HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Grunwald, S. Articles by Lamsal, S. Search for Related Content PubMed Articles by Grunwald, S. Articles by Lamsal, S. GeoRef GeoRef Citation Agricola Articles by Grunwald, S. Articles by Lamsal, S. Related Collections Phosphorus Geostatistics Spatial Variability

Incorporation of Auxiliary Information in the Geostatistical Simulation of Soil Nitrate Nitrogen

^a Soil and Water Science Dep., Institute of Food and Agric. Sciences, Univ. of Florida, 2169 McCarty Hall, P.O. Box 110290, Gainesville, FL 32611-0290, USA
^b BioMedware, Inc., 516 N. State St., Ann Arbor, MI 48104, USA

View larger version (70K): [in a new window]   Fig. 1. GIS layers: soil orders (Soil Survey Geographic Database, Natural Resources Conservation Service); digital elevation model (National Elevation Dataset, USGS), and stream network (USGS and Florida Department of Environmental Protection).

View larger version (30K): [in a new window]   Fig. 2. Location maps of data (i.e., profile average NO3–N, µg g–1) for the three sampling events.

View larger version (55K): [in a new window]   Fig. 3. GIS layers: drainage classes, Floridian aquifer DRASTIC index, and land use. (Drainage class code: VP = very poorly; SP = somewhat poorly; E = excessive; SE = somewhat excessive; MW = moderately well; P = poorly; W = well drained).

View larger version (95K): [in a new window]   Fig. 4. (a) Map of the probability of exceeding a threshold of 0.582 µg g–1 in September 2003 estimated using the proportional odds model. (b) Map of the mean of the local prior distributions of probability, that is, a prior estimate of nitrate concentration (µg g–1). Polygons denote the limits of the drainage subbasins in the Santa Fee watershed.

View larger version (30K): [in a new window]   Fig. 5. Omnidirectional semivariograms of indicator residuals computed at nine thresholds for the January 2004 sampling campaign. The solid line depicts the isotropic model fitted using weighted least-square regression.

View larger version (22K): [in a new window]   Fig. 6. Scatterplot of estimated vs. observed NO3–N concentrations for each sampling period.

View larger version (28K): [in a new window]   Fig. 7. Plots of the proportion of observed NO3–N data falling within probability intervals (accuracy plot) and the width of these intervals vs. the probability p. The goodness statistics measures the similarity between the expected and observed proportions in the accuracy plots (best if one). Open circles in the graphs of right column represent the width of probability intervals computed from the sample histogram (cdf).

View larger version (107K): [in a new window]   Fig. 8. First two realizations of the spatial distribution of NO3–N concentrations generated using sequential indicator simulation for each period (units: µg g–1).

View larger version (77K): [in a new window]   Fig. 9. Mean and standard deviation of the distribution of 100 realizations of NO3–N concentrations generated using sequential indicator simulation and aggregated within each subbasin (units: µg g–1).

View larger version (49K): [in a new window]   Fig. 10. Average variance across all 100 realizations of the spatial distribution of nitrate values simulated within each subbasin (units: (µg g–1).