COLEGIOS PROFESIONALES Y SOCIEDADES CIENTÍFICAS

B elk isk oy (100 702 sq. km) 40 Euphrates iaverage i 30 20 1st critical’! period :• 10 1980 1965 1975 1935 1940 1945 1950 1955 1960 1970 Year Source: Bagis, 1989, 34

According to discharge records obtained between 1937 and 1980 at the Belkiskoy (Birecik) gauging site, ju st upstream from the point where the Euphrates crosses the Syrian border, the annual average flow is 30.37 billion n P per annum (GAP, 1990, Vol.

4, E6). This figure is very similar to the World Bank figure for flows of the Turkish -

Syrian border which Clowson (1971, 205) recorded as 33.69 billion m^ per annum.

Table B.l:

Hydrological data for the E uphrates river

Turkey Syria Iraq Saudi Arabia Total

Drainage area

(1,000 km2) 125 76 177 66 444

% of total area 28 17 40 15 100

% of country 16 41 39 5

Annual discharge T urkey Syria Iraq

(10 /m3) OUTFLOW INFLOW OUTFLOW INFLOW

(1937-1963) Minimum 12,600 12,600 14,000 14,000 Mean 28,400 28,400 32,400 32,400 Maximum 42,000 42,000 45,000 45,000 % of mean discharge 88 12 0 Source: Beaumont, 1978,37

Since the discharge value of the Sajur, Balikh, and the Khabur in Syria has been measured at about 2.05 billion m^, the average "natural" river flow at Hit should be about 32.4 billion m-^/yr. This figure is 1.3 billion m^ less than calculated by Clawson but Ubell (1971), Beaumont (1978), and Gischler (1979), used the amount of 31.8 billion m^/yr. as the annual average volume of flow from 1931 till 1969 (Ubell, 1971, 3; Beaumont, 1978,

35; Gischler, 1979, 100). According to Abbas (1984) the average annual flow of the river

is only 29.26 billion (Abbas, 1984, 87). Another source, Al-Khashab (1958), quoted

the lowest amount of the average annual water surplus of the Euphrates river at Hit, at 26.4 billion m^ based on 22 years of measurements (1925-1946), and the Haigh report (1951), calculated the same amount (Al-Khashab, 1958 46; Haigh, 1951, 39). The annual discharge varied from 16.8 billion m^ per annum in 1961, to a maximum of 53,5 billion m^ per annum in 1969 and 65 per cent of this discharge occurred during the flood

(Beaumont 1978, 36).

From the examination of the data in the amount of river water, upon which the various researchers base their findings, it is no wonder that there is, in fact, no agreement about the amount of water naturally flowing in the river. The natural flow can only be calculated

up to the W inter of 1974 when Turkey began to fill the reservoir behind the Keban Dam and Syria began to fill the reservoir behind the Tabqa Dam. This intervention by states in the process of the river's natural flow makes it virtually impossible to calculate the natural flow after the event. There is no doubt, however, that due to the very large perennial variation in the amount of water flowing in the river (which can be seen in figure Bl.), calculation of the average flow becomes a statistical manipulation and there are long periods in which the amount of flowing water is significantly greater than or smaller than the average. It is difficult, however, to explain the differences in the flow as is presented by various researchers, distorted by partial national water recording agencies. One way to explain the different results may arise out of relating to different periods of time those studies took place. One must also consider that the amount of water in a river is a mathematical calculation of data - something which produce the possibility of making arithmetical errors.

Figure B2:

M onthly v ariatio n s in discharge o f the

E u p h rates a t K eban and Y usef Pasha 1950-1966

3 0 0 0 Keban Y ussef Pasha 2000 £ 1000- & s3 o 2

Jan. Feb. M ar. A p r. May. Jun. Jul. Aug. Sept. Oct. Nov Dec.

Source: Beaumont, 1978,39-40

Minimum instantaneous discharge, according to Cressey, is 181 m-^/sec (equivalent to 5,700 m illion m^/yr.), w hile m axim um instantaneous discharge is 5,200 m-Vsec (equivalent to 164.000 million m-^/yr.) (Beaumont 1978, 37). There were two severe droughts in the Euphrates area between 1937 and 1980 (see fugure B 1). The first was in

1958-1962, with the most severe period (with an annual flow as low as 14,883 million m3 at the Turkish/Syrian border), being in 1961. The second critical period began in 1970 and ended in 1975, the lowest flow being in 1973, when the annual flow fell to 62 per cent of the annual average flow over the 1937-1980 period. Total flow reached a peak in 1969 when it was recorded at 53,548 million m3 which represented 86 per cent increase over the average (GAP, 1990, Vol. 4, E6).

Table B.2:

The average water flow of the Euphrates river at selected locations

Gauging station Years Watershed area Average flow

(km3) (Billion m3/yr.) Keban, Turkey 64,100 20.12 Tabqa, Syria 120,700 28.84 Hit, Iraq 1924-1970 264,100 29.36 Hindiyah, Iraq 1930-1971 274,100 19.50 Shinafiya, Iraq 1954-1971 280,000 14.90 Al-Nasiriyah, Iraq 1930-1971 289,000 15.00 Source: Abbas, 1984, 90

At the Keban station in Turkey the mean annual flow of the Euphrates is about 20.12 billion (see table B.2) and the flow increases between Keban and Tabqa to 28.84 billion m^ per year. Further downstream at Hit, Iraq, near the Syrian border, the annual flow of the river reaches 29.26 billion m3 per year while still further to the south in Iraq at the city of Al-Nasiriyah, (as a result of diversions and evaporation), the average flow of the river drops to about 15 billion m3 per year. Table B.2 shows the annual flow of the Euphrates river.

The annual cycle of the Euphrates River discharge can be divided into three parts (see figures B2-B3):

a. Period of high discharge - March to June b. Period of low discharge - July to October

c. Period of average discharge - November to February

The melting of the winter snow in the uplands of Turkey releases large quantities of water into the river to produce a discharge peak during April and May, when the discharge at Hit, Iraq averages 2,400 nAsec. The discharge drops sharply in June and July as the frozen precipitation of the winter season is exhausted and the nearly rainless summer begins.

Figure B3:

Monthly variations in discharge of the E uphrates at Hit and Hindiya 1931-1966

3000 h Hit Hindiya 2 0 0 0- o 59 $ ^ 1000-

I

Jan. Feb. M ar. A pr. May. Jun. Jul. Aug. Sept. Oct. Nov Dec.

Source: Ubell, 1971,6

In August, September and October the mean discharge at Hit is around 300 m^/sec. In a year of heavy winter precipitation, however, the peak discharge in May can reach 4,300 m^/sec, while there is little increase in the average summer flow level. After a dry winter the discharge in April or May can be as low as 1,300 m^/sec and may drop to about 100 m^/sec in August and September. Thus, in one year, as much as twice the average amount of water may flow in the Euphrates while, in another, little more than half the average annual discharge will be generated. The discharge of the Euphrates diminishes systematically with distance downstream after its confluence with the Khabur, primarily as a result of evaporation and infiltration into the subsurface. In the swampland of region the upper delta, both before and after confluence with the Tigris, the influence of large scale transpiration by aquatic vegetation further diminishes the flow (GAP, 1990, Vol. 4, E6). An examination of the origin of the content and discharge of the river reveals that 88 per cent of the mean annual content is generated within Turkey and virtually the whole of the remaining 12 percent in Syria (Table B.l). This means that Iraq's contribution to the total content of the river, under average conditions, is practically nil (Beaumont 197B, 36).

Figure B4:

The E uphrates river mean monthly discharge in Iraq: 1926-1948 3000 Hit Hindiya Shinafiya N asiriyah 2500 - 2 0 0 0- « 1 50 0 - 1 0 0 0- 5 0 0 -

Jan. Feb. Mar. A p r. May June J u ly Aug. Sep. Oct. Nov. Dec,

Source: Haige, 1951,3.2

The seasonal distribution of the water supply of the system does not coincide with crop needs. Winter crops in the riparian countries need water from May onwards, but the low water season, lasts from July to December and, during this period, the mean water discharge of the Euphrates is 421 m^/sec - thus the river reaches its lowest levels in September and October when water is badly needed.

When the crops are either half-grown or almost ready for harvest, and water is no longer so badly needed, the fields are subject to the danger of inundation since spring is the flood season During this period the mean water discharge of the river is 1,765 m^/sec.

In the case of summer crops which need water from April to September, the situation is reversed. At first they receive abundant supplies, and then the supply declines gradually until it reaches a low point in September (Qudain, I960, 57). The normal difference between high and low levels is about 3.3m (see Figure B5).

Storage of the river water is desirable because it increases the water available for economic use, especially in Turkey, but also in Syria and Iraq. The flow in low of low

years at the Syria-Iraq border illustrate the problems for cultivators depending on the natural flow of the river. Regulating the flow also addresses the problem of the timing of the flood w hich is too late for the winter crops and too early for the summer ones. Once major storage has been effected perennial irrigation can be extended in each of the riparians allowing two crops a year to be grown on the same land. Another reason for storage is to achieve flood control and the utilization of the water for the generation of hydroelectricity

(Ubell, 1971, 3).

Figure B5:

High and low levels of the E uphrates: 1911-1932

(in m etres above sea level)

High Low 50- 47- 4 6 “ 4 5 - 44

Jan. Feb. M e r.A p r. May Jun Jul. Aug. Sept. Oct. Nov. Dec.

Source: Ionides, 1937,3

B3: The correlation between annual rainfall and annual