CAJ | 학술논문

为了定量评估变量灌溉对喷灌机灌水深度和水量分布均匀性的影响，该文通过在圆形喷灌机中安装电磁阀、压力调节器、变频器及变量灌溉控制系统，搭建了圆形喷灌机变量灌溉自动控制平台，评估了均匀灌溉、部分喷头开启式变量灌溉和脉冲式变量灌溉条件下的水量分布特性。结果表明，均匀灌溉条件下，当喷灌机行走速度百分数为20%～100%时，沿径向修正赫尔曼-海因均匀系数和分布均匀系数变化分别为92%～94%和87%～89%，行走速度的影响很小；沿喷灌机旋转方向（周向），修正赫尔曼-海因均匀系数为95%，分布均匀系数为93%，与喷灌机行走速度和测量位置关系不大；通过控制喷灌机行走速度可以获得准确的灌溉水深。变量灌溉条件下，喷灌机周向水量均匀性不变，但径向水量均匀性降低。与均匀灌溉相比，部分喷头开启式变量灌溉的径向修正赫尔曼-海因均匀系数和分布均匀系数分别降低10和19个百分点，降低程度随喷头分组数增加而增大。与均匀灌溉相比，脉冲式变量灌溉的径向修正赫尔曼-海因均匀系数和分布均匀系数分别降低9和12个百分点，降低程度与相邻管理区内的灌水深度差呈正相关。为保证变量灌溉管理区内的径向修正赫尔曼-海因均匀系数≥85%，部分喷头开启式变量灌溉需在管理区两端分别设置0～3m的过渡带，脉冲式变量灌溉需设置0～4m的过渡带。变量灌溉条件下通过调整喷灌机行走速度控制灌溉水深的精度与喷灌机行走速度和电磁阀占空比有关，部分喷头开启式变量灌溉灌水深度平均低估0.48 mm，脉冲式变量灌溉平均低估1.46 mm。
위료정량평고변량관개대분관궤관수심도화수량분포균균성적영향，해문통과재원형분관궤중안장전자벌、압력조절기、변빈기급변량관개공제계통，탑건료원형분관궤변량관개자동공제평태，평고료균균관개、부분분두개계식변량관개화맥충식변량관개조건하적수량분포특성。결과표명，균균관개조건하，당분관궤행주속도백분수위20%～100%시，연경향수정혁이만-해인균균계수화분포균균계수변화분별위92%～94%화87%～89%，행주속도적영향흔소；연분관궤선전방향（주향），수정혁이만-해인균균계수위95%，분포균균계수위93%，여분관궤행주속도화측량위치관계불대；통과공제분관궤행주속도가이획득준학적관개수심。변량관개조건하，분관궤주향수량균균성불변，단경향수량균균성강저。여균균관개상비，부분분두개계식변량관개적경향수정혁이만-해인균균계수화분포균균계수분별강저10화19개백분점，강저정도수분두분조수증가이증대。여균균관개상비，맥충식변량관개적경향수정혁이만-해인균균계수화분포균균계수분별강저9화12개백분점，강저정도여상린관리구내적관수심도차정정상관。위보증변량관개관리구내적경향수정혁이만-해인균균계수≥85%，부분분두개계식변량관개수재관리구량단분별설치0～3m적과도대，맥충식변량관개수설치0～4m적과도대。변량관개조건하통과조정분관궤행주속도공제관개수심적정도여분관궤행주속도화전자벌점공비유관，부분분두개계식변량관개관수심도평균저고0.48 mm，맥충식변량관개평균저고1.46 mm。
Application uniformity coefficient is an important parameter to quantify the quality of water distributions. When applying variable rate irrigation through a center pivot sprinkler system, the uniformity of water application both in the direction of pivot travel and along the pivot lateral within each management zone is greatly concerned. In this study, a variable rate irrigation (VRI) system was retrofitted from one three-span (140 m) conventional center pivot system outfitted with 34 rotating sprinklers spaced at 4.2 m through installing solenoid valve, pressure regulator, frequency transformer and control software. The performance of the constructed VRI system was evaluated under 3 typical operating conditions: all sprinklers on, partial sprinklers off, and sprinklers regulated by “on/off” pulsing of the solenoid valves. Catch-cans were arranged in transect, arc-wise, and grid patterns to test the accuracy of application depth in the direction of pivot travel and along the pivot lateral. The results indicated that the modified Heermann and Hein uniformity coefficient (CUHH) and the lower quarter distribution uniformity (DUlq) along the pivot lateral ranged from 92% to 94% and from 87% to 89%under condition of all sprinklers on, respectively, when the pivot rotation speed was changed between 20%and 100% of the full speed. This suggested a minor influence of moving speed of center pivot on application uniformity along the pivot lateral. In the direction of pivot travel, a uniform water distribution was observed with CUHH 95%and DUlq 93%regardless of pivot rotation speeds and measuring locations. A target water application depth could be obtained accurately through setting a specific rotation speed of the pivot. Under the conditions of variable rate irrigation, uniform water distributions in the direction of pivot travel were received with the uniformities similar to the values under all sprinklers on. However, the CUHH and DUlq values along the pivot lateral were reduced by 10 and 19 percentiles for partial sprinklers off, respectively, decreasing with an increasing number of sprinkler banks. The CUHH and DUlq values were reduced by 9 and 12 percentiles when sprinklers were regulated by “on/off” pulsing of the hydraulic valves. This reduction was positively related to the difference in application depth between the adjacent management zones. Application uniformity was impacted at the border of adjacent irrigation zones along the pivot lateral when the zones were applying different irrigation depths. To guarantee CUHH≥85%within each management zone along the pivot lateral, a 0 to 3 m wide buffer zone should be implemented between adjacent irrigation zones when partial sprinklers were turned off, and a 0 to 4 m wide buffer zone should be used when sprinklers were regulated by “on/off” pulsing of the hydraulic valves. The accuracy of application depth obtained through regulating moving speed of variable rate center pivot irrigation system was related to pivot speed and duty cycle of solenoid valve. Overall, the actual application depth was 0.48 mm and 1.46 mm underestimated when variable rate irrigations were achieved by partial sprinklers off and by sprinklers regulated by“on/off”pulsing of the hydraulic valves, respectively.