Water Quality
The low flow rates in drip emit-
ters are conducive to clogging
problems. While it is relatively
easy to spot blocked openings, it
is very difficult to identify openings
that are partially blocked. Both
alter the hydraulics of the entire
system, result in a decrease in
the uniformity of application and
give rise to reduced yields. The
DSS use criteria gleaned from
literature, to assess the potential
of several water constituents to
cause clogging problems in drip
irrigation systems.
Conclusions
This paper described the suit-
ability indicators that are used in
the newly developed electronic
Decision Support System (DSS)
that assists users to assess the
fitness for use of irrigation water.
The identified suitability indica-
tors provide the means whereby
those sub-components of soil
quality, crop yield and quality,
References
and irrigation equipment that
are likely to be affected under
irrigation with a specific water,
can be identified and the signifi-
cance of the effect quantified. A
more in-depth account of suit-
ability indicators and criteria
used, have been described by du
Plessis et. al., 2017.
Electronic copies of the DSS can be downloaded from:
https://www.nbsystems.co.za/downloads.html
Please send comments and feedback to [email protected]
DU PLESSIS M, ANNANDALE
J, BENADE N 2019
Help to assess the fitness for use
of irrigation water at a specific
site using a risk based approach.
SABI Journal 7: 20 - 25.
DU PLESSIS M, ANNANDALE
J, BENADE N, VAN DER LAAN
M, JOOSTE S, DUPREEZ
C, BARNARD J, RODDA N,
DABROWSKI J, GENTHE B
and NEL P 2017
Risk-based, site-specific, irriga-
tion water quality guidelines:
Volume 1 Description of Decision
Support System. WRC Report
No.TT 728/17 Water Research
Commission, Pretoria
Climate Action Summit
Great Green Wall for Cities
T
he UN Food and Agriculture Organization’s Director-
General Qu Dongyu recently announced the Great
Green Wall for Cities initiative that aims to support
nature-based solutions to climate change.
The
Director-General
made
the announcement on the eve
of this week’s Climate Action
Summit in New York.
“The rapid expansion of cities
takes place without land use
design and the resulting human
pressure causes highly damaging
environmental effects through
clearing or degradation of forests
and other green spaces in and
around urban areas,” Qu said.
“The problem is particularly severe
in drylands, where the effects of
climate change are expected to
increase the exposure of cities
and surrounding areas to severe
droughts, sand and dust storms,
heatwaves,
extreme
winds,
floods and landslides.” This he
added, has detrimental effects on
millions of people.
FAO, together with partners,
is aiming to support at least
Urban Forests ture will reduce the costs of
preventing and addressing the
impacts of climate change and
improve the well-being of citizens,
the Director-General said.
By 2030, the bold action will have
helped cities create up to 500,000
hectares of new urban forests and
restore or maintain up to 300,000
hectares of existing natural forests
in and around cities in the Sahel
and Central Asia. If well managed, urban forests and
trees can reduce air temperature
by up to 8 degrees Celsius, reduce
the costs of air conditioning by up
to 40 percent, reduce stormwater
flows and improve air quality by
filtering dust and pollutants.
Once completed, the Wall would
capture 0.5-5 Gigatonnes of
carbon dioxide (CO2) per year.
The enhanced green infrastruc- By 2050, the proportion of
people living in cities will be
almost 70 percent.
three cities’ green walls in each
of 30 countries in Africa and
Asia, Dr Qu said.
SABI | OCTOBER/NOVEMBER 2019
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