Runoff and Infiltration
Subsurface Drainage
Project
Team
Thanos Papanicolaou, Filippo Bressan
Overview

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Flood and Erosion Mitigation
Project
Team
Thanos Papanicolaou, Mohamed Elhakeem, Dimitrios Dermisis, Ozan Abaci
Overview
Conversion of the natural prairie-forested landscape in U.S. Midwestern states to a corn-soybean crop rotation has altered the runoff condition and stream hydrology throughout the region by creating more dynamic surface water flow regimes and increasing the likelihood of severe floods. Flooding and the associated water quality issues in the region adversely affect crop yields, downstream ecosystem health, and water availability. In response to these concerns, Midwestern agricultural producers have adopted Best Management Practices (BMPs) to increase runoff retention and reduce sediment delivery. Common BMPs in the region are Grassed WaterWays (GWWs), which have been found to effectively reduce runoff/sediment conveyance by slowing water flow and increasing infiltration rates. This study examined the storm-event based efficiency of GWWs at reducing runoff within an agricultural watershed of the U.S. Midwest using the Water Erosion Prediction Project (WEPP). Reductions in runoff volume in a representative field increased by 9 times as the length of the GWW increased. GWW efficiency was governed by the hydrology, expressed as Qpeak. The GWWs were more efficient during events with smaller Qpeak values, while the efficiency decreased during larger events. Building on these simulations for a single hillslope, a standardized hydrologic analysis was conducted in the watershed using established hydrologic modeling techniques (i.e., WIN TR-20) to quantify and mitigate potential flooding impacts for the entire watershed. The outcome of this study was to identify and quantify the management practices (e.g., conversion to grass or no-till) needed to mitigate large flood events in the watershed. The results suggested that the landscape changes are best used as secondary efforts. A high level of land use conversion was needed to produce significant runoff reductions. Average reductions in runoff volumes of about 12% were observed for a 25% conversion of agricultural land to grasslands, with about an average 15% reduction for a 50% conversion. However, these land conversions will likely decrease sediment and contaminant loads in the streams, which has other significant benefits.Learn more>>>[1]
Managing and Optimizing Nutrient Loads in Clear Creek, IA
Project
Team
Thanos Papanicolaou, Ozan Abaci, Dimitrios Dermisis, and Benjamin Abban
Overview
It is estimated that 90% of U.S. cropland is losing fertile soil above the sustainable rate. In Iowa, one-half of the fertile topsoil has been lost during the last century of farming. In addition, 60% of Iowa soils are over-fertilized which drastically lowers water quality. In response to soil degradation and decreasing water quality, Best Management Practices (BMPs) have been widely adopted by Iowan agricultural producers to increase retention of runoff volume, as well as reduce sediment delivery and Non-Point Source (NPS) pollution. Common BMPs in the croplands of southeast Iowa are Grassed WaterWays (GWW’s) which have been found to effectively reduce runoff/sediment conveyance and gully formation by slowing water flow and increasing infiltration rates. This research investigates the scale-dependent, storm-event based efficiency of GWW’s within an agricultural Iowa watershed. The efficiency of the GWW’s was examined by utilizing the physically based, distributed parameter Water Erosion Prediction Project (WEPP) model, which was calibrated for single storm events. It is hypothesized that GWW’s provide localized erosion protection, thus the impact of implementing GWW’s is likely to decrease with catchment size.Subsurface Flow and Water Quality Measurements
Project
Team
Thanos Papanicolaou, Mohamed Elhakeem, Yi-Jia Chang
Overview
When infiltration rate reaches the steady state condition, it is defined as the saturated hydraulic conductivity, Ksat. Ksat is a key variable in the hydropedologic studies determining soil suitability for agricultural uses, water relationships for plant growth, and potentials for pesticide leaching. In addition, Ksat directly influences the amount of runoff and eroded surface soil that are delivered to local waterways, thereby affecting both in-field soil quality and in-stream water quality. Therefore, accurately measure and estimate of Ksat is of paramount importance when predicting hydrologically-driven processes or making catena assessments in landscapes. The main objective of the proposed research study is to introduce an innovative and versatile method to make adequate dynamic Ksat predictions at large scales (e.g., watershed, township, county, state, etc.). This method will involve in-situ measurements, and the use of watershed models and pedotransfer functions (PTFs) coupled with geospatial tools and satellite data. The proposed method will be complemented with field data for calibration and verification.Learn more>>>[1]
Erosion and Carbon Dynamics
Multi-Scale Carbon and Nitrogen Initiatives
Projects
- Iowa’s Multiscale Carbon and Nitrogen Studies (IMCANS): Combining Remote and In-Situ Approaches in Agricultural Landscapes (08/01/2008 – 07/31/2012)
- EPSCoR: Agricultural soil erosion and carbon cycle observations in Iowa: Gaps threaten climate mitigating policies (08/01/2010 – 07/31/2013)
Team
Thanos Papanicolaou, Kenneth Wacha
Overview

Sustainable Agro-Ecosystems
Projects
Team
Thanos Papanicolaou, Kenneth Wacha
Overview
To ensure food security for an exponentially growing global population that is grown on a finite number of farm fields, intensive agricultural management practices are being used. Intensive management practices can trigger rainfall-and tillage-induced erosion events, degrade soil and water quality, and increase atmospheric fluxes of carbon dioxide (CO2). Conservation practices, including reduced tillage and no-till, have been shown to offset some of these negative environmental effects. These good land stewardship practices provide additional ecosystem services or benefits to a large number of stakeholders.
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Land-Water-Human Systems
Project
Team
Thanos Papanicolaou, Kenneth Wacha
Overview
External pressures from a transitional climate, intensifying agriculture, and farm consolidation are affecting our ability to establish a sustainable, agro-centric way-of-life here in Iowa. Our responses to date have been to develop watershed management plans that called for implementing several Best Management Practices (BMPs). Unfortunately, many of these management plans have produced little improvement in downstream pollution problems for more than 10 years after installation. We propose a holistic approach should be used to investigate how our agro-ecosystems are responding to changes in climate, ecology, economics and policy, as well as how they are interacting with the natural world. Only with this complete knowledge of the ecological, economic, and ethical aspects of our agro-centric ecosystem in response to different production systems can stakeholders make a conscientious and informed decision regarding land stewardship. To achieve this we are developing a holistic framework consisting of a coupled biogeochemical- watershed erosion model, a simple economic model that determines the net revenue of different production systems with a risk premium that accounts for the benefits associated with different ecosystem services, and a measure of the quality of life that different production systems will have on the individuals and communities, which accounts for the natural, human, and social capitals. Collectively, this framework will be used to protect valuable natural resources (e.g., air, water, and soil), which in fact are needed for achieving a harmonious balanced system.
Sediment Source Identification in Human-Impacted Watersheds
Projects
- Differentiating Flash Flood-Borne Sediments in a Small Agricultural Headwater System Using Isotopic Tracers (04/01/2011 – 03/31/2013)
- Identifying the Primary Sources of Sediment in an Anthropogenically Altered Watershed (03/01/2010 – 02/28/2012)
Team
Thanos Papanicolaou, Kevin Denn
Overview

Channel Geomorphology
Knickpoint Erosion
Projects
- The Effects of Headcut and Knickpoint Propagation on Bridges in Iowa (09/01/2005 – 08/31/2007)
- Monitoring the Effects of Knickpoint Erosion on Bridge Pier Structural Damage and Scour (11/01/2010 – 12/31/2011)
Team
Thanos Papanicolaou, Filippo Bressan
Overview
Knickpoints are geomorphic bed features characterized by the formation a sharp change in the channel slope leading to the creation of a wide crest staircase. Knickpoints migrate upstream and cause bank instability, exposure of bridge crossing foundations, as well as the deterioration of fish habitat. They are a common geomorphic hazard in many streams of the Midwestern United States that is partly due to prevailing management practices, including stream channelization, which mostly occurred during the first half of the 20th century. Over the last forty years, local governmental agencies have attempted to halt knickpoint migration by constructing different types of grade control structures (GCS). Despite these attempts, the problem still persists. Understanding of the mechanisms triggering the onset of knickpoint migration is at a primitive stage. In this study, a field evaluation of a representative channel reach containing a knickpoint in the Deep Loess Region of western Iowa was used to test current theoretical and numerical models of knickpoint migration. Continuous stage and periodic flow measurements were recorded for almost two years and included an extreme event, which occurred during the catastrophic 2008 Midwestern United States floods. In addition, soil samples from the river bed and banks were collected and the bathymetry was measured in order to fully characterize the stream reach. The data were used to estimate the parameters of various models to quantify the knickpoint migration rate and evolution during various hydrological events. The final goal of this research is to identify the most suited approach to model the knickpoints found in Midwestern streams. The results of the study can then be used by federal or state agencies to define better plans for the future control of bed degradation using more adequate GCS.Learn more>>>[1]
Automated Bank Erosion Monitoring
Project
Team
Thanos Papanicolaou, Tommy Sutarto, Fabiene Bertrand
Overview

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Fluvial Erosion
Team
Thanos Papanicolaou, Tommy Sutarto
Overview
Cohesive streambank erosion is characterized by two main mechanisms, mass failure due to gravity and fluvial entrainment of individual particles (Thorne, 1980). Mass failure is defined as a process, when blocks of bank material collapse, triggered by the collective action of gravity and fluid forces (e.g., Millar and Quick, 1998; Duan, 2005) and mainly occurs during and right after the recession of high flow events. Fluvial entrainment refers to a continuous process that commences when the hydraulic forces exceed the resistance forces (Millar and Quick, 1998; Papanicolaou et al., 2007). For non-cohesive soils the resistance force is dependent on the submerged weight and friction angle (angle of repose) and for cohesive soils is function of the cohesion strength (Papanicolaou et al., 2007; Thorne and Tovey, 1981). Fluvial erosion, comparatively to mass failure results to less erosion on an event scale and for this reason has received much less attention compared to mass failure.In this study, relative importance of fluvial erosion (compared to mass failure) was determined in two reaches from different locations of the Clear Creek Watershed (CCW). One site was selected at the second order stream and another site was located at the fourth order stream. Each of them was characterized by different flow condition and land-use.
Videos
Clear Creek Watershed
Large-Scale Environmental Research and Analysis Network of the Upper Mississippi River Basin
Project
Team
Thanos Papanicolaou, Dimitrios Dermisis, Benjamin Abban, Kenneth Wacha
Overview
The Clear Creek, IA watershed (CCW) drains approximately 270-km2 of east-central Iowa to the Iowa River. CCW is representative of most U.S. Midwestern watersheds regarding land use (predominantly agricultural), soil type/order (Alfisols and Mollisols), and climate (humid, continental). The combination of extensive agricultural activities, increased urbanization, highly erodible soils, and a wet climate on the steep slopes within the CCW has influenced the runoff and erosion processes in the watershed. The Clear Creek watershed currently has available a plethora of biogeochemical data from an existing network of remote and in situ sensors. Analysis of the physical samples collected within the watershed is conducted with state-of-the-art laboratory instruments. In addition to the biogeochemical data that exist for CCW, a detailed history of land use and management practices exists for the watershed. As a result of changing land use coupled with the predominant climate, soil types, and topography, average annual erosion rates are approximately 11 Mt/ha/yr with most of this erosion occurring in the early summer months when high-intensity rains impact bare soil surfaces in the recently planted agricultural fields. Stream destabilization as a result of widespread channelization and drainage system construction has further increased sediment loadings to the stream. The high sediment loads in CCW have been exacerbated by recent flooding resulting from the high-intensity rainfall prompting concern local residents.Learn more>>>[1]
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