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33
FOCUS
Irrigation
Special
The technique not only produced accurate results, but is also
cost-effective as it can be applied on both vegetated and non-
vegetated fields, requires no empirical data, makes use of freely
available imagery (SPOT-5 and 6); and has the potential to be fully
automated.
Quantification of salinity, sodicity and
waterlogging in South Africa
From previous studies it appears that severe waterlogging, salinity
and sodicity affects 8% to 18% of the area under regular irrigation in
South Africa (Backeberg
et al
., 1996). Ghassemi
et al
. (1995) stated
that a survey of five major irrigation schemes in South Africa indi-
cated that, on average, 28% of irrigated land shows signs of either
waterlogging or harmful high salt contents or both.
Salt-affected and waterlogged figures of 18% to 28% for South
Africa seem unrealistic if compared to the current study of 6,27%
(
Table 1
on page 30).
If the figure of 6,27% of areas affected is applied to the 1,5 million
hectares under irrigation in South Africa, the area that is
salt-affected and waterlogged on South African irriga-
tion schemes is 94 050 ha.
References
Backeberg, GR, Bembridge, TJ, Bennie, ATP, Groenwald, JA, Hammes, PS, Pullen,
RA and Thompson, H. 1996.
Policy proposal for irrigated agriculture in South Af-
rica
. WRC Report No. KV96/96, Water Research Commission: Pretoria.
Ghassemi, F, Jakeman, AJ and Nix, HA. 1995.
Salinisation of land and water re-
sources: Human causes, extent, management and case studies
. University of New
South Wales Press Ltd: Sydney.
Kanthaach, FE. 1909. Irrigation development in the Cape Colony: Past, present
and future. Proc.1st S. Afr. Irrig. Cong., 24 - 35. Cape Times Ltd: Cape Town.
Nell, JP, Van Niekerk, A, Mulller, SJ, Vermeulen, D, Pauw, T, Stephenson, G and
Kemp, J. 2015.
Methodology for monitoring waterlogging and salt accumulation on
selected irrigation schemes in South Africa
. Water research Commission Report:
TT 648/15, Pretoria.
Scotney, DM and Van der Merwe, AJ. 1991.
Irrigation: Long-term viability of
soil and water resources in South Africa
. Proceedings of the Southern African
Irrigation Symposium. 4 - 6 June 1991, Elangeni Hotel: Durban.
Salt-affected soils and waterlogging
Grain SA/Sasol photo competition
Produk-inligting
Jou eerste keuse
vir waterberging
N
oordwes Damme is bekend vir dienslewering, goeie
kwaliteit produkte en die grootste verskeidenheid
van waterbergingsmetodes in Suider-Afrika. Ons lewer
sinkdamme, sementdamvoerings, drinkwatertenks,
brandbestrydingstenks, graandamme en gronddamme met HDPE-
voering aan die landbou-, myn- en industriële sektore.
Die oprigting van damme en die installering van voerings word
regoor Suid-Afrika, asook in buurlande, gedoen met enige van ons
vyf professionele spanne.
Sinkdamme word plaaslik vervaardig van ZincAl-gegolfde plate,
wat die beste weerstand teen roes bied en word gepas met ‘n
850 gsm PVC-voering wat spesiaal vir damme geformuleer is.
Ons bied billike pryse, klop enige geskrewe kwotasie en gee
boonop ‘n tien jaar-waarborg. Selfdoen-damme is ook beskikbaar.
HDPE-voerings is beskikbaar in verskillende diktes na gelang
van jou behoeftes. Installasie word gedoen volgens SABS-
spesifikasies om te verseker dat jou gronddam nie lek nie en die
maksimum lewe gee.
Swaardiens epoksihars-bedekte tenks is ook beskikbaar vir die
berging van grootmaat water tot en met 15 miljoen liter.
JACO BARNARD,
Noordwes Damme