Climate Interactive, Milwaukee Green Infrastructure Scenarios Tool

Climate Interactive, a “climate change think tank” has created a Green Infrastructure Scenarios Tool (GIST) for Milwaukee, Wisconsin, that allows for scenario testing related green infrastructure investment and future precipitation scenarios. The simulation allows users to test investments into different types of infrastructure for managing stormwater, and supports exploration of different possible future rainfall patterns, to see how investments might turn out under various future climate conditions.  Users can build more grey infrastructure or invest in new green infrastructure for 8 different classes of green infrastructure, such as green roofs, pervious pavement, and rain gardens. The simulation reports a full picture of the implications of each investment.

The GIST focuses on the Kinnickinnic River watershed, a 26 square mile area in greater Milwaukee. One of the most densely populated and highly paved parts of the city, this watershed has experienced repeated extreme flooding and combined sewer overflows.

According to Climate Interactive, the inspiration for the work is the increase in flooding events in Milwaukee and the expectation that, with climate change, there will be a further increase in extreme precipitation events. But the project goes far beyond the single dimension of stormwater management by helping the community identify the actions and investments that build readiness for more intense storms and improve the everyday livability of the community.

The tool is a system dynamics simulation that tracks the value of green and grey infrastructure based on a user’s decisions about current or future allocation of investment. The user can also set different precipitation projections and modify the assumptions about the effectiveness of different types of green infrastructure at capturing and retaining water. The simulation makes it easier to understand how storm water systems might perform in response to different future rainfall patterns, as well as the implications for both upfront and operational costs and the non-stormwater benefits that accrue with each scenario. A range of benefits beyond stormwater management are tracked and reported, including water quality improvements, jobs, air quality improvements and energy savings.

The available outputs from the Green Infrastructure Scenarios Tool include:

  • measurements of system performance including annual number of overflow events and basement flooding;
  • capital and operations costs; and
  • co-benefits, including jobs, property values, beach closures, water quality, and energy savings.



Climate Interactive has created this prototype system dynamics simulation of investment in green infrastructure in partnership with the Milwaukee Metropolitan Sewerage District (MMSD) and with support from the Surdna Foundation.


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