal to the mean from 2013 to 2019). In the next two scenarios, climate is held constant (2010–2019) to isolate the impact of agriculture on baseflow. In terms of agricultural changes, we consider scenarios representative of either increases or decreases with respect to the production of corn and soybeans. Changes in the climate system point to increases in baseflow that are likely a result of increased precipitation and antecedent wetness. Seasonally, warmer temperature in the winter and spring (i.e., February to July) is expected to cause increasing trends in baseflow. Changes in land use showed that agriculture would either mitigate the impact of climate change or possibly amplify it. Expanding corn and soybean areas would increase baseflow in the Corn Belt region. On the other hand, converting land back to perennial vegetation would decrease baseflow throughout the entire year. Despite its simplicity, this study can provide basic information to understand where to expect adverse effects on baseflow and thus improve land management practices in those areas.

Stream Habitats and Aquatic Communities in an Agricultural Watershed: Changes Related to a Mandatory Riparian Buffer Law

“…In addition, the higher current velocities observed in the SFWR post-buffer law should continue to prevent or reduce deposition of nes, as higher and more variable current velocities are likely to produce greater substrate heterogeneity (Duehr et al 2006). When coupled with the increasing regional stream base ows in the midwestern United States (Ayers et al 2018(Ayers et al , 2021a, greater current velocities could increase the relative abundance of gravel, cobble, and boulder stream-bottom substrates with reduced embeddedness within the SFWR.…”

“…However, SFWR sites also demonstrated increased habitat (e.g., reduced dominance by runs, increased ri e abundance) and substrate diversity and nearly a doubling of instream vegetative cover for sh during 2018 surveys, opposite of how stream habitats normally respond to increased ooding and disturbance(Lorang and Hauer 2006;Rosgen 2006; Duehr et al 2008). Increased base ows of streams in this region(Ayers et al 2018(Ayers et al , 2021a, b) also could be responsible for the greater depths and stream widths and faster velocities observed at SFWR sites in 2018. Consequently, we cannot determine whether the habitat changes observed at SFWR sites were the result of buffer improvements, or if they resulted from frequent disturbance from ooding, greater base discharges, or some combination of these.…”

Applying High-Resolution Satellite and UAS Imagery for Detecting Coldwater Inputs in Temperate Streams of the Iowa Driftless Region

“…The influence on headwater streams of groundwater inputs is highly dependent on aquifer geometry and composition [50], location of the groundwater source relative to the stream [51], and seasonal temperature and precipitation patterns [38]. Recently, the groundwater discharge rate and baseflows in the streams of the Driftless Region has changed due to increases in precipitation throughout the year as well as land use changes [52,53]. Besides long-term trends in groundwater flows, annual variation in flow rates can also influence ice coverage rates observed in winter imagery in a given year.…”

Stream Habitats and Aquatic Communities in an Agricultural Watershed: Responses to a Mandatory Riparian Buffer Law

“…However, SFWR sites also demonstrated increased habitat (e.g., reduced dominance by runs, increased ri e abundance) and substrate diversity and nearly a doubling of instream vegetative cover for sh during 2018 surveys, opposite of how stream habitats normally respond to increased ooding and disturbance(Lorang and Hauer 2006;Rosgen 2006; Duehr et al 2008). Increased base ows of streams in this region(Ayers et al 2018(Ayers et al , 2021a, b) also could be responsible for the greater depths and stream widths and faster velocities observed at SFWR sites in 2018. Consequently, we cannot determine whether the habitat changes observed at SFWR sites were the result of buffer improvements, or if they resulted from frequent disturbance from ooding, greater base discharges, or some combination of these.…”