中文摘要：

以新疆大田棉花地下滴灌系统（SDI）为研究对象，采用定量计时法对使用1～7年的SDI毛管的压力和流量进行了定位观测，研究了毛管水力性能的年内和年际变化规律。结果表明，在同一使用年限（灌水季节）内，随着灌水次数的增加和灌水时间的延长，毛管的流量降低率增加。毛管的性能变化与其所在的位置有关，靠近小区进口（支管首部）处毛管的流量降低率较小，随着距小区进口距离的增加，毛管流量降低率增大。毛管的流量降低率随使用年限的增加而增大。对设计使用寿命为3年的SDI毛管，使用3～4年时，毛管的流量降低率均未超过20％；使用6年时，80％以上毛管的流量降低率超过20％，1／3的毛管流量降低率超过25％，最大降低率为29．13％，此时，应加强系统运行管理，尽可能恢复SDI毛管水力性能，提高系统运行效率。

英文摘要：

The observation of drip line performance in subsurface drip irrigation system（ SDI）, serviced for 1 to 7 years, was carried out at fixed positions in cotton field of the Xinjiang Uygur Autonomous Region, China. The duration of given water volume were used to calculate the flux of drip line. The discharge of drip lines was surveyed under different pressure to evaluate the annual and inter-annual variation of performance. The results show that the drip line flux reduction rate increases with irrigation times and service hours of the SDI system in the same irrigation season or the same service year. The reduction rate varies with locations of line, it is smaller when the drip line is located closer to the inlet of sub-main and increases with service years. For the design life of a 3-year SDI system lateral, the reduction rate is within 10% and 20% from 1 to 4 years of service duration. After 6 years reduction rate of about 1/3 of total lineas will be higher than 25%. Management should be enhanced to recover the hydraulic performance of the drip lines on time for improving the efficiency of the irrigation system.