Food Sources: Earth, Water, and Air - Food Culture and Health in Pre-Modern Islamic Societies - page 41

of dry stone retaining walls for the culti-
vated plots. The need for regular atten-
tion to the upkeep of irrigation works has,
further, been an important factor in mak-
ing the village, rather than the isolated
farmstead, the typical form of settlement
throughout most of Persia.
Artificial irrigation may already have
existed in late Neolithic times. By the
Achaemenid period, there was an exten-
sive network of anāt s, and with the exten-
sion of irrigation there was an expansion
of agriculture. It is probable that drainage
schemes were also undertaken in different
parts of the empire. Later, the Seleucids
brought more land under cultivation by
clearance and drainage and applied new
techniques to irrigation. In Islamic times,
control of water for irrigation remained
crucial to prosperity and settlement.
Such control is a highly complex mat-
ter, and requires for its successful imple-
mentation not only technical skill but also
political stability. The heavy load of solids
carried by streams in spate makes storage
and control both difficult and costly. Flash
floods often destroy irrigation works, espe-
cially those connected with anāt s, while
spring floods may also cause much dam-
age in lowland districts. On the plateau,
the lowering of the stream-beds through
normal erosion results in the lowering of
the water-table itself and leaves irrigation
canal intakes above the new water level. In
modern times, the lowering of the water-
table by the extraction of water by pump
operation connected with the sinking of
semi-deep wells has led to many anāts
falling into disuse, especially round the
central desert but also in other regions.
Inadequate drainage, on the other hand,
often leads to a rising water-table under
irrigated lands, water-logging, salinisation
and alkalinisation, which result in con-
siderable loss of output. These processes
vary widely in different districts and dif-

ferent years. In some regions, notably
‡ ūzistān and Sīstān, deterioration of
the soil because of a change in the water-
table due to over-lavish irrigation and
inadequate drainage, or both, has been a
major problem. Another problem is that
ground water in some districts may be
heavily charged with soluble salts and be
too saline for use in irrigation. This is the
case in many districts on the borders of
the central desert and in the Persian Gulf
littoral.
Natural conditions and agricultural
practices cannot alone, however, explain
the fluctuation in the history of irrigation
in Persia. The shifting of centres of politi-
cal authority which accompanied dynastic
changes and demographic changes result-
ing from invasion and the increase in dead
lands because of the slaughter or flight of
their inhabitants have also played a part.
A breakdown in the control of water, for
whatever reason or reasons, was inevitably
followed by a decline in prosperity. The
decay of ‡ ūzistān, which culminated
under the Abbāsids, is an illustration of
this. Under the Sāsānids, the waters of the
Kar ¶ a, Diz and Kārūn had been util-
ised by an elaborate system of barrages,
tunnels, inverted syphons, lifting devices
and canals. Cereals, sugar cane, rice and
dates were produced in abundance. In
the last fifty years or so of Sāsānid rule,
irrigation was neglected. Under the rule
of the Orthodox Caliphs and the Umayy-
ads, adequate attention was not paid to
artificial drainage of the irrigated land,
and under the Abbāsids the province
declined—rising water-tables under irri-
gated land may have been responsible for
the attempts of the Abbāsids to irrigate
new lands of poorer quality. Water-log-
ging, alkalinisation and salinisation, and
the hazards of flood, all contributed to
the decline of the region which occurred
in post-Abbāsid times. Changes in pros-