How does imperviousness develop and affect runoff generation in an urbanizing watershed?


  • Gerald Krebs Aalto University School of Engineering, P.O.Box 15300, FI-00076 Aalto FINLAND
  • Ulla-Maija Rimpiläinen City of Vantaa
  • Outi Salminen Department of Forest Sciences P.O. Box 27 FI-00014 University of Helsinki FINLAND


urban planning, land-use, imperviousness, stormwater runoff, imperviousness-components


Imperviousness associated with urbanization remains one of the biggest challenges in sustainable urban design. The replacement of forests, marshlands, buffers, and wetlands with impervious surfaces, strongly influences hydrological processes in urbanizing areas. This study analyzed the contribution of four constructed surfaces types – roofs, yards, roads, and an international airport – to surface runoff within a 21 km2 watershed, and presents the development over five decades (1977−2030). The land-cover model, used to assess watershed imperviousness in 2030, utilized coefficients between impervious areas generating surface runoff and the floor area, developed during the study. The conducted imperviousness analysis allowed the evaluation of land-use development impacts on the stream network, and the identification of hydrologically active areas for urban planning and stormwater management. Research revealed the importance of yard imperviousness related to suburban residential housing for stormwater runoff generation, and the impacts of transport-related imperviousness on stormwater runoff.

Research Papers



How to Cite

Krebs, G., Rimpiläinen, U.-M., & Salminen, O. (2013). How does imperviousness develop and affect runoff generation in an urbanizing watershed?. Fennia - International Journal of Geography, 191(2), 143–159. Retrieved from