Waukee-Iowa Land Use Planning Layers

3D Land Use Planning


Application for Land Use Planning

You can see the planners of this subdivision in Central Iowa considered the natural water pathways when designing the subdivisions on the right hand side of the figure.   Along these waterways, the designers created conservation areas that were planted with native vegetation to filter and clean the water before it enters the sugar creek (Hubbel, 2016). 

Building in this way saves both time and money, and also protects waterways quality.   It can also prevent water problems for homeowners. Compare these developments with those  in the lower left side of the picture were older developments were created with more of a rectangular grid.   You can see that some of flow lines are oriented along the grid.

Developing in this way involves moving more earth and involves short circuiting the hydrologic cycle and usually results in more water quality and storm water management problems.   Providing developers with these these kinds of 3D representations can allow the planners to more accurately and quickly design your neighborhoods and subdivisions. Our company is ramping up capabilities that will allow us to our visualizations models of storm water flow created using EPA SWMM GIS-based software.

Concentrated water-flow pathways and basins

Figure 1. Concentrated water-flow pathways and basins derived from LiDAR elevation data overlain on an aerial NAIP image with these layers draped over a LiDAR-derived 3D terrain model.



Application for Land Use Planning:

Flooding potential derived based on FEMA are based on hydrologic modeling while the potential maps from soil surveys are created from field observations of the color throughout the soil profile.  You can see in the image below that sometimes that these layers conflict.  This is because neither predicts the potential for flooding with absolute certainty.  Specifically, hydrologic modeling often does not account for all subsurface flow, changes in land management and utilization, and surface infiltration capacity perfectly accuracy. 

Further, soil surveys are created using relatively sparse field observations and are only intended for coarse scale land-use planning.  Soil maps are used to determine where historical flooding has occurred because soil color changes from brown to gray (as iron is reduced) when soils are saturated and oxygen is excluded (i.e., iron becomes the terminal electron acceptor, rather than oxygen).  However, evidence of historical flooding does not necessarily reflect the current hydrologic condition.

The LiDAR derived flow maps and basins help planners determine where drains and retention areas could be placed in a landscape to reduce the potential for flooding.  While none of these layers are not perfect, they are very useful for planning and development.  But when all of these together, they are a very powerful tool that can help optimize designs, reducing both the cost of development, improving storm-water management, and reduce headaches for future homeowners.  

Water planning map with flood potential layers

Figure 2. Water planning map with flood potential layers derived from NRCS soil survey and FEMA 100-year flood zone maps and water flow and basin data derived calculated from LiDAR data draped over a semi-transparent NAIP image orthoimagery on top of a hillshade map.

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