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ali mokhtaran; abdali naseri; Heidarali kashkuli
Abstract
In the new drainage conditions in the center and southwest of Khuzestan Province, by reducing the depth of drainage installation and controlled drainage, studying the dynamics of the mixing zone, understanding the specifications of this region, and its effect on the flow rate of drainage water and salinity ...
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In the new drainage conditions in the center and southwest of Khuzestan Province, by reducing the depth of drainage installation and controlled drainage, studying the dynamics of the mixing zone, understanding the specifications of this region, and its effect on the flow rate of drainage water and salinity is important. In this study, seven groups of piezometers, each consisting of 8 piezometers placed at different soil depths (0.8 to 5m) and at different distances from the drainage water collector were studied in two research farms, namely, field R9-11 Dabal Khazaei agro-industry (with an average drainage depth of 2 m and distances of 65 m) and field R8-7 in Salman Farsi agro-industry (with an average depth of 1.4 meters and 42 meters distances).Water level in piezometers, water salinity in different soil layers, and drainage water flow rate and salinity were monitored daily in three periods of heavy irrigation of sugarcane (March to October of 2013, 2014 and 2017). Results indicated that by starting a heavy irrigation, hydraulic head increased and hydraulic head variance between bottom layer (4 and 5 m) relative to the surface layers, established vertical flow and saline inflow upwards. Reducing the installation depth of drains up to 60 cm from in R9-11 compared to farm R8-7 and moving away from the collector up to 400 m in each farm, reduced the installation depth of drains up to 40 cm, and increased the hydraulic load by an average of 8-12 cm. The thickness of the mixing area was up to one meter and the reduction of the average salinity line in the mixing area was 8%. It was found that in addition to irrigation water salinity, drainage water salinity was affected by groundwater salinity and the difference in drainage depth, position of the impermeable layer, and the presence of sand lenses. By decreasing drainage depth, the drainage water discharge decreased sharply, such that the averag drainage water from each lateral in farm R9-11 was 10 mm/day, and in farm R8-7 it was 3.3 mm/day. The results showed that with increasing the thickness of the salt and fresh water mixing zone due to the optimal reduction of drainage depth, the volume of water consumed in each irrigation cycle decreased due to plant use of this zone, which can be an effective factor in conserving soil and water resources.
h k; m a
Abstract
This investigation was performed to evaluate the suitability of threeSynthetic Envelopes PP450 manufactured by three local workshops in Khouzestan for drainage purposes in three projects, namely, Dehkhoda, Hendijan, and Ramshir projects (respectively, in the north, south, and in the middle of the Khouzestan ...
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This investigation was performed to evaluate the suitability of threeSynthetic Envelopes PP450 manufactured by three local workshops in Khouzestan for drainage purposes in three projects, namely, Dehkhoda, Hendijan, and Ramshir projects (respectively, in the north, south, and in the middle of the Khouzestan province). Experiments were performed in the laboratory using an upward flow permeameter. Recommended criteria for the evaluation of the envelopes were steady discharge with time, gradient ratio (GR) for the determination of soil particle movement and envelope clogging potential, and hydraulic conductivity of soil envelope. According to the results for all the three criteria, type 1 envelope (with tiny pores) was considered suitable for Dehkhoda project soils while for Ramshir project soils, based on the same 3 criteria, envelope 3(with macro pores) was the most suitable followed by envelope 1, while envelope 2 (with medium-sized pores) had a lower technical performance for this soil. For Hendijan project soils, envelopes 3 and 2 were partially suitable because hydraulic conductivity of soil envelope was very low. Summing up, envelope 1 and 3 are recommended for Ramshir project and envelope 1 for Dehkhoda project soils .For Hendijan project soils, envelope 3 needs further testing before making recommendation .