SOUTH AFRICA
Laser technology is automating
Africa’s future
Traditional city modelling practices are starting to give way to new
data-driven methods and practices, such as building information
modelling (BIM), used to drive down costs and reduce carbon
reductions in new urban developments, as well as ensuring future
needs are considered in the early planning stages.
Says regional general manager Matthew Bester from geospatial
technology supplier 3D Laser Mapping, “Successful BIM projects rely
on the application of three-dimensional data to accurately measure
the structural elements and infrastructure within an urban landscape,
including wastewater pipes. Remote sensing is one of the most
effective methods of gathering this data,” he says.
“Light detection and ranging (LiDAR) based mobile mapping
systems allow operators to collect vast amounts of information in the
same amount of time it takes to drive around the target area. These
measurements are taken by calculating how long it takes a laser
beam to be reflected back to the system. When integrated with a
localisation system (GNSS) that provides accurate global positioning
and an inertial measurement unit (IMU) that measures linear and
angular movement, these millions of measurements are combined to
create a three-dimensional ‘point cloud’ or visualisation of the area.”
Unlike sound and radio waves, light is incapable of passing
through solid matter. LiDAR is, therefore, unable to detect
underground elements such as sewer pipes; yet, when combined with
ground penetrating radar, this technology can map an entire city’s
infrastructure precisely and replicate all these elements in three
dimensions, all to an accuracy of under 1cm.
Bester adds, “A scan provides details of a road’s surface,
including markings, defects and manholes, as well as a detailed
reconstruction of surrounding features such as built structures,
power lines, and even trees and vegetation — all common sights in an
urban environment.”
Once a scan has been completed, specialist software such as
Terrasolid is used to process the data. This turns the millions of
collected ‘points’, or returns, into a meaningful geospatial model
where features can be enhanced and extracted depending on the
results required. “City planners, civil engineers, and construction
teams can then use this vital intelligence to plan future works, with
more knowledge about the current environment than photos alone
would be able to provide. In a wastewater context, this means being
able to identify the existence of existing pipework accurately, as well
as plan routes and connections for new developments or upgrades to
current pipelines,” he says.
Mass urbanisation also alters the natural water cycle in emerging
suburbs, since once undeveloped areas are now covered with
buildings and roads. New planning practices need to be put in place
to mitigate the effects of decreased levels of evapotranspiration and
increased runoff volumes and rates. Typically, geospatial impact
assessments of potential hydrologic effects are based on traditional
land management principles that do not adequately address the
needs in an urban setting. Datasets collected using such systems can
be used to create high-resolution surface terrain models of urban
areas. These can then assist with the creation of hydrologic models
that tackle sanitation issues, as well as consider environmental
considerations such as flooding and urban agriculture.
The uniquely detailed nature of LiDAR data means that it offers
great potential for extracting surface information fit for many
different applications. The benefit of being able to scan large areas
quickly, including densely populated cities and towns, means that
the technology is seeing use that is more widespread in urban
planning applications, which, in turn, will lead to a future that is more
sustainable and planned for all. u
6
Water Sewage & Effluent May/June 2017
Mandela Bay to get
mega desalination plant
A desalination plant, although expensive to
operate owing to high energy requirements,
would play a key role in preparing sea water for
human consumption through desalination, along
with removing other minerals in the process.
In the Nelson Mandela Bay region, where
water stocks are presently at dire levels, this
would provide a new source of potable water.
The prospect of establishing the desalination
plant in drought-stricken Port Elizabeth has come
about through the national government’s Adopt-
a-Municipality programme. This involves three
major stakeholders in the Bay region — the local
authority, beer producer SABMiller, and Marina
Sea Salt, whose products are derived from
desalinated seawater.
According to Annette Lovemore, Nelson
Mandela Bay Municipality mayoral committee
member for infrastructure and engineering, a
meeting with the three role players has already
taken place. In support of the venture, she
commented that it is a win-win outcome for all
stakeholders.
The Adopt-a-Municipality programme is
driven by the national Department of Cooperative
Governance and SABMiller’s agreement, through
which the company is about to be renewed.
The desalination concept forms part of the new
agreement.
Lovemore said SABMiller used large
quantities of high-quality water to produce its
product, and that it was looking for cleaner
sources of water, while Marina Sea Salt produced
partially desalinated water as a by-product of its
salt production.
The Nooitgedacht water scheme, still to come
online, will give the metro about 50 megalitres of
water a day. Since the salt production operation
produces about 30 megalitres of water a day, the
idea would be to put more water through the salt
operations.
Lovemore explained that this water, which has
already been partially purified, would be further
filtered through a desalination plant, in an aim to
make it fit for human consumption.
Stressing that the project was still at
preliminary discussion stage, Lovemore said
the Coega Development Corporation (CDC) was
also investigating desalination, as it was a water
requirement for gas-related initiatives within the
Coega Industrial Development Zone. The entire
project, inclusive of harvesting desalinated water,
is projected to cost USD109.5-million. u
The Nooitgedacht water scheme,
still to come online, will give the
metro about 50 megalitres of water
a day.