灌区计量率定物理试验研究方法探析及应用

Application and exploration of physical test research on water consumption measurement calibration in irrigation area

目前灌区渠道计量方式多采用水位-流量法,部分渠道受制于渠道结构复杂多变及率定条件不理想等,难以准确测定水位-流量关系。针对实践中大量灌区结构条件较好但率定条件不理想的渠道,探索采用单一物理模型试验研究的方法,实现对多渠道水位-流量关系的精确率定。构建包含矩形、梯形及复式断面的规则渠道单一物理模型,采用动态比尺方式实现水位-流量关系模型到原体的还原;通过现场可测的少量水位流量数据对物理模型进行率定,然后由全工况物理模型试验,确定多组外包的水位流量,通过相关分析实现对水位-流量关系的插补外延。经实际验证,由该方法及现场监测水位推算的流量与实际值平均相差不超过5%,可为规则渠道的水位-流量关系率定提供借鉴和参考。

At present, water level-discharge method is mostly used in irrigation canal water consumption measurement. With different project constructions, it is found that some canals are constrained by complex and changeable canal structure and unsatisfactory calibration conditions, which make it difficult to accurately determine the relationship between water level and discharge, thus affect the measurement accuracy of irrigation areas. In view of the fact that a large number of irrigation canals have good structural conditions but unsatisfactory calibration conditions, the physical model test method is explored to achieve accurate calibration of the relationship between water level and discharge in regular canals. The physical models of regular canals such as rectangular, trapezoidal and compound sections are constructed, and the conversion of the physical model of water level-flow relationship to the original body is realized by changing the ratio. The physical model is calibrated by a small amount of water level-flow data which can be measured in the field, and then the physical model test under the whole working condition is carried out. Then it can obtain the interpolation and extension relationship of water level and discharge through correlation analysis. Relative mean deviation between the actual discharge and the calculated value from the method is not more than 5%. The method can provide reference for the calibration of water level-discharge relationship in regular canals.