topic Re: Creating Precipitation Isohyets in Forestry Questions

Creating Precipitation Isohyets

RyanHaines1 — Fri, 26 Jun 2015 11:06:05 GMT

Hello!

This is my first time posting so please forgive me if I am doing anything wrong

I am working on a project to map the average precipitation of British Columbia in the year 2000. I currently have 1048 sample data points loaded into my map, all of which have an annual precipitation value. I am trying to create a map that depicts the average rainfall of BC using isohyets (contours). Initially I used the kriging tool to create the raster necessary to generate contour lines. However, with further investigation and research I have discovered this is not the best tool to interpolate precipitation data. There is a bias in the sample point distribution. A majority of the points are in southwestern BC (Vancouver and Victoria), while there are significantly less in the northern parts of BC. With this bias in data points, what is the best interpolation method? I believe it may be the spline tool, but I cannot be certain. I have not run any spatial statistics on my data but it is something that I am going to investigate.

Re: Creating Precipitation Isohyets

XanderBakker — Fri, 26 Jun 2015 12:46:34 GMT

There is a comparison document here that you might be interested in:

http://proceedings.esri.com/library/userconf/proc07/papers/papers/pap_1451.pdf

This document (although a bit dated and mainly about surfaces) gives a nice visual comparison:

http://www.esri.com/news/arcuser/0704/files/interpolating.pdf

And I suppose that you have already consulted the Help: Comparing interpolation methods—Help | ArcGIS for Desktop

Re: Creating Precipitation Isohyets

XanderBakker — Fri, 26 Jun 2015 13:04:02 GMT

In addition, this document is also quite nice:

http://web.pdx.edu/~jduh/courses/Archive/geog492w08/Projects/PraskieviczCoeEbtehaj.pdf

After the interpolation you can convert the "continuous surface": Deriving contour lines from a surface—Help | ArcGIS for Desktop

Re: Creating Precipitation Isohyets

NICOLAPEDDIS — Fri, 26 Jun 2015 15:04:46 GMT

May be useful also this presentation.

http://www.ce.utexas.edu/prof/maidment/CE374KSpr12/Visual/Precipitation.pptx