地面灌溉水流特性及水分利用率的田间试验研究

Field evaluation of water flow performance and application efficiency for border irrigation

在内蒙古风沙区一种砂土和壤质砂土的春小麦生育期内进行了畦田规格和灌水技术要素对水流推进和消退过程、田间水利用系数、灌水效率及灌水均匀系数影响的田间试验。试验中畦田坡度基本一致 ,畦长均为 60 m ,畦宽变化范围为 1～ 4m ,单宽流量为 3 .8～ 15 .2 L / ( s· m )。结果表明 ,畦田水流推进曲线可用幂函数表示。在所研究的畦田中 ,1m宽度的畦田灌水效率最低 ,宽度 2 m和 3 m的畦田灌水效率相近 ,畦宽由 3 m增加到 4m时 ,灌水效率呈降低趋势 ,因此试验条件下的畦田适宜宽度为 2～ 3 m。对所研究的土壤来说 ,春小麦生育期内平均灌水效率 (田间水利用系数 )仅为 0 .5左右 ,与规范规定值 ( 0 .90以上 )尚有很大差距。利用水量平衡法求出的土壤入渗参数和观测的入渗时间 ,计算了入渗水深均匀系数。结果表明 ,入渗水深均匀系数随畦宽的变化趋势与灌水效率相同 ,但可以达到 0 .8以上。对地面灌溉来说 ,高均匀系数并不一定意味着高灌水效率 (田间水利用系数 )。

Field experiments were conducted in a sandy soil in the arid region to investigate the influences of border dimensions and irrigation variables on the performance of water advance and recession, application efficiency and distribution uniformity (DU). In the experiments, all the borders studied had an approximately equal slope and constant length of 60 m, while the width of the border strips was varied from 1 to 4 m and the inflow rate was varied from 3.8 to 15.2 L/(s·m). Results showed that the relationship between advance distance and time could be represented by a power function. Of the borders studied, 1 m wide borders gave the lowest application efficiency, whiley borders with 2 and 3 m in width gave an approximate similar efficiency. Application efficiency showed a decreasing tendency as the border width increased from 3 m to 4 m. All the borders produced relatively low application efficiency, with an average value of about 0.5 for the whole irrigation season. Infiltration parameters (K and α) for Kostiakov's equation were estimated by a volume balance approach and distribution uniformity (DU) for infiltrated depth was calculated. It was found that DU varied with border width in a similar pattern to application efficiency. A high DU of greater than 0.75 was observed for most of the borders. The results suggest that a high DU value does not necessarily mean a high application efficiency for surface irrigation.