1.
Irrigation instructions
The irrigation instructions for each county and corps (Wang 2006) list the irrigation schedule
and quota for 13 kinds of crops and landscapes which are irrigated by the river water. They
are winter wheat, maize, sequential cropping maize, rice, cotton with flood irrigation, cotton
with drip irrigation, beet, oil plant, other economic plants, orchard, vegetable, forest and
grassland. For example, in the county Wushi, winter wheat is planed to be irrigated 5 times a
year. The five irrigation periods are 15th Aug. – 5th Sep. (before sowing), 20th Oct. – 10th Nov.
(planting), 10th Apr. – 20th Apr. (tillering stage), 10th May – 25th May (jointing-booting stage)
and 1st Jun. – 9th Jun. (maturity) with irrigation quota of 1500, 1050, 1050, 1050, 1050 m3/ha,
respectively. In total, 5700 m3 water is needed to irrigate one hectare of winter wheat per year.
Combined with the crop area in each irrigation unit, such irrigation instructions serve as a
good basis of estimating the annual and monthly water use for scenarios. As there is no
detailed information about the irrigation practices, we assumed that the irrigation quota is
evenly distributed in each irrigation period. Given the irrigation area (Area: ha) and the daily
irrigation quota (Quota: m3/ha) for each crop or landscape, the daily irrigation demand of each
irrigation unit (D: m3) can be calculated using equation 1:
13
D j   ( Areai , j * Quotai , j )
(1)
i 1
where j indicates the irrigation unit, i means the 13 crops and landscapes. Then the monthly
(MDj) and annual irrigation demand (ADj) for each irrigation unit j can be summed by the
daily values. The monthly share is obtained by the ratio of MDj to ADj. Finally, the annual
water use (AQj) is calculated using equation 2:
AQ j  AD j / c j ,
where c is the irrigation efficiency coefficient of irrigation unit j.
(2)
2.
Tables
Table 1: irrigation units in the studied area
Administrative
Irrigation area
Irrigation unit
department
Water source
in 1998 (ha)
Yuejin
Wushi couty
Toshkan R.
4670
Qiugeer
Wushi couty
Toshkan R.
20130
Lianhe
Wushi couty
Toshkan R.
12000
Xiehela
Wensu couty
Kumarik R.
3170
Qiagelake
Wensu couty
Kumarik R.
7500
Arele
Wensu couty
Toshkan R.
9320
Geming
Wensu couty
Kumarik R.
15750
Duolang
Aksu city
Kumarik R.
35470
Situan
FAD*
Kumarik R.
8730
Liutuan
FAD
Duolang
6930
* the First Agricultural Division under Xinjing Production and Construction Corps