Deep, Coarse-Grained Alluvium: Worthier than Oil

Deep, Coarse-Grained Alluvium: Worthier than Oil
Sayyed Ahang Kowsar
Fars Research Center for Agriculture and Natural Resources
Shiraz, I.R. Iran (a partner of SUMAMAD and GWAHS)
UN-Water Regional Expert Consultation on Water
Security in Asia-Pacific
9-10 November 2015, Bangkok, Thailand
• The volume of water consumed for food and feed grains
production in the I.R. Iran during 1995 was 26.5 km3, of which
8.27 km3 was provided through the artificial reservoirs, while
only 10. 64 km3 would have been consumed in the grainexporting countries for the same amount of grains delivered to
the I. R. Iran.
• Iran imported 15.93 million tons of agricultural commodities at
the cost of $ 9,296.9 million (19% the monetary value of the
imports) in the Iranian calendar year 1392 (2012-2013).
• Iran imported 37 km3 of virtual water per year during the 19972001 period. The estimated grain imports to the I.R. Iran for 2025
is 11.36 million tons equivalent of 47.27 km3 of water; 12.71 km3
of water from the artificial reservoir have to be delivered to the
farm fields to produce this much grains.
• Iran has used 85% of its fresh groundwater resources, mostly
since 1985.
• Only 119 km3 of the long time average of 415 km3 of mean
annual precipitation is readily available in the I.R. Iran.
• Some 62 km3 of the annual runoff in the I.R. Iran end up in
playas, salt lakes or seas.
• The Land of Iran is endowed with 420,000 km2 of deep, coarse
grained alluvium with a capacity of > 5,000 km3 of water, 12
times its mean annual precipitation.
• Moreover, that country is endowed with 60,000 km2 of Brown
Soils underlain with coarse grained calcareous alluvium. They
form most of rain fed farms that produce small grains and
fodder.
• 149,000 km3 of these 480,000 km2 have an excellent potential
for the artificial recharge of groundwater (ARG).
• Iran has built > 550 operational large dams in the past 60 years,
and has 144 under construction and 500 under study. The total
capacity of the reservoirs of these dams is < 100 times that of
our potential alluvial aquifers.
• The average cost of providing 1 m3 of empty space behind large
dams at the November 2014 current currency rate in Iran was
$2.50; therefore, 5×103km3×109m3 km-3×$2.50 m-3=$12.5×1012
is the theoretical value of the empty space in the country's
alluvium.
• As hand digging a new qanat shaft and gallery at the November
2014 currency rate conservatively costs $80 and $150 per meter,
respectively, and taking the length of shafts and galleries equal
(1,000 m km-1 each), Iran has 50.094×109 dollars theoreticaly
buried in the alluvium.
• Iran was the land of droughts, floods and qanats before the
1950s. Of > 50,000 qanats, 33,000 are desiccated.
• Artificial recharge of groundwater activities on the recharge area
of these qanats may eventually rejuvenate them.
Longitudinal section of a qanat showing the different component parts.
An aerial view of 5 strings of qanat in central Iran. The "mole
holes" are the openings of the shafts used for extraction of the
burrowed materials and ventilation of the galleries.
Example for a loam pit on former irrigated farmland (depth about
10 m). Due to desiccation of their qanats as a result of illegal overpumping, the owners had no choice but to sell their land to brick
manufacturers after millennia of irrigated farming.
• The world is losing some 20 million ha of arable land per year.
If this horrible trend continues unchanged, Thomas Robert
Malthus shall be exonerated at the end of 21st century.
• Iran has one of the highest rates of soil erosion in the world:
16 tons per hectare per year.
• Soil building is an integral part of spate irrigation. The world
will be without most of its arable land by the end of 21st
century if the current rate of land degradation continued
unchanged. Floodwater harvesting on low sloping degraded
farm fields restores their productivity.
• Our 34 years of experience in the Gareh Bygone Plain indicates
that floodwater spreading for spate irrigation and ARG –AQUIFER
MANAGEMENT- may be the most appropriate method for
sustainable management of marginal dry lands (SUMAMAD).
• Spate irrigation of the farm fields on Brown Soils not only
at least doubles their yield, but also recharges the underlying
aquifers, while improving the water holding capacity and
enhancing their nutritional status while mitigating the
flooding hazards.
Interpolated map
of the
accumulated
sediment depth
(cm) of the
Bisheh Zard1
ARG system
after 22 years of
operation;
coordinates of X
and Y are based
on UTM zone 39
(based on
Esmaeili
Vardanjani et al.
2013).
Sowbug (Hemilepistus shirazi
Schuttz) is my best friend!
A cast of the sowbug’s
nest; a green way to
increase infilterability!
• The project has diverted some 197 m3 of floodwater to 2034 ha
of afforested area and rangeland of which 76% has recharged the
groundwater.
• The cultivated area during the 2010-2011 growth season was
1234 ha, 13.2 fold when compared to the pre-FWS period.
• Mean forage production of the spate-irrigated rangeland from
1992 to 2014 was 387.1 kg ha-1year; it was 140.9 kg ha-1year for
the control; the difference is adequate nutritious forage for about
700 sheep per year, which has been provided since 1991.
• Ground cover for the spate-irrigated rangeland was 31.91%; it
was 19.8% for the control.
Spate irrigation has greatly increased the yield of indigenous
range plants growing in a sandy soil.
• Organic honey production in 2005 was 35 tons; however the
potential is 50 tons per year.
• The carbon sequestration potential of 80 ha of eucalypt and
acacia shelterbelts, 31 km of windbreaks consisting of
eucalypts and acacias, and 1934 ha of improved rangeland, is
400 tons per year.
• Salinity reduction was quite significant during the 1983-1993
period. That of Rahim Abad decreased from 4.9 mS cm-1 in
1989 to 1.5 mS cm-1 in 1993; however, over pumping has
raised it again but not to the previous level.
• The floodwater emanating from the Agha Jari Formation
contains 60.3 ± 21.6 mg L-1 geologic NO3ˉ on average; this is
reduced to 7.1±3.9 mg L-1 NO3ˉ after passing though the
Eucalyptus camaldulensis Dehnh. plantations.
Thank you for your
attention!