Browsing by Subject "Landsat"
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Item A New Method to Assess Best Management Practice Efficiency to Optimize Storm Water Management(2014-12-16) Tu, Min-chengFor TSS, TN, and TP, this study examined the relationship between BMP pollutant removal efficiency and environmental factors such as ratio of BMP/catchment area, dominant land use, ratio of the dominant land use/catchment area, slope, and BMP type, and derived optimal installation plans based on different criteria. A SWMM model was built for the Shoal Creek Watershed in Austin, Texas. Inverse modeling (i.e. fitting model to observation data) was used to calibrate the BMP removal efficiency. The relationship can then be derived by using multiple linear regression analysis with BMP removal efficiency as the response variable and the environmental factors as predictive variables. However, before inverse modeling can be applied, SWMM pollutant buildup and washoff parameters must be derived. A few types of land use were identified as main source of pollutant. The numerical distribution of the parameters suggested that the buildup and the washoff parameters are controlled by forces of different spatial scales. Also, the SWMM model simulated only direct runoff in order to simplify the calibration. Mean pollutant concentration in base flow is required to convert observed concentration to that in direct runoff. The Shoal Creek Watershed discharges into Lady Bird Lake, and changes of water quality in the lake during base flow dominant dates were used to estimate concentration in base flow from Shoal Creek Watershed. Water quality of the lake was determined by Landsat imagery. The equations predicting BMP removal efficiency based on environmental factors were analyzed to show the most efficient and least efficient type of BMP and the land use that BMPs will have the highest and lowest removal efficiency for TSS, TN, and TP. Two planning criteria were utilized for the optimal BMP plans and different time frames were considered. One criterion is goal concentrations in runoff, and the other is a combination of goal concentration and a budget constraint. For each criterion, the associated optimal plan showed an areal ratio between BMP types throughout different time frame. It was also found that the Shoal Creek Watershed needs more BMPs. Suggestions to the Environmental Criteria Manual of Austin were also made based on this study.Item Cottonwood distributions across the Rolling Plains of Texas and Kansas(2007-12) Walker, Ryan Nicholas; Wallace, Mark C.; Ballard, Warren B.; Janis, Michael W.; Rahman, A. FaizThe presence of trees is a limiting factor for wild turkeys (Meleagris gallopavo) throughout the arid and semiarid portions of their range. Any long-term changes that occur to local tree populations will likely impact local wild turkey populations. Cottonwoods (Populus spp.) are the primary riparian tree of western North America and are linked to the flow regime of the river system. From 2000 through 2006, we measured 3,832 Plains cottonwoods (P. deltoides ssp. monilifera) at four sites in the Rolling Plains of Texas and Kansas. Only 132 (3.4%) of these cottonwoods were <10 cm in diameter at breast height. We documented large declines in daily flow following dam completion along the Canadian River, Texas. We documented small declines in daily flow following dam completion along the Salt Fork of the Red River, Texas. We documented low or intermittent flows along the Cimarron River, Kansas. The large declines in flow rate along the Canadian River have led to channel narrowing and vegetation encroachment throughout the floodplain. The small declines in flow rate along the Salt Fork of the Red River did not alter the meandering status of the river, sheltering it from the changes that occurred along the Canadian River. The sporadic flow along the Cimarron River suggested this river was more unstable than the other rivers. Regardless of river flow status, we failed to detect large quantities of cottonwood regeneration across the study area. This leaves the future unclear for cottonwoods and wild turkeys in this region. We were concerned by the limited regeneration of riparian cottonwoods and wanted to examine a period >7 years. We used Landsat satellite imagery to identify changes, from 1973 to 2005, in riparian trees that may have occurred concurrently with changes in local wild turkey populations. Our supervised classification accuracies ranged from 0.9 to 64.0%, which were insufficient for us to complete our objectives. Landsat imagery was not sufficient to identify changes in riparian trees in our study area. Other satellite-based systems provide improved spatial resolution, but currently lack the necessary temporal resolution to be effective. We suggest aerial photography and ground-based surveys remain the most useful tools for documenting changes in riparian trees.Item The use of GIS remotely sensed data in predicting the occurrence of two endangered avian species in central Texas(Texas A&M University, 2006-08-16) Cummins, TiffanyOver the last 50 to 150 years there has been widespread conversion of grassland to shrubland throughout the western United States. A major management concern on the Edwards Plateau is the encroachment of Ashe Juniper (Juniperus ashei). To facilitate brush management programs, I investigated relationships of two endangered species, the black-capped vireo (Vireo atricapillus) and the golden-cheeked warbler (Dendroica chrysoparia), with their habitats at the landscape level. GIS (Geographic Information Systems) and remotely sensed data, such as Landsat imagery, DEMs (Digital Elevation Maps), and DOQQs (Digital Ortho Quarter Quads) were used to evaluate vegetative and geomorphic features within both 100m- and 400m-radius areas surrounding occupied and (assumed) unoccupied sites. Stepwise-logistic regression was used to develop probability models for each species within a catchment and was then applied to the entire Leon River Watershed and evaluated for accuracy. Golden-cheeked warblers were identified in areas with mean juniper cover greater than 70%, mean departure from North (aspect), and maximum slope. For black-capped vireos, mean shrub cover, mean departure from North, and mean slope were important in habitat selection. Variables at the 400m spatial scale best identified areas of probable occurrence for both species, indicating that features of landscape surrounding a territory may play an important role in habitat selection.