GIS Based Chemical Fate Modeling: Principles and Applications

Chapter 5

Distance Calculations

With Contributions by Paolo Mazzoli

5.1 Concepts of Distance Calculations

Distance calculations are among the most frequently used GIS functions. Indeed, geography as a discipline is strongly based on distance, Tobler's first law of geography stating that “everything is related to everything else, but near things are more related than distant things” [1].

Distance calculations are required in practically all spatial models of contamination, as chemical fate depends strongly on the distance from the emission source. GIS analyses typically distinguish between Euclidean distance and weighted distances, also termed cost distances.

Euclidean distance, or straight line distance, between two points having respective coordinates and is computed in principle as

5.1

The Euclidean distance is widely used in vector maps analysis. Typical operations on vectors involving distance are (1) the buffering of features and (2) the association of elements based on distance.

Example: Feature Buffering

Snow is an important driver of chemical fate in mountain environments. Snow depth may be predicted on the basis of morphology, energy, and precipitation balance at the ground ...