Prepared by Matt Unruh
ES 771 Remote Sensing Emporia State University
Remote sensing technology has quickly become one of the primary means of research for the various environments on Earth. The wide availability of data as well as the quality of data for little to no cost have allowed the rapid expansion of use for this technology to occur. Today, remote sensing data have worked into mainstream media. Weather websites have been created that allow users to view near real-time visible satellite imagery as well as sophisticated radar imagery. This type of information has provided an introductory knowledge base for the general public regarding remote sensing technology. But much of the general public is not aware that remote sensing technology can be utilized to study environmental conditions right in their own backyard. Remote sensing data sets that have been available over several decades allow for the analysis of environmental conditions of a specific location over a period of time. Changes in land cover conditions can be seen through analysis, thus this information can be utilized to assist with future planning activities.
This project will examine a segment of the Big Blue River below Tuttle Creek Reservoir just outside of Manhattan, Kansas. Imagery collected for this particular site will be analyzed to highlight changes to the area over a roughly two decade period.
The area of analysis for this project is a segment of the Big Blue River just outside of Manhattan, Kansas. This portion of the Big Blue can be accessed from Barnes Road north of Manhattan in Riley County or Dyer Road in Pottawatomie County. The study area is below Tuttle Creek Lake, which indicates that flows experienced on this stretch of the river are highly controlled by releases from the reservoir.
Tuttle Creek Lake is a United States Army Corp of Engineers reservoir that was constructed to the regulate streamflow along the Kansas River in northeast Kansas. Two extreme hydrologic events have characterized the reservoir since its completion in 1962. During 1966 an extended period of drought led to the lowering of the pool, augmenting flows along the Kansas River to maintain navigation along the Missouri River (USCOE, 2009). After this drawdown a record low elevation of 323.34 meters was recorded on January 4, 1967 (USCOE, 2009). The other extreme event took place during the summer of 1993. River systems across the Midwest experienced flooding during this time period, and the Big Blue River Basin was no exception. A record high pool elevation of 346.79 meters was recorded on July 23, 2003, which is nearly 19.2 meters above normal pool elevation (USCOE, 2009). During this event spillway gates were opened for the first time and released a record 1,699 cubic meters per second into the Big Blue River below the reservoir (USCOE, 2009). The United States Geological Survey at Big Blue River near Manhattan streamflow gaging station (on the bridge in the study area) recorded a maximum daily peak streamflow of 1,665 cubic meters per second (USGS fact sheet 019-03) during this event. This streamflow is not a record for this gaging station, with maximum daily peak streamflows being recorded at higher levels in association with the 1903 and 1951 flood events (USGS fact sheet 019-03).
The Big Blue River Basin covers roughly 25,097 square kilometers in northeast Kansas and southeast Nebraska (UNL, 2009). Agriculture is the primary land use type within the basin, with over 70 percent of the land area devoted primarily to corn, sorghum, and soybean cultivation (UNL, 2009). Pasture and range land for grazing practices is also a common land use type.
To assess riparian conditions within the study area, National Aerial Photography Program (NAPP) and National High Altitude Photography Program (NHAP) imagery were obtained via USGS EarthExplorer (http://edcsns17.cr.usgs.gov/EarthExplorer/). The NAPP/NHAP data archive contains high quality aerial photography that has been acquired dating back to 1980 (NAPP, 2009). This imagery can then be utilized in Geographic Information Systems (GIS) to produce base maps or to manually interpret land use, land cover, and feature changes over a period of time (NHAP, 2009). EarthExplorer is a user-friendly program that provides access to a variety of remotely sensed data as selected by geographic location. NAPP imagery was downloaded from 1991, 1996, and 2002. NHAP imagery was downloaded from 1981 and 1985. NAPP imagery obtained was higher resolution data, but both data sets provided sufficient opportunity for assessment of riparian conditions within the study area.
After data acquisition, images were loaded into IDRISI Andes for further investigation. Appropriate titles were given for referencing purposes and visual analysis was performed for each image. Changes were noted between images in a chronological sequence so that conditions of the riparian corridor could be noted approximately every 4 to 6 years. Changes within the riparian corridor of the study area are discussed in the project results.
The period of time between 1981 and 1985 marked little change to the riparian corridor of the study area. Agriculture is the primary land use for the area, as noted by the continuous tracts of land on the CIR images. The 1985 images appear to have been collected at a higher flow than the 1981 image, but the sandbar upstream of the bridge is still visible. This reinforces the notion that the 1985 image was not taken at a particularly high flow. One potential area of erosion is noted immediately upstream of the bridge. The particular area appears to have been overtaken by water. In comparison, this same area on the 1981 image does not appear to be under water.
Between 1985 and 1991, relatively few changes are noticable to the study area as well. Agricultural practices continue to prevail as the primary land use type, and many of the same areas that are tree-lined streambank remain in place. One new development from the 1985 image is a potential area of deposition immediately upstream of the bridge. Based off of simple analysis of the images it is difficult to determine whether or not this feature is new. This image appears to be taken at a period of low flow, as noted by the width of the sandbar. The possibility of low flow conditions could play a factor in the presence of the potential new area of deposition.
The major changes of the study area took place between collection of the 1991 and 1996 images. As previously noted, the summer of 1993 marked major flooding on many stream networks in the Midwest. Even though the USGS stream gage located on the bridge in the study area did not register a record streamflow during this event, the nearly 1,700 cubic meters per second being released from Tuttle Creek Lake for a prolonged period of time undoubtedly produced major erosion on the Big Blue River. These erosional forces can be seen by comparison of these two images. In the area noted as potential new deposition on the 1991 image it is evident that soil has been eroded away. The sandbar located upstream of the bridge appears to have grown in size, which could reflect continued deposition from upstream or simply low flow conditions. The area noted as straight streambank in 1991 has a "v" shape immediately upstream and downstream of the bridge, highlighting an area of major erosion. Further downstream from this feature is a long stretch of what appears to be a cutbank, as well as no trees and no bend in the agricultural access road. This suggests major erosion took place on this section of streambank.
Comparison of the 1996 and 2002 images reveals major changes to the riparian corridor despite the fact a flood event the magnitude of the 1993 flood did not take place during this time period. Streambank stabilization features are present on the streambank in the 2002 image. It is not known at this time when these features were installed, but it is possible that they were in place for the 1996 image. Upstream of the bridge just behind one of the highlighted weirs is a pocket of new erosion. Also, it appears that new deposition has occurred immediately upstream of the bridge. Further expansion of the sandbar is noted, which could be a result of new deposition or low streamflow conditions. The cutbank feature previously noted in the 1996 feature is highly visible in the 2002 image. Agriculture remains the dominant land use type for the area of study, but out of view to the south and southwest suburban development is moving closer from the fringes of Manhattan.
|Figure 3: NHAP CIR Image of Study Area, 1981.||Figure 4: NHAP CIR Image of Study Area, 1985.|
|Figure 5: NAPP BW Image of Study Area, 1991.||Figure 6: NAPP BW Image of Study Area, 1996.|
|Figure 7: NAPP BW Image of Study Area, 2002.|
This particular segment of the Big Blue River in Kansas appears to be highly erodible, but streamflow needed to produce eroding conditions is directly related to discharge from Tuttle Creek Lake. River valley soils are high in nutrient content and generally produce high-yield crops, so farmers should implement land use practices that help protect streambanks. With suburban development moving towards this particular area of Riley County, Kansas, developers and potential landowners/tennants should be aware of discharge levels coming out of Tuttle Creek Lake. Future development of streambank and the areas immediately surrounding the Big Blue River should take place with knowledge of past streambank erosion events and be planned for accordingly.