Nader Salamati; Peyman Varjavand; Shokrola Absalan; Azarakhs Azizi; Moheydin Goosheh
Abstract
In order to optimize the efficiency of water in agriculture, it is necessary to know the extent of water leakage in the lined canals. In this study, water conveyance efficiency and seepage/leakage losses were determined to evaluate earth and concrete lined channels in Khuzestan irrigation networks. The ...
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In order to optimize the efficiency of water in agriculture, it is necessary to know the extent of water leakage in the lined canals. In this study, water conveyance efficiency and seepage/leakage losses were determined to evaluate earth and concrete lined channels in Khuzestan irrigation networks. The result of this assessment was to identify the problems of management and damages in these channels. Thirty channels were studied and evaluated in the main irrigation and drainage networks of Khuzestan province, including Karun, North Khuzestan, Karkheh, Shavour and, Zohreh and Jarrahi, and channels managed by the farmers. There were 17 tertiary and quaternary canals and 6 earth channels in irrigation networks, as well as 1 canal and 6 earth channels under farmers’ management. The water conveyance efficiency in canals ranged from 38.9% in Ramshir to 99.7% in Shushtar; and in the earth channels, from 46.9% in Baghmalek to 89.3% in Shush. The comparison of means of the measured and calculated indices was performed by t-test and showed that seepage per km length of the unlined earth canals was 3017.7 m3/day, which had no statistically significant difference with lined canals with a leakage of 2166.2 m3/day/km. The results of Pearson correlation coefficients showed that there was a negative and significant (at p<1%) correlation between distribution efficiency with the amount of seepage per kilometer channel length, and between losses and the input flow rate per km of channel length. Also, 16.7% of the total canals had a water distribution efficiency of less than 67.8% (between 38.9% and 67.8%), while 50% of the canals had a conveyance efficiency of less than 68.6%. The low water losses in half of the concrete lined canals and the excessive water loss in 11% of such canals, which even increased water losses in the earth's channels, reveals the necessity of paying attention to the optimal management of these canals. This optimal management should be considered at the design and construction stages of the structure as well as during the installation in agricultural lands. Attention should also be paid to use of proper seals and other suitable equipment to prevent water leakage.
Mohiaddin Gousheh; s ghalebi
Abstract
Basically, sever ecological features of Khuzestan Plain such as soil salinity, saline water resources, shallow watertable, heavy clay soils, poor drainage and high temperature as well as significant evaporation rates intensify reductions in crop yield, spacially in cases of inappropriate irrigation regime. ...
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Basically, sever ecological features of Khuzestan Plain such as soil salinity, saline water resources, shallow watertable, heavy clay soils, poor drainage and high temperature as well as significant evaporation rates intensify reductions in crop yield, spacially in cases of inappropriate irrigation regime. Besides, saline water is utilized to irrigate crops as an inevitable alternative of scarcely available fresh water resources. In order to cope with drought and salt stresses, an experiment was carried out to investigate the effects of soil salinity on grain yield of spring wheat (Triticum aestivum L.) at three irrigation frequencies, with 30%, 50% and 70% plant available water (PAW), and at three salinity levels of irrigation water (≤2, 3-5, and 6-8 dS.m-1), during 2006-09. Based on the results, electrical conductivity of 5 dS.m-1 could be preferentially recommended for irrigating wheat at studied intervals providing 30% PAW without any significant yield loss under the experimental conditions. Irrigation water with electrical conductivity of 6-8 dS.m-1 substantially reduced the grain yield at all irrigation intervals.