Green Storm Water

To Green or not to Green: Modeling Incentive-based Programs for Green Infrastructure Investment on Private Propertities

This research project is led by our PhD Student Seth Brown and is carried out in cooperation with Storm and Stream Solutions, LLC


Communities are in need of cost-effective and innovative strategies for stormwater management infrastructure investments.  This need is driven by the fact that stormwater pollution is the only major increasing or fast-growing source of water pollution across much of the country including sensitive waterbodies such as the Chesapeake Bay and Puget Sound (U.S. EPA, 2012).  The focus of the research presented in this proposal is on the development of a methodology to analyze the use of investments of green stormwater infrastructure (GSI) on private property to address this growing problem. 


Agent-based Modeling

Considering that decision-making in the context of GSI adoption in this study focuses on private property owners, a modeling approach that can capture the dynamics of a large heterogeneous population of decision makers should be considered.  One approach that is well-designed for this type of application is agent based modeling (ABM), which has unique advantages for simulating a "bottom-up" system, such as private investment of GSI at the property or site level.  This type of modeling approach is in contrast to a deterministic analytical (equation-based) method of analysis, which may be well-suited to physical systems that follow consistent and predictable patterns of behavior.  The basis for ABM is that some systems, such as based in socio-economic dynamics, are non-deterministic by nature; therefore, deterministic modeling approaches may not capture the behavior of the system as well as a non-deterministic approach, such as ABM.    


Decision Dynamics

The use of the Theory of Planned Behavior (TPB) as a valid tool to capture decision-making dynamics as well as innovation adoption has been presented.  Specifically, TPB posits that one's personal beliefs (attitude, AT) regarding a potential action taken along with social pressure (social norms, SN) and perceived behavioral control (PBC), which refer to one's perception of the ease or difficulty of performing an action or behavior, taken together represent behavioral intention (BI), and that this relationship is summative (Armitage and Christian, 2003).  An assumption of TPB is that the stronger the intention in a behavior, the more likely that action will be taken reflecting this intention (Ajzen, 1991). 


Research Subject and Plan

Washington D.C.'s Department of the Environment (DDOE) also uses an incentive-based approach to promote the adoption of GSI on private property, but this approach uses a trading mechanism as well as a credit/rebate program to drive the program.  The program, known as the Stormwater Retention Credit (SRC) program, is the first credit trading program in the U.S. whose currency is stormwater retention.  The SRC trading program requires that developers meet half of their regulatory requirement of capturing 1.2 inches of runoff onsite; however, the remaining 0.6 inches of runoff can be met through the purchase of stormwater retention credits (SRCs).  SRCs are generated by property owners retaining more than is regulatorily required on their site.  The owners who generate SRCs can then sell them to those who need SRCs to meet regulatory needs.  In addition, the installation of retention-based practices can generate up to a 55 percent reduction of the stormwater fee administered by DDOE.  This program will be the subject of this research. 

A research plan has been developed that is broken into three phases:  

  • The first phase (Generalized Model Development) focuses on initial ABM development efforts based upon assumed agent behavioral data and modeling parameters.  
  • The second phase (Data Collection and Synthesis) involves gathering and processing of information and data. 
  • The third phase (Applied Model Development and Analysis) integrates data from the second phase into modeling developed in the first phase.  The result is an ABM that can simulate GSI adoption on private properties under a variety of scenarios based upon financial conditions and policy frameworks.  Additional activities beyond phase 3 are considered here as well.  These activities would likely focus on transitioning the phase 3 modeling platform into a more complex and powerful modeling environment.  
  • Additionally, the integration of a water resources model with the ABM developed in phase 3 may be potentially accomplished in this phase

Download Recent PowerPoint Presentations here:

Brown, S.; Behera, Pradeep; Ferreira, C. M. and Houck, M. (2015) "To Green or Not to Green: Modeling an Incentive-based Program for Green Infrastructure Investment on Private Property" American Water Resources Association (AWRA) National Capital Region Symposium 2015, Washington, DC