AGU hydrology days 2010

2010 annual AGU hydrology days was held at Colorado State University on March 22 - March 24, 2010.Includes bibliographical references.Numerous studies have been conducted to assess the impacts of urbanization on stream geomorphology and ecology. Recent research has shown benthic macroinvertebrates to be good indicators of stream health. Furthermore, significant correlations have been shown to exist between these benthic indicators and certain hydrologic metrics in receiving streams. These studies have used stream gage data and/or computer models to study such relationships but the scale of the watersheds has been large; typically greater than two square miles. This study examines the application of such research to a small-scale urban environment in Fort Collins, Colorado. The study uses benthic data collected approximately 10 years ago and stream flow measurements from the City's flood early warning system. These data provide an opportunity to determine if the findings in other research can be applied to relatively small urban streams. Such trends could help guide development and stream rehabilitation efforts in the City to minimize future impacts of urbanization on these streams and provide guidance in prioritizing stream reaches for rehabilitation. However, the use of such small scale real data in an ever-changing urban environment makes the application of hypothetical trends more difficult. Stream alteration, data limitations, and annual runoff variations present additional challenges for developing relationships between stream health and hydrology that are seen to exist in larger watersheds

AGU hydrology days 2004

24th annual AGU hydrology days was held at Colorado State University on March 10-12, 2004.Includes bibliographical references.Urbanization of a watershed increases impervious area, and consequently increases stormwater runoff. When left uncontrolled, these increases in stormwater runoff cause downstream flooding, accelerate channel erosion, and impair aquatic habitat. Increases in the magnitude and duration of stormwater runoff that accompany uncontrolled development allow a stream to carry more sediment than it could prior to watershed development. When a watershed cannot supply the stream with the volume of sediment it has the capacity to carry, channel degradation may occur in the form of incision, lateral migration, or a combination of both. This study evaluates the potential impact of watershed development on sediment transport in a prototype headwater stream subjected to typical residential development. Event based and continuous simulations, using 50 years of hourly rainfall records were performed with two climatically different locales. The first in the semiarid climate of Fort Collins, Colorado and the other in a typical southeastern climate, Atlanta, Georgia. Five conditions were evaluated for the study watershed, including: current (undeveloped) conditions, fully developed conditions, without stormwater controls, and fully developed conditions with stormwater controlled using (a) the City of Fort Collins flood control standard, (b) the City of Fort Collins flood control standard and water quality capture volume (WQCV) criteria, and, (c) using common standards of practice in the United States: control of the 100- and 2-year storms to historic peak discharge rates and control of the WQCV. For each scenario examined, sediment transport potential is evaluated for two noncohesive soil types: medium gravel and medium sand

Mathematical models for time series of monthly precipitation and monthly runoff

October 1966.Includes bibliographical references (page 35)

AGU hydrology days 2011

2011 annual AGU hydrology days was held at Colorado State University on March 21 - March 23, 2011.Includes bibliographical references.The Fossil Creek Lakes, located in Fossil Creek Community Park in south Fort Collins, Colorado, are the remnants of the old Poertner Reservoir constructed more than 100 years ago, which is an aesthetic and recreational fishing amenity to park visitors. However, the accumulation of 100 years of organic matter and sulfur compounds in the bottom coupled with summer and winter thermal stratification results in extremely low redox potentials in the bottom sediments and high concentrations of reduced sulfur (S-II). The presence of H₂S (g), particularly during lake turnover events has resulted in numerous odor complaints from park visitors and residents living nearby. In addition, fish kills occur during the late summer and through the winter, which has forced water managers to look for solutions to eliminate air quality impacts and protect water quality. As maintenance of aerobic conditions in the hypolimnion is an important consideration for successful lake management, this research focused on the use of artificial aeration to increase hypolimnetic dissolved oxygen levels. The number of aerators was substantially less in number than would typically be used in a lake of this size, because it was hypothesized that by placing the aerators in the deeper pockets of the lake, density differences would cause the heavier bottom water to "flow downhill" toward the aerators, increasing the effective circulation cells of the individual aerators. The experimental method involved monitoring of specific water quality constituents prior to and after the aeration. Preliminary findings show the aeration system significantly eliminated summer and winter lake stratification, reduced the odor problems, improved the water quality, including pH, solids, and nitrogen and phosphorus species