Online Submissions Now Being Accepted for the Esri Map Book, Volume 28

Online submissions are now being accepted for the Esri Map Book, Volume 28. If you have an ArcGIS map you would like to be considered for publication, please visit the Map Book online submission site at http://www.esri.com/apps/mapbook. There you will find contact and permission forms plus details about how to submit image files.

The submission deadline is Friday, November 16, 2012,at 5:00 p.m. (PST).  If your map is chosen, you will receive a notification by e-mail. The Esri Map Book, Volume 28 will be released in July 2013 at the Esri International User Conference.

Modeling Experimental Cross-transiograms of Neighboring Landscape Categories with the Gamma Distribution

International Journal of Geographical Information ScienceInternational Journal of Geographical Information Science, Volume 26, Issue 4, 2012

Weidong Li, Chuanrong Zhang & Dipak K. Dey

“Effectively fitting the major features of experimental transiograms (or variograms) is crucial in characterizing spatial patterns and reproducing them in geostatistical simulations. Landscape patterns usually tend to contain neighboring structures. The experimental cross-transiograms of frequent neighboring landscape categories normally demonstrate apparent peaking features at low lag distances – they first quickly increase to a peak and then gradually flatten out. The flattening process may be smooth or may be through one or more alternate attenuating troughs and peaks. While alternate peaks and troughs may be a reflection of the cyclic occurrence of landscape categories, the single peak or the first peak at low lag section should be a signal of the neighboring structure of two related categories. This is further proved by the peaking features of some idealized transiograms calculated from single-step transition probability matrices. To effectively fit the first peak, especially when it is the single one, we propose using the gamma distribution function and the commonly used variogram models to form additive composite models. Cases of fitting experimental cross-transiograms of landscape data (here soil types and land cover classes) show that the additive gamma-exponential composite model works very well and may closely fit the single-peak features. Although it has multiple parameters to set, model fitting can be performed manually by trial and error. Other two composite models may provide alternatives for fine fitting of the root section (i.e., the left side of the peak). These models may also be applicable to fitting experimental variograms with similar features. We also reintroduce the multiplicative composite hole-effect models proposed for variogram modeling by earlier researchers, and test them on experimental cross-transiograms. It is found that composite hole-effect models are not sufficiently flexible to effectively fit the peak shapes of experimental cross-transiograms of neighboring categories, unless multiple peaks and troughs appear in regular shapes and rhythms.”

Spatial Analysis of Bioavailable Soil Lead Concentrations in Los Angeles, California

Environmental ResearchEnvironmental Research, May 2010, 110 (4)

Wu J, Edwards R, He XE, Liu Z, and Kleinman M

“Lead (Pb) poisoning causes permanent neurologic and developmental disorders and remains an important environmental health problem for US children, despite removal of Pb from gasoline and household paints. To better understand the contribution of Pb from historical traffic and residential Pb based paint to soil Pb concentrations in Los Angeles, we analyzed 550 soil Pb samples from south central Los Angeles County, CA, in relation to land-use patterns (commercial, industrial, residential, and parks and open areas) and proximity to freeways, highways, and major arterials. House age variables (surrogates of historical Pb-based paint) and traffic index variables (surrogates of historical traffic) were created at different buffer distances (10-5000m). Total and bioavailable Pb concentrations near freeways and major arterials were significantly higher than those collected elsewhere. Total and bioavailable Pb concentrations were highly correlated (r=0.96) after the removal of one outlier. Both parcel-age related variables and traffic variables were important predictors of current soil bioavailable Pb concentrations. Average age of parcels within 30m and length of small streets within 3000m explained 57% and 38% of the variance, respectively, in soil bioavailable Pb concentrations in residential areas away from freeways and major arterials (N=44). Road length of freeways within 750m explained 28% of bioavailable Pb concentrations in parks and open areas (N=26). Multi-variable regression models predicted 16-61% of the variances in bioavailable Pb concentrations, depending on land-use type and spatial relationship to roadways. Based on these models a map of spatial distributions of soil Pb concentrations was created for the Los Angeles area that shows promise as a screening tool to evaluate continued Pb poisoning in children.”