PONDS DELINEATION IN VARIOUS URBAN LANDFORMS. CASE STUDY FOR CLUJ-NAPOCA, ROMANIA
Urbanization and industrialization have led to the increase in impervious surfaces, the reduction of water seepage into soil and
the increase of runoff discharges in urban areas. The overland flow may be carried over long distances along the streets and
sidewalks depending on the land slope and morphology, while in lowland, water tends to accumulate in ponds. In this research,
we aim to identify these ponds in the floodplain, slope and urbanized interfluves in Cluj-Napoca. The ponds outline the locations
that are most prone to urban floods. The preferential flowpathways were identified based on the flow direction and flow
accumulation determined using the D8 method, while the ponds were automatically extracted using an algorithm developed
based on the Contour Polygon Screening method. Based on four digital elevation models (DEM) of different resolutions (DEM 5
m, DEM 20 m, ASTER DEM 30 m and STRTM 90 m) and one Digital Surface Model (DSM) incorporating urban buildings, we
highlighted the effect of the spatial resolution and buildings on the water flow delineation in urban areas. Our results revealed an
increase in the number of flow pathways and ponds with the increase in DEM resolution and a more realistic outline of flow
pathways and ponds delineated based on the DSM. In the urbanized floodplain, the ponds have distinctive features, while on the
urbanized slope and interfluves these are temporary. The identification of ponds in a varied and urbanized relief provides useful
information to support local authorities in the overland flow management and flash flooding in urban areas.