Managing storm water is a major issue for all GIS Consortium communities. When a recent home improvement was proposed in a small subdivision of the Village of Northbrook, engineers were concerned about the ability of the retention ponds for that subdivision to hold increased storm runoff. Engineering contacted GIS to help determine the capacity or volume of water the two retention ponds can hold.
GIS was able to used contour data and as-built drawings to model the slopes and depths of the retention ponds. That data was then converted to a Raster, a GIS feature used to model elevation as seen in the image above, which can then be used to perform complex analysis.
Using the GIS Consortium shared resource, Spatial Analyst Extension, GIS was able to utilize tools that analyze the elevation raster and calculate volumes and surface areas at given elevations. GIS was then able to provide engineering staff with the retention pond capacities (volumes) at many different elevation levels. The retention pond capacities could then be compared with impervious surface calculations and projected runoff volumes to determine if the ponds can handle the additional water load.
The retention pond capacity study completed by GIS provided engineering with useful and accurate information that otherwise would have been taken many hours of hand calculations perform. The data provided allowed engineering staff to make the best possible decisions regarding home improvements and storm water runoff.