Despite the widespread availability of relatively detailed soil maps in the USA, few areas have a surficial geology map published with as much spatial detail. This apparent gap between disciplines calls to question the accuracy of soil maps to represent the spatial distribution of surficial geologic materials. Therefore, the purpose of this research was to test the agreement between maps from these two sources.
Author: Bradley Miller
UPDATE: Because of the tremendous response to this blog post, we’ve initiated a survey to better understand how different people around the world are defining colluvium and alluvium. Respondents have told us that taking the survey was fun and thought-provoking. Please add your perspective by completing the survey today! TAKE THE SURVEY As I interact … Continue reading Colluvium vs Alluvium
Quantifying uncertainty can be a very useful and often important aspect of evaluating results of calculations, particularly in modelling. The same applies for spatial layer mashups where the grids provide the input variables for equations that are calculated spatially (i.e. raster calculator). This toolbox for ArcGIS uses standard error propagation equations to simultaneously calculate the … Continue reading Error Propagation Toolbox
A zip file containing a suite of tools for analyzing continuous particle size curves from laser diffractometry. Includes: export templates for Malvern software, analysis template for recommended quality control procedure, reporting templates for organized presentation of results with additional metrics, and a data filter for removing the larger particle size peak from bimodal curves.
Results suggest that models with limited predictor pools can substitute other predictors to compensate for unavailable variables. However, a better performing model was always found by considering predictor variables at multiple scales. Although the scale effect of the modifiable area unit problem is generally well known, this study suggests digital soil mapping efforts would be enhanced by the greater consideration of predictor variables at multiple analysis scales.
Scientists often measure and predict things. Therefore, we need ways to describe how much we know, how close a number is to reality, and how likely we are to get the same number again. The terms accuracy and precision are generally used to describe these things, but there can be some ambiguity. This post explains … Continue reading Accuracy vs Precision
When you read the phrases “large scale” or “small scale,” do you know what they mean? Sometimes “large scale” is describing a large area and sometimes it is describing a small area, depending on if the author was thinking about process scale or cartographic scale. This is a problem for communication. In this post I … Continue reading Types of Scale
In the process of creating a map, geographers often have to engage in the activity of spatial prediction. Although there are many tools we use to accomplish this task, they generally boil down to the use of one or two fundamental concepts. Waldo Tobler is credited for identifying the ‘first law of geography’, stating “Everything … Continue reading Fundamentals of Spatial Prediction
This raster provides an estimate of the wetland water regimes in Iowa, prior to the implementation of drainage systems. These estimates are based on the spatial information in the USDA-NRCS gSSURGO database and soil series characteristics described in the official soil series descriptions (OSD). Soil series characteristics were matched as best as possible to the … Continue reading Pre-settlement Water Regimes of Iowa Wetlands