MONITORING DISCHARGE AND SEDIMENT SIZE CHANGE OVER TIME ON THE MENOMINEE RIVER, ILLINOIS

As climate change influences precipitation patterns across the US, some regions will experience more intense storm events that may cause flash floods and influence sediment transport and hillslope processes along river systems. To understand the potential changes to river systems, it is useful to monitor changes in the river geomorphology and processes over time. This study focuses on the Menominee River in Jo Daviess County, Illinois. The Menominee River travels through agricultural land, where it is important to understand how agricultural land-use changes affect the rivers that run through the land. Data were first collected in 2019. We revisited the site again in 2022 to observe potential changes. This study will compare river discharge from upstream to downstream in the two study years. We also observed how sediment sizes changed within the river channel after a rockfall from the bedrock hillslope along the river channel. We completed grain size observations by categorizing 100 clasts at the same three locations on the Menominee River observed in the 2019 study. We also collected cross section measurements to graph the shape of the channel bottom, calculate channel area, and record flow velocity in the river. These methods were repeated in 2019 and 2022. In 2019, we observed that the discharge decreased downstream from site 1 to site 2, and then increased again at site 3. In 2022, we observed an increase in discharge downstream from site 1 to site 2, then a decrease from site 2 to site 3. We observed that there were larger clast sizes recorded in the 2022 data than in the 2019 data. Our results record changes in discharge and sediment size over time on the Menominee River, Illinois.