Aotearoa BiodiverCity / Design Guide / Design Strategies /

Stormwater planters

SCALES /
SYNERGIES / , , ,

CASE STUDIES //

Stormwater planters — engineered green infrastructure systems intercepting and filtering urban runoff through planted soil media integrated into streets and developments in Aotearoa New Zealand.

Definition

Stormwater planters are engineered green infrastructure systems that intercept, filter, and temporarily store urban runoff using planted soil media.

What this strategy does

Treats stormwater at source while providing small, distributed habitat patches integrated into streets and developments. Avoids reliance on purely grey conveyance systems.

Context

In highly impervious urban environments, stormwater planters provide a space-efficient method to manage runoff and improve ecological performance where land availability and underground services constrain larger systems.

Technical considerations

Design considerations

Habitat zonation

Provide distinct terrestrial, periodically inundated, and saturated zones within planters to increase plant and invertebrate species richness and overall ecological performance.1

Structural complexity

Incorporate varied planting heights, vegetation layers, and microhabitats to support diverse macroinvertebrate and plant communities.2

Plant diversity

Specify native polycultures with varied rooting depths and flood–drought tolerances to improve resilience and pollutant treatment.3 Avoid monocultures, which reduce both biodiversity value and stormwater treatment performance.4

Implementation considerations

Maintenance planning

Design for ongoing access to manage shading, sediment accumulation, and invasive species establishment, which strongly influence long-term ecological outcomes.5

Pollutant management

Select soil media and planting tolerant of nutrient and metal accumulation to avoid unintended ecological traps.6

Connectivity

Where feasible, locate planters near other green spaces to improve colonisation potential and reduce isolation effects.7

Issues and barriers

Pollution risk

Accumulated contaminants can attract sensitive species to habitats that negatively affect survival and reproduction.6

Invasive species pressure

Older or poorly maintained planters are prone to invasive plant dominance, reducing native biodiversity value.8

Design constraints

Uniform designs, limited surface area, or poorly managed hydroperiods (the timing, frequency, and duration of water presence) can limit species richness and habitat quality.7

Governance and capacity

Lack of clear guidance, funding, and organisational responsibility can undermine long-term ecological performance.9

Synergies and opportunities

Climate change – Distributed stormwater retention reduces flood peaks and increases urban resilience under changing rainfall regimes.10

Human wellbeing – Biodiverse green infrastructure improves urban amenity and psychological wellbeing.11

Disaster risk reduction – Localised runoff management reduces damage to infrastructure during extreme storm events.12

Freshwater security – Stormwater capture and treatment support non-potable reuse and groundwater protection.13

Financial case

Urban value uplift

Well-designed, vegetated stormwater infrastructure improves streetscape quality and neighbourhood desirability.14

Cost-effectiveness

Infrastructure efficiency

Stormwater planters reduce demand for costly downstream grey infrastructure by managing runoff and improving water quality at source.10

Monitoring and evaluation metrics

Core metric

Plant, macroinvertebrate, and soil biodiversity richness and composition can be assessed through periodic field surveys.15

Advanced metric

Water quality monitoring (nutrients, heavy metals) to detect pollutant accumulation and ecological risk.6

Additional resources or tools

New Zealand – stormwater guidance

Bioretention Planting Guide (Auckland Transport)

Native plant selection and maintenance guidance.

Manaaki Whenua – Bioretention Devices

NZ research, case studies, and performance metrics.

WSD for Stormwater Treatment Device Guideline (Wellington Water)

Sizing and performance requirements.

References
  1. Holtmann, L., Kerler, K., Wolfgart, L., Schmidt, C., & Fartmann, T. (2019). Habitat heterogeneity determines plant species richness in urban stormwater ponds. Ecological Engineering. https://doi.org/10.1016/j.ecoleng.2019.07.035
  2. Sinclair, J., Reisinger, L., Adams, C., Bean, E., Reisinger, A., & Iannone, B. (2020). Vegetation management and benthic macroinvertebrate communities in urban stormwater ponds. Urban Ecosystems, 24, 725–735. https://doi.org/10.1007/s11252-020-01072-5
  3. Winfrey, B., Hatt, B., & Ambrose, R. (2018). Biodiversity and functional diversity of stormwater biofilter plant communities. Landscape and Urban Planning, 170, 112–137. https://doi.org/10.1016/j.landurbplan.2017.11.002
  4. Corduan, D., & Kühn, N. (2024). Planting for the urban rain — Vegetation in urban bioretention systems: A systematic review. Sustainability. https://doi.org/10.3390/su16208861
  5. Morash, J., Wright, A., Lebleu, C., Meder, A., Kessler, R., Brantley, E., & Howe, J. (2019). Increasing sustainability of residential areas using rain gardens. Sustainability. https://doi.org/10.3390/su11123269
  6. Hale, R., Swearer, S., Sievers, M., & Coleman, R. (2019). Balancing biodiversity outcomes and pollution management in urban stormwater treatment wetlands. Journal of Environmental Management, 233, 302–307. https://doi.org/10.1016/j.jenvman.2018.12.064
  7. Lenzewski, N., Jensen, K., & Ludewig, K. (2024). Urbanization affects plant species diversity of stormwater ponds in a large German city. Ecological Engineering. https://doi.org/10.1016/j.ecoleng.2023.107166
  8. Sinclair, J., Reisinger, A., Bean, E., Adams, C., Reisinger, L., & Iannone, B. (2019). Stormwater ponds: An overlooked but plentiful urban ecosystem provides invasive plant habitat. Science of the Total Environment. https://doi.org/10.1016/j.scitotenv.2019.135133
  9. Soanes, K., Taylor, L., Ramalho, C., Maller, C., Parris, K., Bush, J., Mata, L., Williams, N., & Threlfall, C. (2023). Conserving urban biodiversity: Current practice, barriers, and enablers. Conservation Letters, 16. https://doi.org/10.1111/conl.12946
  10. Eckart, K., McPhee, Z., & Bolisetti, T. (2017). Performance and implementation of low impact development: A review. Science of the Total Environment, 607–608, 413–432. https://doi.org/10.1016/j.scitotenv.2017.06.254
  11. Pataki, D., Alberti, M., Cadenasso, M., Felson, A., McDonnell, M., Pincetl, S., Pouyat, R., Setälä, H., & Whitlow, T. (2021). The benefits and limits of urban tree planting for environmental and human health. Frontiers in Ecology and Evolution, 9. https://doi.org/10.3389/fevo.2021.603757
  12. Alves, A., Vojinovic, Z., Kapelan, Z., Sanchez, A., & Gersonius, B. (2019). Exploring trade-offs among the multiple benefits of green-blue-grey infrastructure for urban flood mitigation. Science of the Total Environment. https://doi.org/10.1016/j.scitotenv.2019.134980
  13. Fisher-Jeffes, L., Carden, K., Armitage, N., & Winter, K. (2017). Stormwater harvesting: Improving water security in urban areas. South African Journal of Science, 113. https://doi.org/10.17159/sajs.2017/20160153
  14. Cabanek, A., De Baro, M., Byrne, J., & Newman, P. (2021). Regenerating stormwater infrastructure into biophilic urban assets. Sustainability, 13, 5461. https://doi.org/10.3390/su13105461
  15. Ferzoco, I., & McCauley, S. (2024). Freshwater biodiversity in stormwater management ponds: A systematic review and meta-analysis. Science of the Total Environment. https://doi.org/10.1016/j.scitotenv.2024.173467