Examining the Effects of Urbanization on the Indian Creek WatershedK. F. Golson-Garner, T. D. Tsegaye, T.L. Coleman, W. Tadesse, and D. Spencer

Alabama A&M University, Department of Plant and Soil Science,P.O. Box 1208, Normal, AL. 35762

ABSTRACT

The Indian Creek watershed continues to be one of the fastest growing areas in North Alabama. Despite environmental concerns, the population of this area and surrounding areas continues to grow, initiating the transformation of undeveloped land at an unprecedented rate. The watershed, which is a part of the Tennessee River Basin, is located in Madison County near Huntsville, Alabama. Indian Creek is the major water system for this particular watershed and is in close proximity to much of the urbanization that is taking place. Historically, this watershed as been frequented with flooding and continues to be a flood prone area and subject to increasing concerns as urbanization continues to flourish. The objectives of this study are assess the impact of changes in landuse/landcover and examine the soil and hydrological parameters that affect the processes that take place in this particular watershed. The recent increases in urbanization have inflicted this watershed with even more drainage problems as the percentage of impervious zones is drastically increased. In addition, most of the sources of the pollution in this watershed are non-point source and Geographical Information Systems and Remote Sensing provide the most efficient methods for examining the sources of this pollution and identifying potential problems.

INTRODUCTIONThe Indian Creek watershed continues to be one of the fastest growing areas in

North Alabama. The commercial and residential communities in this area are growing at an alarming rate. The watershed, which is a part of the Tennessee River basin, is located in Madison County near Huntsville, Alabama. Indian Creek is the major water system for this particular watershed and is in close proximity to much of the urbanization that is taking place. Historically, this watershed as been frequented with flooding and continues to be a flood prone area and subject to increasing concerns as urbanization continues to flourish. This makes the Indian Creek Watershed the focus of numerous environmental and government groups. This particular watershed is also the site of the second largest research park in the United States and the Providence Town Community, which is a new development with homes ranging from the $200,000 to 2 million dollars and a myriad of commercial properties. The recent increases in urbanization have inflicted this watershed with even more drainage problems as the percentage of impervious zones is drastically increased, as well as surface runoff. The construction of the Providence Town Community is less than twenty feet from Indian Creek; therefore, much of the loose sediment and debris from this construction site flows directly into the creek and downstream. These urban areas have large surfaces (both paved areas and roofs) which block the natural passage of water into the soil. As water runs over the land and paved surfaces, sediment, debris, and pollutants are picked up, and from there, flow into storm drains and ditches which lead to Indian Creek and eventually the Tennessee River. Because there is less infiltration, peak flows of storm water runoff are larger and arrive earlier, increasing the magnitude of urban floods (Donaldson, 2005).

Nonetheless, Madison County’s population continues to grow at an enormous rate, almost fifty percent over the last two decades. Hence, undeveloped land is being transformed at an unprecedented rate and the environmental effects are alarming. A research project conducted using analyzed data from Landsat imagery showed the changes in landuse/landcover from the mid 1980’s through 2000 with projections to the year 2020. According to Laymon, 2005, in 1984, 13% of the total land area of Madison County was developed. In 1990, only 21% was developed (Fig. 1). By the year 2000, 30% of the county was developed; in just sixteen years, the amount of developed land in Madison County had doubled. Observations of developed land areas for 1984, 1990, and 2000 suggested that by the year 2010 developed land may total 38% and that 50% of the land in Madison County may be developed be by the year 2020 (Laymon, 2005).

Notably, these changes in landuse/landcover are causing severe damage to the ecosystems of Madison County, in particular the Indian Creek Watershed. According to a report published by the Alabama Department of Environmental Management (ADEM) the Indian Creek Watershed has historically been dominated by agriculture and forested areas. As seen in Figure 2, a landuse classification performed by ADEM in 2002 showed that over 41% of the watershed was occupied by cropland, 32.7% was occupied by forest, 15.7 was occupied by residential, 10.1 was occupied by pasture and 0.5% was unclassified (Thompson, 2002). In 2002 the predominant landuses in the upper portion of the Indian Creek Watershed were cropland and pasture. These areas are now being replaced with urban infrastructure. Increased construction and the presence of loose sediment in this watershed have created soil erosion problems and various sources of water contamination.

To date, siltation is the most significant problem for the Indian Creek. Most of the pollution in Indian Creek is non-point source pollution. In 2002, agriculture was the #1 contributor to siltation in the watershed. Indian Creek has also been on the State of Alabama’s 303(d) list since 1996 for its presence of nutrients, organic loading/low dissolved oxygen, and siltation and currently, it has two separate impaired segments. Although, its use is currently classified as Fish and Wildlife, biological data collected by the Tennessee Valley Authority (TVA) in 1994 and 1995 indicated impaired macro-invertebrate and fish communities. The impairment was attributed to siltation and organic enrichment/low dissolved oxygen but water column sampling was not conducted at the time to support this assumption. Besides the TVA study conducted in 1994 and 1995, there have been two additional studies performed by ADEM on Indian Creek. None of the samples from either study showed a dissolved oxygen violation. Nevertheless, environmental conditions have changed drastically since 2002 and flooding and pollution continues to worsen in this watershed. Because water often acts as an integrator of events at other locations in the watershed, it is critical that knowledge of the drainage system within the watershed is be known and practices be implemented that would improve the current conditions of this watershed. Geographical Information System (GIS) and Remote Sensing provide a number of ways to compile and interpret data that would help foster new ideas for environmental preservation and monitoring (Jensen, 2005).

REFERENCES 1. Donaldson, Susan. 2005. The Effects of Urbanization on the Water Cycle. University of Nevada Cooperative Extension Service: Fact Sheet FS-04-42. Reno, NA. pp 1-2.

2. Jensen, John. R. 2005. Introductory Digital Image Processing: A Remote Sensing Perspective. Pearson Prentice Hall. Upper Saddle River, NJ 07458. pp. 1-131.

3. Laymon, Charles A. 2005. "Greenprint for Growth” in Huntsville and Madison County, Alabama: A Plan for Land Preservation. Huntsville, AL. pp. 1-4. Internet Online.

4. May, Christopher W., Richard R. Horner, James R. Karr, Brian W, Mar, Eugene B. Welch. 2004. Effects of Urbanization on Small Streams in the Puget Sound Ecoregion. Watershed Protection Techniques. Seattle WA. 2(4): 483-494.

5. Thompson, David. 2002. Final TMDL Development for Indian Creek/AL 06030002_250_02. Low Dissolved Oxygen /Organic Loading. Water Quality Branch Water Division. Alabama Dept. of Environmental Management. Montgomery, AL. pp. 2-31.

MATERIALS AND METHODSStudy Area

The Indian Creek watershed, which is a part of the Tennessee River Basin, is located in Madison County near Huntsville, Alabama. Indian Creek, the major water source for this watershed is a tributary to the Tennessee River (Fig. 3). It is a part of the United States Geological Survey 06030002, which includes Wheeler Lake. Of the 103,400 acres of land that make up the Wheeler Lake Basin, approximately 49,200 acres are inundated or floodprone. Indian Creek begins Northwest of Huntsville in Section 34, Township 2S, and Range 2W. It has a linear distance of 5.95 miles and a total drainage area of 38.8 square miles. Its elevation beings at 544 ft and ends at to 1398 ft. Its classification is Fish and Wildlife. The predominant geology of the watershed consists primarily of Tuscumbia Limestone Formation of the Mississippi System in the Interior Low and Appalachian Plateau province. The parent material is karst natured limestone and chert. The natural vegetation for the region is transitional between the oak-hickory type to the west and the mixed mesopyhtic forests of the Appalachian ecoregions to the east. The flatter areas of the watershed to the east and on both sides of the Tennessee River contain very deep, well-drained reddish, soils that are intensively farmed. The Natural Resource Conservation Service (NRCS) sub-watershed basin #250 represents this watershed (Thompson, 2002). Data Analysis

The watershed was delineated using BASINS (Better Assessment Science Integrating Point & Nonpoint Sources). BASINS, is a multi-purpose environmental analysis system that integrates a GIS, national watershed data, and state-of-the-art environmental assessment and modeling tools into one convenient package. BASINS includes a data extractor, projector, project builder, GIS interface, various GIS-based tools, a series of models, and custom databases. Delineation, which is a process known as watershed segmentation, divides the watershed into discreet land and channel segments to analyze watershed behavior. Delineation of a watershed provides a bounded area wherein the physical processes are similar. Because of the integrating nature of water in a drainage basin, analysis of the water can track activities elsewhere in the watershed. BASINS, which, is a Geographical Information Systems database was also the source of several other forms of information. A GIS is an information system for spatial data that are referenced by geographic coordinates. It is designed to acquire, store, retrieve, manipulate, analyze and display geographic data.

RESULTS AND DISCUSSIONGeographical Information Systems was used to gather the soil and hydrological data for

the study. Results from BASINS showed that there were five major soil classes of soil in the Indian Creek Watershed. As indicated in Figure 4, the most dominant soil class was Decatur-Emory-Bewleyville, which is a normally a silt loam soil in its natural state. The other dominant soil types ranged from clay loam to fine sandy loam. Interesting the Chennby-Ennis-Etowah series was the least dominant according to the Statsgo data. Unfortunately, Statsgo, provides a very broad description of the soils present in any area. It is expected that the variability that exist in the soils for this area were not captured, since the Chennby-Ennis-Etowah is the series most common to creek side areas and was shown to be native the southern tip of the watershed. It is expected that there will be extensive variability in the soils of this area, because of the nature of the flooding for this watershed. In addition, most of the soils have been extensively washed from there natural location in the watershed.

The Digital Elevation Model (DEM) was used to show the variability within elevation for this particular watershed. Elevation, which ranged from 544 to 1398 feet, is very important because the significant effect that it has on drainage and flooding within the watershed. Areas at higher elevations tend be less vulnerable to flooding, in fact these are the areas that are more susceptible initiating soil runoff or erosion. The lowest elevation was observed at the southern tip of the watershed and is also the flood prone area of the watershed. The highest elevation was observed at the northern corners of the watershed (Figure 5 ).

This research project analyzed data from the Landsat satellite imagery. Madison County is entirely contained within a single Landsat scene. A set of georeferenced maps were created to show the changes in landuse/landcover for the Indian Creek Watershed from the year 1980 to year 2003. As shown in Figure 6, a variety of band combinations, along with digital ortho maps and analogue maps were used to determine landuse classification for watershed. A total of 10 classes were used for each classification. Unsupervised Classification for 1980 and 2003, respectively, showed that the landuse/landcover and has changed significantly over the last twenty-three years. The landuses for 1980 are also much more concentrated than those for the year 2003. Notably, a significant amount of forest and agricultural land has been converted to urban transportation and urban commercial and residential areas. Nonetheless the dominant landuses are still agriculture and forestry as indicated in Figure 7. However, urbanization is flourishing in the middle and lower portions of the watershed. According Figure 8, these also the areas that are more prone to flooding. These areas are therefore very sensitive to urbanization and should be the areas of focus in terms of monitoring. There were some apparent differences in the two in the downtown area as well. In 1980 the landuse was more uniform; today there is a lot more variability in the landsuses for this area. The most obvious manifestation of urban development is an increase in impervious cover and the corresponding loss of natural vegetation. Land clearing, soil compaction, riparian corridor encroachment, and modification to the surface water drainage network all typically accompany urbanization. Although impervious areas themselves do not generate pollution, they are the major contributor to changes in watershed hydrology that drive many of the physical changes affecting streams (May et al, 2004).

CONCLUSIONUrbanization exerts heavy social, ecological, environmental and climatic pressures on surrounding lands. Madison County is currently facing the loss of wetlands, forests, wildlife habitat, and agricultural lands forever. Because of its rapid growth, the Indian Creek Watershed has been identified by the Huntsville Land Trust as a target area for acquisition and preservation. This program is termed the “Greenprint for Growth” and it identifies valuable undeveloped land and works to acquire and preserve them. Remote Sensing is a good tool for watershed monitoring and preservation. In addition, remote sensing has the ability to improve current practices within a watershed. Land cover classification can improve current practices by providing a means to check whether an area has been developed consistent with the planning documents and whether the development within a given community is consistent with the standard assessments of percent impervious surfaces.

Indian Creek at the GreenWay Walking Trail

ACKNOWLEDGMENTSThis work is supported by the Center for Hydrology, Soil Climatology and Remote Sensing (HSCaRS) and the Department of Plant and Soil Science Department at Alabama A & M University.

Figure 3. Boundary of the Indian Creek Watershed and the Wheeler Lake Basin.

Figure 4. Soil Class Descriptions for the Indian Creek Watershed. (BASINS)

Map Unit Soil Type

AL005 CHENNEBY-ENNIS-ETOWAH

AL006 DECATUR-EMORY-BEWLEYVILLE

AL021 FULLERTON-DECATUR-COLBERT

AL026 NELLA-GORGAS-HARTSELLS

AL251 DICKSON-FULLERTON-DECATUR

Figure 5. Digital Elevation Model for Indian Creek Watershed. (BASINS)

Landsat 2003 Image

Water 1,2,3

Water 1,2,4

Figure 6. Band Combinations for water landuse classification for the Indian Creek Watershed.

Indian Creek at the Providence Bridge Indian Creek at the GreenWay Walking Trail Indian Creek at the Madison Pike

Construction Site of Providence Town Community

Indian Creek Cattle Farm

Construction Site of Providence Community School

Indian Creek

Figure 8. FEMA data for flood prone areas in theIndian Creek Watershed. (BASINS)

1984 202020001990

Land Use in the Upper Indian Creek Watershed

Cropland

Forest

Pasture

Residential

Commericial

Water

Figure 2. Land Use in the Upper Indian Creek Watershed (ADEM-2002)

Figure 1. Projected Land Development in Madison County and the Indian Creek Watershed.

Results & Discussion

2003 1980

Figure 7. Landuse Classification for the Indian Creek Watershed (1980 &1990)

Wheeler LakeState BoundariesIndian Creek Watershed N

EW

S50 0 50 100 Miles