Abstract

In this study a comparative assessment of the impacts of urbanization and of forest fires as well as their combined effect on runoff response is investigated using earth observation and the Soil Conservation Service Curve Number (SCS-CN) direct runoff estimation method in a Mediterranean peri-urban watershed in Attica, Greece. The study area underwent a significant population increase and a rapid increase of urban land uses, especially from the 1980s to the early 2000s. The urbanization process in the studied watershed caused a considerable increase of direct runoff response. A key observation of this study is that the impact of forest fires is much more prominent in rural watersheds than in urbanized watersheds. However, the increments of runoff response are important during the postfire conditions in all cases. Generally, runoff increments due to urbanization seem to be higher than runoff increments due to forest fires affecting the associated hydrological risks. It should also be considered that the effect of urbanization is lasting, and therefore, the possibility of an intense storm to take place is higher than in the case of forest fires that have an abrupt but temporal impact on runoff response. It should be noted though that the combined effect of urbanization and forest fires results in even higher runoff responses. The SCS-CN method, proved to be a valuable tool in this study, allowing the determination of the direct runoff response for each soil, land cover and land management complex in a simple but efficient way. The analysis of the evolution of the urbanization process and the runoff response in the studied watershed may provide a better insight for the design and implementation of flood risk management plans.

Highlights

  • Since past decades, impact assessment of land use/cover changes (LUCC) on runoff response attracts a constantly growing attention by the scientific community, due to their immense effect on flood risk increase, soil erosion evolution, hydrological regime and aquatic ecosystems functioning, transfer of pollutants, etc. [1,2,3,4,5,6,7]

  • Accurate LUCC and vegetation features can be obtained from satellite and air photo images of complex landscapes, using various digital-image processing techniques, like photointerpretation and band ratioing

  • For small-scale catchments, with peri-urban heterogeneous cover affected from continuous wildfires, the high and very high-resolution data offer the advantage of being able to select precisely the information useful at the scale of the hydrological modelling units

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Summary

Introduction

Impact assessment of land use/cover changes (LUCC) on runoff response attracts a constantly growing attention by the scientific community, due to their immense effect on flood risk increase, soil erosion evolution, hydrological regime and aquatic ecosystems functioning, transfer of pollutants, etc. [1,2,3,4,5,6,7]. Impact assessment of land use/cover changes (LUCC) on runoff response attracts a constantly growing attention by the scientific community, due to their immense effect on flood risk increase, soil erosion evolution, hydrological regime and aquatic ecosystems functioning, transfer of pollutants, etc. The terms land use (LU) and land cover (LC) are used collectively (LULC), while in fewer occasions they are interchangeably met. Various sports facilities were manufactured for the 2004

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