| Furrow irrigation is a commonly used irrigation technique for cultivating crops,but the quality of irrigation is still a major problem at present.In order to further improve irrigation quality of furrow irrigation,this paper adopts a technical route combining experimental re-search,theoretical analysis and numerical simulation to analyze the impact of field roughness on furrow irrigation flow and irrigation performance,and establish soil pedotransfer functions for estimating infiltration parameter normalization factors,put forward the irrigation technology element optimization combination of typical field,and achieved the following main research conclusions:(1)Based on the measured data of farmland soil in Guanzhong area of Shanxi Province,the spatial variability of soil physical parameters and infiltration parameters was analyzed.The results showed that the spatial variability of soil clay,sand content in Guanzhong area was greater than that of silt content and bulk density;The infiltration coefficient k of kostiakov for-mula had a strong spatial variability,and its a coefficient of variation of 0.707.The spatial var-iability of ? is relatively weak,and its coefficient of variation is 0.372.It can be explained that the infiltration coefficient k can be used to reflect the spatial variability of soil infiltration char-acteristics in the study area to some extent.(2)Based on the experimental data of corn furrow irrigation in Guanzhong area of Shaanxi Province,numerical inversion method was used to estimate the soil infiltration param-eters and field roughness values of each experimental farmland,and its reliability was verified.The results showed that the simulation of the process of furrow irrigation based on the obtained inversion parameters showed a high consistency with the field measured values,and the abso-lute values of relative errors were 3.90%and 6.41%;Explain the use of furrow irrigation flow advancing process and ditch head water depth data,and the use of SIPAR_ID software to invert soil infiltration parameters and field roughness is feasible and has high reliability.(3)Numerical simulation method was used to analyze the effects of different field roughness values on the process and irrigation quality of furrow irrigation.The results show that the simulated water flow curves and irrigation quality evaluation indexes of the typical field with different values of field roughness(n=0.041,0.075,0.178)are consistent with the measured values,and the absolute values of relative average errors are smaller than 14.00%;At the same time,when n=0.075,the absolute value of the relative error is smaller than the other two scenarios;It shows that the impact of field surface roughness on furrow irrigation flow process and irrigation quality is relatively small,and the field roughness in corn furrow irriga-tion process can be 0.075 as a typical value.(4)A soil pedotransfer functions was established to estimate the normalized factor F of the Kostiakov formula.The effects of different soil infiltration parameters and field roughness on the quality of furrow irrigation were analyzed,and put forward the irrigation technology element optimization combination of typical field.The results showed that the soil pedotransfer functions of the normalized factor was highly reliable,the mean absolute value of the relative error between the estimated value and the actual value was 3.120%;The comprehensive irriga-tion performance indicator of furrow irrigation are basically consistent under different values of soil infiltration parameters and field roughness,further indicating that the spatial variability of soil infiltration characteristics in the study area can be reflected by the infiltration coefficient k,and 0.075 can be used as the typical value of the field surface roughness in corn gully irrigation;It is recommended that the furrow length should not exceed 50m,and flow into the furrow should be 3-41/s of typical field in Guanzhong region.This optimization result is only applica-ble to the case where the planned irrigation quota is 55mm,the water conversion number is 1 and the tail is closed.For other optimization of ditch length and ditch flow rate under other ir-rigation quota conditions,similar methods can be used to optimize the study.It needs to be pointed out that the effects of factors such as time of stopping irrigation and field slope on the flow process and irrigation quality of furrow irrigation were not taken into consideration;At the same time,the furrow length recommended in the research only proceeded from the perspective of improving irrigation quality of furrow irrigation,without considering the factors such as farmland mechanical cultivation efficiency.Further research is going to need for the irrigation technology element optimization combination under more complicated factors and combinations. |
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