Streamflow monitoring in the Colorado River Basin (CRB) is essential to ensure diverse needs are met, especially during periods of drought or low flow. Existing stream gage networks, however, provide a limited record of past and current streamflow. Modeled streamflow products with more complete spatial and temporal coverage (including the National Water Model [NWM]), have primarily focused on flooding, rather than sustained drought or low flow conditions. Objectives of this study are to (1) evaluate historical performance of the NWM streamflow estimates (particularly with respect to droughts and seasonal low flows) and (2) identify characteristics relevant to model inputs and suitability for future applications. Comparisons of retrospective flows from the NWM to observed flows from the United States Geological Survey stream gage network over 22 years in the CRB reveal a tendency for underestimating low flow frequency, locations with low flows, and the number of years with low flows. We found model performance to be more accurate for the Upper CRB and at sites with higher precipitation, snow percent, baseflow index, and elevations. Underestimation of low flows and variable model performance has important implications for future applications: inaccurate evaluations of historical low flows and droughts, and less reliable performance outside of specific watershed/stream conditions. This highlights characteristics on which to focus future model development efforts.
Granular activated carbon (GAC) media for filtration of drinking water can be used to remove microscopic substances at extremely effective rates though a process of adsorption. Two major problems with GAC are the high start-up costs and the short effective removal timeline before GAC replacement or reactivation. Three years ago, the Birmingham Water Works Board (BWWB), undertook a project sponsored by the Water Research Foundation (WRF) to evaluate GAC for removal of organics, pharmaceuticals, and pesticides. These results were published in December 2010. A primary coagulant change at the plant occurred shortly after the initial study and a spin-off study commenced. The GAC filters are continuously monitored for any significant changes in performance. Grab samples including total organic carbon (TOC), heterotrophic plate counts, and nitrates are collected and sent for analysis. Initial results show there is still significant reduction in TOC through the filters. This is important because previous research suggests the media has an adsorption timeline of approximately six months after which GAC media was determined to be biologically active. If GAC is effective at removing organics several years after installation through biofiltration which doesn't require reactivation, it may be a cost effective alternative to current procedures enabling BWWB to meet future regulations on drinking water.
TreatmentDesiring a more versatile treatment option, an Alabama utility undertook a pilot-plant study to evaluate various coagulant doses to improve TOC removal, provide consistent floc formation, and reduce settled turbidity.
Birmingham Water Works (BWW), like every business and institution, was faced with tremendous challenges related to COVID‐19 in 2020. But using Partnership for Safe Water principles, BWW was able to keep operations at its Putnam Filter Plant running while keeping the plant's staff safe.
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