Kevin Wang
Subdivision and Planned Unit Development Planning
Soil Type, Runoff, and Stormwater Management
Soil
Soils are one of the most important factors that can influence the Griffin Memorial Hospital development on the site. Climate, landform position, and parent material are key physical factors in soil genesis and morphology. Soil properties are also affected by the previous and current land uses. Subsurface conditions affect not only the complexity of excavation and construction but also the project design (LaGro, 2013). Therefore, I created the map of soil conditions on the Griffin Memorial Hospital Area in order to provide useful information in assessing a site’s suitability for the proposed residential land uses. The Map of Soil represents that there are seven soil type on the Griffin Memorial Hospital Area, including Kirkland-Urban land-Pawhuska complex, Kirkland- Pawhuska complex, Kirkland-Pawhuska complex, Bethany-Urban land complex, Renfrow-Huska complex, Renfrow-Urban land-Huska complex, Port silt loam. In addition, I also created soil attributes table in order to analyze the soil types, areal dispersion, and description of each type.
Soil Attributes Table
Areas of potential runoff and stormwater management
The information about soil types as outlined in the Soil Attributes Table represents that the Griffin Memorial Hospital Area has the potential of runoff. In addition, the Griffin Memorial Hospital development can also have significant impacts on local and regional hydrology, including increased volumes and rates of runoff discharges, reduced time needed for runoff to reach surface waters, increased frequency and severity of flooding, reduced streamflow during prolonged periods of dry weather (LaGro, 2013). As understanding the hydrology in the Griffin Memorial Hospital area is paramount, I collected numerous data and reviewed tremendous literature pertaining to the hydrologic analysis in order to provide sustainable stormwater management strategies, which might be incorporated into the Griffin Memorial Hospital infrastructure design.
First and foremost, I reviewed literature and study that compares the differences in the surface runoff in the before and after construction conditions. The left image represents the conditions before constructions. In particular, trees, ground vegetation and natural soil conditions are able to absorb a great deal of a storm’s water and surface runoff is minimized. However, after the buildings and paved surfaces are introduced, the absorption capacity of the land is greatly reduced, as shown on the right image (LaGro, 2013).
A substantial literature and study represent that there are several techniques are intended to mitigate runoff problems, including building Channels, Retention Basins, and Culverts. Therefore, I used numerous information and data to analyze the subsurface geologic characterization through the combination of the varieties of analytical implement. In particular, I created varieties of maps as well as suggested the potential Retention Basins to protect ecologically sensitive areas.
Because there are only few sources and materials for the Griffin Memorial Hospital area can be obtained at this point, it may be difficult to get the most accurate and scientific outcome and result as desired. First, I examined the high and low points of elevation on the area. When conducting the calculation of elevation, it is paramount to obtain the digital elevation model (DEM) and the topographic maps, which provide useful information that the plan designer can use generating drainage patterns, slope, and the location of Retention Basins.
These DEM and the topographic maps are carefully and appropriately documented in graphical format. The DEM map contains the topographic information obtaining from United States Geological Survey quadrangle maps. The topographic map contains the topographic information obtaining from the City of Norman Geographic Information System Online Mapping Service, Interactive Base Map.
Both the digital elevation model (DEM) and the topographic map represent that the Griffin Memorial Hospital area and the surrounding areas are mostly flat with an elevation near 350 meters. The elevation in the south side of the Griffin Memorial Hospital area is modestly higher than the north side. The low point within the Griffin Memorial Hospital area limits is approximately from 350 to 360 meters above sea level. The high point is approximately from 360 to 380 meters above sea level.
While the Griffin Memorial Hospital area is mostly flat, the terrain is not strictly horizontal and there are several gentle slopes that are often hardly noticeable without using geographic analysis software. Therefore, further research is necessary to identify the slopes on the Griffin Memorial Hospital area. In particular, I conducted two methodologies to identify the slope information.
The first method is to analyze the contour lines on the topographic map. The contour lines on a map provide a direct indication of the changes in the Griffin Memorial Hospital area topography. The height of each contour line is labeled on the map so that the steep and flat area can be identified. The contour lines on the steep areas are close together and vice versa. Furthermore, The closer the contour lines, the steeper the slope. The wider the contour lines, the flatter the slope. The second method is to analyze the DEM map through analytical software.
Calculating the slope of the Griffin Memorial Hospital area using DEM raster is simpler and more accurate. The slope can be expressed in two types, degrees or percent. In the Slope Map, I expressed slope in degrees as well as examined slopes over 10% on the Griffin Memorial Hospital area.
In an effort to prevent significant environmental and aesthetic impacts, development regulations may prohibit construction on slopes over 10% for the Griffin Memorial Hospital area. The slope layer is colored with a spectrum ranging from green colors (for lower elevations) to red colors (for higher elevations). Most part of the area are flat and there are merely four small parcel are labeled dark green, which represents the slope from 4% to 10% on the area. Hence, there is no slope over 10% on the area.
Creating the DEM and slope maps can help me predict where the Retention Basins is likely to locate. The following map represents several scenarios for developing drainage patterns and there are a number of places that will be the Potential Retention Basins.
In an effort to prove my prediction is accurate, I conducted future analysis for the physical components of the Griffin Memorial Hospital area surface. Using geographic analysis software helped me to estimate, analysis and predict the streamflow to make stable water use and flood control. In particular, I identified sinks, created flow direction, calculated flow accumulation, and ultimately created stream networks. Therefore, I concluded that the Retention Basins could be located on the parcels that labeled on the stream networks map. Using these information, planners and developers will be able to provide sustainable stormwater management strategies that aims at reducing the stormwater risk to public health and safety, property and infrastructure, as well as increasing community understanding for stormwater.
