Analisis koefisien debit bangunan ukur debit ambang lebar saluran sekunder jamur wetan dan jamur kulon daerah irigasi Karangtalun Yogyakarta

The irrigation system is a crucial role in regulating soil water availability to support crop growth and optimize yields. One of the essentialinfrastructuresinanirrigationwaterdistributionnetworkisthe wide-crested weir structure, which functions to monitor water discharge. However, field operations of these measurement structures often face technical constraints in the form of sedimentation accumulation due to the weir's elevation being higher than the upstream channel, thereby triggeringadegradationindischargereadingaccuracy.Thisstudyaims to analyze the discharge coefficient (Cd) values obtained from direct measurements, compare them with the SNI 8137-2015 standard, and formulate the calibration rating curve equation for wide-crested weir flow measurement structures. The research method applied is quantitative, involving the collection of primary data, including the physicaldimensionsofthe rectangularchannelsand directflowvelocity measurements using a current meter. The actual discharge in the field was calculated using the mean section method. The results of the data processing are expected to present the actual field discharge coefficient (Cd) valuesand theoretical values based onthegraphical correlation of dimensionalratioparameters. The constructed mathematical function of the calibration rating curve (Q = A(H+) will serve as an effective evaluation instrument to predict flow discharge fluctuations practically through water level readings alone. In practice, the output of this research is intended to improve the accuracy of water discharge distribution calculations. The discharge coefficient value at the board-crested weir on the jamur wetan secondary channel is 0,76.