Tides and Water Levels

This site serves as a gateway to three sections devoted to learning about tides and water levels: an online tutorial, an list of links to tidal resources, and formal lesson plans. The tutorial is an overview of the complex systems that govern the movement of tides and water levels. It is content rich, is presented in easy-to-understand language, and includes many illustrative and interactive graphics to visually enhance the text. The links direct users to specific tidal and current data offered within the National Ocean Service and National Oceanic and Atmospheric Administration's family of products. Lesson plans integrate information presented in the tutorial with online data. These lesson plans have been developed for students in grades 9-12 and focus on the forces that cause and effect tides, analysis of the variations in tidal patterns and what conditions may cause them, and the effect of lunar cycles on living organisms. Educational levels: High school

Identification of Critical Water Levels in Flooded Rice Fields

A mathematical model was developed to simulate the transient hydrology of a flooded rice field. With the model, users can determine the critical interlevee areas in which to monitor the water levels so that the irrigation well can be turned on at the critical low water level, and turned off at the critical high water level, in order to maximize water application efficiency. Sensitivity analysis performed with the model showed that it will be necessary to calibrate the model for each specific field. A calibration procedure has been developed

Water levels in artesian and nonartesian aquifers of Florida in 1960

The purpose of this report is to summarize the trends and fluctuations of water levels in the principal artesian and nonartesian (water-table) ground-water reservoirs or aquifers of Florida during 1960. (Document has 24 pages.

Ice-Cover and Jamming Effects on Inline Structures and Upstream Water Levels

River ice cover is a reoccurring phenomenon in the Northern United States every year. Sheets and layers of ice result in a rise of water surface elevation and may lead to ice jams in a river. This research explains the modeling of a river reach through Northern Illinois containing a structural weir and how the water profile is effected during ice cover and ice jam events. The Hydraulic Engineering Center’s River Analysis System was used in conjunction with Esri ArcMap software to model a portion of the river for analysis. The study area of the Rock River flowing through Oregon, IL is known to freeze and ice over during the winter months in Northern Illinois. Data from the United States Geological Survey and National Oceanic and Atmospheric Administration were utilized to obtain cross-section and discharge measurements. The impacts of an ice jam occurring upstream of the weir and downstream of the weir were studied. The effects of the ice jam on the upstream water levels were also evaluated to observe if any flooding may occur inside the town or even farther upstream. Results of the ice cover and ice jam data were then compared to those of the Rock River under normal open flow conditions thus observing the change in water level, Froude number, and flow velocity. Results from this study help to point out the significance of ice jam occurrences and their effects on inline structures and future flooding concerns in the surrounding area

Natural and anthropogenic rapid changes in the Kara-Bogaz Gol over the last two centuries reconstructed from palynological analyses and a comparison to instrumental records

Palynological analyses (pollen and dinocysts) of a sediment core taken in the Kara-Bogaz Gol have been used to reconstruct rapid and catastrophic environmental changes over the last two centuries (chronology based on 210Pb). A natural cyclicity (65 years) of water level changes in the Caspian Sea and in the Kara-Bogaz Gol and anthropogenic factors (building of a dam separating the CS and the KBG waters) combine to induce rapid changes in water levels of the KBG, in the salinity of its waters and in vegetation cover of its surroundings. The impact of low water levels on the dinocysts is marked by a lower diversity and the survival of two species that are typical of the KBG, the Caspian Sea species present in the KBG having disappeared. During periods of higher water levels (AD 1871 to 1878), the lake is surrounded by a steppe-like vegetation dominated by Artemisia; whereas during periods of low water levels (AD 1878 to 1913 and AD 1955-1998), the emerged shore are colonised by Chenopodiaceae. The period of AD 1913 to 1955 corresponding to decreasing water levels has an extremely low pollen concentration and a maximum of reworking of arboreal taxa. During the last low-level period, humans responded by abandoning the shores of the bay. What happened to the KBG can be used as an example of what may happen in the future for the Aral Sea. A problem of reworking of Tertiary dinocysts into modern deposits has been detected owing to the knowledge of the modern dinoflagellate assemblages recently made available through a water survey. A comparison to modern surface pollen samples from Central Asia (Anzali, Caspian Sea south and central basins, Aral Sea, Lake Balkhash, Lake Issyk-Kul and the Chinese Tien-Shan range) allows us to establish the potential reworking of at least five arboreal pollen taxa possibly by run-off and dust storms

Process description of SWQN : A simplified hydraulic model

SWQN is a simplified hydraulic model for surface water systems which computes water levels and flows in a network of nodes labelled as ‘volumes’ and segments labelled as ‘connectors’. The user can specify a variety of connectors like open water courses or structures such as weirs, gates, culverts or pumps. Water levels are calculated in the ‘volumes’ driving the one dimensional flows through the ‘connectors’ linking up the ‘volumes’. The assumption is that the flow between two nodes with an open connection in between is linearly dependent on the difference in water level, if necessary augmented with the difference in velocity head, the wetted profile, and a given resistance

Influence of Foliar Exposure, Adjuvants, and Rain-free Period on the Efficacy of Glyphosate for Torpedograss Control

The proportion of torpedograss tissue exposed to glyphosate at application rates of 0.28, 0.56, 1.12, 2.24, and 4.48 kg/ha affected control as measured by regrowth. The effect of tissue exposure was more pronounced as application rate decreased. This study suggests that higher rates of glyphosate need to be used during higher water levels, when less torpedograss tissue is exposed to herbicide spray and lower rates may be used during periods of low water levels. Addition of the water conditioning agent Quest (R) (0.25% v/v) to glyphosate spray mixtures diminished the influence of simulated rain events following glyphosate application. Twelve other adjuvants did not influence the effect of simulated rain events

Low Water in Lake Meade

This lithograph shows images from NASA’s Landsat 7 Enhanced Thematic Mapper Plus instrument of the Boulder, Virgin, and Gregg basins that comprise the southern portion of Lake Meade. About 96% of the water in Lake Mead is from melted snow that falls in Colorado, Utah, New Mexico, and Wyoming. During the period from May 2000 to April 2003 severe drought occurred in the western states, and Colorado River runoff was far below normal. Noticeable differences in water levels can be seen in these images. The top image shows the area on May 3, 2000; the bottom image is from April 19, 2003. Noticeable differences in water levels can be seen. Educational levels: High school, Undergraduate lower division, Informal education, General public

Great Lakes Water Levels Trends

This paper began as a literature review paper for Great Lakes Issues class and was adapted for an Environmental law paper. The paper explores the past, present and future trends of the Great lakes fluctuating water levels. Special emphasis is given to how trends are determined and how those trends can be extrapolated to predict future water levels. Additionally, the paper touches upon anthropogenic interactions with water levels, both causation and the effects of water level fluctuations on human activity. Lastly the paper discusses the goals, outlook, and public perception of the newly adopted plan 2014 for Lake Ontario