MONITORING ANNUAL SEDIMENTATION PATTERNS AND ASSOCIATED GEOMORPHIC CHANGE ON THE ONE HUNDRED AND TWO RIVER NEAR MARYVILLE, MISSOURI

The One Hundred and Two River (102) near Maryville, MO is prone to seasonal flooding impacting alluvial sedimentation patterns. Changes in floodplain geomorphology are mainly based on post-flood sediment distribution and floodplain drainage characteristics. In this study, we examined the post-flood sediment distribution at a specific location of the 102 River floodplain and periodically monitored the site over the course of a year. Sediment samples were collected for characterization by sampling/coring twenty locations throughout the floodplain study area. The samples were analyzed by grain size, then mapped. Geomorphologic changes were recorded by monitoring the site periodically with photography and field observations.

Based on the data collected, the flood plain area was mapped according to sediment size. Geomorphologic changes to the floodplain were considerable for one year, specifically during the flood season (April-July). The grain size distribution did not fully adhere to the generally accepted sediment distribution for floodplains such as grain size distribution as a function of distance from the channel. The unexpected location of some of the sediment was most likely due to the geomorphology of the floodplain pathway bisecting the study area. In one section in particular, highly variable levels of sediment erosion and deposition were observed. Additionally, parts of the floodplain along the bank failed and were lost during high river levels. The formation of a sandbar occurred just south of the failure of the floodplain and bank.