| dc.description.abstract | As human population continues to rise, an ever increasing burden is being placed on earth’s water resources. Between 1950 and 2010, the world’s population increased from 2.6 billion to almost 7 billion, and the population of the United States increased from 150 million to 310 million, while available water resources have remained constant. The 2050 worldwide population is projected at over 9 billion and the population of the United States is projected at 400 million. The increasing demand, and the uncertainty of the impacts that climate change will have on available water resources, make it increasingly important that society more effectively manage our water resources in a sustainable fashion.
One of the many issues that must be addressed is sedimentation of reservoirs. The World Commission on Dams reports that “25% of the world’s existing fresh water storage capacity may be lost in the next 25 to 50 years in the absence of measures to control sedimentation.” In 2010, the Oklahoma Water Research Advisory Board (OWRAB) identified development of methods for estimating sediment yield in reservoirs as a “higher priority research topic”, and others stress the need for further research on streambank and gully erosion as part of managing reservoir sedimentation.
This study initiated the process of assessing the suspended sediment transport occurring in the Little River and other tributaries to Lake Thunderbird, which is the primary source of drinking water for approximately 200,000 people residing in Norman, Midwest City, and Del City, in central Oklahoma, and provides numerous and valuable recreation benefits. The study documented the current hydrological and morphological characteristics of the watershed and evaluated the use of an Acoustic Doppler Current Profiler (ADCP) for measuring sediment transport in small rivers.
Documentation of the hydrology within the watershed was accomplished using HOBO pressure transducers installed at seven locations, site surveys, and discharge measurements to generate discharge rating curves. Rating curves were used to estimate cumulative runoff for the watershed during the period of study, which occurred during a drought, and to assess the effects of antecedent conditions on runoff volume. The morphological characteristics of the watershed were documented by conducting fluvial geomorphological (FGM) surveys at 25 sites. Each of the sites was classified using Rosgen’s classification system and Simon’s Channel Evolution Model, and scored using various bank stability indices (BSIs). The channels at the sites were found to be predominantly type G5c channels, at Stage IV of the channel evolutionary process, and were mostly rated as unstable to highly unstable by all of the BSIs used in the study, although additional work is required to validate the individual BSI scores. The study provides a base-line for future studies on the hydrology and the changing morphology of the channels within the watershed, which are required to better understand the sedimentation of Lake Thunderbird.
The ADCP was evaluated by comparing sediment flux curves generated using a Teledyne RDI 600 kHz Workhorse Rio Grande ADCP, coupled with Aqua Vision’s ViSea Plume Detection Toolbox (PDT) software, to curves generated using traditional grab, and depth-integrated suspended sediment sampling methods. Data from this study show no statistical difference between flux curves developed using grab samples, depth-integrated samples, or ADCP/PDT methods. Data were only obtained from two sites however, and the number of samples was limited at one of them, so additional study is required to validate the use of ADCPs for estimating suspended sediment transport in small rivers. | en_US |
