Database of soils on parcels

In 1975 the VERMONT GEOLOGICAL SURVEY authored by Charles G. Doll, State Geologist published GEOLOGY FOR ENVIRONMENTAL PLANNING IN THE BRATTLEBORO-WINDSOR REGION, VERMONT

In the introduction to the project he writes: “The accumulation of geologic data is an essential prerequisite to many facets of environmental planning. All environmental problems that involve the movement of water, the supply of ground water, the strength of earth materials and the reserves of earth resources are related to the geology of the subsurface. These factors, in turn, are controlled by the texture of rock and soil, the degree of metamorphic change, the fractures in the rock, the ability of earth materials to hold and transmit water, and the plasticity of the unconsolidated sediment above bedrock. The availability of water and the pollution of water supplies are related to the movement of liquids. The thickness, strength and stability of surficial material determines their suitability for foundations for heavy construction. In addition, special consideration mustbe given to the location of economically important geologic resources when planning for land use. It is the intent of this report to explain how these specific factors are influenced by the geologic conditions of the Brattleboro-Windsor region and how they relate to the environmental problems of that area.”

Soils of Windham
Each color is a different soil

So we see that soils are a big deal. The soils map for Windham is a complicated picture and I wanted to find a way of linking the soil type and description to a particular parcel. I already have a digital parcel map, but how to create a link between the soils and a parcel was a new problem for me. I found that it is a very common problem in GIS work and the software I use does have a procedure for doing just that. Its called join attributes by field value. In practical terms that means that data can be exchanged between two GIS layers overlaying the same area.

Once I had the parcel number it was possible to link the parcel and different soils. Windham has 720 parcel, but when I linked the soils I had a table with over 3,100 rows because almost all Windham parcels are sitting on more than one soil. My parcel has 8 different soils.

I wanted to create a database that would show a parcel and all the soils under that parcel and the way to do that looks like this:

Top part is the main form showing grandlist information and the bottom is the sub-form showing all soils on that parcel. One parcel, many soils

This database was created using the free and open source database manager in the LibreOffice suite. LO Base is quite similar to Microsoft Access; the database, forms, queries and reports are all contained in one file. All one needs to do is to install Libre Office Base ( https://www.libreoffice.org/download/download/ ) on their Linux, Windows or Mac laptop or desktop and then open the soils database to get to the form and data shown above. Then open the form and use the control bar across the bottom to navigate through the data or click the little magnifying glass at lower left and enter your search criteria to find the record(s) you are looking for.

Here’s what that looks like:

Search form

Clicking on the magnifying pops up the screen seen above and simply select the data field you’d like to search, enter what you’re looking for and click search. Once you’ve found the record you want a paper report can be printed by clicking the Report icon on shown here:

Landing area of Libre Office Base:
shows tables, queries, forms and reports

The soils database was created using only the capabilities built into LibreOffice Base. I did no programming at all, just used the form builder. However, finding the data, getting it into a GIS and doing the data management things does take a bit of experience. The report I’ve already created is a parameter report which means that it will print information about a particular parcel if you enter the parcel number when the pop-up window asks “What?” to produce a report like this:

Report

Every town planning commission, conservation commission and Listers could make use of such a database and I hope that this post shows how we can use the GrandList data we have to build additional uses.

I intend to create a users guide for the soils database and also put a copy available for download here. Here is a link to the soilsofWindham.odb database.http://tinyurl.com/yxpvfzo4