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Nitrates in groundwater in the southeastern USA
Published in Domy C. Adriano, Alex K. Iskandar, Ishwar P. Murarka, Contamination of Groundwaters, 2020
Research information on NO3-N movement in the southeastern US is primarily available for the Coastal Plain physiographic region. Jacobs and Gilliam (1985) measured N concentrations and surface water flow for a 3 year period from two watersheds in the Atlantic Coastal Plain of North Carolina. They found losses of NO3-N and total N in surface water from a Middle Coastal Plain watershed with 1,299 ha of predominantly well to moderately well-drained soils to be 2.5 and 4.5 kg ha−1 yr−1, respectively. Nitrate and total N losses from a Lower Coastal Plain watershed with 6,998 ha of somewhat poorly to poorly-drained soils were 0.5 and 2.5 kg ha−1 yr−1 respectively. The values from both watersheds were lower than expected, and the authors concluded that denitrification between the field and stream was the primary reason for these low values. Concentrations of NO3-N in streams near the field outlets also decreased significantly as N enriched water moved through the transport system, and the authors concluded that further denitrification was the primary loss mechanism in the stream transport system.
Management Measures for Nitrate Pollution Prevention
Published in Larry W. Canter, in Groundwater, 2019
The CREAMS model, described in Chapter 6, has been used to simulate the long-term effects of seven different BMPs on nitrate-nitrogen loadings to a shallow, unconfined groundwater system (Shirmohammadi, Magette, and Shoemaker, 1991). The study area included two watersheds in the Coastal Plain physiographic region of Maryland. Seven different management practices commonly used or viable for this region were selected; the practices are listed in Table 7.13 and the associated fertilization plans are summarized in Table 7.14 (Shirmohammadi, Magette, and Shoemaker, 1991).
Access feature areas within clearcut harvests by region across the southeastern US
Published in International Journal of Forest Engineering, 2023
Celeste N. Horton, S.M. Barrett, B.S. Hawks, W.M. Aust, M.C. Bolding
Measured areas of each operational feature were obtained from 112 sites and subsequently used to calculate percent area for each operational feature as a percentage of the total harvest area. Measured areas and the percent area occupied by five operational features were categorized by the three broad physiographic regions (Mountains, Piedmont, and Coastal Plain). Descriptive statistics and evaluations were performed using JMP™ (JMP®, Version 16.0 1989-2022). Shapiro–Wilks Goodness-of-Fit tests were used to determine if data followed the normal distribution. Nearly all the data were not normally distributed; therefore, non-parametric statistical procedures were applied. Data were analyzed using the Kruskal Wallis test using α = 0.10, as suggested for forest operations data (Stephano 2001). If significant differences between independent variables were detected by the Kruskal–Wallis test, then significant differences of means were examined by utilizing Steel Dwass nonparametric mean separation tests. Differences in harvest size and percent area were compared for combined and individual regions. We conducted a Spearman ρ correlation analysis, which is a non-parametric substitute for the Pearson’s correlation coefficient tests (Hauke and Kossowski 2011) to evaluate the correlation between total harvest area and percent area in each feature.
Elevation: a consistent and physically-based framework for classifying streams
Published in Journal of Hydraulic Research, 2018
A database consisting of 873 sets of field data describing channel characteristics of river reaches from Canada (92 values), UK (74 values) and USA (707 values), were prepared from several published and issued sources. A detailed list of these data sources is included in Table 1. These cumulative 873 points possibly represent one of the largest datasets ever used for developing any classification system of stream reaches. All of the values associated with US streams were obtained from USGS reports on channel morphology characteristics for different states. More than 90% of the UK and Canada data included in this study were obtained from Church and Rood’s (1983) catalogue of alluvial river channel regime data. Data reported in both these literature sources are restricted to measurements that have been obtained by similar means and pertain to cross sections that are within a homogenous reach of single thread channels. The conterminous states of USA are divided into eight separate physiographic regions and 25 provinces, where all regions and provinces show significant differences amongst themselves in terms of climatic, hydrologic and geologic factors. For example, the Great Plains province in south-eastern Wyoming is characterized by a high elevation range of 335 m to 3000 m, coarse gravel and cobble streams, semi-arid climate and 0.25–0.51 m of average annual rainfall. In comparison, the coastal plain physiographic province in north-west Florida is characterized by low elevation range of 20 m to 125 m, sandy streams, humid sub-tropical climate and 1.32–1.65 m of average annual rainfall. Table 1 provides a detailed description of regions covered within each of the three countries. Even though these regions do represent a wide range of conditions, additional data from other parts of the world would be necessary to test the broader validity of the results presented here.