Examples of use new function for Hydro disaster

With new Hydro disaster for ArcGIS Desktop feature, available use to Increment of heights and smoothing of the landscape.

Increment	Smoothing

Suppose, for defined area of the river is necessary to calculate flooding zones within flooding period. As primary digital elevation model data (DEM), using last version of Shuttle radar topographic mission (SRTM). In the case of absence of digital vector maps, among the free sources, SRTM data is often most suitable source of information about DEM. Let calculate the flood zone when the water rises by 2 meters. The module takes the slope of the water surface, which in this case set by the coastal marks. As result will get flood zone as a picture:

At the first look flood zone looks believable. However, any local resident or person, who knows this area, will say, that flood zone is wrong. Because this is due for the presence of dams, that limiting flooding of the floodplain. They are looking clear at high resolution space imageries. These dams holding the spreading of the river, also at high levels of water (7 – 8 meters) at the flooding time.

Consider use new function for DEM modification. For this case, In the separate linear layer (possible use graphics) indicate the axis of the dams. Then launch master of the DEM modification. Choose primary DEM raster dataset, choose raster dataset for saving modify DEM (possible rewrite original dataset), choose created linear layer and enter buffer distance, choose rising landscape level, same for all lines (possible use data from attributes).

As result will be get modify DEM. At the end, run secondary calculation of the flooding zone for same case (high level of water).

As we can see, result is different and more realistic, what confirmed by using satellite imagery, made for this period of spring flooding.

For the next example, let’s use variation for landscape alignment. This variation makes simulation “bulldozer operation”, in which at once or at several landscape areas making absolute alignment by maximal, middle or by individual entered high or gradual smoothing. Consider area at the floodplain. Primary known, this area crosses the highway, which partly visible at the SRTM DEM dataset. If calculate flooding zone, it will be spreading via low areas, however, highway is smooth section of the road without visible differences. For elimination this defect at the DEM data, will be used absolute alignment by maximum function or gradual smoothing by maximum function for several iteration. At pictures lower shown received changes. At the modify DEM dataset as result shown, if water rise in the river will be at middle level, flooding zone will not spread beyond the highway.

original DEM	gradual alignment by maximum	absolute alignment by maximum