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Farmers response to water scarcity and
salinity in a marginal area of Northern Syria
Schweers, W., Bruggemann, A.,
Rieser, A. and T. Oweis
2004
First published in:
Journal of Applied Irrigation Science, Vol. 39. No 2/2004, pp. 241-252
ISSN 0049-8602
This electronic version of the publication has been supplied for personal use only.
Farmers response to water scarcity and salinity in a
marginal area of Northern Syria
Wassernutzung durch Landwirte in Abhängigkeit von
Wassermangel und Salzgehalt des Grundwassers an
einem marginalen Standort Nordwest-Syriens
Stichworte
Grundwasser, Zusatzbewässerung, Wassernutzeffizienz, Salzgehalt,
Trockengebiete, Syrien
Keywords
Groundwater, supplemental irrigation, water-use efficiency, salinity, dry areas,
Syria
Zusammenfassung
Grundwasser ist eine wichtige Resource in Trockengebieten, wird aber oft nicht nachhaltig genutzt. Das Ziel
dieser Untersuchung bestand darin, den Wasserverbrauch für die Bewässerung von Winterkulturen im
Khanassertal, Nordwest-Syrien zu ermitteln. Das Untersuchungsgebiet, am Rand der syrischen Steppe
gelegen, ist mit 209 mm Jahresniederschlag marginal für den Trockenfeldbau. Die Bewässerungsfläche mit
Anbau von Gerste (Hordeum vulgare L.), Kreuzkümmel (Cuminum cyminum L.) oder Weizen (Triticum
aestivum L. und Triticum turgidum L.) wurde mit GPS vermessen. Zwanzig Prozent wurden im Hinblick auf
Wasserverbrauch und Produktivität untersucht. Oberflächenbewässerung (OB) und Beregnung (BR) wurden
verglichen. Der durchschnittliche Wasserverbrauch (m³/ha) unterschiedlicher Kombinationen von
Bewässerungsmethoden und Kulturarten war: BR-Gerste (949), OB-Gerste (1447), BR-Kreuzkümmel (273),
BR-Weizen (1053) und OB-Weizen (3270).
Abstract
Groundwater is an important resource in the dry areas, but often used unsustainably. The objective
of this study was to monitor groundwater use for the irrigation of winter crops in Khanasser
Valley, northwest Syria. The study area lies at the border of the steppe and is marginal for rainfed
agriculture with 209 mm mean annual rainfall. The irrigated area sown to barley (Hordeum
vulgare L.), cumin (Cuminum cyminum L.) or wheat (Triticum aestivum L. and Triticum turgidum
L.) was surveyed by GPS. Twenty percent of it was monitored for water-use and productivity. The
average water-use (m³/ha) for different combinations of crops and irrigation methods was: sprinkler-
barley (949), surface-barley (1447), sprinkler-cumin (273), sprinkler-wheat (1053), and surface-
wheat (3270).
Zeitschrift für Bewässerungswirtschaft, 39. Jahrg., Heft 2 /2004, ISSN 0049-8602 Seiten 241 - 252
W. Schweers, A. Brug-
gemann, A. Rieser
and T. Oweis
1. Introduction
Water resources are under threat in many dry areas of the world with serious problems
in developing countries having high population growth rates. In Western Asia, Syria
is still relatively gifted with water, since about 15% of the country is part of the Fertile
Crescent with good rainfall (more than 350 mm/yr), productive aquifers and the
Euphrates River. Irrigation from wells accounts for 60% of the total irrigated area of
about one million ha (MAAR, 2001). In some areas, the water table has fallen
substantially due to overpumping. For example, 25 km south of Aleppo, an average
annual drop of 1.75 m has been observed for the past 20 years (DIEKMANN, 2003).
The Khanasser Valley (Fig.1) is located approximately 80 km southeast of Aleppo.
It stretches 20 km between the Jabboul salt lake in the north and the border of the
Syrian steppe near Adami village in the south. Basalt plateaus of the Tertiary age
border the valley in the east and west. The annual average long-term rainfall in
Khanasser Valley is 209 mm with about 53 % probability (BRUGGEMAN, 2004). The
deep soils in the central valley have a silt loam to clay loam texture. They are prone
to capping and hardening when dry, but when moist and tilled, have a high infiltration
rate of more than 30 mm/hr as measured by KASMO (1997) and WILDE (1998).
According to the FAO classification system (DECKERS et al., 1998), the dominant
soil classes are Luvic Calcisol and Calcic Gypsisol (LOUIS BERGER
INTERNATIONAL, 1982).
The similarity index for climate and land use/land cover is high for a large part of
the agriculturally used winter rainfall areas in Western Asia and Northern Africa (DE
PAUW, 2003). Solutions for improved land and water management developed in the
Khanasser valley could thus potentially have a larger impact. The most common
production system is barley-livestock. Barley provides the main feed source for
small ruminants, mainly sheep, and the most reliable yield under rainfed conditions.
In low rainfall years, farmers do not harvest the grain, but let their sheep graze the
entire crop. Farmers take the risk to grow some rainfed wheat, which they need for
making bread, their staple food. In the last three years, production of cumin has
expanded rapidly. About 4 % of the cultivated area in the Khanasser Valley is under
irrigation. Surface irrigation is done mostly in the form of basin irrigation. Sprinkler
irrigation has become widespread since 3 – 4 years.
Well yields from the marley limestone aquifer are too low for continuous pumping.
Wells in the more productive alluvial aquifer are usually quite saline, with electrical
conductivities (EC) ranging between 2.5 to 26 dS/m (SCHWEERS et al., 2003). A
comparison with five wells observed in the 1960s (MIKHAILOV et al., 1966) indicated
that the water table decreased during the main well construction period from 1988 to
1997 (SCHWEERS et al., 2003). In a period of average rainfall from 1999 to 2002, there
was no significant change in water levels.
242 Journal of Applied Irrigation Science, Vol. 39, No. 2 /2004
The objectives of this study were to identify the potential for saving groundwater
resources and to quantify the limits of sustainable water use for agricultural
production on a watershed level. Since the water levels had remained stable during
a period of average rainfall, groundwater recharge appeared to be in balance with
groundwater abstractions. It was assumed that, if groundwater abstractions could
be determined with sufficient accuracy, the recharge rate and thus the volume of
water available for sustainable use could be computed. This would provide the basis
for planning a more economical allocation of groundwater resources under conditions
of scarcity. In this article, “water-use” is defined as the amount of water abstracted
from the aquifer, not the amount actually consumed by crops.
Figure 1:
Overview of Northwest Syria
Zeitschrift für Bewässerungswirtschaft, 39. Jahrg., Heft 2 /2004 243
2. Materials and methods
The farmers who cooperated in the resource study were given forms to register the
date, the crop, the irrigation method, pump operation hours and, if available, meter
readings before and after operating the pump. No incentives were used to convince
the farmers to cooperate. Twenty-two out of 156 operative irrigation wells were
monitored. These were chosen to represent water-use throughout the valley. Wells
and fields were recorded by GPS. During the survey, crops, irrigation methods and
other parameters were registered. Arc View® GIS was used to draw maps and compute
the areas of the field units.
Records of agronomic variables, such as variety, planting date, seed rate,
fertilization, harvesting date, irrigated yield of mapped parcels and rainfed yield of
neighbouring parcels complemented the information on water-use. Farmers were
visited approximately every two weeks and their observations on irrigation and
agronomic practices were recorded. During the interviews, water-use was documented.
Date and duration of irrigations were checked and revised together with the farmers
if there was a gap in the records. The discharge of wells without water meter was
measured by barrel or by installing hosepipes on sprinkler nozzles to collect the
water. The electrical conductivity of the irrigation water was measured with a WTW®
conductivity meter. The data were registered and processed in a relational database.
Total agricultural water-use for the 2002/03-winter season was determined as
follows: Fields were categorized according to the crop and the irrigation method,
considered important determinants with respect to water use. There were five possible
combinations: Barley-sprinkler irrigation, barley-surface irrigation, cumin-sprinkler
irrigation, wheat-sprinkler irrigation and wheat-surface irrigation. The average water-
use of the “crop-irrigation method combinations” derived from the monitored fields
was extrapolated to the respective share of all mapped fields. The total agricultural
water-use was computed by adding up these volumes:
∑×=
ii
iAWUTWU (Formula 1)
where:
TWU = Total water-use (m³)
i
WU = Average water-use of crop-irrigation method combination i (m³/ha)
i
A= Total irrigated area of crop-irrigation method combination i (ha)
i= Index for crop-irrigation method (e.g. barley-sprinkler)
244 Journal of Applied Irrigation Science, Vol. 39, No. 2 /2004
Reference Evapotranspiration (ET0) was computed using the FAO Penman-Monteith
equation from climatic data of an automatic weather station located in the middle of
the valley and crop evapotranspiration (ETcrop) was determined by defining growth
stages and crop factors (ALLEN et al., 1998). According to DASTANE (1978),
ineffective rainfall is that portion of rainfall which is lost by surface run-off,
unnecessary deep percolation losses and the moisture remaining in the soil after the
harvest of the crop, which is not useful for next season’s crop. Owing to deep
homogeneous soils, high infiltration rates, flat topography in the irrigation area and
dry soil conditions at harvest, all rainfall was assumed effective. The net irrigation
requirement was defined as the difference between the crop water requirements and
effective rainfall. Water-use efficiencies (OWEIS and ZHANG, 1998) for rainfall, total
water, and irrigation water were determined as follows:
R
Y
WUE rf
rf =(Formula 2)
RWU
Y
WUE ir
tot +
= (Formula 3)
(Formula 4)
where:
R= rainfall during crop growing period (m³/ha)
Y= yield (kg/ha)
WU = water-use (m³/ha)
WUE = water-use efficiency (kg/m³)
ir = irrigated
rf = rainfed
3. Results
The 2002/03 rainfall was above average: 298 mm. The first rain occurred in October
2002 and the last major rainfall event in March 2003. After that, only small occasional
events were recorded until May. Average planting dates for irrigated crops were
October 29 (barley), November 26 (wheat), and December 31 (cumin). The average
harvesting dates were May 15 (barley and cumin), and May 26 (wheat). Crop water
WU
YY
WUE rfir
ir
−
=
Zeitschrift für Bewässerungswirtschaft, 39. Jahrg., Heft 2 /2004 245
requirements during the growing season were determined as 372 mm for barley, 259
mm for cumin and 390 mm for wheat. The EC of the groundwater was generally high,
ranging from 2.3 to 16.8 dS/m. The highest groundwater EC used for sprinkler-irrigated
crops was 14.2 dS/m (barley), 7.9 dS/m (cumin) and 11.4 dS/m (wheat). On average,
the EC of groundwater used for sprinkler irrigation was 38.5% lower (barley) and 42%
lower (wheat) compared to surface irrigation (Fig. 2).
Figure 2:
Water-use, yield and electrical conductivity for combinations of crops and irrigation
methods
Sprinkler-irrigated barley yields were 21% lower than surface-irrigated yields, whereas
sprinkler-irrigated wheat yields were only 8% lower than surface-irrigated yields. In
contrast to barley, which received 100% more nitrogen on surface-irrigated fields,
nitrogen applications to wheat were equally high for sprinker irrigation and surface
irrigation (Table 1). Wheat had the largest net irrigation requirement (122 mm), followed
by barley (88 mm) and cumin (31 mm). Compared to net irrigation requirements, the
monitored farmers applied on average 1.1 times the amount of water (949 m³/ha) to
sprinkler-irrigated barley, 1.6 times (1447 m³/ha) to surface-irrigated barley, 0.9 times
(273 m³/ha) to cumin, 0.9 times (1053 m³/ha) to sprinkler-irrigated wheat, and 2.7 times
(3270 m³/ha) to surface-irrigated wheat (Table 2).
The monitored area accounted for 20.5% of the total irrigated area (Fig. 3) of
which 73% was irrigated by sprinkler irrigation and 27% by surface irrigation (Table
3). Total ground water abstractions for winter crops in the valley were found to be
about 636,000 m³, equal to 2.6 mm over the area of the two watersheds or 1.25% of the
0
500
1000
1500
2000
2500
3000
3500
4000
4500
barley-sprinkler barley-surface cumin-sprinkler wheat-sprinkler wheat-surface
Water Use and Yield
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
Elec trical c onductivit
y
WU (m³/ha) Yield (kg/ha) EC (dS/m)
246 Journal of Applied Irrigation Science, Vol. 39, No. 2 /2004
annual average rainfall. This volume was applied to surface irrigated wheat (48.4%),
sprinkler-irrigated wheat (29.5%), sprinkler-irrigated barley (12.7%), surface-irrigated
barley (6.4%), and sprinkler-irrigated cumin (3.0%).
Table 1:
Sample size and average agronomic parameters
barley-
sprinkler barley-
surface barley-
rainfed cumin-
sprinkler cumin-
rainfed wheat-
sprinkler wheat-
surface wheat-
rainfed
No. of monitored fields 9 5 12 5 4 12 7 11
Monitored area 26.8 6.8 71.7 7.8 22.5 37.5 14.6 39.2
Dominant Variety Arabi
aswad Arabi
aswad Arabi
aswad Local Local Cham 6 Cham 6 Cham 6
Planting date 01/11/02 28/10/02 25/11/02 31/12/02 30/12/02 26/11/02 26/11/02 21/11/02
Harvesting date 16/05/03 14/05/03 15/05/03 15/05/03 17/05/03 26/05/03 26/05/03 27/05/03
Growing period (days) 196 198 171 135 138 181 181 187
Seed rate (kg/ha) 237 310 146 37 34 241 321 153
P-Fertilizer (kg/ha) 67 130 12 90 64 106 143 55
N-Fertilizer (kg/ha) 39 80 39 20 11 98 100 52
Yield (kg/ha) 2174 2762 1959 500 471 3175 3472 1856
Barley-
sprinkler Barley-
surface Cumin-
sprinkler Wheat-
sprinkler Wheat-
surface
EC of irrigation water (dS/m) 7.2 11.7 4.9 5.8 10.0
EC values (min - max) 3.3-14.2 8.4-16.8 2.5-7.9 2.3-11.4 3.3-14.2
Crop water requirements (mm) 372 372 259 390 390
Effective rain (mm) 284 284 228 268 268
Net irrigation requirement (mm) 88 88 31 122 122
Water-use (mm) 94.9 144.7 27.3 105.3 327.0
Water-use / irrigation requirement 1.1 1.6 0.9 0.9 2.7
WUErf (kg/m³) 0.7 0.7 0.2 0.7 0.7
WUEtot (kg/m³) 0.6 0.7 0.2 0.9 0.6
WUEir (kg/m³) 0.2 0.6 0.1 1.2 0.5
Table 2:
Electrical conductivity and water-use parameters
Zeitschrift für Bewässerungswirtschaft, 39. Jahrg., Heft 2 /2004 247
4. Discussion
Wheat accounted for 78% of the water applied to winter crops in Khanasser Valley.
Two thirds of the irrigated wheat was produced with sprinkler irrigation using only
40 percent of the water applied with both methods. Despite the higher productivity
of sprinkler irrigation, farmers who had wells with a high EC (average: 10 dS/m) were
using surface irrigation, because the crop is more sensitive to salinity than barley.
Toxicity effects resulting from foliar application of saline water are exacerbated by
strong winds and low air humidity (AYERS and WESTCOT, 1985), which are typical
of the spring season in Khanasser Valley.
Some farmers changed to sprinkler irrigation despite having high salinity irrigation
water. They usually avoid toxicity effects by not applying water at sensitive growth
stages. Farmers prefer sprinkler irrigation for economic reasons: Harvesting costs
are three times higher for surface irrigation, because combine harvesters need more
time to harvest a ridged field; additional tractor passages are needed for soil
preparation; higher seed rates, more fertilizer and more fuel are required. On the other
hand, this is compensated by the investment costs for sprinkler systems.
The grain yield of irrigated barley was affected by controlled grazing, a land use
practice with a comparatively high gross margin in northern Syria (MÄRZ, 1990).
Compared to crop water requirements, barley receives more water by sprinkler
irrigation than wheat. This water is applied mostly to enhance the vegetative
development of barley. Farmers stop the grazing after tillering stage. Cumin appears
to be more sensitive to sprinkler irrigation with high salinity water than wheat.
However, small quantities of moderately saline water, applied before flowering, can
help secure yields in low rainfall years.
Irrigated area Groundwater abstractions
Crop-irrigation method
combination (ha) (%) (m³) (%)
Barley-sprinkler 85.3 18.7 80,960 12.7
Barley-surface 28.1 6.2 40,656 6.4
Cumin-sprinkler 69.1 15.2 18,834 3.0
Wheat-sprinkler 178.5 39.2 188,041 29.5
Wheat-surface 94.1 20.7 307,723 48.4
Total 455.1 100.0 636,215 100.0
Table 3:
Irrigated areas and groundwater abstractions in Khanasser Valley
248 Journal of Applied Irrigation Science, Vol. 39, No. 2 /2004
Figure 3:
Khanasser Valley, 2002-03 croping season: Fields irrigated by sprinkler irrigation
and surface irrigation
Zeitschrift für Bewässerungswirtschaft, 39. Jahrg., Heft 2 /2004 249
Supplemental irrigation is defined as the application of a limited amount of water to
the crop when rainfall fails to provide sufficient water for plant growth, to increase
and stabilize yield (OWEIS et al., 1999). In the 2002/03 season, a majority of farmers
used sprinkler technology for supplemental irrigation of wheat. On average, these
farmers were applying irrigation water quite efficiently. In the individual case, however,
the applied quantities were sometimes above and sometimes well below the net
irrigation requirement, which indicated some potential for improvement. However, in
those cases where water applications were strictly limited by well yields, water-use
efficiency could hardly have been improved much, as farmers were already using
deficit irrigation (ENGLISH and RAJA, 1996), i.e. applying less water then necessary
to exploit the full yield potential of the crop.
In the 2002/03 season, winter irrigation in Khanasser Valley accounted for an
equivalent water use of about 0.64 million m³. A higher degree of groundwater use
can be expected for an average rainfall year. Although supplemental irrigation in the
rainy season represents the major share of total water abstractions in the valley,
summer irrigation and domestic water use are not negligible and need to be also
evaluated.
5. Conclusions
Based on the extrapolation of results from the monitored area, farmers in the Khanasser
Valley applied on average about 33% more water than the net irrigation requirement.
Considering that application efficiencies or leaching requirements were not taken
into account, in general, farmers seem to have applied water efficiently.
In view of the scarcity of water resources in the study area, this result is quite
encouraging. However, the water use study also highlighted areas of concern and
topics for participatory research, such as salinity management and water use economy.
The use of saline water for leaching is problematic. On the one hand, farmers can
remove temporary peaks of soil salinity by applying extra water for leaching, on the
other hand, yet more salts are added to the soil profile, which can only be removed
by substantial rainfall. Ways of how to optimise leaching shall be discussed with
farmers in the context of participatory experiments.
Less water is required for achieving the maximum income than for achieving the
optimum yield, particularly since water is more limited than land. This topic will be
addressed in trials with farmers who are using sprinkler irrigation. The target will be
to get a higher income from irrigation with less water.
250 Journal of Applied Irrigation Science, Vol. 39, No. 2 /2004
Acknowledgments
The German Ministry of Economic Cooperation and Development (BMZ) and
GTZmbH (German Agency for Technical Cooperation) are acknowledged for financial
and administrative support to the Khanasser Valley Integrated Research Site (KVIRS)
Project. The authors are grateful for the assistance of Ahmed Hamwieh with fieldwork
and Piero d´Altan with the preparation of GIS maps.
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Address of authors:
Schweers, W., corresponding author
(University of Bonn, Germany, seconded to ICARDA)
International Center for Agricultural Research in the Dry Areas (ICARDA),
P.O. Box 5466, Aleppo, Syria
Email: W.schweers@cgiar.org
Bruggeman, A.
ICARDA, Natural Resource Management Program;
Oweis, T.
ICARDA, Natural Resource Management Program
Rieser, A.
University of Bonn, Department of Agricultural Water Engineering and Land
Improvement;
Nussallee 1, Bonn, Germany
252 Journal of Applied Irrigation Science, Vol. 39, No. 2 /2004
