The principles of the Town and Country model are based on three key factors – 

• the natural environment as defined by mature forest tracts, stream corridors, watershed divides and existing hydrology
• the transportation system, supporting facilities that encourage desirable distribution of new development.
• the neighborhood as the basic building block, and the village as the focus for new growth

Several key environmental factors help to delineate areas suitable for development and those that should be preserved. These include existing hydrology, watersheds, rivers and streams, and mature forest tracts. Taken together these features help to define natural edges and create relief in the urban development pattern. The stream s and the associated riparian forests can be the basis for a contiguous countywide greenway system. Understanding, expanding and enhancing the existing environmental system distinguishes growth areas from preservation areas and rural landscapes. The concept of “zones” for potential development emerges from the composite mapping of environmental features.

6.1.1 Watershed Divides

The high ground running from northeast to southeast Richland County defines the major watershed divide in Richland County. See Figure 6-1. From this ridge water either flows south and west into the Broad and Congaree Rivers or north and east into the Wateree River. Watershed divides are on the high ground, an are environmentally and economically beneficial to locate land development and roads. Most existing Richland County roads follow the watershed divides or other high ground. This establishes a useful guide to locating future land development in the county.

6.1.2 Mature Forest Tracts

Mature forests represent the native ecosystems that have evolved in Richland County over the millennia. These forests are the home for interior forest species including neotropical migrant songbirds and the Red Cockaded Woodpecker. These species need substantial contiguous areas of mature forest to maintain adequate breeding populations. Where forests are fragmented by clearing and development, opportunistic species thrive at the newly created edges. Often recently introduced species, they displace the native species, resulting in a loss of the environmental capital of Richland County. 

For this reason, large tracts of mature forests should be identified for preservation to retain what is left of the original native populations. Where possible, reforestation and linkage of forest tracts by forested corridors can effectively mitigate some of the adverse impacts of forest fragmentation.

6.1.3 Regional Hydrology

Figure 6-2 illustrates the major aquifer recharge area located in the Northeast/Ft. Jackson area. Unlike other areas with lower infiltration rats, most of the rainfall in this area of very porous sandy soils percolates into the ground. This area is thus the dominant source of regional groundwater recharge. This groundwater not only supplies wells with adequate water, it keeps streams flowing between storms as base flow. It is the source of the headwaters of the major streams and creeks, through which it makes its way to the Wateree, Congaree, and Broad Rivers. This aquifer recharge area is thus a critical part of the region’s natural hydrological system and an area where groundwater recharge must be maintained.

Where development is intense, rainfall flows overland as runoff instead of infiltrating to supply base flow. Higher runoff means more flooding, more bank erosion, and more sediment deposition in the streams. This eliminates most of the structural habitat essential for healthy streams. Reduced recharge means that local wells begin to go dry, and base flow falls to a trickle, so much of the remaining stream habitat goes dry.

Only with the use of Best Management Practices (BMPs) can these impacts be mitigated. At the foremost, infiltration of relatively clean roof runoff should be integrated into the required storm water detention strategy. The extent of impervious surfaces should also be limited as much as possible. A Conservation Design approach by clustering dwelling units with minimal paving per unit is a major benefit of the Town and Country model.

6.1.4 Riparian Corridors – Waterways and floodplains.

Riparian corridors are defined as the low lying ground adjacent to the streams, rivers and floodplains in the region. Whereas watershed divides follow the high ground and are likely areas for development, riparian corridors follow stream networks and are areas that should be considered for conservation. 

South Carolina streams have evolved in forested ecosystems, so loss of forest cover has a myriad of negative impacts. The ecosystem of streams is based upon the various insects and other invertebrates that graze on and shred leaves and sticks from streamside forests. These organisms reproduce by emerging from the stream to lay their eggs on the adjacent trees. Where this breeding habitat and food is absent, the invertebrate community shifts to types that can feed on algae and detritus. As a result, the fish community shifts accordingly, resulting in less desirable species. Forested streams are also up to ten degrees cooler than unshaded streams, with much more oxygen capacity during the hottest months. 

Therefore, riparian corridors should retain their original forest cover as much as possible as Riparian Forest Buffers (RFBs). Riparian Forests have considerable benefits for pollutant removal as much of the sediment in surface runoff can be captured by the forest floor. Riparian forests also provide a much-needed corridor for land creatures. As upland forests fall to clearing, riparian forests are often the only linkages left between the remaining upland forest tracts. Riparian corridors are thus essential to preserve the gene pool of remaining upland populations.

As can be seen in Figure 6-3, Richland County has a rich and extensive underlying structure of riparian corridors. It is significant that the county’s forest system generally follows the riparian corridor system. This feature, more than any other, establishes a natural basis for defining the “environmental rooms” and creating the separation between development areas through the use of open space.

The composite mapping of the natural features that form the environmental basis for the Vision is shown in Figure 6-4. This broad-scale mapping suggests an approach in which preservation areas define the zones for potential development. These areas are distinguished and separated from each other by the riparian corridors that provide the Countywide structure for open space.