干旱区生态环境知识资源中心

A field study evaluating wetted radius (Wr), downward depth (Dd), and upward movement (Um) under different emitter discharges and lateral depths was conducted. Four emitter discharges (2, 4, 8, and 16L/h) and four lateral depths (0, 10, 20, and 30cm) were tested in a clay loam soil. Relationships were found between the emitter discharge and lateral depth versus Wr, Dd, and Um. Wetting area at the surface occurs under different emitter discharges and lateral depths except at 30cm lateral depth. At lateral depth of 0 and 10cm, Wr and emitter discharge were positively correlated. The Dd was not affected by emitter discharge except for laterals installed at 20cm depth. At 30cm lateral depth, the correlations between each of Wr, Um, and Dd with emitter discharge were poor. The ratios of Wr/Dd and Um/Dd, with respect to emitter position, were less than unity over different emitter discharges and lateral depths. These results shed some light on the design of subsurface drip irrigation scheme so that the spacing between emitters should be determined based on the lateral depths and discharge of emitters. Evaporation losses were negligible for the 30-cm-lateral depth since the upward moisture movement has not reached the soil surface area at all discharge rates tested in the study.