Beyond the Plan: Tapping the Potential of Drones (UAVs) for Urban Development Control.
Updated: Apr 19, 2020
As cities or urban areas continue to expand in size, density and area extent due to urbanization ( increase in population with attendant increase in demand for land for various uses), there is the need for city authorities or urban land use planners to ensure effective development control. Development control simply refers to the process of managing the physical environment: protecting residential areas from unwanted intrusions, preserving green belts or nature reserves, retaining healthy buildings and trees, avoiding ugly environmental signs or buildings etc by using land use plans (master plans, zoning plans, development plans), building codes etc.
In Ghana, land use plans are one of the ways the Physical Planning Department ensures that activities on land do not counteract good practices in terms of aesthetics, convenience, economy, harmony, health and safety. They are essentially zoning plans which outline the future location and type (residential, office, retail, industry) of development activity that is to be permitted and not permitted (i.e. green space, parks, etc.) within urban and regional areas over a period of time. When successively followed, land use plans can help create workable and conducive towns or settlements. Therefore, effective and efficient development control is required to tackle or address environmental problems that are mostly associated with urban growth such as slum formation, incompatible uses, congestion , poor accessibility and flooding among others.
Land use plans of parts of Kumasi Metropolitan Area (KMA) in Ghana
The challenge of Development Control in most MMDAs
A key component of development control is land use monitoring. Land use monitoring is basically the process of continually observing and checking the progress or quality of development in a particular jurisdiction over a period of time. It has been noted that weak monitoring is one of the reasons for poor development control situation in most MMDAs.
Currently, most Physical Planning and Works Department in Ghana rely on traditional method involving only field inspection and manual measurement taking for monitoring. However, this approach is expensive and time consuming and as result does not guarantee efficient monitoring exercise. In many cases, field officers or building inspectors involved in monitoring exercise are deterred just by the difficulty of this approach. As a result, encroachment on public rights of way and open spaces, disregard for building setbacks, unauthorized conversion and unauthorized development go unnoticed.
Building in flash flood zones as a result of weak monitoring ( development control) in Abuakwa , Kumasi - Ghana
A Novel Approach
Now-a-days, collecting exhaustive, accurate and meaningful spatial information about any given phenomenon with emphasis on maximum efficiency in terms of cost and time is a requirement in most discipline. Development control monitoring exercise can be made effective and less cumbersome by incorporating digital technologies such as Unmanned Aerial Vehicles ( UAV) or Drone etc. Drones offer unlimited capabilities and range of benefits in several fields. In terms of development control, drones can be used together with other Geographic Information System applications such as Arcmap and QGIS to map and analyze large areas within the shortest possible time. With this approach, time and cost for regulating development in a particular jurisdiction can be minimized and accurate result obtained.
To demonstrate this, Ziongate Geospatial & Research Services Ltd collaborated with the Physical Planning Department (PPD) and Works Department (WD) of Oforikrom Municipal Assembly and the Traditional Council of Kodiekrom to present a technical procedure for monitoring development in Kodiekrom ( a suburb in Ashanti region of Ghana) based on UAV technology. The main focus of this project was to leverage UAV technology with GIS based decision support applications to identify unauthorized developments ( typically parcels within unapproved zones and parcels with unapproved conversion) such as parcels found within nature reserves and parcels with uses other than uses specified in land use plans
Stakeholder Consultation and Engagement
The Physical Planning Department and the traditional council of Kodiekrom were engaged to discuss on relevant issues before commencement of work. The stakeholder consultation and engagement was very useful in the sense that it served as the basis for obtaining useful information on the operation of PPD and WD with regards to development control in the area. Also, through this meeting baseline data such as the land use scheme of Kodiekrom was made available. The traditional council also provided relevant data that was helpful in determining the boundary of their land.
Approved land use plan showing the legal boundary of Kodiekrom
The next line of action after engaging relevant stakeholders in a meeting was to acquire relevant dataset for this project. Here, we begun with determining the boundary of Kodiekrom township. Boundary dispute is a very common issue in Ashanti region. Therefore, we paid critical attention to carrying out the mapping within the exact legal boundary of Kodiekrom. Based on relevant information provided by the traditional council of Kodiekrom, the boundary outlined in the approved land use plan above was no longer in operation since certain portion of land has been offered to other stool land ( Deduako stool land). Hence, a new boundary was delineated. In delineating the new boundary, Physical Planning Department, Works Department and the Traditional Council were involved in a field survey where ZGRS surveyors picked ground coordinates of the new boundary using trimble real time Kinametic GPS machine.
Setting base station for boundary survey
New boundary of Kodiekrom
Aerial mapping with UAV ( drone)
The next line of action was flight planning based on the new boundary. This was done using the Pix4D drone flight application. Mapping large areas has never been easy using conventional surveying method. Therefore, Matric 210 real time kinematic (RTK) drone was deployed to map the entire Kodiekrom township at an elevation of 200 meters and at a resolution of 5.45 cm/pixel. In order to further improve accuracy of the mapping, ground control points (GCPs) were collected for Geo-referencing and check points processing
Flight planning with Pix4D application
Data Processing and Spatial Analysis
Firstly, Agisoft Metashape: a stand-alone software product that performs photogrammetric processing of digital images and generates spatial data such as orthophoto, digital terrain and was used in processing the drone images.
Performing aerial triangulation and orientation within Agisoft software environment
Secondly overlay analysis: a Geographic Information System ( GIS) operation that superimposes multiple data sets (representing different themes) together for the purpose of identifying relationships between them was done using the the Arcmap application. This was achieved by first geo-refereincing the planning scheme and the orthophoto within the same coordinated space. Unauthorized buildings or parcels were then identified using selection by location approach. This was complemented by field inspection to verified whether the proposed uses in the land use scheme were respected.
Orthophoto and land use scheme overlay in Arcmap
Results and Findings
Mapping large areas has been made easier in modern times. With the introduction of drone technology it is now possible to map large areas and access inaccessible areas. Flight was successfully launched. In less than an hour, a team of two ( 2) consisting of a pilot and a field observer mapped a total area of 770 acres
ZGRS drone in autonomous mission based on the flight plan to map the entire Kodiekrom township
ZGRS drone landing after completing autonomous mission
Image processing was done using the Agisoft photogrammetric software. After processing the images, orthophoto, digital terrain and surface models were produced. The orthophoto was cloud free and had a resolution of 5.45 cm / pixel. At this resolution it was possible to identify buildings at foundation level and fences.
High resolutions ( 5.45 cm/ pix ) aerial imagery of Kodiekrom
In order to identify cases of encroachment and building in unauthorized locations, both the land use plan and the orthophoto was geo-referenced to a common coordinate system ( Accra Ghana Grid ) so that they can both be referenced in the same location. The image below shows the result of the overlay method after projecting the land use scheme and the orthophoto to the same coordinate system.
Overlay analysis in Arcmap Environment
Identification of unauthorized parcels ( Building)
Encroachment on Nature Reserves ( Open Spaces)
It was identified form the spatial analysis that most developers, especially residential developers have encroached on almost all open spaces or nature reserves in the area by not adhering to the approved layout in Kodiekrom. This is a burgeoning problem across most urban areas in Ghana. Statistics from researches that have been conducted on urban green spaces have shown that urban green spaces are depleting at an alarming rate with green spaces now occupying small fraction of the landmass of several urban areas.Hence, nature reserves or green spaces proposed in land use plans need to be protected since this can directly or indirectly affect local and regional air quality. All structures found within this zone were noted and pending decision for demolishing or payment of penalty.
Encroachment on nature reserves and open spaces.
Encroachment on Major and Minor Streets.
Physical accessibility is one of the key elements of land use planning. Hence, land use plans often propose streets and lanes to direct flow in and out of a particular jurisdiction. Unfortunately, in many urban areas where there is a high demand for land or space, accessibility is highly compromise. Developers often disregard street and lanes during construction. This situation often leads to congestion or inaccessibility. In times of emergency such as fire outbreaks, it is difficult to navigate through areas with poor accessibility. From the spatial analysis conducted, such issues were easily identified. Superimposing the approved land use plan on the UAV orthophoto made it easier to identify cases of encroachment on road or street corridors..
Land use plans are mostly prepared based on the result of the needs assessment carried out in a particular locality. Depending on the result from needs assessment by the Physical Planning Departments, clinics, libraries, hospitals, schools, and markets are some of the uses that are proposed. Most often than not, these uses are not adhered to. Developers often do not inquire and do not care about the type of use zone their unit of land fall within. As a result, land for clinics, market and other uses apart from residential are often converted to residential uses because of the high prices associated with residential land in most urban areas. From the spatial analysis undertaking, it was possible to identify such cases.
Unauthorized conversion of light industrial land to residential land
Unauthorized conversion of land allocated for market or commercial use to residential use.
Impact of our UAV approach for development control
Quick: The first key metric to understand the impact of our approach is that it is quick and efficient compared to traditional or conventional method of monitoring development in a particular jurisdiction. A total duration of 2 days was spent to produce all the deliverable with high accuracy. It takes several months using traditional approach.
Digitalized data: Additionally, digitalizing data is also synonymous to preserving it for future scope and opening up new frontiers of application. The data resulting from this project are all in digital format and can be used in other areas of application.
Accurate and Exhaustive data: Traditional approach to development control monitoring produces limited data for analysis. A single flight using a drone, one can obtain orthophoto, digital terrain model, digital surface and point clouds. These data become useful in other areas of application.
Map otherwise inaccessible areas: An aerial mapping drone can take off and fly almost anywhere. You are no longer limited by unreachable areas, unsafe steep slopes or harsh terrain unsuitable for traditional measuring tools. You do not need to close down highways or train tracks. In fact, you can capture data during operation without an organizational overhead.
We acknowledge the Physical Planning Departments of Oforikrom Municipal Assembly headed by Mr. Kweku Adjei Asante and the Kodiekrom Traditional Council for their support