Research On Regulation Of Soil-Water Movement In Irrigation Design Parameters Under Subsurface Drip Irrigation

Abstract: Research on regulation of soil-water movement in irrigation design parameters of SDI has important points in improving its irrigation design and guiding its practical function. On the basis of the review of the research results of soil water movement characteristics and hydraulic parameter determinations,this paper adopted the solution of theoretical analyses and laboratory experiments. Experiments are carried out about research on regulation of soil-water movement in irrigation design parameters under subsurface drip irrigation. The main investigation content are as follows: 1. The effects of discharge on soil-water movement under subsurface drip irrigation(SDI) is analyzed: The greater flow emitter from 0.76L/h to 1.25L/h, within a certain distance from 0 to 30cm the emitter, the higher the moisture content in soil with drip irrigation vertical depth direction, the greater flow emitter, Emitter in the bottom of the higher the moisture content of the emitter at the top of the water content of the corresponding decrease. Emitter flow is determined by the size of the speed of wetting front migration.2. The effects of capillary-depth on soil-water movement under subsurface drip irrigation(SDI) is analyzed: With the increase in depth from 5cm to 35cm, whether vertical or horizontal direction the soil moisture content are constantly reduced from 21% to 10%. The greater depth, humid front of moisture on both sides of the closer, the sub-region are not of the increase. With the increase in depth, moist front to the surrounding migration in the distance gradually decreased. Capillary depth of the deep, wet on the wall in front of the more lag time.3. The effects of irrigation on soil-water movement under subsurface drip irrigation(SDI) is analyzed: With the increase in irrigation from 4.6L to 9.2L, vertical and horizontal direction the water rates are increasing 10% to 20%, the level of sub-feng direction at the rate of migration of Bianhuan gradually, The vertical direction of the wetting front migration rate is greater than the horizontal direction.4. The effects of initial water content on soil-water movement under subsurface drip irrigation(SDI) is analyzed:The results show that the wetting front transport speed become quickly in down but reduce in up and level direction along with the increment of the siol initial water content from 7.71% to 11.14%,and the water content under the emitter soil is higher than other direction.the water content in level direction presents symmetry distribute.Under the same amount water,the distance of wetting front transport up is less than down when the initial water content become bigger.5. The effects of covered on soil-water movement under subsurface drip irrigation(SDI) is analyzed: Under the drop neighbor membrana tectoria's moisture content is high. The membrana tectoria may reduce the soil moisture the evaporation, thus urges the moisture content downward migration, causes the soil the moist body depth to increase, is advantageous grips the depth downward to the root system. 6. The effects of irrigation frequency on soil-water movement under subsurface drip irrigation(SDI) is analyzed:The difference of the distribute of soil moisture is not big when the longer interval under the condition of same amount of water,the difference of the distribute of soil moisture is bigger when the shorter interval,and the water content is higher. The moisture content in the emitter nearby is higher when the same amount of water is divided to 3 times and the interval time is 12 hours.