基于样本流量偏差率的微灌灌水均匀度评价方法

Estimation of micro-irrigation water application uniformity based on sample emitter flow variation

为了探索一种简便有效评价大田微灌系统灌水均匀度的新方法,定义了样本流量偏差率.基于灌水器流量服从正态分布的假设,建立了样本流量偏差率与现有灌水均匀度评价指标之间的关系,推导了抽样误差的计算公式,提出了合理的样本容量和样本分组数.建立了基于样本流量偏差率的灌水均匀度评价标准,最终提出了基于样本流量偏差率评价大田微灌灌水均匀度的新方法.案例应用表明:相比图解法,新方法根据数值计算结果评价灌水均匀度,可避免人为画线误差,提高评价结果的可靠度;相比传统数值法,新方法计算量少,可作为快速评价大田微灌系统灌水均匀度的有效方法.

The field estimation of water application uniformity is the major way to assess the hydraulic design,operation and management and the equipment quality of the micro-irrigation system. The traditional emitter flow variation using the maximum,minimum and average emitter discharge is only used as the hydraulic design uniformity criterion,which could not be used to evaluate the field water application of micro-irrigation systems. The sample emitter flow variation was defined to evaluate the field water application uniformity. The relationships between the sample emitter flow variation and the other traditional indexes of water application uniformity were developed based on the assumption that the emitter flow of the field micro-irrigation systems obeys the normal distribution. The related formulations of sample errors were derived. The sample size and grouping number were also proposed. The criteria of sample emitter flow variation under different sample grouping number were proposed by comparison with those of the ASABE and GB standards. The estimation procedure of sample emitter flow variationwas then proposed to assess the field water application uniformity. The application case indicates that the new method is easily adaptable and reliable for estimating the field water application uniformity.