Flood Defense and Water/Sediment Management—With Particular Reference to The Yellow River - River Dynamics and Integrated River Management - page 353

6.3.2.3 Water Management
1) Water-Demand Reduction
The total area of irrigated farmland in the delta was 141,000 ha, of which only 3,333 ha, or 2.35% of the
total, had been equipped with water-saving irrigation facilities. The average water use efficiency in
irrigation was 0.46. The total length of canals in the area was 1,474 km, of which only 75 km, or 5.11%
of the total, was lined. There were almost no sprinkler and drip irrigation and there was great potential
for water-demand reduction in irrigation. For instance, in a small irrigation district, 64% of the water was
lost due to seepage in irrigation canals and 17% was lost in conveyance canals. When the canals were
lined for seepage prevention the percentages of water loss due to seepage was reduced to 35% and 6%
for the two kinds of canals. The average water use efficiency of the Caodian irrigation district was increased
to about 0.5.
Dongying plans to enhance the water use efficiency to 0.65. If the irrigation canals are replaced by
pipelines, the conveyance water use efficiency in transportation can be up to 0.99 and the average water
use efficiency can reach 0.7. The area with water conservation measures will also increase from 14,670
ha to 133,000 ha and the rate of water use will reduce from 8,310 m 3 /ha to 5,580 m 3 /ha.
Water conservation in industrial production has gotten attention since the 1980s. In the 1990s, the rate
of water consumption is 272 m 3 per $1200 and the rate of water reuse is about 20%. It is planned to
reduce the rate of water consumption to 149-167 m 3 per $1200 and to increase the rate of water reuse to
45%. Water for urban and industrial use is mainly supplied by the Genjing and Guangnan Reservoirs. In
the 1990s, each of the reservoirs stored 165 million m 3 of water, and the amount of water supplied by
each reservoir was 99 million m 3 . Therefore, the water use efficiency of the two reservoirs is about 0.6,
giving room for water conservation measures.
2) Utilization of Sediment-Laden Water
Water demand by agriculture is over 50% of the total. According to statistics, about 50% of the required
amount of water for agriculture can be met by using sediment laden flood water from the Yellow River.
The Yellow River delta is very flat. There is no place to construct desilting basins at the headwork of
canals. At distances from the river there are saline spots, which can be used to construct plain reservoirs
or develop agriculture after artificial siltation by using the Yellow River sediment. The canals have gentle
slopes and are used to convey water and sediment for long distances. It is important to avoid siltation in
the canals. In the Caodian Irrigation District, all canals are lined with concrete and stones. Low head
pump stations are used to raise the water head and silty water with sediment concentrations up to 30-40
kg/m 3 has been transported in the canals for over 50 km without accumulated siltation. In the Mawan
Irrigation District, the main canal is 26 km long fed by a pump station with a capacity of 30 m 3 /s.
Although it is an earthen canal without a desilting basin, the canal has been used to transport silty water
for four years without serious siltation. These experiences are valuable and are going to be applied
generally in the area.
3) Other Water Resources
Water resources other than the Yellow River in the delta include industrial waste water, urban sewage
water, brackish ground water, local runoff, the Xiao-Qing River and the Zi-Mai-Gou River, water from
South China via the east route of the South-North Water Transfer Project, and recovery of water lost due
to seepage from the Yellow River. The total amount of these kinds of water is over 2 billion m 3 per year.
These water resources may be exploited if the economic and environmental conditions allow.