Clear Creek Experimental Watershed, IA

The Clear Creek Experiment Watershed (HUC-10: 0708020904) drains approximately 240 km2 in Iowa and Johnson Counties of east-central Iowa. Clear Creek flows approximately 40 river km with an elevation drop of approximately 300 ft. from west to east into the Iowa River. IIHR research is focused in the headwaters of the CCW, more specifically within the predominantly rural South Amana Catchment (SAC). The SAC encompasses 26 km2. The average gradient is 4%, ranging from 1% to 10%.

The Clear Creek Experiment Watershed predominantly has fine, organic-rich soils that leads to very high soil quality and productivity. Some of the highest erosion rates in the CCW are observed within the SAC mainly due a combination of swelling and highly erodible soils with steep gradients and intensive agriculture

Recently in the SAC, there are nine main land uses. Six of the land uses represent the various corn-soybean rotations currently present in the watershed. Each rotation involves a unique set of the following management practices: no-till, reduced spring tillage, convention fall tillage with secondary tillage in the spring. Three of these rotations encompass over 80% of the watershed acreage. Hay farming, pastures and CRP are the other land uses.

The SAC is the focal point of the Clear Creek Experimental Watershed. This catchment is currently being instrumented by IIHR – Hydroscience & Engineering at the University of Iowa to monitor rainfall, streamflow, suspended sediment concentration, and other water quality parameters.

Experimental test plots throughout the CCEW help to evaluate processes on the particle, plot, and field scale, namely incubation studies of carbon and nitrogen, as well as, soil-SOM-nutrient loss.

Experimental Test Field with corn

Experimental Test Field with soybeans