Journal Name:
- International Journal of Science and Engineering Investigations
| Author Name | Faculty of Author |
|---|---|
Abstract (2. Language):
A series of field experiments were carried out in sandy clay loam soil to determine the wetting pattern following irrigation from a line source in subsurface drip irrigation (SDI) system in the horizontal and vertical directions. In each experiment 10m of drip tube was buried at 20 cm below soil surface with 0.3m spacing between emitters. Irrigation water was applied at three different irrigation durations; 2.5, 5.0, and 10.0 hours. Five volumetric water content sensors (Decagon Devices Inc. 2365 NE Hopkins Court, Pullman, WA 99163) were installed at each of (10, 20, 30, 40 and 50) cm depths below the soil surface for water content measurements. In this study a zero distance is represent by a sensor located exactly at the source emitter (SE) of measurements and the horizontal distances 7.5 and 15 cm represent the locations of two sensors installed on both sides of the SE. Hydrus 2D program was used to simulate two dimensional pattern of moisture front during 24hour after starting irrigation. At 20cm depth and 2.5 hour irrigation duration the results indicated a horizontal progress of the wetting front to 7.5 and 15.0cm after 5.0 and 10 minutes from the start of irrigation, respectively. While initial water content (0.07cm3.cm-3) at the SE increased to 0.42 cm3.cm-3 after 5 minutes, values increased to 0.24 and 0.19 cm3.cm-3 at 7.5 and 15cm after 10 and 45 minutes, respectively. Measured water content at the minutes 1440th attained constant values (0.29 cm3.cm-3) in the horizontal domain at 10, 20 and 40cm, 0.32 cm3.cm-3 at 30cm and no change occurred in at 50cm. At 10cm depth moisture front attained 7.5 and 15cm after 45 and 120 minutes respectively. Water content values after 150 minutes were 0.42, 0.38 and 0.19cm3.cm-3 for 0.0, 7.5 and 15cm respectively. When irrigation time increased to 5 and 10hours the moisture front moved to deeper depths with similar moisture distribution patterns were obtained in the horizontal domain, however differences must be originated from heterogeneity in soil profile. The results showed excellent agreement between measured and simulated water content values by Hydrus 2D program with highest R2 values of 0.983, 0.967 and 0.986 and lower RMSE values of 0.008, 0.016 and 0.007 for experience 1, 2 and 3, respectively. The results also showed excellent agreement between values of measured, 25, 65 and 105cm after 2.5, 5 and 10 hours, and values of simulated, 30, 92 and 110cm depths of moisture after 24 hour, where the depth of the moisture front below SE increased with increasing irrigation time. Hydrus 2D program can precisely predict water distribution and redistribution process and can be used as a designing tool for water management practices in the SDI systems.
Bookmark/Search this post with
FULL TEXT (PDF):
- 8