Evaluating the Role of Sinuosity in Nitrate Removal from Little Kickapoo Creek

The hyporheic zone, a sub-stream area where surface and ground water mix, can remove excess nitrate from stream waters and is an integral part of natural stream function. Areas supporting heavy agriculture input excess nitrogen into the natural system, putting ground water at risk of nitrate contamination. Low gradient streams have been found to create increased hyporheic zone areas as a result of the interaction beneath meander lobes. It is anticipated that flow through meander lobes in areas with high sinuosity values will have a greater decrease in nitrate flux than areas of low sinuosity. To evaluate sinuosity's role in nitrate removal, six segments along Little Kickapoo Creek (LKC) a low gradient, third order perennial stream located in central Illinois were examined. Four of the six segments in the study area are predominantly agricultural but have some small residential areas within them. Restored wetlands and a residential area comprise the other two segments. Sampling and stream gauging were performed during base flow conditions to eliminate additional complexities such as surface flushing and variable hyporheic interaction. A Geographic Information System (GIS) was used to delineate land use in the area and to determine possible sources and explanations for excess nitrate contributions. Paired t-tests will be used to evaluate the relationship between sinuosity and nitrate removal. Preliminary results show a decrease in nitrate concentrations in 3 of the 6 segments, occurring as sinuosity increases. Nitrate loss may be due to denitrification or plant uptake.