Progress 01/05/04 to 09/30/09
OUTPUTS: This project had two major objectives related to agricultural drainage. The first objective focused on characterization of the effects of agricultural drainage practices on watershed hydrology, which involved both mapping of subsurface drains and simulation of the their hydrologic impact. Outputs related to this objective include a methodology for mapping potentially tile drained land using available geospatial datasets, a methodology for mapping actual subsurface drainage intensity using classification of high-resolution aerial images, maps of drainage density for the Hoagland watershed in White County, Indiana and hydrologic model simulations demonstrating the portion of streamflow derived from tile drainage for two catchments in the Wabash River drainage system. These outputs have been disseminated to academic audiences through journal publications and presentations at regional and national conferences, including the Association of Agricultural and Biological Engineers (ASABE), the American Geophysical Union (AGU), the Indiana Water Resources Association (IWRA) and the Agronomy Society of America (ASA). Other stakeholders have been more directly engaged through an extension seminar on mapping of subsurface tile drains and a draft Web-based frequently asked questions (FAQs) document on the mapping of subsurface tile drainage. The second objective evaluated the potential of alternative land management techniques to mitigate the impact of agricultural drainage on water quality and quantity. Outputs related to this objective include the first simultaneous evaluation of the DRAINMOD N2 drainage and water quality model for corn-corn and corn-soybean rotations, suggested operational strategies for drainage water management control structures for fields with varying drain spacings, an evaluation of climatic controls on the effectiveness of drainage water management for crop yield enhancement and drainage reduction and hydrology model simulations of the spatial distribution of soil moisture in a tile drained agricultural field. These outputs have been disseminated to both academic and other stakeholder audiences through journal publications, presentations at the same national conferences, and participation in controlled drainage field days at both the Davis Purdue Agricultural Center and cooperative farmers fields in White County, IN. PARTICIPANTS: This project contributed directly to the training of three graduate students in Agronomy and Agricultural and Biological Engineering, and Earth and Atmospheric Sciences: Ms. Bibi Naz, Dr. Srinivasulu Ale and Ms. Linda Sylvester, respectively. Collaborators at Purdue University included Dr. Jane Frakenberger, Dr. Sylvie Brouder, Dr. Eileen Kladivko, Dr. Chris Johanssen, and Dr. Jess Lowenboerg-DeBoer. We also collaborated with Dr. Wayne Skaggs and Dr. Muhammed Youssef at NC State University. TARGET AUDIENCES: Our target audience includes: farmers who might be interested in adopting drainage water management or who have need to better understand their existing drainage system; drainage contractors who install and target drainage and water table management systems; and agency personal tasked with funding and evaluating conservation practices. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Our work on subsurface drainage mapping has led to a change in understanding regarding the techniques available for mapping subsurface drains and the prevalence of drains in the landscape. A decision tree classifier used to locate potentially tile-drained fields in poorly drained agricultural landscapes from a series of data sets including land use class, soil drainage class, and surface slope can correctly identify 95% of known tile-drained area as potentially tile-drained. Image processing techniques used with high resolution aerial images can be useful tools to estimate the drainage extent in agricultural landscapes. Comparison of estimated tile drained areas from aerial image analysis shows a close agreement of estimated tile drained areas from previous studies (50% versus 53% drained area). The presence of crop residue in the fields has an impact on the accuracy of the tile line detection. Disturbance of the soil during installation of tile lines makes the locations of the tile more distinct. Aerial images from multiple years based on tile installation time and crop rotation may yield the best possible tile line map. In the White County area, approximately 29% of cropland suitable for subsurface drainage has been drained. One potential impact of this work is anticipated to be the increased use of aerial image-derived maps of subsurface drains by farmers and conservation districts to enable better water management decisions at the field level. A future impact will be improved selection of management practices for water quality improvement in tile-drained landscapes through better predictions of the effectiveness of different practices. Investigations into the simulated effectiveness of drainage water management (DWM) systems has led to recommendations for improved operational strategies. All operational strategies considered result in a reduction of annual drain flow (and therefore nitrate load) between 52 and 55%. For narrower spacings, drainage water management can mitigate the increased nitrate loss while positively impacting crop yields. For spacings wider than 30 m it may be better to operate the DWM systems in the non-growing season only. On average, the highest positive impact of DWM on yield occurs in cool-dry years and the greatest negative effect occurs in cool-wet years. The operational strategy therefore needs to respond to annual weather conditions. As drain spacing decreases, the preferred growing degree days (GDD) for raising the outlet decreases and the antecedent precipitation index (API) increases, indicating that these may be useful criterion for determining real-time operational strategies that reflect year-to-year climate variability. The impact of this research will be to increase knowledge of farmers regarding the potential impact and management of drainage water management systems; this will allow farmers to better decide if drainage water management is an appropriate conservation measure for their fields. An eventual impact of this research could also be increased funding from the USDA and other agencies for targeting implementation of conservation practices by watershed or other criteria.
- Naz, B. and L.C. Bowling, 2008, A decision analysis system for mapping of subsurface drainage systems. Trans. of ASABE, 51(6): 1937-1950.
- Ale, S., L.C. Bowling, S.M. Brouder, J.R. Frankenberger and M. Youssef, 2009, Simulated operation strategy for drainage water management. Ag. Water Mngmnt, 96(4), 653-665.
- Naz, B., S. Ale and L.C. Bowling, 2009, Estimating Subsurface Drainage in Agricultural Landscapes, Ag. Water Mngmnt, 96(4), 627-637.
- Ale, S., L. Bowling, J. Frankenberger, S. Brouder and E. Kladivko, 2009, The influence of climate variability on drainage water management operation for Drummer soil in Indiana, U.S.A., Vadose Zone, In-press.
- Ale, Srinivasulu, 2009, Drainage water management impacts on simulated watershed nitrate load, Ph.D. Thsis, Purdue University.
Progress 10/01/07 to 09/30/08
OUTPUTS: Activities over the past year included both field and theoretical experiments, as well as teaching. Field experiments include: 1) On-going collaboration with faculty in the Agronomy, ABE and Agricultural Economic Departments in a four farm trial of drainage water management, 2) Primary responsibility for drainage monitoring at the Davis Purdue Agricultural Research Center, and 3) Continued characterization of the water balance and nutrient load for a natural wetland receiving subsurface drainage from the Purdue Agronomy Center for Research and Education. Theoretical assessments involve computer simulation modeling and data analysis: 1) Evaluation of the simulated and observed nitrate load from the water quality field station (WQFS) at the Agronomy Center for Research and Education, and theoretical assessment of the role of drainage water management, 2) Quantification of the impact of different drain spacings and climate variability on the performance of drainage water management systems, and 3) Initial exploration of techniques for modeling the nitrate load in Hoagland watershed in White County, IN and the potential impact of drainage water management. In addition, I continue to teach classes at the undergraduate and graduate level that focus on hydrology and environmental change. Output products in the last year include expanded field-based curricular materials, in particular a unit on discharge measurement for the undergraduate Environmental Hydrology course (AGRY 337). Outputs have been disseminated through 1) an interview with the Gary Indiana Post-Tribune, 2) as a guest lecturer in a graduate course on future water resource issues and 3) as a global climate change panel member at the Indiana State Fair, representing potential impacts on Indiana agricultural and water. PARTICIPANTS: In addition to collaborations previously reported for this project, I have initiated collaboration with Dr. Suresh Rao and Dr. Nandita Basu (Purdue Uiniversity, Civil Engineering) regarding the influence of tile drainage on nutrient transport and the development of source distribution functions for large-scale modeling of nutrient loads. TARGET AUDIENCES: This project is designed to reach target audiences ranging from individual farmers to government officials, including the state Department of Environmental Management and US Environmental Protection Agency. The research on recommended operational strategies for drainage water management systems can help individual producers to manage their own field drainage in a manner to improve both crop water use and downstream nitrate load. Larger scale investigations of the role of tile draiange in streamflow variability and nutrient load can help government officials in decisions regarding allocations of conservation programs and initiatives designed to address hypoxia in the Gulf of Mexico. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Many of the outputs related to quantification of drainage water management impacts were made possible through funding provided by the Cooperative State Research, Education, and Extension Service, U.S. Department of Agriculture. Continued exploration of streamflow impacts from tile drainage are being supported through the USDA National Research Initiative. Project outputs related to teaching were made possible by a Purdue University Instructional Innovation grant, which allowed purchase of several current meters for instructional discharge measurement. Overall, the various outputs associated with this project impact the way we think of subsurface tile drainage in the US corn belt. In terms of water quantity the impact of tile drainage on the annual water budget and the potential that exists for water conservation through the implementation of drainage water management is established, but there are increasing questions regarding the rate of vertical seepage through the surface confining soil unit and the net effect of artificial drainage conduits at watershed scales.
- Sylvester, L., 2008, Characterization and analysis of a natural wetland receiving agricultural runoff, Purdue University, M.S. Thesis, pp. 120.
Progress 10/01/06 to 09/30/07
OUTPUTS: Output activities over the past year center around both field and theoretical experiments, as well as teaching. Field experiments include: 1) On-going collaboration with faculty in the Agronomy, ABE and Agricultural Economic Departments in a four farm trial of drainage water management, 2) Participation with Indrajeet Chaubey, in the ABE Department, to perform nutrient spiraling studies to understand the in-stream transport rates of nitrate in drainage water, and 3) Initial investigation and characterization of the water balance and nutrient load for a natural wetland receiving subsurface drainage from the Purdue Agronomy Center for Research and Education. Theoretical assessments involve computer simulation modeling and remote sensing based assessments: 1) Continued development of a theoretical assessment of drainage water management at the Purdue Water Quality Field Station (WQFS). Work in the last year has been diverted to focus on improving the meteorological datasets
used to run the DRAINMOD drainage model. 2) Initial experiments on the simulated nitrate load from the WQFS, including working closely with the developers of the DRAINMOD NII model, at North Carolina State University to identify errors with the current model. 3) Completion of a map of subsurface tile locations and tile drain spacings for the entire Hoagland watershed in White County, IN based on aerial images and image processing techniques. In addition, I continue to teach classes at the undergraduate and graduate level that focus on hydrology and environmental change. Output products in the last year include expanded curricular materials, in particular an expanded unit on drainage and water quality for the undergraduate Environmental Hydrology course (AGRY 337). Outputs have been disseminated through special lectures at invited events, including the following. 1) Participation as a program leader at a wetland field day for local farmers sponsored by the Spencer County Soil and Water
Conservation District. 2) Special seminar for the Environmental Science and Engineering graduate seminar series on the hydrology of intensively managed landscapes. and 3) Invited lecture for the Purdue student Pugwash on the hydrology of environmental change.
PARTICIPANTS: New collaborators during the last 12 months include Dr. Indrajeet Chaubey, in the Department of Agricultural and Biological Engineering at Purdue University and Dr. Mohamed Youssef, Assistant Professor at North Carolina State University.
TARGET AUDIENCES: Target audiences include environmental regulators (e.g. Indiana Department of Environmental Management), planners (such as the Area Plan Commission), local soil and water conservation district personnel, sureveyors and individual land owners (farmers).
PROJECT MODIFICATIONS: No major changes to report.
The most significant outcomes of this project in the last year include changes in knowledge and conditions. Sampling of in-ditch nitrate degradation in managed agricultural ditches has resulted in new fundamental knowledge of nitrate transport. Application of our drain tile mapping technique at the watershed scale has resulted in development of the discipline of watershed-scale drainage hydrology, through increased understanding of the location and density of artificial drainage conduits in managed, agricultural environments.
- Ale, S., B.S. Naz and L.C. Bowling, 2007. Mapping of tile drains in Hoagland watershed for simulating the effects of drainage water management, ASABE Annual Meeting Paper No. 072144. St. Joseph, MI: ASABE.
- Naz, B. S, L. C. Bowling, E. J. Kladivko and K. A. Cherkauer, 2006, Evaluation of distributed hydrology-soil-vegetation model (DHSVM) for simulating tile drained landscapes, ASA-CSSA-SSSA International Meeting, Indianapolis, IN, November 12- 16, Agron.Abs. (CD-ROM)
- Naz, B., L.C. Bowling and C. Johanssen, 2007, A decision analysis system for mapping of subsurface drainage systems. Trans. of ASABE. Submitted.
Progress 10/01/05 to 09/30/06
An automated detection algorithm has been developed which works with readily-available aerial photographs to detect the location of tile lines in unmapped areas. Such maps are essential for accurate flood forecasting and water quality predictions in river systems impacted by tile drainage. The mapping tool may also be of use to individual landowners with unknown legacy tile lines. Two different computer simulation hydrologic models are being evaluated through comparison with field observations to determine the best methodology for representing discharge from drained and undrained fields. One such model has been used to conduct theoretical experiments in an effort to develop operational strategies for water table management that balance agronomic and ecosystem concerns.
Artificial subsurface drainage of agricultural fields is prevalent in northern and central Indiana. While increasing the productivity and workability of these lands, such large scale changes to the natural drainage system influence the frequency of high and low streamflows, groundwater recharge, carbon fluxes and water quality.
- Naz, B.S., 2006, Hydrologic impact of subsurface drainage of agricultural fields, M.S. Thesis, Purdue University.
- Ale, S., L.C. Bowling, S. Brouder, and J.R. Frankenberger, 2006, Simulating the effects of drainage water management using DRAINMOD, ASABE Paper Number: 062313, presented in Portland, OR. St. Joseph, MI: ASABE.
Progress 10/01/04 to 09/30/05
An image classification system has been developed for the remote detection of subsurface tile lines in multi-field regions based on commercially-available aerial photographs. We compiled a digital map of tile locations for an area of approximately 90 acres based on historic maps to be used for verification of the classification system. Detection of the correct number of tile lines per field varies between 50% to nearly 100%, depending on field surface condition, with accuracy in areas of corn residue being particularly low. On-going simulations using the Distributed Hydrology-Soil-Vegetation model are being used to quantify the required accuracy of estimated tile maps for the purposes of hydrologic assesment. We continue to characterize the effect of subsurface drainage on native hydrologic response and water quality on several fronts. The applicability of the DHSVM model for drained landscapes has been evaluated through comparison with historic field observations
from the Southeast Purdue Agricultural Center, resulting in high prediction efficiencies for both the water table and drainflows. Data quality assurance/quality control processing software is being developed to prepare historic observations from the Water Quality Field Station at the Agronomy Center for Research and Education for analysis. We have also conducted preliminary simulations using the DRAINMOD model to represent the WQFS conditions. These simulations show a tendency towards overprediction of drain flows during the winter months that we will continue to investigate.
Artificial subsurface drainage of agricultural fields is prevalent in northern and central Indiana. While increasing the productivity and workability of these lands, such large scale changes to the natural drainage system influence the frequency of high and low streamflows, groundwater recharge, carbon fluxes and water quality. Aerial photographs have been used to digitally detect the location of tile lines in unmapped areas. A variety of computer simulation models are being evaluated through comparison with field observations to determine the best methodology for representing drained and undrained fields. These models can then be used to conduct theoretical experiments in an effort to develop water management strategies that balance agricultural and ecosystem concerns.
- No publications reported this period