Landscape Processes

Runoff and Infiltration

Subsurface Drainage

Project
Team

Thanos Papanicolaou, Filippo Bressan, Christopher Wilson

Overview
Subsurface Investigations Good gravel roads are needed for efficient transportation around the farm and in farming communities.  An efficient subsurface drainage is a fundamental requirement to achieve this effectiveness.  Although there are technical specifications for subbase composition, in the engineering practice, the subbase soils are comprised of whatever material is found at the site in order to minimize costs for transporting graded material from a quarry. As a result, the soil composition is far from ideal with detrimental effects on unpaved road conditions.  The resulting prolonged residence time of water and sustained high moisture levels from excessive rainfall lead to the formation of frost boils atop the surface of the roads, which, in turn, jeopardize the strength of the road and regular maintenance is required.  This research will explore the mechanisms triggering frost boils and determine whether current design and/or maintenance alternatives can guarantee subgrade drainage performance.  A practical model will be developed for evaluating post-construction subdrain performance using soil borings and/or NRCS soil maps.  Field monitoring of representative county roads and controlled laboratory experiments will focus on analyzing the role of hydraulic and geotechnical parameters related to drainage.  In addition, alternative design options, as the application of Polyacrylamide (PAM) will be considered to improve the current drainage capacity of unpaved county roads.  The final products of the proposed research will be to (i) assess the efficiency of current subbase design in Iowa, and to provide improved design specifications to ensure an excellent drainage under the current climate and groundwater conditions.  The compilation of updated specifications and guidelines will provide a practical and valuable tool to be used by contractors and engineers to lessen the effects of frost boils in gravel roads throughout the state of Iowa.

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Flood and Erosion Mitigation

Project
Team

Thanos Papanicolaou, Mohamed Elhakeem, Dimitrios Dermisis, Ozan Abaci, and Christopher Wilson

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.

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Managing and Optimizing Nutrient Loads in Clear Creek, IA

Project
Team

Thanos Papanicolaou, Ozan Abaci, Dimitrios Dermisis, Christopher Wilson, 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.

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Subsurface Flow and Water Quality Measurements

Project
Team

Thanos Papanicolaou, Mohamed Elhakeem, Yi-Jia Chang, and Christopher Wilson

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.

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Erosion and Carbon Dynamics

Multi-Scale Carbon and Nitrogen Initiatives

Projects
Team

Thanos Papanicolaou, Kenneth Wacha, Chris Wilson

Overview
Multiscale Carbon ObservationIn Iowa, projected climate shifts coupled with intense agriculture activities create a challenging set of questions and choices for scientists, policy makers, farmers, and businesses. Motivated by these challenges and opportunities, our NASA EPSCoR program will focus on the links between intense agriculture, climatic shifts, CO2 emissions, and Soil Organic Carbon (SOC) dynamics.  Our objectives are: 1) to investigate the impacts that Land Use/ Land Cover (LU/LC) has on SOC sequestration potential and provide more accurate estimates of projected CO2 emissions in the Midwest; 2) to further NASA earth science priorities by improving the understanding of how soil and atmospheric measurements at local and regional scales can im-prove the biogeochemical models used for NASA forecasts of CO2, land cover, and climate at decade-to-century time scales; and 3) to build research capacity within Iowa and the Midwest for quantifying the links between agriculture, climate, SOC and CO2 while establishing a program of national stature for carbon cycle studies in intense agricultural systems.

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Sustainable Agro-Ecosystems

Projects
Team

Thanos Papanicolaou, Kenneth Wacha, Chris Wilson

Overview

Ecosystem ServicesTo 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.

In this study, a Multifunctional Agriculture (MFA) assessment of a representative agricultural watershed in Iowa was conducted by assessing dominant ecosystem services, including: water quality (runoff), crop/grain production, soil carbon sequestration, and reduction in CO2 emissions. Services were identified using a newly developed coupled erosion and biogeochemical model framework with a geo-spatial platform. An economic cost-benefit analysis was also conducted to assess the feasibility of adapting various practices and the possibility of future monetary incentives.

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Land-Water-Human Systems

Project
Team

Thanos Papanicolaou, Kenneth Wacha, Chris Wilson

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
Team

Thanos Papanicolaou, Kevin Denn, Christopher Wilson

Overview
Identifying Sediment Sources in a WatershedAccording to estimates by the Natural Resources Conservation Service, the state of Iowa loses 128.6 million tons of soil annually due to fluvial erosion, the most of any state in the nation. A majority of this soil loss is the result of erosion from intensively managed agricultural fields. Once the soil is lost from the fields, small, first-order streams transport the massive amounts of soil as suspended sediment to the watershed outlet.  However, suspended sediment can also be produced from the stream banks and bed as the water completes its journey from the headwaters to the watershed outlet.  Therefore, in small agricultural watersheds, three general suspended sediment sources exist:  i) upland areas, ii) stream banks and iii) stream bed.  The goal of this study was to quantify the relative proportions of eroded upland surface soils and channel sediments in the fine suspended sediment load of agricultural watersheds in Iowa during single runoff events using activities of 7Be and 210Pbxs.  The two radionuclides provide unique biogeochemical signatures to the eroded upland soils and channel sediments due to their profiles in the soil column and the dominant erosion processes in the source areas.  Eroded surface soils will have higher activities of 7Be and 210Pbxs than channel sediments.  The fine suspended sediment will have an intermediate radionuclide signature that is quantified through a simple two-end member mixing model.  Runoff events were sampled in different landform regions of Iowa, one with rolling hills and well drained soils and the other, which is flat and has poorly drained soils.  Results suggest that eroded surface soils are more abundant in the suspended sediment early in the runoff event in both watersheds; however, the overall upland contributions from the poorly drained watershed were less than upland contributions from the well drained system.  This is partly due to decreases surface runoff and sediment settling before it enters tile intakes.

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Channel Geomorphology

Knickpoint Erosion

Projects
Team

Thanos Papanicolaou, Filippo Bressan

Overview

Knickpoint migration

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.

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Automated Bank Erosion Monitoring

Project
Team

Thanos Papanicolaou, Tommy Sutarto, Christopher Wilson, Fabiene Bertrand

Overview
Photo-Electronic Erosion PinsConventional monitoring methods of erosion of bank soils and removal of abutment fill material have difficulty capturing the exact time of the event because they provide only net measurements since the previous sampling. Moreover, these methods are laborious and expensive, which often leads to undersampling. This pilot study developed of a protocol for monitoring erosion near bridge abutments using innovative technology, namely Photo-Electric Erosion Pins (PEEPs). PEEPs provide automated and continuous monitoring of localized erosion, especially, in areas that channel surveying and/or installation of erosion pins is difficult to take place. The primary goal of this pilot study was the development of a protocol for monitoring erosion near bridge abutments using innovative technology (namely PEEPS). A PEEP is an optoelectronic device consisting of an array of photovoltaic cells (photodiodes) connected in series and enclosed within a transparent acrylic tube. The PEEPs are initially inserted into the bank face parallel to the water surface, all the diodes are covered by the bank sediment and the voltage received by the datalogger is low. However, as the bank face retreats, more diodes are exposed and the voltage received by the datalogger increases. This voltage is normalized against a reference value, which corresponds to the voltage if all PEEP diodes are exposed. This ratio is then related to an erosion length.

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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.

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Videos

 

Clear Creek Watershed

Large-Scale Environmental Research and Analysis Network of the Upper Mississippi River Basin

Project
Team

Thanos Papanicolaou, Christopher Wilson, 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.

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Video