EFFECTS OF CLIMATE AND DEVELOPMENT ON THE GEOMORPHOLOGY AND HYDROLOGY OF THE YELLOW CREEK WATERSHED, SUMMIT AND MEDINA COUNTIES, OHIO

The goal of this on-going study is to determine the relative contributions of increased flood frequency and continued land development on geomorphic change and damage to infrastructure throughout the Yellow Creek, OH watershed. Comprised of five sub-watersheds, the Yellow Creek watershed is located in Northeast Ohio and is a tributary of the Cuyahoga River. In Northeast Ohio, a statistically significant change point in both heavy precipitation and stream flow occurred in July 2003. On the USGS Cuyahoga River Old Portage stream gage record, there were only 9 days of mean daily discharge above 80 m³/sec during the 12.5 years prior to July 2003 compared to 68 days in the 12.5 years after July 2003. Land cover data from NOAA reveals that development in the watershed has constantly increased by 3.0% from 1985-1996, 2.8% from 1996-2001, 3.5% from 2001-2006, and 1.4% from 2006-2010. The five sub-watersheds have contrasting development histories and vary from 70% to 15% developed. We installed water level loggers to measure hydrograph variability between the five sub-watersheds. Initial results show that following precipitation events, discharge occurs first in steep and highly developed sub-watersheds and last in less developed sub-watersheds having gentle slopes. Aerial photos for eight years between 1994 and 2014 are being used to assess changes in stream geomorphology through time. Preliminary results show that geomorphic change has been greater after July 2003 compared to before July 2003. These post 2003 geomorphic changes include an increase in unvegetated mid-channel bars and point bars as well as amplified channel migration. Elsewhere, Yellow Creek shows straightening and widening in response to increased flooding events. Although urbanization in the watershed results in increased runoff, initial results suggest that since 2003 increased flood frequency has a larger effect on geomorphology change than increases in development.