As was detected, compared to dry season state the area of inundated land increases by up to 500% during the monsoon. Thanks to the city’s elevated position, floods do not threaten large urban areas. Villages, which are periodically flooded, have apparently applied counter-measures. Distribution of flood inundation extent should be, however considered when developing the city to the south and to the north.
Example of assessment of flood risk outputs.
Furthermore, flood inundation model has been calculated using precise digital elevation model (DEM) for selected flood return periods. Resulting inundation extents and depth exceed those achieved during typical flood events in the last decade.
In combination with land use zoning the outputs support assessment of risk to population, infrastructure and agriculture land especially at the most exposed stretches of rural landscape beyond the urban areas, where urban development is planned.
Results
The chart below shows the area of flood extent as detected from imageries from respective years (sqkm) (within extent of Service 2 AOI, including area of reference dry season water extent). This graph summarize outcomes from flood inundation mapping using archive satellite data. Assuming the extent of reference dry season water level as detected from the imagery (50 sqkm), it is obvious that typical large monsoon floods lead to increase of flooded area by three times - five times.
The chart below shows the area of hypothetic floods as modelled for 10yr, 50yr and 100yr recurrrent flood events (sqkm) (within extent of Service 2 AOI, including area of reference dry season water extent). This graph summarize outcomes from flood inundation modelling using given floodrecurrent frequency probabilities. Assuming the extent of reference dry season water level as detected from the imagery (50 sqkm), it is obvious that typical large monsoon floods lead to increase of flooded area by three times - five times.