TOWARDS AN INTEGRATED WATER POLICY MODEL FOR SOUTH CAROLINA

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 0213397
• Project Start Date: Jan 1, 2008
• Project End Date: Dec 31, 2011
• Program Code: [(N/A)]- (N/A)

Recipient Organization
CLEMSON UNIVERSITY
(N/A)
CLEMSON,SC 29634

Performing Department
School of Agricultural, Forest, & Environmental Sciences

Non Technical Summary
Over the last few decades, South Carolina's phenomenal population growth has focused attention on the likelihood that the region's long-term water supply may be insufficient to satisfy all competing demands for this precious commodity -- for consumption, waste treatment, hydropower, recreation, irrigation, wildlife protection, navigation and industry -- and ensure an adequate supply for future development, under current water allocation rules and managerial policies. State policy makers are acutely aware that the state needs to both aggressively protect the quantity and quality of the state's scarce water supplies, and efficiently allocate this valuable resource to its most valuable uses to maximize the socio-economic return to its water resources over time. Few would question the need to allocate scarce water supplies for wildlife, irrigation, industrial, recreation, municipal uses, and drought mitigation. But what is the optimal allocation between these competing uses both at a point in time, and through time? What types of institutions and policies are required if the state is to optimally allocate scarce water resources? How should current legal statutes be modified for the purpose of reducing transaction costs and facilitating optimal water use? Should water supplies be reserved for future but currently unknown needs? Before these and other related questions can be satisfactorily addressed, water policy-makers will need a new generation of planning tools. These new tools must be capable of addressing important basin-wide economic, environmental, and hydrologic concerns, yet have sufficient spatial disaggregation to allow for a meaningful sub-basin level analysis of the distribution of both the economic and biophysical impacts of a potential water policy. Given the variety of questions that need to be answered and the complexity of the issues, an integrated interdisciplinary modeling approach is needed to successfully analyze the complex policy issues confronting the state of South Carolina. Successful regional development and implementation of a consensus based water management plan is highly dependent upon understanding the complex interrelationships between economic and hydrologic parameters that govern water use. Given the political realities of collective bargaining, decision-makers will remain reluctant to establish water use quotas and/or production fee-based conservation programs in the absence of information on the economic, hydrologic and environmental consequences of each potential policy. Informed decision-making requires accurate knowledge of the economic cost-effectiveness of water conservation and/or water quality policies. Conventionally constructed economic water policy models do not adequately account for the spatial variability of a hydrologic characteristics and hydrologic response to surface diversions and/or pumping induced hydrologic stresses and resulting transient changes. Complex water policy questions can only be resolved by developing spatially and temporally disaggregated basin-wide water planning models that accurately link economic behavioral models to hydrologic response models.

Animal Health Component

75%

Research Effort Categories

Basic

25%

Applied

75%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
111	0210	3010	50%
112	0210	3010	10%
132	0210	3010	10%
133	0210	3010	10%
134	0210	3010	10%
135	0210	3010	10%

Knowledge Area
135 - Aquatic and Terrestrial Wildlife; 133 - Pollution Prevention and Mitigation; 134 - Outdoor Recreation; 112 - Watershed Protection and Management; 111 - Conservation and Efficient Use of Water; 132 - Weather and Climate;

Subject Of Investigation
0210 - Water resources;

Field Of Science
3010 - Economics;

Keywords

water policy modeling

linking economic and hydrologic models

wetland protection

water marketing

ground water management

salt water intrusion

water conservation

drought management

reservoir management

Goals / Objectives
The complexity of water policy issues confronting South Carolina requires an integrated interdisciplinary modeling framework that fully integrates economic behavior with hydrologic and environmental response to behaviorally driven hydrologic stresses. The analytic framework must maintain sufficient spatial variability to accurately account for unique hydrologic characteristics and heterogeneous land use patterns. The modeling approach must also account for the spatial and temporal distribution of economic, biological and environmental impacts associated with the status quo water policy and potential new policies. Given the wide array of water issues confronting South Carolina policy makers, the proposed integrated water policy model will utilize three hydrologic models that will be calibrated for the eight major drainage basins in South Carolina. The three distinct hydrologic models are needed to accurately address surface flow, groundwater, and wetland management and policy issues. Each hydrologic model will be linked to an economic optimization model constructed for each major drainage basin. Economic optimization will be performed using the Generalized Algebraic Modeling System (GAMS) language. MODFLOW will be the groundwater simulator used, MODSIM the surface flow hydrologic simulator, and APEX will be used as wetland hydrologic simulator. Regardless of the specific hydrologic model used in a given policy analysis, impacts on water supply, quality, and associated environmental habitat will be driven by optimizing economic behavior of individual agents acting in their self-interest with regard to their land use and water use decisions. The data used to simulate hydrologic and environmental impacts will be driven by both economic behavior and stochastic climatic parameters. The specific research objectives are: (1) Develop an integrated water policy model to estimate the economic and hydrologic consequences of alternative water allocations and/or uses. (2) Use the integrated water policy model to estimate the aggregate public policy benefits and cost of alternative allocation and/or use regimes. (3) Use the integrated water policy model to estimate the distributional consequences of alternative water allocations among uses and individual users. (4) Use the integrated water policy model to estimate the economic marginal benefit and marginal cost of water quality improvements. (5) Use the integrated water policy model to estimate the economic benefit and hydrologic impact that future changes in groundwater pumping in the Savannah River Basin are likely to have on saltwater intrusion between Savannah and Hilton Head where it has been observed or has the potential to occur. (6) Use the integrated water policy model to estimate the economic cost and benefits of alternative reservoir management policies within the Savannah River Basin. (7) Use the integrated water policy model to estimate the economic benefits and costs of alternative policies to protect wetlands.

Project Methods
The MODFLOW (McDonald and Harbaugh) grid for the land surface above the aquifer will be used to spatially link surface land-use attributes and/or land-use practices to aquifer characteristics at a one square mile of resolution for the groundwater component of the model. By linking the dynamic economic model to the hydrologic model at the one square mile level of resolution, the integrated modeling approach will control for both the spatial variability in hydrologic response to anthropocentric induced groundwater stresses and stress location. The integrated model will accurately simulate the relationship between hydrologic stresses (groundwater withdrawals) imposed by economic activity and the resulting change in aquifer status. Spatial sub-regional detail is essential because it provides policy makers with a tool for targeting specific water uses and/or geographic areas within a watershed that can most cost effectively achieve a policy dictated change in either the timing or quantity of groundwater withdrawals. MODSIM-DDS, a generalized river basin Decision Support System, will be the surface flow program used to develop the surface flow hydrologic component of the integrated water policy model. MODSIM-DSS can be linked with MODFLOW models for analysis of the conjunctive use of groundwater and surface water resources. Modeling the economic and hydrologic impact of changing reservoir storage is especially relevant in South Carolina given that the Army Corps of Engineers Savannah District is considering modifying Savannah River storage reservoir management from a policy that primarily manages for flood control to a policy that gives greater emphasis to drought mitigation. The surface flow component of the policy model will use the MODSIM stream flow continuity equation to link the economic model to the surface flow model. The economic model will estimate economically efficient out-of-stream surface diversion levels and associated return flow levels for a given policy. Economic impacts will be estimated on an annual basis, but the economic model will maintain an internal set of water accounts to quantify daily out of stream diversions and return flows that will be passed to the surface flow model. The Agricultural Policy/Environmental eXtender (APEX) model developed by the USDA at the Blackland Research Center (Williams, et. al., 2004) will be used as the wetland hydrologic model. The wetland policy component of the integrated economic model will link a dynamic economic model of land use practices to APEX to estimate the land use management practices that maximize the sum of all net economic net benefits derived from wetland protection and land use activities. The hydrologic wetland model will accurately simulate and quantify the cumulative impacts of anthropocentric caused chemical and sediment runoff associated with adjacent land-use practices deposited into the wetland.

Progress 01/01/08 to 12/31/11

Outputs
OUTPUTS: No research accomplished since 2010 report due to reassignment of principal investigator. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
No research accomplished since 2010 report due to reassignment of principal investigator.

Publications

• Smith, Loren M., Scott T. McMurry, David B. Willis and David A. Houkus. Ecosystem Services Provided by Playa Wetlands in the High Plains: Potential Influences on USDA Conservation Programs and Practices. Ecological Applications, Vol. 21(1):82-92, April 2011.
• Willis, David B., Jeff Stovall, Jeff Johnson, Ken Rainwater, Lucia S. Barbato, Kevin Mulligan, and Earnest B. Fish. The Impact of Spatial Heterogeneity in Land Use Practices and Aquifer Characteristics on Groundwater Conservation Policy Cost. Presented at annual meeting of Southern Association of Agricultural Economists, Corpus Christi, TX, February 6-9, 2011. Abstract published in Journal of Agricultural and Applied Economics, Vol. 43(3):466, August 2011.
• Willis, David B. Water Scarcity: Future Uses and Implications for Policy. Invited paper presented at the Annual Meeting of the Southern Association of Agricultural Economists in Corpus Christi, Texas, February 6-9, 2011.
• Willis, David B. Water Scarcity: Future Uses and Implications for Policy. Journal of Agricultural and Applied Economics, Vol. 43(3):79-84, August 2011.

Progress 01/01/10 to 12/31/10

Outputs
OUTPUTS: Three funded multi-disciplinary research projects are ongoing within the scope of this overall project. The research objective of the first project is to develop computer based decision making policy tool to facilitate the cost-effective design of low impact residential developments in urban watersheds. The spreadsheet has been completed for South Carolina's Saluda-Reedy Watershed and provides developers with a preliminary cost estimate of utilizing low impact best management practices to decrease storm-water runoff and the transport of nitrogen, phosphorus, sediment, and bacteria from residential subdivisions. The decision-making tool provides developers with a means to assess water quality benefits and costs of adopting a specific best management practice to reduce urban storm-water runoff and/or improve the quality of urban runoff. Upstate Forever, a South Carolina non-profit environmental group, is now beta testing the spreadsheet based tool in Greenville County, South Carolina. The second project is a multi-disciplinary project designed to develop a protocol to establish bio-economically efficient minimum flow recommendations for the Great Pee Dee River watershed in South Carolina. The watershed transferable methodology has the potential to become a management tool that will help facilitate the establishment of effective minimum allowable flows (MAF) for surface waters, to simultaneously satisfy urban freshwater demands and protect surface water ecosystems from harm associated with flow level fluctuation. In an era of increasing environmental and economic resource limitations, this research is designed to help decision makers identify biologically efficient and sustainable MAF at the lowest social-economic cost. Anticipated projected outputs will be the ability to (a) use dominant land-use parameters in combination with hydrologic parameters to establish effective MAF; (b) recommend MAF standard for the research watersheds; (c) recommend an appropriate scale for modeling a given watershed; (d) increase public awareness and knowledge of MAF and how land use practices influence MAF; (e) provide policy makers with a planning tool that allows planners to target specific areas within a basin where environmental, ecological, and anthropocentric values can be most cost effectively maintained and/or enhanced; and (f) apprise interested stakeholders of the inherent tradeoff between environmental quality and economic development. The third related and funded project has developed an integrated economic and hydrologic model to examine the economic cost-effectiveness of alternative groundwater conservation policies. The model is now being used to investigate the impact of five conservation policies and the role of heterogeneous land use practices and/or heterogeneous aquifer characteristics on policy cost. This research has been well received by the USDA ARS funded Ogallala Research Initiative and additional funding is anticipated to incorporate the impact of climate change on conservation policy effectiveness. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
The urban watershed project is designed to provide water policy planners and residential developers with accurate estimates for both the cost and environmental effectiveness of using a specific best management practice, or a combination of best management practices to enhance/protect water quality in urban settings. A downloadable Microsoft EXCEL version of the low impact development (LID) decision-making tool will be made available on the Upstate Forever web-page. A beta version of the spreadsheet has been tested in Greenville County South Carolina. In 2010, five papers related to storm-water management were presented at professional conferences. The minimum allowable stream-flow research will allow the South Carolina legislature to establish MAFs based on science-based research. This will allow better management of South Carolina's fresh surface waters and benefit the citizens of South Carolina by cost-effectively providing a sustainable water supply for human consumption and services, as well as protecting ecosystem integrity. The data needed to calibrate the USDA CEOTT-SWAPP wetland model is now being collected. A web page documenting our research progress has been created. In 2010, two papers related to the economics of groundwater conservation were published, three presentations were made at professional meetings, and a book chapter on groundwater conservation policy was published.

Publications

• Willis, David B. and Jeff W. Johnson. "Groundwater Depletion in the Texas High Plains". In "Water Policy in Texas: Responding to the Rise of Scarcity". Edited by Ronald Griffin. Resources for the Future. Washington, D. C. 2010:178-200.
• Willis, David B., Matthew C. Huber, John C. Hayes, and Charles V. Privette III. "An Incentive Compatible Policy to Promote the Voluntary Use of Enhanced Stormwater BMPs in New Residential Developments". Presented paper at the South Carolina Water Resources Conference. Charleston, South Carolina. Sponsored by the Clemson Restoration Institute and the Clemson Center for Watershed Excellence. October 13-14, 2010.
• Hayes, John C., Charles V. Privette III, David B. Willis, Elizabeth Temple, and Matthew C. Huber. "Enhancing Land Development Decision-Making to Reduce Water Quality Impacts". Presented paper at the South Carolina Water Resources Conference. Charleston, South Carolina. Sponsored by the Clemson Restoration Institute and the Clemson Center for Watershed Excellence. October 13-14, 2010.
• Huber, Matthew C., David B. Willis, John C. Hayes, and Charles V. Privette III. "Incentive Compatible Stromwater Policies and Water Quality Benefits". Presented paper at the 2010 Annual Meetings of the Southern Economics Association. Atlanta, Georgia, October 2010.
• Willis, David B., Jeff Stovall, Jeff Johnson, Erin Wheeler-Cook, and Ken Rainwater. "The Impact of Spatial Variation in Land Use Patterns and Aquifer Characteristics on the Agricultural Cost of Groundwater Conservation for the Southern Ogallala Aquifer". Selected paper presented at the Annual Meetings of American Agricultural Economics Association, Denver, Colorado. July 25-27, 2010.
• Huber Mathew C., David B. Willis, John C. Hayes, and Charles Privette, III. "Price Endogeneity and Marginal Cost Effects on Incentive Compatible Stormwater Management Policies". Selected paper presented at the Annual Meetings of American Agricultural Economics Association, Denver, Colorado. July 25-27, 2010.
• Hasing, Thomas C., Carlos E. Carpio, David B. Willis, Olha Sydorovych, and Michele Marra. "The Effect of Label Information on Farmers' Pesticide Choice". Selected paper presented at the Annual Meetings of American Agricultural Economics Association, Denver, Colorado. July 25-27, 2010.
• Hayes, J. C., C.V. Privette III, David B. Willis, Elizabeth Tempel, and Matt C, Huber. "A Low Impact Development Decision-Making Tool to Evaluate Impacts of BMP Selection". Proceedings of 21st Century Watershed Technology Conference held at Earth University, Costa Rica and sponsored by ASABE, ST. Joseph, MI. February 21-25, 2010.
• Carpio, C., S. Zapata, O. Benavides, and D. Willis. "The Economic Value of Basin Protection to Improve the Quality and Reliability of Potable Water Supply: The Case of Loja, Ecuador". Meeting of Ecuadorian Economists Organized by the Interamerican Development Bank and Universidad de las Americas, Quito, Ecuador, July 12-13, 2010.
• Willis, David B. "The Economic Impact of Controlling for Heterogeneous Aquifer Characteristics and Land Use Practices in Groundwater Conservation Policy Analysis". Conference hosted by the United States Department of Agriculture-Agricultural Research Service, Amarillo, Texas as part of the Ogallala Aquifer Research Initiative, March 1-4, 2010.
• Smith, Loren M., Scott T. McMurry, David B. Willis and David A. Houkus. "Ecosystem Services Provided by Playa Wetlands in the High Plains: Potential Influences on USDA Conservation Programs and Practices". Ecological Applications, December 2010.
• Das, Biswaranjan, David B. Willis and Jeff Johnson. "Effectiveness of Two Water Conservation Policies: An Integrated Modeling Approach". Journal of Agricultural and Applied Economics,Vol. 42(4):695-710, November, 2010.

Progress 01/01/09 to 12/31/09

Outputs
OUTPUTS: Three funded multi-disciplinary research projects are ongoing within the scope of this overall project. The first project has developed a beta version of a computer based spreadsheet policy tool to facilitate the cost-effective design of low impact residential developments in urban watersheds. The specific study area is South Carolina's Saluda-Reedy Watershed. The decision-making tool provides developers with a means to assess the water quantity and quality benefits and associated probable cost of adopting a specific best management practice to reduce urban storm-water runoff and/or improve the quality of urban runoff. Upstate Forever, a South Carolina non-profit environmental group, is now beta testing the spreadsheet based tool in Greenville County, South Carolina. The second multi-disciplinary project involves the development of a protocol to establish minimum allowable flow recommendations for the Great Pee Dee River watershed in South Carolina. By establishing effective minimum allowable flows (MAFs) for surface waters, the State hopes to simultaneously satisfy urban freshwater demands and protect surface water ecosystems from harm associated with substantial fluctuation in flow levels. Moreover, in an era of increasing environmental and economic resource limitations, this research will aid decision makers in identifying the biologically efficient and sustainable MAF level at the lowest social-economic cost. Anticipated projected outputs will be the ability to (a) use dominant land-use parameters in combination with hydrologic parameters to establish effective MAFs; (b) recommend MAF standards for the research watersheds; (c) recommend an appropriate scale for modeling a given watershed; (d) increase public awareness and knowledge of MAFs and how land use practices influence MAF's; (e) provide policy makers with a planning tool that allows planners to target specific areas within a basin where environmental, ecological, and anthropocentric values can be most cost effectively maintained and/or enhanced; and (f) apprise interested stakeholders of the inherent tradeoff between environmental quality and economic development. The third related and funded project has developed an integrated economic and hydrologic model to examine the economic cost-effectiveness of alternative groundwater conservation policies. The model has been used to investigate the impact of five conservation policies and the role of heterogeneous land use practices and/or heterogeneous aquifer characteristics on policy cost. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
The urban watershed project is designed to provide water policy planners and residential developers with credible estimates for both the cost and environmental effectiveness of using a specific best management practice, or a combination of best management practices to enhance/protect water quality in urban settings. A downloadable Microsoft EXCEL version of the low impact development (LID) decision-making tool will be made available on the Upstate Forever web-page. A beta version of the spreadsheet is currently being tested in Greenville County South Carolina. In 2010, two papers related to this research have been presented at the annual professional conferences, and another three papers have been accepted for presentation later this year. The minimum allowable stream-flow research will allow South Carolina's legislature to establish MAFs based on science-based research. This will allow better management of South Carolina's fresh surface waters and benefit the citizens of South Carolina by cost-effectively providing a sustainable water supply for human consumption and services, as well as protecting ecosystem integrity. A web page documenting our research progress has been created. In 2009, two papers related to the economics of groundwater conservation were published, and three presentations were made at professional meetings.

Publications

• Wheeler-Cook, Erin, Eduardo Segar, Phillip Johnson, Jeffrey Johnson, and David Willis. "Water Policy Conservation Evaluation: The Case of the Southern Ogallala Aquifer". Texas Journal of Agriculture and Natural Resources vol. 22:87-100, December, 2009.
• Willis, David B., and Norman K. Whittlesey. "Water Management Policies for Stream Flow Augmentation in an Irrigated River Basin". In "International Library of Critical Writings in Economics: Economics and Water Resources", edited by R. Quentin Grafton. Edward Elger, Cheltenham, United Kingdom, 2009:112-132.
• Johnson, Jeff W., Philip P. Johnson, Eduardo Segarra, and David B. Willis. "Water Conservation Policy Alternatives for the Ogallala Aquifer in Texas". Water Policy, Vol. 11: 537-552, 2009.
• Willis, David B. "The Impact of Irrigation Efficiency Increases and the Loan Deficiency Payment Program on Agricultural Groundwater Use". Presentation at the Western Agricultural Economics Association meetings, Lihue, HI June, 2009.
• Zapata, Samuel D., Holger M. Benavides, Carlos E. Carpio, and David B. Willis. "The Economic Value of Basin Protection to Improve the Quality and Reliability of Potable Water Supply: Some Evidence from Ecuador". Journal of Agricultural and Applied Economics, Vol. 41(2):546, August, 2009.

Progress 01/01/08 to 12/31/08

Outputs
OUTPUTS: Consistent with the scope and design of this project an extensive review of water policy issues in South Carolina has been completed. Two funded multi-disciplinary research projects have been initiated within the broad scope of this project. The first project is in the initial stage of designing a computer based spreadsheet policy tool to facilitate low impact residential developments in urban watersheds. The specific study area is South Carolina's Saluda-Reedy Watershed. The decision-making tool will provide developers with a means to assess the water quantity and quality benefits and associated probable cost of implementing specific best management practices to reduce urban storm-water runoff and/or improve the quality of urban runoff. The second multi-disciplinary project involves developing a protocol to establish minimum allowable flow recommendations for the Great Pee Dee River watershed in South Carolina. By establishing effective minimum allowable flows (MAFs) for surface waters, the State hopes to simultaneously satisfy urban freshwater demands and protect surface water ecosystems from harm associated with substantial fluctuation in flow levels. Moreover, in an era of increasing environmental and economic resource limitations, this research will aid decision makers in identifying the biologically efficient and sustainable MAF level at the lowest social-economic cost. Specific projected outputs will be the ability to (a) use dominant land-use parameters in combination with hydrologic parameters to establish effective MAFs; (b) recommend MAF standards for the research watersheds; (c) recommend an appropriate scale for modeling a given watershed; (d) increase public awareness and knowledge of MAFs and how land use practices influence MAF's; (e) provide policy makers with a planning tool that allows planners to target specific areas within a basin where environmental, ecological, and anthropocentric values can be most cost effectively maintained and/or enhanced; and (f) apprise interested stakeholders of the inherent tradeoff between environmental quality and economic development. PARTICIPANTS: Stephen Klaine, Institute of Enviromental Toxicology, Clemson University. John Hayes, Agricultural and Biological Engineering, Clemson University. Charles Privette,Agricultural and Biological Engineering, Clemson. University. Mary Walsh, Upstate Forever, Clean Air and Water Program. Dara Parks, Pee Dee REC, Clemson University. TARGET AUDIENCES: Government Officials, Water Policy Planners, Residential Developers, Recreational Water Users, and Concerned Citizens. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
The urban watershed project will provide government water policy planners and private residential developers with credible estimates for both the cost and environmental effectiveness of using a specific best management practice, or a combination of best management practices, to enhance/protect water quality in urban settings. A downloadable Microsoft EXCEL version of the low impact development (LID) decision-making tool will be made available on the Upstate Forever web-page at the completion of the project. The minimum allowable stream-flow project will allow South Carolina's legislature to establish MAFs based on science-based research. This will allow better management of South Carolina's fresh surface waters and benefit the citizens of South Carolina by cost-effectively providing a sustainable water supply for human consumption and services, as well as protecting ecosystem integrity.

Publications

• Willis, David B., Joel R. Hamilton, M. Henry Robison, Norman K. Whittlesey, and John Draper. "Secondary Damages in Interstate Compact Litigation". Natural Resources Journal, 2008 (in press).
• Johnson, Jeff W., Philip P. Johnson, Eduardo Segarra, and David B. Willis. "Water Conservation Policy Alternatives for the Ogallala Aquifer in Texas". Water Policy, 2008 (in press).
• Willis, David. "Efficiently Allocating Scarce Water Supplies: An Economic Perspective and the Role of Contingent Water Markets". Presented paper at the South Carolina Water Resources Conference. October 13-14, 2008. Charleston, South Carolina. Sponsored by the Clemson Restoration Institute and the Clemson Center for Watershed Excellence.
• Willis, David B., and Justin S. Baker. "A Coasian Approach to Efficient Water Allocation of a Transboundary River". Journal of Agricultural and Applied Economics, Vol. 40(2):473-484, August 2008.
• Willis, David. "Impact of Irrigation Efficiency Improvements and Government Payment Programs on the Agricultural Cost of Groundwater Conservation in the Texas High Plains". Selected paper presented at the Annual Meetings of American Agricultural Economics Association, Orlando, Florida. July 27-29, 2008.
• Willis, David B. "Linking Economic and Hydrologic Models for Water Policy Analysis". Paper Presented at the conference on the Economics of Water and Ecosystem Services sponsored by the Southern Economic Regional Association (SERA 30 Natural Resource Annual Meeting). USDA-Economic Research Service, Washington DC, May 22-23, 2008.
• Willis, David B. "Calibrating the Ogallala Aquifer Water Policy Model for the Texas High Plains". Conference hosted by the United States Department of Agriculture-Agricultural Research Service, Amarillo, Texas as part of the Ogallala Aquifer Research Initiative, March 11-13, 2008.
• Willis, David B. "Cost Effectiveness of On-Farm Conservation Practices to Protect Playa Lake Hydroperiod in the Texas High Plains". Presented paper at the annual meeting of the Southern Agricultural Economics Association, Dallas, Texas, February, 2008. Abstract published in the Journal of Agricultural and Applied Economics, Vol. 40(2):718, August 2008.
• Willis, David B., and Justin S. Baker. "A Coasian Approach to Efficient Water Allocation of a Transboundary River". Presented paper at the annual meeting of the Southern Agricultural Economics Association, Dallas, Texas, February, 2008. Abstract published in the Journal of Agricultural and Applied Economics, Vol. 40(2):720, August 2008.