Geographic Information Systems Applications in Natural Resource Management Chapter 10 Updating GIS databases Michael G. Wing & Pete Bettinger

Chapter 10 Objectives Why GIS databases need to be periodically updated and maintained, What issues might be associated with an update process, and What GIS processes could be used to physically update a database.

GIS databases are rarely static Particularly in forestry and natural resources  Vegetation change due to time, disturbances, and management activities  Roads and trails are built and are sometimes obliterated  Stream conditions and structure changes GIS databases should be updated periodically to reflect changes that occur in resources over time Either the spatial locations, the attributes of the locations, or both the locations and attributes will require updating The question is how often and thoroughly a database should be updated

Table 10.1 Reasons for updating GIS databasesUpdate SpatialTabular EventsExamplesDataData Stochastic disturbancesHurricanes, fires, insect outbreaksXX Transitions of forestsGrowth and yieldX Management activitiesHarvesting, road construction, XX installation / removal of culverts, creation of trails, thinnings. TransactionsLand acquisitions, donations, salesXX RegulationsRiparian management areas, owlXX habitat areas, woodpecker habitat areas Organizational policiesSpecial areas, personal reservationsXX Improvements in Digital orthophotographs, GPS captureXX technologyof road data, ownership boundaries, etc. Organizational initiativesPeriodic / annual cruises, XX photo interpretation of harvested areas not normally recorded via normal processes New data availabilityDatabases developed by other organizationsXX Changing map projectionsNew organizational standardsX Collaborative projectsWatershed analyses, landscape planningXX efforts Periodic maintenanceCleaning up databases after spatialXX operations, after digitizing or attributing processes

Digitize an area Erase overlaps using corporate database Attribute the new spatial features Update corporate database Digitize an area Erase overlaps using corporate database Select and copy newly digitized features Paste new features into corporate database Attribute the new spatial features Collect GPS data for an area Edit spatial features (e.g., remove multipath) Select and delete features to be updated (if necessary) Add GPS features into corporate database Attribute the new spatial features Figure Three example of update processes related to a land acquisition. Process AProcess BProcess C

GIS database updates Many organizations have developed processes and protocols to guide database updates The update interval is the period of time between updates  May range from hours to years  Will depend on organizational resources and database analysis goals

Organizational resources and goals Updates require investments of time and personnel If the goal of a forest management company is to generate revenue for stockholders  timber resources should be updated more frequently than other resources, such as hiking trails  updating resources such as roads, streams, and culverts may or may not be important In addition to determining the update interval, organizations will also need to determine how best to meet update needs

Table Inputs and process that can be used to assist a GIS database update. Input: Hand-drawn mapsGPS features Tabular databasesField notes A person's memoryGIS features developed by field personnel GIS processes: DigitizeScan JoinUpdate Link Copy / paste ImportAttributing Querying & verificationOverlay

Annual Update Example Example: A forest management company in Florida has decided to update its forest stand inventory annually- why?  This GIS database is perhaps the most important  Most corporations require an annual estimate of the value and volume of corporate holdings for tax and planning purposes  Given the relatively short rotation that is typical of industrial forests in the south, a longer update interval may not be sufficient  A shorter update interval will lead to increased costs and may add confusion among field foresters if databases change too often

Updating a forest stand database Inventory changes can be recorded through:  Hardcopy maps, cruise forms, or through digital means (GPS) Field foresters, timber procurement managers, and others will note the changes on hardcopy maps The hardcopy maps will be sent to a central office  Checked for errors  Updated into the GIS database  GIS database checked for errors  GIS database delivered to field offices

Continual Update Example In Washington state, all forest management plans must be submitted to the Department of Natural Resources (DNR) for review and approval  A map must accompany the plan  Must show the relation of the proposed activities relative to the landscape and any surrounding stream systems  The DNR provides a statewide streams database for mapping purposes

Updating a streams database The DNR streams database is continuously updated as new information becomes available A land owner that surveys a stream and notes changes from the DNR streams database can submit a change request The DNR has a review protocol for change requests  Requests are either denied or approved  Approved requests will be used to update the streams database Although several months or more may elapse in the reporting, review, and update process, this is considered a continual update since an update may occur any time during the year

Updating existing GIS databases with new landscape features Example 1: A land purchase results in the addition of two stands into an existing GIS database Example 2: Incorporating a new trail into a GIS database For both examples assume  The new features were either digitized or measured with a GPS or other equipment and are available in a GIS database  The new features are initially stored separately from the existing resource database

Two new stands The owners of the Daniel Picket have purchased 80 acres (30.4 ha) adjacent to current land holdings Original stands Stands in land purchase area Figure Daniel Pickett forest stands and land purchase area. VegetationBasal StandAcrestypeareaAgeMBF 142.6A B1570.8

The two new polygons could be manually copied into the existing database- however, attributes would not follow Figure Daniel Pickett forest stands and land purchase area after copying and pasting features from the land purchase GIS database to the stands database. StandVegTypeBasal AreaAge 31C11025 C19045 A MBF Timber stands C 0000

Three options for updating Digitize the shape of the two stands into the existing stands database  Will require a manual entry of attribute data Use a merge process to combine the newly digitized stands into the existing stands database  Must ensure a perfect fit between the adjoining (common) edges of the new stands and existing stands databases Use an update command (available through ArcToolbox and XTools in ArcGIS)  A good fit between databases in the update should also be present but the update process typically will examine new link and node intersections in the creation of an output database

Update Results Figure Daniel Pickett forest stands and land purchase area after updating the stands database using the land purchase GIS database. StandVegTypeBasal AreaAge 31C11025 C19045 A MBF Timber stands C A B

Ensuring a perfect fit: options  Use snapping techniques while digitizing to force the new features to fir the existing  Use GIS tools Digitize a shape that overlaps the existing database Use the existing stands layer to erase the overlap Original stands Stands in land acquisition area Overlap

Updating a trails database The existing trail system for the Brown Tract was digitized several years ago from hardcopy maps Over time, people will tend to develop new trails on their own  These are know as unauthorized trails Figure Trail system of the Brown Tract. Trails Roads Forest boundary

A new trail An unauthorized trails has emerged as a candidate for inclusion into the existing trail system The new trail’s location is captured by a GPS and entered into a proposed trails GIS database Figure Proposed new trail on the Brown Tract. Trails Roads Proposed trail Forest boundary

Integrating the new trail Since the databases are linear, and not polygon, no need to worry about area overlaps A merge can be used to bring the databases together Should ensure however, that the lines meet at intersections  Snapping tools may help in this process Some attribute work may need to be done manually Trails Proposed trail Figure Proposed new trail and its relation to another trail from the original trail GIS database.

Figure Updated trail system of the Brown tract. Trails Forest boundary TrailLengthCondition Unauthorized 704.1Unauthorized 410.5Authorized Source Trails Proposed_trails Collect GPS data for an area Edit spatial features (e.g., remove multipath) Attribute spatial features Merge new features into original database Edit spatial position of new features Verify / edit attribute data in updated database

Updating an existing GIS database by modifying existing landscape features and attributes This implies that we physically alter existing databases rather than previous examples where we created a separate database to capture changes Some danger in possibly damaging the existing database- make a copy! May be difficult to detect and correct any mistakes unless processing steps have been carefully documented Two examples: using a digital orthophotograph quadrangles (DOQs) and updating attributes using a join process

Digital Orthophotograph Quadrangles (DOQs) Given that the projection of a DOQ exactly matches that of your existing databases, you can use DOQs to judge database accuracy in representing resources If the DOQ and is of sufficient quality, you can use it to create update information You can digitize point, line, and polygon features directly from the DOQ and incorporate them into existing databases or create new databases The DOQ can be viewed simultaneously as other vector layers

Brown Tract DOQ being displayed beneath the Brown Tract boundary Reveals that either the boundary database has an error or that a harvesting operation on an adjacent landowner’s property was incorrectly located Figure Boundary line issue on the Brown tract.

Uncertain boundary can be adjusted Use the DOQ as a guide to adjust the vertices along the boundary database to match the DOQ line If precision and accuracy are an issue, you may want to capture the boundary location through a property boundary survey  Total station or survey GPS measurements Updates to the boundary database may impact other databases!  Stands and soils on the Brown Tract  May want to also update other databases to reflect the boundary update

Updating attributes using a join process In some cases, only attributes may require updating  If stand units (boundaries) have not been altered, only the growth and structural information need be updated  The changes might be estimated through a growth and yield model A structural changes could be summarized in the output and saved in the form of a nonspatial database The nonspatial database can be joined to the stands database The joined data can be used to replace existing structural data with the updated data

Figure A process to update attribute data in the Daniel Pickett stands GIS database. Forest growth and yield model Summarize stand-level data Remove the join Replace old summaries with new summaries Stands GIS database Stand-level forest inventory data Stand-level summaries Stands GIS database joined with summaries Updated stands GIS database