Drakenstein has a rich historic

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1 Drakenstein GIS heritage management system by Janine Penfold, Drakenstein Municipality The National Heritage Resources Act 25 of 1999, Section 30 paragraph 5 states: On request, need or revision of a zoning scheme or SDF the planning authority shall produce an inventory and submit to the authority to be listed in the register. Effective date being April Drakenstein has a rich historic component and includes amongst others the towns of Saron formerly a mission station, Wellington known for its institutional history, Paarl the official birth place of Afrikaans, and Bain s Kloof Pass built by Andrew Bain in the mid 1800s. The area has been renowned since early Cape days for its wine and fruit production, as well as slave history, agricultural practices, wagon industry, and more recently for its cultural landscapes and historic werfs and vineyards. With such a rich historic background, management of heritage resources is crucial. In 2004 a heritage officer was appointed and shortly after a tender advertised for the undertaking of a heritage survey for Drakenstein. Included in the TOR was that the product be "GIS compatible". The tender was awarded to a group of heritage experts known as the Drakenstein Heritage Survey Group (DHSG). The initial request put to the GIS office was to review the draft survey table and advise on requirements to ensure GIS compatibility. As practical implications were made apparent and the power and benefits of GIS for management of resources understood, the project developed to include much more. Legislation only required that a list of resources be submitted to the authority, but no guidelines regarding methodology or grading were provided in the Act. This was researched and pioneered by the DHSG in consultation with various stakeholders following best practices. The two main components of this project were firstly the survey and listing of tangible objects found in the built environment that were older than 60 years and considered preservation worthy (see Fig. 1). This included objects (resources) from category types such as industrial, religious, political, residential, werf, ruin, institutional, scenic route, mountain landscape, etc. Intangibles such as oral history, folk stories, music etc. are not part of this project. The second component is a set of heritage overlay zones or "landscapes" that give context to the resources. They contain various topographical, manmade, political, cultivated and landmark features providing character to the overlay zone. Methods Resources Fig. 1: Heritage resource photos. Both the shape and extent of resources were considered significant. The draft survey table provided included a field for recording shape (polygon, linear or point), one for a GPS co-ordinate, and one for an erf or farm number. This was presumed to be sufficient for providing a link to GIS. Once the GIS office was brought on board it was pointed out that multiple vector data types were not possible in one layer and multiple layers describing one dataset were not considered good practice. It was also immediately apparent that for rural areas a single resource (werfs) could straddle cadastral boundaries and the extent would be considerably smaller than farm cadastral. Multiple GPS readings might be required for one resource and in densely distributed urban areas accuracy obtained from handheld devices might be unsuitable. Taking this into consideration, it was agreed that a polygon resources layer be created with a unique number assigned to each record in the survey table and captured as an attribute for the polygon. The table could then be linked to the polygon and a new resources layer created. Linear and point features occurring with the 38 PoPositionIT Nov/Dec 2011

2 to cadastral and a new urban resources layer created. The urban and rural layers were then combined. Using differing methods to capture objects for one layer could be questioned, however on exploring other options, it became clear this was a practical solution. The datasets have integrated well and integrity for designed use has not been compromised (see Fig. 2). Fig. 2: Visual integration of rural and urban polygons. Rural resources can be seen north of the small stream and urban resources to the south. Fig. 3: Overlay zone legend. Indicates the various landscape features identified as significant to overlay zones. Figs. 4 (a) and (b): Overlay zone map extract. Extracts from urban and rural overlay zone maps. resource (driveway avenues etc.) would be described as part of the description attribute. Resources were initially identified using 1938 SG ortho photos. From this the field survey was undertaken and additional resources not apparent on the images were included. For rural areas, the resource and its unique number was marked up on the ortho photo and captured into GIS. In urban areas resources didn t straddle erven and provided full coverage therefore cadastre was used as the base for the polygon. Cadastral maps were marked up during field survey and unique numbers assigned. Erf numbers were included in the table which was linked Key attributes for resources are location, type of resource, current protection status, grade, chronology, significance and description. Photos were taken of each resource and these have been linked to their respective resource polygon via a hyperlink. At a later stage documents pertaining to individual resources will be included in the hyperlink. The layer includes existing national and provincial sites, suggested national or provincial sites, and suggested grade 3As, Bs and Cs in total 1700 resources. One resource is less than 60 years old but of significant architectural value. Twenty-nine could not be accessed, graded or described due to security measures. Owners who did not respond to requests to provide access will be required to do so when submitting building or other applications. Where resources have been lost post the survey (fire, storm, granting of demolition approvals at provincial level, etc.) this has been noted and the record maintained in order to provide historic information. Overlay zones (landscapes) Features and objects adding character to the overlay zones were marked up on hard-copy 1: topographical sheets. These were geo-referenced and captured. Spatial accuracy was later improved using current satellite and aerial images. A table for each overlay zone was provided describing the features and significance of the landscape. These tables are linked to the overlay zone boundary layer using a hyperlink. Boundaries of the 15 identified overlay zones were captured in a single layer, in addition also the boundary of the existing provisional Cape cultural landscape. A separate layer was created for each type of feature or object identified as adding context to the landscape. These vary from mountain backdrops, river corridors, cultivated fields, dominant views, social nexus, structural axis, streetscapes, PositionIT Nov/Dec

3 cadastral had been used to create the polygon. Investigation brought to light that incorrect erf numbers had been read and recorded during the field survey. The difficulties encountered by persons not familiar with cadastral map reading in correctly identifying the relevant erf on a map without an image backdrop was not given enough consideration. Compounding the problem was that at the time Drakenstein did not have hardware capable of outputting suitable hard-copy maps with an aerial backdrop. Current oblique images were of immense value in identifying and correcting these errors (see Fig. 5). Completeness of database Fig. 5: Location errors: It can clearly be seen how this resource with its adjacent parking area could easily be mistaken as being located on the corner erf. The addition of aerial photography as a backdrop would have provided vital information as to the exact location of the building. For both rural and urban areas the field survey was divided into sections and undertaken by members of DHSG working in pairs. Survey tables were returned piecemeal and over an extended period of time. It was only when these had been converted and one database created that the extent of incompleteness was realised. Completing the database required that records with missing data had to be identified, maps created indicating their location, and these sites revisited to collect missing information, the information gathered, collated and returned for capture into the database. Fig. 6: Heritage resource report. landmarks and monuments, scenic routes and views, tree lines, cemeteries, Group Areas Act, political marches, etc. in total 25 feature layers (see Figs. 3 and 4). Verification The products from this data will have certain legal status and implications. Users must therefore have full confidence in the integrity of the data. Fittingly a very intensive verification process was undertaken. As the data was checked, two areas requiring attention became apparent. The correct location of the polygon for each resource had to be verified, and the database attributes needed to be complete. Location of resource polygons For location verification, photographs taken during the survey were compared with aerial orthogonal and oblique Pictometry images as well as the description attribute of the resource. It became apparent that in some instances ID numbers had been incorrectly assigned on the mark-up map resulting in the wrong table record linking to the polygon. For rural areas minimal location mark-up errors were found. They occurred mostly where werfs were closely distributed and especially where the original farm name was retained and repeated for subdivisions. A considerable percentage of errors were found for urban areas where Standardisation of values Values captured in the tables were not standardised and this was addressed during verification. Although not excessively time-consuming the importance of having standardised data is significant enough to warrant mention and especially important to attribute analysis and symbology in map compilation. Lessons learned Projects such as this require sufficient and dedicated GIS staff. During this project various other projects were often given higher priority. Working piecemeal was very disruptive especially during verification when months could pass between work sessions, requiring processes to be re-visited in order to re-cap. It also resulted in important planning steps being ignored simply because there was not always time to give due consideration at critical milestones. There is a general lack of understanding of the importance of 40 PositionIT Nov/Dec 2011

4 project planning such as user requirement, design, planning and identification of the end-product format and scale amongst non-gis professionals. This needs to be addressed by the GIS community. At the time of field capture the end product use and scale for overlay zone layers could not be described and resulted in data having to be recaptured to a more suitable scale once its use had been established. The difficulties encountered by persons not familiar with cadastral map reading in correctly identifying the relevant erf on a map without an image backdrop was not given enough consideration especially considering that this was crucial to correctly locating the resource. The co-incidental availability of oblique photography at the point when photos were linked proved extremely useful for location verification and resulted in significant reduction in the amount of field work that would otherwise have been required. Fig. 7: Regional landscape character zone map. A dual screen was imperative during verification especially when matching photos to resources. While the need for tables and values to be standardised was initially addressed not enough emphasis was placed on this requirement. The short-comings regarding completeness of the tables was significant and would have been better addressed prior to converting to GIS format. Once put into GIS it became the responsibility of the GIS office to provide maps and tables indicating shortcomings, and to ensure completeness. The process for and format of returned field data during verification must be clearly stated and complied with. This must be done in such a way that the need for having to edit individual records is minimised and most can be calculated back into the database. Future maintenance of the dataset Fig. 8: Distribution patterns: The distribution of resources along rivers and valleys in the south are clearly visible, while in the dryer northern part they are sparsely distributed. The long linear resource in the far north east is a historic irrigation furrow that provided water to Saron Village and Mission Station mill. A re-survey of the area will be required roughly every five years and the database suitably maintained. Lessons learned during this project will be used to improve future survey processes. Once complete the new dataset will be combined with the existing one. An editing facility will be set-up providing heritage staff with the means to maintain and edit existing data. PositionIT Nov/Dec

5 Products Heritage resource reports An A4 size heritage report for each resource has been created. It includes information such as resource number; survey year; location (address); chronological age; grading; NHRA protection status; property number at time of survey; type; significance and description; and from one to three photographs of the resource (see Fig. 6). Base maps The obvious products are a set of base maps for resources and one for overlay zones. These include topological features and aerial image backdrops. Resources are labeled with unique resource numbers for referencing to heritage resource reports. For the written report, a map was produced indicating three identified regional landscape character zones (see Fig. 7). Published data Paper or digital copies of all base maps and individual heritage resource reports are freely available. Also available for heritage professionals are an area extract of a heritage resource and an overlay zone map together with the resource report. There is no cost attached to the acquisition of this data other than copy media. Hard-copies will be charged at the tariff described in the current council tariffs document. Staff will have access to a heritage resources map on their desktops via intranet. Access can be limited to certain staff if considered necessary. The map includes aerial photography for 1938, 2000, 2005 and Heritage attributes can be accessed via the info button. Ownership from financial data can be included if required. An option to click and access photographs will be added. An example of users would be the Building Control Department and Property Management Section. On submission of a building plan, heritage constraints on a site can quickly be ascertained and the client immediately informed. It also becomes apparent at the onset of the approval process that circulation for comments must include the heritage section. Once Drakenstein Municipality has the necessary fire-wall protection in place, it is envisaged that a product similar to that available to staff will be provided publically via internet. Analysis While having data in table or database format provides some opportunities for attribute analysis and summarising, adding a GIS component with its spatial component has greatly increased analysis capabilities. It is generally recognised in the heritage field that the older werfs are concentrated along rivers and valleys. Heritage professionals were excited to see this distribution pattern emerge as data was captured (see Fig. 8). Managing heritage National and provincial resources are managed at those respective government levels, while grade threes will be managed at local authority level. On submission of the list to Provincial Government, Drakenstein Municipality will request competency to manage grade 3 resources within its area of jurisdiction. Full competency will require the necessary staff, tools and processes, by-laws and regulations to be in place. By-laws will be written for the management of heritage overlay zones while resources will be managed using current by-laws. Heritage layers will be of great value during future studies such as re-vision of the Spatial Development Framework, Urban Edge, development trends, and development potential etc. It could also be used to the benefit of tourism for the area. Conclusion Although this project has taken a long time with the final stages still underway, it has been very rewarding to recognise how much value has been added to the dataset by adding a spatial element, and in seeing the benefits and possibilities for the preservation and management of our precious heritage resources. This project received the 2010 Excellence Award for Innovation as presented by Drakenstein Municipality. Contact Janine Penfold, Drakenstein Municipality, Tel , [email protected] 42 PositionIT Nov/Dec 2011