Table 1 |.

Summary of factors affecting resilience of selected urban BMPs

BMP Class	Climate Change Sensitivity	Adaptation Strategies
Biofiltration	• Performance of biofiltration practices is decreased by short runoff contact time, channelization, large storm events, frozen ground, short grass heights/sparse vegetative cover, and high runoff velocities and discharge rates • Changes in precipitation intensity could lead to concentration of sheet flow and increased transport of sediment and other contaminants	• Use flow diversion structures to bypass intense events, and/or increase size of pretreatment/energy dissipation structures • Alter vegetation species for drought and/or moisture tolerances • Provide supplemental irrigation during extreme drought periods • Modify maintenance and media replacement frequencies based on changes in decay rates, humidity distribution
Bioretention	• Changes in precipitation may affect retention time reducing effectiveness • Changes in soil moisture could affect infiltration capacity and plant uptake, while higher temperatures may amplify microbial activity in the soil media • Expansion potential may be limited in dense urban areas	• Alter vegetation species for drought and/or moisture tolerances • Provide supplemental irrigation during extreme drought periods • Adjust organic matter content of soil media • Modify maintenance and media replacement frequencies based on changes in decay rates, humidity distribution
Infiltration systems	• Changes in seasonal water table could affect infiltration capacity and increase risk of groundwater contamination • Rainfall fluctuations could affect design standards and make some existing facilities obsolete	• Incorporate flow diversion structures to bypass intense events, and/or increase size of pretreatment/energy dissipation structures • Where feasible, excavate to increase treatment volumes • Provide flow equalization storage at inlet • For vegetated systems, replant with species better adapted to climate
Green roofs	• Changes in temperature and precipitation may alter the species composition best suited for green roofs in a particular ecoregion • Greater precipitation volume and intensity may increase export of sediment/growth media and limit flow attenuation benefits	• Replant and adjust species composition to changing climate conditions • Incorporate downstream storage practices (e.g., cisterns) that help mitigate extreme event overflows and provide supplemental irrigation of green roof • Increase media organic matter content to improve moisture retention
Wet detention ponds	• Redesign of wet pond treatment volume and live storage in response to increased precipitation volume and intensity is likely to be difficult	• Retrofit outlet control structures and increase storage for new design storms • Supplement water during drought periods to maintain permanent pools
Dry detention ponds	• Redesign of pond treatment volume and live storage in response to increased precipitation volume and intensity is likely to be difficult	• Retrofit outlet control structures and increase storage for new design storms
Permeable pavement	• Treatment is controlled by infiltration rate; higher intensity storms may limit effectiveness	• If solids load increases, use pretreatment or divert flows from high load areas • Increase frequency of maintenance to reduce clogging
Grassed waterways	• More intense rainfall could increase concentrated flow erosion • Extended growing seasons could benefit functional processes, while significantly warmer temperatures could reduce soil cover and thus the overall effectiveness of the practice	• Retrofit to increase flow width and freeboard heights. • Modify outlet design to accommodate larger storms • Alter vegetation species composition to adapt to changing climate • Adjust mowing/grazing management as needed
Riparian buffers	• Extended growing seasons could improve filtration, while significantly higher temperatures could alter species composition and/or reduce soil cover/OM • More intense rainfall may promote concentrated flow through the buffer	• Increase up-gradient erosion control practices • Extend buffer widths, where feasible • Adjust species composition to adapt to altered climate
Constructed wetland	• Climate change may change suitability of native wetland plants and promote invasive or non-native species affect treatment capacity • Extended growing seasons could increase performance of constructed wetlands, but higher evaporation rates could alter desired water balance	• Incorporate flow diversion structures to bypass intense events, and/or increase size of pretreatment/energy dissipation structures • Provide flow equalization storage at inlet • Adjust plant species to match water balance changes • During extreme droughts, provide supplemental water to maintain pool

Note: See Supplementary material for references.