DIRECTORATE Spatial and Land Information Management: SERVICES

The Business Information directorate provides information services from the acquisition, analysis, storage and distribution, management and application of spatially-referenced data to the provision of information products. It embraces the traditional areas of surveying and mapping, such as geodesy, cadastral surveying, photogrammetry and hydrographic surveying, as well as the comparatively new fields of remote sensing and spatial information systems.

Below is a description of the services that DWAF Geomatics provides:

1. Hydrographic Surveys
2. Engineering and Topographic Surveys
3. Land Matters
4. Training
5. Remote Sensing
6. Geographical Information and Archiving

1. HYDROGRAPHIC SURVEYS – FIELD SURVEYS AND DATA PROCESSING

The results of hydrographic surveys are used to calculate the amount of sedimentation in a dam, to show where the sediment is collecting in the dam and to calculate a revised capacity table. This information is used by the Department of Water Affairs to manage available storage water, floods and planning for the future.

To determine sediment deposits a sophisticated, automated measuring and calculating method is used. The original dam basin is divided into a number of compartmentalised areas bounded by accurately measured cross-sections taken between permanent silt beacons. The positions of permanent silts beacons are determined beforehand. A capacity table of volume is then drawn up for each compartment. Areas and volumes of every compartment for each contour interval are determined.

To determine the volume of silt deposited, only the end areas (sections) of the compartments need to be resurveyed. This is done electronically. The boat is equipped with an echo sounder for measuring accurate depths. GPS is used to obtain accurate position data and this data is used for calculation purposes.

The Hydrographic Section consists of a field team fully equipped with a boat, echo sounder, GPS and survey instruments. All the data processing is done at Head Office.

2. ENGINEERING AND TOPOGRAPHIC SURVEYS

This comprises the following surveys.
· Dam Deflection surveys
· Control Surveys
· Topographic and Engineering Surveys
Dam Deflection Surveys

Dam Deflection Surveys entails the monitoring of large dams to determine the movement or displacement of the structures. Monitoring is done for the following reasons:

· Diagnostic – to provide scientific information to the Civil Engineering for design verification
· Research – to establish the long term behaviour of the dam
· Prediction – to monitor the safety of the structure.

The most accurate and modern electronic survey instruments and sophisticated software are used to determine co-ordinates and heights of stable reference pillars around the structure as well as monitoring points on, in and around the structure to 1 millimeter accuracy.

Control Surveys

Control Surveys entail the establishment of control beacons for larger water related projects which include control beacons for tunnels and dams. The control beacons serve as reference beacons for construction and are done to a very high standard of accuracy. A combination of GPS and terrestrial observations are employed in the process.

Topographic and Engineering Surveys

Topographic surveys provide plans for planning, design and as-built requirements. Plans are produced either by conventional ground survey methods or photo control points are fixed for photogrammetric processing. Engineering surveys are done for the design and construction of various water related infrastructure, which include dams, reservoirs, pipelines, pump stations, canals and access roads. Apart from conventional survey instruments, GPS using post processing techniques, as well as RTK (Real Time Kinematic), are used extensively in all these surveys.

3. LAND MATTERS

3.1 This section handles the:

(i) Expropriation of Land: Land Matters is responsible for the supply of correct expropriation data of Land needed by the Department for the building of dams, Canals etc.,
(ii) Alienation of Land:
- To enable the Department of Water Affairs to transfer land to other parastatal organisations like Water Boards, SAFCOL etc. This office supplies the correct data to sub- divide the relevant properties that are transferred.
- Servitudes are registered to locate the position of pipelines.
- Issues landed before the Land Claims court must be cleared by this division.
(iii) Forest Maps: Forestry Maps must be prepared and updated for all forest areas under control of the Department. New forest areas that were previously under control of the Former Independent States and the Homelands are being attended to. This work is done in conjunction with the Photogrammetry Division.

3.2 Topo-Cadastral Draughting services:

This division calculates Cadastral data and provides a CAD and draughting service within a survey environment.

Our main objective in this office is the accurate capture of spatial data.

Documentation of purchase areas and servitudes are our main task. This is done after beacons planning. The documentation consists of ground schedules, diagrams, locality plans and compilations where the affected area is highlighted. This section also does the Topo-Cadastral inset onto pipeline profiles. A strip of the necessary Topo-Cadastral information is plotted onto the pipeline profile plans – both longitudinal and cross sections. Data of the structures and the dimensions of longitudinal and cross sections are scribed onto a plan. Plans for proclamations are compiled for the Government Gazette of a proclaimed area. The plan shows all main rivers, towns, dams and roads.

3.3 The Cadastral section:

A project required the collecting of all concerned dam and servitude diagrams, compilations, general plans

3.4 LAND MANAGEMENT SUB-DIRECTORATE

Responsible for alienation of land and State resources by:

1. Identification of areas for alienation
2. Surveying of the areas for alienation
3. Providing documentation for registration of new rights
4. Warehousing and issue of information on land under DWAF custodianship
5. Identification of properties and ownership for departmental use

LAND INFORMATION

Waterworks Section handles:
- Identification, sourcing and capturing of cadastral data for dams and waterworks
- Preparation of cadastral plans and survey documents
- Design of servitude or purchase areas
- Preparation of documentation for expropriation (locally plans, plans, diagrams, property indexes, ground schedules), provision of certified copies of S.G. Diagrams
- Issue and control of Tenders for cadastral surveys
- Warehousing of information in a project context
- Provision of information on property rights on dams and waterworks
Forestry Section handles:
- Sourcing and capture of cadastral data for forests
- Determination and alienation of property rights for forests
- Issue and control of Tenders for cadastral surveys
- Production of cadastral plans and participating in preparation of GIS maps
- Warehousing of information in a project context
- Provision of information on property under forests rights
- LIS

4. TRAINING

The mission of the training section of Business Information is to provide practical interventions in the field of training and development of Technical surveyors in line with SAQA directives which contribute to improve in the delivery of survey services and skills development and mentoring in the workplace.

The priorities of the Training Section are:

· Practical Training of Technical Surveyors in conjunction with the Technicons.
· Practical Training of Technical Students in Survey i.e. Civil, Mechanical, Electrical etc.
· Training of Business Information and unattached students for Survey, GIS, Cartography and cadastral careers.
· Training of field Assistants.
· Training of Assistant Survey Technicians (Survey officers)
· Training of DWAF Personnel in Survey related aspects like GPS and GIS.

5. REMOTE SENSING

Technicians in this category are - independent of, in co-operation with or in support of engineers and professional personnel, concerned with the surveying as well as the gathering and processing of aerial, remotely sensed and terrestrial survey data and the interpretation thereof according to the discipline: Photogrammetry and Remote Sensing.
Stereoscopic observations and interpretation thereof are done by precision photogrammetric- instrument measurements utilising aerial and terrestrial photography. Accurate map production is done by means of CAD-assisted Wild A7, A8 stereoplotters, a Wild BC2- PC analytical stereoplotter, two VIRTUOZO digital photogrammetry systems and a Usmart Softcopy (digital photogrammetric) system. Microstation CAD is utilised to gather and process digital map data.
The maps produced are used in the planning and designing of new dams, canals and pipelines, rehabilitation of mine dumps and other water supply and sanitation projects as well as for the development of irrigation schemes and for the supply of bulk water to Industry.
Photogrammetry is also utilised to support GIS in gathering large scale accurate DTM’s of dam basins for catchment analysis purposes.
In addition to the standard black and white aerial photography used for most mapping projects, colour, false colour and colour infra-red photography can be supplied and utilised for mapping and interpretive purposes, e.g. water pollution control.
Information is also gathered using other remotely sensed data, namely satellite imagery. The data gathered in this manner is used primarily for the mapping and evaluation of water use and irrigation, done on a regional as opposed to local level. This is extremely useful for determining lawful water use, for abstraction control and for the monitoring of the licensing process.

6. GEOGRAPHICAL INFORMATION AND ARCHIVING

This sub-directorate manages digital spatial data, required for water resource management. 

Spatial data is captured in-house, by consultants or obtained from other sources. This includes vector as well as raster data, digital photography, digital orthophotos and imagery. All data sets held by the Department are documented on a Data Inventory that is published on the Web.

Geographic Information System (GIS) technology is used to process and/or quality assure data before it is incorporated in the departmental Corporate Spatial DataBase. The database is populated and maintained and GIS data is distributed on-line to head office users using SDE technology.

Cartographic Services are provided for users that require paper maps on an ad hoc basis or as published maps. 

The Resource and Information Centre, which comprises of a Map and Aerial Surveillance Library and a Map Shop, provide hardcopy printed maps, posters, pamphlets, aerial photographs and orthophotos to departmental users and the public.