Automated Land Mapping Requires an Updated Grid
The adoption of geographic information systems (GIS) to facilitate effective management of land leases, pipelines, utilities and forests to improve the efficiency of energy exploration and production activities is spurring demand for better data describing public lands. There are several sources of online data maintained by government agencies; however, not all data sets work well for automated land mapping, which relies on clean data for successful processing.
The Public Land Survey System (PLSS,) originally proposed by Thomas Jefferson over 200 years ago, provided a set of rules for surveying public lands that resulted in legal descriptions of townships and ranges in 30 states, primarily in the western and southern parts of the country. The U.S. Bureau of Land Management (BLM) uses available PLSS data and other official surveys to populate the Geographic Coordinate Data Base (GCDB), which is updated on a continuous basis. Although conveniently available online, the GCDB version of the PLSS can contain gaps and overlap errors that need to be corrected before being ingested into a GIS.
WhiteStar Corporation, based in Lakewood, Colo., has been tackling the problem of incomplete and inaccurate land grid data for over 20 years. Its large proprietary data set is based on hand-digitized USGS topo map data, which is then augmented with BLM data. Whenever appropriate, corrected BLM data replaces the USGS data. This most often happens in a few states such as Wyoming, Montana and Colorado. The goal is to combine all of the most accurate available data state by state to create a reliable land grid that can be used for legal transactions.
The digital cartography firm is six months into a three-year project to create lots and tracts (polygons within a section) nationwide. The result will be a unique data set of accurate boundaries and attribute information that is suitable for use with land-mapping systems, such as those developed by Quorum Business Solutions and LandWorks. Work is progressing state-by-state determined by customer demand. Complete coverage is already available of Arkansas, Montana, Oklahoma, Oregon, Washington and Wyoming, with Colorado, Kansas, Louisiana and North Dakota expected to be complete by the end of 2013. A system for online delivery is planned for 2014.
“Our current project involves updating lots and tracts for all of the state data sets, including the 20 states not included in the PLSS, which are primarily in the eastern U.S. We go through a very controlled process to verify and correct errors using any new information from any source that is available,” explained Robert White, president and CEO of WhiteStar. “Our staff members conduct geospatial adjustments by comparing the GCDB and PLSS to topo maps and more recent high resolution maps to ensure township and state edges match. Sometimes errors have been made in digitizing over the years, so we have to compare current maps to original plats. If we identify big gaps— sometimes as big as 300 feet wide— we research every possible source to address that. And we perform cleaning to correct meridian or township numbers and other attributes. We are always trying to find the latest updates and review and install them into our grid product.”
In the last few years, White has noticed a sharp increase in demand for updated land grid data from oil and gas and forestry companies, as well as utilities. GIS has been slow to infiltrate the land departments of these organizations, but as the emphasis on improved efficiency and cost cutting continues, automated land mapping has gained in popularity, thus creating a need for better data sets. Clean land grid information that can be seamlessly loaded into land-mapping software provides benefits to a variety of departments, such as land, exploration and production.
“Historically, there have been two silos of information within energy companies and utilities— land and geology— and they would compete for budget and resources,” White said. “Communication and collaboration is enhanced by the use of one data set, available in multiple formats for all the applications that users need. There is no reason to buy it twice, and with a data subscription service, the customer also receives regular updates. Accurate and current data helps prevent costly errors.”
Caption for Figure 1: A General Land Office plot of a township map dated April 24, 1868.
Caption for Figure 2: WhiteStar lot and tract data in Mountrail County, N.D., dated approximately 1898.