Geographic Information Systems Applications in Natural Resource Management

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

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

GIS databases are rarely static n 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 ¨ n n n 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 databases Events Stochastic disturbances Transitions of forests Management activities Transactions Regulations Organizational policies Improvements in technology Organizational initiatives New data availability Changing map projections Collaborative projects Periodic maintenance Update Spatial Examples Data Hurricanes, fires, insect outbreaks Growth and yield X Harvesting, road construction, X X installation / removal of culverts, creation of trails, thinnings. Land acquisitions, donations, sales Riparian management areas, owl habitat areas, woodpecker habitat areas Special areas, personal reservations Digital orthophotographs, GPS capture of road data, ownership boundaries, etc. Periodic / annual cruises, XX photo interpretation of harvested areas not normally recorded via normal processes Databases developed by other organizations New organizational standards X Watershed analyses, landscape planning efforts Cleaning up databases after spatial operations, after digitizing or attributing processes Update Tabular Data X X X X

Process A Process B Process C Digitize an area Collect GPS data for an area Erase overlaps using corporate database Edit spatial features (e. g. , remove multipath) Attribute the new spatial features Select and copy newly digitized features Select and delete features to be updated (if necessary) Update corporate database Paste new features into corporate database Add GPS features into corporate database Attribute the new spatial features Figure 10. 1. Three example of update processes related to a land acquisition.

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

Organizational resources and goals n n 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 n In addition to determining the update interval, organizations will also need to determine how best to meet update needs

Table 10. 2. Inputs and process that can be used to assist a GIS database update. Input: Hand-drawn maps Tabular databases A person's memory GPS features Field notes GIS features developed by field personnel GIS processes: Digitize Join Link Import Querying & verification Scan Update Copy / paste Attributing Overlay

Annual Update Example n 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 n 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 n The hardcopy maps will be sent to a central office n ¨ Checked for errors ¨ Updated into the GIS database ¨ GIS database checked for errors ¨ GIS database delivered to field offices

Continual Update Example n 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 n n n 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 ¨ ¨ n 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 n n n 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 n The owners of the Daniel Picket have purchased 80 acres (30. 4 ha) adjacent to current land holdings Figure 10. 3. Daniel Pickett forest stands and land purchase area. Original stands Stands in land purchase area Vegetation Basal Stand Acres type area 1 2 42. 6 37. 4 A B 190 15 Age MBF 55 7 21. 3 0. 8

Timber stands The two new polygons could be manually copied into the existing databasehowever, attributes would not follow Stand Veg. Type Basal Area Age MBF 1 2 A C 200 175 50 40 21. 2 12. 9 30 31 0 0 C C 190 110 0 0 45 25 0 0 17. 3 4. 1 0 0 Figure 10. 4. Daniel Pickett forest stands and land purchase area after copying and pasting features from the land purchase GIS database to the stands database.

Three options for updating n Digitize the shape of the two stands into the existing stands database ¨ n Use a merge process to combine the newly digitized stands into the existing stands database ¨ n Will require a manual entry of attribute data Must ensure a perfect fit between the adjoining (common) edges of the new stands and existing stands databases Use an update command (available through Arc. Toolbox and XTools in Arc. GIS) ¨ 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 10. 5. Daniel Pickett forest stands and land purchase area after updating the stands database using the land purchase GIS database. Timber stands Stand Veg. Type Basal Area Age MBF 1 A 200 50 21. 2 2 C 175 40 12. 9 30 C 190 45 17. 3 31 C 110 25 4. 1 0 A 190 55 21. 3 0 B 15 7 0. 8

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 n Use the existing stands layer to erase the overlap n Original stands Stands in land acquisition area Overlap

Updating a trails database n n 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 Trails Roads Forest boundary Figure 10. 9. Trail system of the Brown Tract.

A new trail n n 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 10. Proposed new trail on the Brown Tract. Trails Proposed trail Roads Forest boundary

Integrating the new trail n n n 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 ¨ n Snapping tools may help in this process Some attribute work may need to be done manually Figure 10. 11. Proposed new trail and its relation to another trail from the original trail GIS database. Trails Proposed trail

Collect GPS data for an area Edit spatial features (e. g. , remove multipath) Figure 10. 12. Updated trail system of the Brown tract. Trails Forest boundary Attribute spatial features Merge new features into original database Edit spatial position of new features Verify / edit attribute data in updated database Trail Length Condition Source 1 410. 5 Authorized Trails 2 1183. 2 Authorized Trails 42 704. 1 Unauthorized Trails 43 1261. 5 Unauthorized Trails 1 3372. 3 Authorized Proposed_trails

Updating an existing GIS database by modifying existing landscape features and attributes n n 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) n n 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 n n 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 10. 14. Boundary line issue on the Brown tract.

Uncertain boundary can be adjusted n n 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 n 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 n 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 n n n 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

Stand-level forest inventory data Stands GIS database Forest growth and yield model Figure 10. 15. A process to update attribute data in the Daniel Pickett stands GIS database. Summarize stand-level data Stand-level summaries Stands GIS database joined with summaries Replace old summaries with new summaries Remove the join Updated stands GIS database