Browsing by Subject "Playa Lake"
Now showing 1 - 5 of 5
Results Per Page
Sort Options
Item Agricultural cost of maintaining playa lake hydroperiod to preserve playa lake ecosystems in the Texas High Plains(2005-08) Peabody, Phillip J.; Willis, David B.; Smith, Loren M.; Lansford, Vernon D.The Agricultural Policy Environmental Extender (APEX) model was used to simulate playa lake hydroperiod in the Texas High Plains and the effect of sedimentation from agricultural operations on the storage capacity of playa lakes.Item Agricultural cost of maintaining playa lake hydroperiod to preserve playa lake ecosystems in the Texas High Plains(Texas Tech University, 2005-08) Peabody, Phillip J.; Willis, David B.; Smith, Loren M.; Lansford, Vernon D.The Agricultural Policy Environmental Extender (APEX) model was used to simulate playa lake hydroperiod in the Texas High Plains and the effect of sedimentation from agricultural operations on the storage capacity of playa lakes.Item Environmental impact of disease vector control(2007-12) McNew, Rachel M.; Presley, Steven; Maul, Jonathan D.; Cañas, Jaclyn E.Control of arthropod vectors of disease encompasses a large realm of science, including the biology and mechanisms of diseases and the ability to control their spread. This combination of studies focuses on the arthropod-borne virus, West Nile virus (WNV), which is endemic in the United States and is maintained in the environment through a bird-mosquito-bird cycle. West Nile virus can incidentally infect humans and other mammals. One means of controlling the spread of this mosquito-borne disease is the systematic use of pesticides to reduce the mosquito population, which in turn has been proven to reduce the number of human and animal infections of the sometimes deadly disease. The first study was performed to understand environmental influence on transmission dynamics of a free-ranging alligator population in Louisiana, USA by surveying for active WNV infection in 93 blood samples from these alligators. Blood samples from alligators were negative for active WNV infection. The second study focused on developing a method to quantify the concentration of a commonly used pesticide in a sediment matrix. The target pesticide was permethrin and we also screened for the pyrethroid synergist piperonyl butoxide (PBO). The combination of these compounds are used in many areas to control the mosquito population that can spread WNV. The third study employed the methodology developed in the second study to quantify permethrin and PBO residues in sediments of playa lakes located in the Lubbock County vicinity. The objective was to assess the fate and transport of permethrin and to identify potential risks or environmental impacts resulting from the control of mosquito vectors.Item Random flow on random graphs: Amphibian Movements in the Playas(2009-08) Murray, Nicholas Michael; Howle, Victoria E.; Martin, ClydeThis thesis examines, through a computer simulation, the movement of Ambystoma tigrinum or Tiger Salamanders through the playa lakes of the High Plains of Texas. Due to the local nature of precipitation in the High Plains of Texas, playas often fill or dry out. During the wet seasons, tiger salamanders often move out of one playa into surrounding playa lakes. It may be possible to track genetic adaptations or track movements of local populations throughout the playa lake system, however only limited research has been done to date in this area. Furthermore, genetic adaptation among a population can be extremely localized, for example, present in only a single playa lake. A population can then spread throughout the playa lake system. The goal, in this thesis, is to acquire a time estimate for the time required for a trait or population propagation starting from one starting playa to the most distant playa lake in the system. This is accomplished by constructing a simple stochastic model simulating the movement of a population carrying the genetic trait. The model will construct a grid to take into account that populations have the most success when propagating to nearest neighbors. The model also accommodates for the drying out and filling of playas on a random basis depending on ecological variables. Based on the average number of time steps for propagation, a time estimate is then applied to the average number of time steps to determine an approximate time required for a trait or population to populate from on playa to the next. From this data, a time estimate can be constructed for any system size or given specific environmental constraints incorporated into the model. The problem reduces to a stochastic flow on a graph that is changing randomly. For small sets of nodes (playas), the problem has the potential for an analytic solution. However, for systems of the same order of magnitude as the west Texas playa system (approximately 20,000 nodes) an analytic solution is infeasible, but computational results give good approximations. Archaeological records suggest the playa system was populated from a few playas on the border of the region during the last 3,000 years. Computational results and archaeological records allow for the construction of a time estimate.Item The value of a playa lake ecosystem service(2012-12) Bian, Dacheng; Benson, Aaron G.; Johnson, Jeff; Knight, TomEcosystem services are benefits people derive from resources in ecosystems. The High Plains (Ogallala) aquifer, which is a large but shallow groundwater aquifer occupies 174,000 square miles and part of eight states of the great plain. The Ogallala aquifer, playa lakes and human compose a general ecosystem in this region. Playa lakes in this region provide many ecosystem services for humans. People withdraw groundwater from Ogallala aquifer, and playa lakes recharge the aquifer. This major service provided by playa lakes makes them important and valuable for society in this region. This study aims to provide information about the characteristics of playa lakes for Ogallala aquifer recharge. Then use economic and econometric models to determine how playa lakes affect the water level of the Ogallala aquifer, and estimate the economic value of the playa lake ecosystem services in recharging the Ogallala aquifer in specific areas.