Download or read book Nitrate Dynamics and Source Within Nested Watersheds of an Agricultural Stream Nebraska USA written by Galen I. S. Richards and published by . This book was released on 2020 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bazile Creek flows north through Northeast Nebraska, entering the Missouri River just east of Niobrara, NE. The headwaters of the stream lie within the Bazile Groundwater Management Area (BGMA), a 1958 km2 region created in 2016 characterized by nonpointsource groundwater nitrate contamination. Elevated nitrate concentrations have been seen in the management area since the 1980s, and over time groundwater nitrate concentrations have continued to rise and affect an increasing number of wells. The BGMA contains parts of the Lower Niobrara, Lewis and Clark, Upper Elkhorn, and Lower Elkhorn Natural Resources Districts (NRDs). These NRDs have been working together to both monitor groundwater nitrate levels through periodic well sampling and curb increasing groundwater nitrate trends by educating landowners on methods to reduce fertilizer nitrogen loss through leaching and runoff. Although groundwater nitrate sampling in the Bazile Creek watershed has been continuous, surface water nitrate sampling has been infrequent and tributaries to Bazile Creek have never been sampled. Bazile Creek is a strongly gaining stream, indicating that a large percentage of its flow is derived from groundwater discharge. Nitrate concentrations in Bazile Creek have been slowly increasing, and nitrate in discharging groundwater is suspected to be the cause. This has led to questions about nitrate concentrations in Bazile Creek over time as well as throughout the watershed. This includes tributaries to Bazile Creek, which may all have similar nitrate concentrations or could vary between each other significantly. The source of nitrate entering Bazile Creek has not been determined, however it is assumed to be nitrogen containing fertilizers applied to the many agricultural fields nearby. A large quantity of well and excessively drained soils in the area indicate that fertilizer loss through leaching is probable. Livestock are present throughout the Bazile Creek watershed as well, indicating that manure-derived nitrate could also be making its way into the stream. Further complicating determinations on nitrate source is its potential seasonality, with manure-derived nitrate inputs being greatest in the spring and summer when frequent rainstorms create runoff that can transport manure off of fields into streams. This thesis aims to answer questions about nitrate dynamics and source within the headwaters of the Bazile Creek watershed. Surface water nitrate samples were collected over a period of 15 months from five tributaries and three locations on the main channel. Source seasonality was investigated through the collection of seasonal and rain event nitrate isotope samples, which also provided insight on denitrification rates. Results were then compared to subwatershed characteristics such as total area, land use, and soil drainage. Watershed-scale seasonal trends in discharge and precipitation were also investigated. These comparisons allow for conclusions to be made on nitrate source, primary transport pathways, and concentration seasonality.
Download or read book Nitrate Dynamics Within an Agricultural Stream written by David Robert Sheridan and published by . This book was released on 1993 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nitrate Occurrence in U S Waters and Related Questions written by John Fedkiw and published by . This book was released on 1991 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Relations of Nonpoint source Nitrate and Atrazine Concentrations in the High Plains Aquifer to Selected Explanatory Variables in Six Nebraska Study Areas written by A. D. Druliner and published by . This book was released on 1996 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nitrate Sinks and Sources as Controls of Spatio temporal Water Quality Dynamics in an Agricultural Headwater Catchment written by Tobias Schütz and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Source Identification of Nitrate Contamination in Shallow Ground Water in Nebraska U S A written by Mary E. Exner and published by . This book was released on 1994 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Vision Towards Developing a Spatially And Temporally Robust Data Driven Modeling Framework To Predict Continuous Stream Nitrate Concentration At Data Scarce Locations written by Gourab Saha and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stream nitrate concentration provides critical insights into nutrient dynamics and can help improve the effectiveness of sustainable ecosystem management decisions. Conventional stream nitrate monitoring is conducted through lab analysis using in-situ water samples, typically at coarse temporal resolution. In the United States, federal agencies and a few state and local agencies started collecting high-frequency (5-60 min intervals) nitrate data using optical sensors in the last decade. These sensor-based high-frequency stream nitrate concentrations at multiple stream locations in a region provide valuable information on the dynamics of nitrate transport, including the timing, magnitude, and sources of nitrate loading in the environmental system. This study hypothesized that the nitrate dynamics information available in a region's high-frequency stream nitrate monitoring sites could be used to estimate spatially and temporally continuous nitrate concentration at other low-frequency monitoring locations. Deep learning (DL) models could use to extract the complex nutrient dynamics from the high-frequency sites and transferred the information to low-frequency monitoring sites. The primary goal of this study was to develop a spatially and temporally robust data-driven modeling framework to predict continuous stream nitrate concentration at data-limited sites in a region using high-frequency nitrate data and biophysical attributes of the region. The objectives of this study are to (1) develop a deep learning (DL)-based modeling approach to generate continuous daily stream nitrate concentration for nitrate data-sparse watersheds and compare the performance of the developed modeling approach with other statistical models; (2) analyze the deep learning approach-based modeling framework to understand the critical environmental drivers of predicting daily nitrate concentrations, and; (3) explore the potential of extending the developed modeling framework to stream discharge unavailable locations for making the framework more spatially robust. This study used a DL model called Long Short-Term Memory (LSTM) to estimate continuous daily stream nitrate. The DL model received climate, land use, fertilization, topography, and soil characteristics data as inputs during the model development. The DL model was trained comprehensively by using four hyperparameters (batch size, hidden layer size, time window, and epoch) and isolating the best combination of hyperparameters based on five performance metrics, including RMSE, bias, correlation, NSE, and KGE. The hypothesis was tested with Iowa, USA, as a case study region because the state had more high-frequency nitrate monitoring sites with long-term data. In the first objective, a DL model-based stream nitrate estimation framework was trained and tested for thirty-four (34) high-frequency and eight (8) low-frequency nitrate monitoring sites. DL model demonstrated median test-period Nash-Sutcliffe efficiency (NSE) = 0.75 to estimate continuous daily stream nitrate concentration, which is unprecedented performance. Twenty-one sites (50% of all nitrate monitoring sites) and thirty-four sites (76%) demonstrated NSE greater than 0.75 and 0.50, respectively. The concentration (c) - discharge (Q) relationship analysis showed that the study watersheds had four dominant nitrate transport patterns from landscapes to streams with increasing discharge, including (i) flushing, (ii) flushing during low Q (Q median Q, Q50) and chemostatic during high Q (Q Q50), (iii) flushing during low Q and dilution during high Q and (iv) chemodynamic. The flushing pattern was identified as the most dominant c-Q relationship pattern. The developed DL modeling framework's performance was compared with other widely used statistical models, including Weighted Regressions on Time, Discharge, and Season (WRTDS) and Load Estimator (LOADEST), for the case study region. The study assumed that each basin had only one high-frequency monitoring site within the region. In this study, high-frequency nitrate data from each site were randomly subsampled to biweekly data and used as a pseudo-low-frequency site to train the DL model. These sites' remaining daily nitrate data were used for the developed DL model's performance evaluation. DL and WRTDS models performed similarly in most low-frequency nitrate monitoring sites. However, the developed DL model performed better at a few low-frequency nitrate monitoring sites. The DL and WRTDS models' performance in continuous nitrate estimation was better than the LOADEST model. Though the developed DL model performed exceptionally well in many sites, the performance was low for a few nitrate monitoring sites. The second objective identified the critical environmental drivers that impacted the data-driven modeling approach in estimating continuous stream nitrate concentrations. DL models were developed to predict daily stream nitrate concentrations at locations lacking continuous data. The sensitivity of daily varying environmental variables, including high-frequency nitrate and stream discharge and day length (representing seasonality) data, was identified in estimating continuous nitrate concentrations. The similarity between the sensitive variables was determined using Dynamic Time Warping (DTW) method to assess the contribution of biophysical similarity on the DL model performance. The DL model learned and transferred nitrate dynamics to sites within a radius of 300 km of a high-frequency nitrate monitoring site. The dominant annual c-Q relationship plots inferred that the DL model potentially learned nitrate dynamics from the data of a high-frequency nitrate monitoring site and predicted continuous nitrate concentrations accurately at low-frequency nitrate sites. DTW analysis indicated a similarity in nitrate concentration, stream discharge, and day length between a low-frequency and a high-frequency nitrate monitoring site, contributing to the accurate daily stream nitrate prediction. The third objective aimed to expand the data-driven modeling framework to those stream locations where stream discharge information is unavailable and make the framework more spatially robust. This study evaluated the potential of precipitation or simulated stream discharge data to be used as a surrogate of observed stream discharge data for the data-driven model development. Five cases were developed based on the DL modeling framework using the combination of precipitation, observed, and simulated stream discharge values to identify the most significant variable for estimating stream nitrate concentrations. The DL model, developed with observed stream discharge as a crucial environmental characteristic, demonstrated the best performance. The DL model performed similarly with simulated stream discharge as the critical variable, indicating that simulated discharge can be a potential surrogate. The cross-correlation analysis showed that precipitation, stream discharge, and temperature influence the winter periods' nitrate dynamics. For the other three seasons (e.g., Summer, Fall, and Spring) except winter, stream discharge was the most significant environmental for stream nitrate variabilities. This comprehensive study offers crucial insights into developing a spatially and temporally robust data-driven modeling framework for continuous stream nitrate estimation. The study results will help understand nitrate dynamics at data-limited locations, isolate the period for water withdrawal, optimize the new nitrate sensors installing locations, and design appropriate conservation practices to restrict landscape nitrate transport.
Download or read book Investigating Non Point Sources of Nitrate Microbes and Antibiotic Resistance Genes in Two Urban Nebraska Watersheds written by Darshan Baral and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Studies were carried out in two small urban watersheds with separated sewer system located in Lincoln, Nebraska to quantify the relative contribution of nitrate, microbes, and antibiotic resistance genes (ARGs) from potential sources. The role of atmospheric nitrate in two watersheds was investigated by comparing concentrations of stormwater nitrate with regional wet deposition and solving an isotope mixing model based on the isotopic ratios of nitrogen and oxygen in nitrate. Atmospheric deposition was found to be a major source of the nitrate in stormwater during smaller storm events (
Download or read book Flux and Sources of Nutrients in the Mississippi Atchafalaya River Basin written by and published by . This book was released on 1999 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effects of urban development on stream ecosystems in nine metropolitan study areas across the United States written by James F. Coles and published by . This book was released on 2012 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Water Quality of the Albemarle Pamlico Drainage Basin North Carolina and Virginia 1992 95 written by and published by . This book was released on 1984 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Stream Corridor Restoration written by and published by National Technical Info Svc. This book was released on 1998 with total page 648 pages. Available in PDF, EPUB and Kindle. Book excerpt: This document is a cooperative effort among fifteen Federal agencies and partners to produce a common reference on stream corridor restoration. It responds to a growing national and international interest in restoring stream corridors.
Download or read book Bibliography of Agriculture written by and published by . This book was released on 1996 with total page 2368 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Riparian Areas written by National Research Council and published by National Academies Press. This book was released on 2002-10-10 with total page 449 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Clean Water Act (CWA) requires that wetlands be protected from degradation because of their important ecological functions including maintenance of high water quality and provision of fish and wildlife habitat. However, this protection generally does not encompass riparian areasâ€"the lands bordering rivers and lakesâ€"even though they often provide the same functions as wetlands. Growing recognition of the similarities in wetland and riparian area functioning and the differences in their legal protection led the NRC in 1999 to undertake a study of riparian areas, which has culminated in Riparian Areas: Functioning and Strategies for Management. The report is intended to heighten awareness of riparian areas commensurate with their ecological and societal values. The primary conclusion is that, because riparian areas perform a disproportionate number of biological and physical functions on a unit area basis, restoration of riparian functions along America's waterbodies should be a national goal.
Download or read book Marine Algal Bloom Characteristics Causes and Climate Change Impacts written by Santosh Kumar Sarkar and published by Springer. This book was released on 2018-05-02 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the marine environment, single-celled, microscopic, plant-like organisms naturally occur in the well-lit surface layer of any body of water. These organisms, referred to as phytoplankton or microalgae, form the base of the food web upon which nearly all other marine organisms depend. Algal bloom is a rapid increase in or accumulation of the population of about 300 species of algae due to excess nutrients (eutrophication), and is of major global interest as it causes reduction in species diversity, abrupt changes in water quality, and discoloration of the water (green, yellow, brown or red) depending on the species of algae and the type of pigments they contain. Dying blooms can also be an environmental concern as when the cells sink and decay, bacteria break down the organic material, which in turn strips oxygen from the water. This microbial oxygen demand at times leads to very low oxygen levels in the bottom waters, harming aquatic life. Documentation of this sporadic high abundance of algae, together with the significant species richness of the diatoms, requires comprehensive studies in the Sundarban coastal environment, which is facing severe degradation due to natural & anthropogenic stressors. In addition, a better understanding of the effects of algal blooms on seafood quality, the complex biological, chemical and physical interactions and subsequent effects on trophodynamics is needed to develop strategies for effective coastal zone management. The book discusses the occurrence of harmful algal blooms (HABs) caused by the dinoflagellates of the genus Alexandrium and Karenia, or diatoms of the genus Pseudo-nitzschia, which have large and varied impacts on marine ecosystems (such as large-scale marine mortality events that have been associated with various types of shellfish poisonings) depending on the species involved, the environment where they are found, and the mechanism by which they exert negative effects. HABs represent a major environmental problem in all regions of the U.S., and their occurrence is on the rise due to increased nutrient pollution. HABs have severe impacts on human health, aquatic ecosystems, and the economy. Such blooms, known colloquially as red tides due to their red or brown hues, are increasing in frequency and magnitude worldwide as a result of changes in oceanic climate, increased coastal eutrophication and enhanced long-distance dispersal in ballast water. As such, the book offers an in-depth account of the complex biological, chemical and physical interactions of the algal blooms (both innocuous and harmful ones). It also discusses the highly topical issue of the impact of global climate change on the frequency and severity of HABs in the context of alterations in temperature, stratification, light and ocean acidification. Focusing on both basic and applied limnology, this book is a reliable and up-to-date reference resource for students, teachers and researchers engaged in the field of coastal research/management at regional and global scales.
Download or read book Nebraska s Natural Resources Districts written by Ann Bleed and published by . This book was released on 2015 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spring Meeting written by American Geophysical Union. Meeting and published by . This book was released on 1993 with total page 1148 pages. Available in PDF, EPUB and Kindle. Book excerpt:
