50 resultados para Self-conservation
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The Iowa State Capitol: A Self-Guided Tour
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Culverts are common means to convey flow through the roadway system for small streams. In general, larger flows and road embankment heights entail the use of multibarrel culverts (a.k.a. multi-box) culverts. Box culverts are generally designed to handle events with a 50-year return period, and therefore convey considerably lower flows much of the time. While there are no issues with conveying high flows, many multi-box culverts in Iowa pose a significant problem related to sedimentation. The highly erosive Iowa soils can easily lead to the situation that some of the barrels can silt-in early after their construction, becoming partially filled with sediment in few years. Silting can reduce considerably the capacity of the culvert to handle larger flow events. Phase I of this Iowa Highway Research Board project (TR-545) led to an innovative solution for preventing sedimentation. The solution was comprehensively investigated through laboratory experiments and numerical modeling aimed at screening design alternatives and testing their hydraulic and sediment conveyance performance. Following this study phase, the Technical Advisory Committee suggested to implement the recommended sediment mitigation design to a field site. The site selected for implementation was a 3-box culvert crossing Willow Creek on IA Hwy 1W in Iowa City. The culvert was constructed in 1981 and the first cleanup was needed in 2000. Phase II of the TR 545 entailed the monitoring of the site with and without the selfcleaning sedimentation structure in place (similarly with the study conducted in laboratory). The first monitoring stage (Sept 2010 to December 2012) was aimed at providing a baseline for the operation of the as-designed culvert. In order to support Phase II research, a cleanup of the IA Hwy 1W culvert was conducted in September 2011. Subsequently, a monitoring program was initiated to document the sedimentation produced by individual and multiple storms propagating through the culvert. The first two years of monitoring showed inception of the sedimentation in the first spring following the cleanup. Sedimentation continued to increase throughout the monitoring program following the depositional patterns observed in the laboratory tests and those documented in the pre-cleaning surveys. The second part of Phase II of the study was aimed at monitoring the constructed self-cleaning structure. Since its construction in December 2012, the culvert site was continuously monitored through systematic observations. The evidence garnered in this phase of the study demonstrates the good performance of the self-cleaning structure in mitigating the sediment deposition at culverts. Besides their beneficial role in sediment mitigation, the designed self-cleaning structures maintain a clean and clear area upstream the culvert, keep a healthy flow through the central barrel offering hydraulic and aquatic habitat similar with that in the undisturbed stream reaches upstream and downstream the culvert. It can be concluded that the proposed self-cleaning structural solution “streamlines” the area upstream the culvert in a way that secures the safety of the culvert structure at high flows while producing much less disturbance in the stream behavior compared with the current constructive approaches.
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This report contains findings on 52 lake restoration projects. It summarizes the interpretation of the detailed project reports, maps, and cost estimates.
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Report on a special investigation of the Mahaska County Soil and Water Conservation District for the period March 24, 2006 through August 31, 2013
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This issue review provides an overview of funds dispersed for the soil and water conservation cost share program in the Department of Agriculture and Land Stewardship, DALS.
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This publication is a 10-step audit for employers to see if they are paying their female employees as much as their male employees
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The Self Instructional Math course book is designed to provide a basic math knowledge for those involved in the planning, design, and construction of highways. It was developed in a manner to allow the student to take the course with minimal supervision and at times that the work schedule allows. The first version of the course was developed in the early 1970's and due to its popularity was revised in the early 1990's to reflect changes in the highway construction math needs. The anticipated move to metric (System International) measurements by the highway industry has necessitated the need to change the math course problem values to metric units. The course includes the latest in Iowa DOT policy information relative to the selection and use of metric values for highway design, and construction. Each unit of the book contains instructional information, section quizzes and a comprehensive examination. All problem values are expressed in metric rather than dual (english and SI) units. The appendix contains useful conversion factors to assist the reader in making the change to metric.
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The main function of a roadway culvert is to effectively convey drainage flow during normal and extreme hydrologic conditions. This function is often impaired due to the sedimentation blockage of the culvert. This research sought to understand the mechanics of sedimentation process at multi-box culverts, and develop self-cleaning systems that flush out sediment deposits using the power of drainage flows. The research entailed field observations, laboratory experiments, and numerical simulations. The specific role of each of these investigative tools is summarized below: a) The field observations were aimed at understanding typical sedimentation patterns and their dependence on culvert geometry and hydrodynamic conditions during normal and extreme hydrologic events. b) The laboratory experiments were used for modeling sedimentation process observed insitu and for testing alternative self-cleaning concepts applied to culverts. The major tasks for the initial laboratory model study were to accurately replicate the culvert performance curves and the dynamics of sedimentation process, and to provide benchmark data for numerical simulation validation. c) The numerical simulations enhanced the understanding of the sedimentation processes and aided in testing flow cases complementary to those conducted in the model reducing the number of (more expensive) tests to be conducted in the laboratory. Using the findings acquired from the laboratory and simulation works, self-cleaning culvert concepts were developed and tested for a range of flow conditions. The screening of the alternative concepts was made through experimental studies in a 1:20 scale model guided by numerical simulations. To ensure the designs are effective, performance studies were finally conducted in a 1:20 hydraulic model using the most promising design alternatives to make sure that the proposed systems operate satisfactory under closer to natural scale conditions.
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Annual report of soil conservation in Iowa.
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Annual report of soil conservation in Iowa.
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The Board, codified in Chapter 466A, is an independent, self-governing body directed to improve the quality of water in the state. The Board is authorized to request water quality improvement applications from soil and water conservation districts, local watershed improvement committees, cities, public water supply utilities, and county conservation boards and award grants to these entities. These grants are issued from the Watershed Improvement Fund. In 2007, the Fund was allocated $5 million for state fiscal year 2008 for water quality improvements from the tobacco settlement trust fund. On September 24. 2007, the Board awarded grants to ten applicants. Total amount allocated to these projects is $2.656.842. A second Request for applications is under way and will close February 22, 2008.
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The Board, codified in Chapter 466A, is an independent, self-governing body directed to improve the quality of water in the state. The Board is authorized to request water quality improvement applications from soil and water conservation districts, local watershed improvement committees, cities, public water supply utilities, and county conservation boards and award grants to these entities. These grants are issued from the Watershed Improvement Fund. In 2008, the Fund was allocated $5 million for state fiscal year 2009 for water quality improvements from the general fund. On February 22, 2008, the Board awarded grants from the SFY 2008 allocation from the Tobacco Settlement Trust Fund to seven applicants. Total amount allocated to these projects is $2,115,694. A Request For Applications was issued Last spring for the SFY 2009 appropriations. On September 12, the Board awarded grants to nine applicants. Total amount allocated to these projects is $3,513,531. A second Request for Applications is underway for the SFY 2009 allocation and will close January 30, 2009.
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The Board, codified in Chapter 466A, is an independent, self-governing body directed to award grants for water quality improvement and flood prevention in the state. The Board is authorized to request applications from soil and water conservation districts, local watershed improvement committees, public water supply utilities, counties, county conservation boards and cities and award grants to these entities. These grants are issued from the Watershed Improvement Fund. Annual appropriations of $5 million plus interest earned on the Watershed Improvement Fund allowed the Board to issue two Request For Applications in 2009. On February 27, the Board awarded grants to seven applicants for a total of $2,366,861. On September 21, the Board awarded grants to thirteen applicants for a total of $5,120,832. In addition to providing environmental benefits, these implementation projects stimulate economic recovery and create jobs through the purchasing oflocal goods and services.
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The Board, codified in Chapter 466A, is an independent, self-governing body directed to award grants for water quality improvement and flood prevention in the state. The Board is authorized to request applications from soil and water conservation districts, local watershed improvement committees, public water supply utilities, counties, county conservation boards and cities and award grants to these entities. These grants are issued from the Watershed Improvement Fund. Annual appropriations plus interest earned on the Watershed Improvement Fund allowed the Board to issue three Request For Applications in 2010. On February 19, the Board awarded grants to five applicants for a total of $1,647,600. On July 23, the Board awarded grants to five applicants for a total of $796,500. Finally, on November 5, the Board awarded grants to eight applicants for a total of $1,203,500.