Urban pluvial flood risk assessment – data resolution and spatial scale when developing screening approaches on the microscale

Abstract

Abstract. Urban development models typically provide simulated building areas in an aggregated form. When using such outputs to parametrize pluvial flood risk simulations in an urban setting, we need to identify ways to characterize imperviousness and flood exposure. We develop data-driven approaches for establishing this link, and we focus on the data resolutions and spatial scales that should be considered. We use regression models linking aggregated building areas to total imperviousness and models that link aggregated building areas and simulated flood areas to flood damage. The data resolutions used for training regression models are demonstrated to have a strong impact on identifiability, with too fine data resolutions preventing the identification of the link between building areas and hydrology and too coarse resolutions leading to uncertain parameter estimates. The optimal data resolution for modeling imperviousness was identified to be 400 m in our case study, while an aggregation of the data to at least 1000 m resolution is required when modeling flood damage. In addition, regression models for flood damage are more robust when considering building data with coarser resolutions of 200 m than with finer resolutions. The results suggest that aggregated building data can be used to derive realistic estimations of flood risk in screening simulations.

Impact of Expansion Pattern of Built-Up Land in Floodplains on Flood Vulnerability: A Case Study in the North China Plain Area

“…Therefore, the above analysis indicates that the spatial resolution of built-up land affects the correlation between expansion pattern (patch size and expansion type) and flood vulnerability [29]. Although the correlation coefficients between small patches, expansion type, infilling type, and flood occurrence varied with the spatial resolution of built-up land, the significant correlation between the three and flood occurrence has not changed (p < 0.01).…”

“…The buffer distance setting is essential for distinguishing the expansion types of new BLF patches in the LEI method. In general, the buffer distance should be roughly equal to or less than the spatial resolution of remote sensing data (i.e., the buffer distance ≤30 m) [29]. However, it remains a question whether using different buffer distances significantly affects the value of the LEI.…”

“…X andȲ are the average values of the new BLF area and cumulative flood area of all prefecture-level cities during the corresponding periods of X i and Y i , respectively. To detect whether the coarse resolution of built-up land affects the relationship between flood vulnerability and expansion type, we evaluated the correlation between the two at resolutions of 150, 250, 500, and 1000 m [29]. The built-up land with 250 m and 1000 m resolution was derived from the original dataset.…”

“…Our research on BLF expansion mode and flood vulnerability has several limitations. Limited by the accuracy of remote sensing data, we only studied the relationship between BLF growth and flood occurrence for resolutions greater than 30 m [29]. Whether there is still a significant correlation between BLF expansion type and flood occurrence when the resolution is less than 30 m remains to be further researched.…”

Penilaian keberkesanan terowong SMART Kuala Lumpur dalam menghalang banjir kilat

“…Kejadian ini sering berlaku di atas jalan raya dan boleh menyebabkan kesesakan lalu lintas. Ianya berlaku kerana kadar air yang jatuh semasa hujan melebihi kadar penyusupan permukaan disebabkan oleh sistem saliran bandar yang kurang cekap dan tidak mencukupi untuk menampung keamatan hujan (Bulti & Abebe, 2020;Lwe & Arnbjerg-Nielsen, 2020;Rubinato et al, 2019;Tiza et al, 2016;Van Der Sterren et al, 2007). Keadaan air bertakung juga berlaku jika longkang atau laluan air tersumbat disebabkan sampah sarap yang dibawa oleh air atau tertutup akibat kerja-kerja pembinaan yang dijalankan di kawasan sekitar.…”