Page 55 - Water and DSİ

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CHAPTER IV - IRRIGATION
Limited water resources corresponding to increasing water demand for non-irrigation uses calls for
water economy in irrigation in which the greatest share takes in the amount of water consumed. A
typical example is the Southeastern Anatolia Project where long tunnels, expensive conveyance
canals, high elevated pumps to convey water to irrigation areas increased the cost of the water so
much that water economy have become compulsory. Water will have greater importance in the
future, thus water is to be used more carefully. Water amount for a plant growth period in DSI
surface gravity irrigations is average 10,000 m³/ha.
Farm efficiency in traditional irrigation systems such as in border or furrow irrigations is about
60%. If leakage, evaporation and operational losses are included, efficiency becomes 50%. In other
words, 2 m³ is consumed to provide 1 m³ water, which means wasting of limited water resources,
constructing distribution and drainage schemes with bigger capacities, thus increasing costs and
additional power consumption if system includes pumping. If we add the cost of the water itself to
abovementioned factors, it may be easily understood that water economy is really important.
Between 1950-1965, open canals were constructed in Turkey. Since 1965, irrigation systems with
canalettes (concrete raised parabolic flume) have been initiated. Between 1970-1980, irrigation
systems with canalettes were largely constructed in Turkey. Since slanting land necessitates a lot
of water structures and since there are many water distribution problems in the case of irrigation
systems with canalettes, low pressure pipe networks have become necessary. Low pressure
concrete pipes were used in irrigation networks in 1980s. As from 1990, low and medium
pressure pipe network have been used thanks to advanced pipe tecnhologies.
Distribution Efficiencies
Irrigation Efficiencies
Classic layered systems
90% Surface irrigation
60%
Concrete raised parabolic flume
95% Sprinkler irrigation
70–80%
Closed systems (pipeline)
100% Trickle irrigation
95%
Diverse Conveyance Canals Current Usage Ratio
Open Canal (44%)
Pipeline 14%
Canalette (42%)