it shows that the flow formula in the measuring
building used today has been used since the building
was built and has never been adjusted until now. In
order to obtain the actual flow coefficient from the
current condition of the measuring structure, it is
very necessary to carry out an analysis of the flow in
the existing measuring structure. The results of this
study can be an important reference related to the
actual flow coefficient so that the distribution of
water by measuring structures is the same as that
required by farmers for irrigating their fields. Thus,
the results of this study can also be used as a guide
for the operation and maintenance system of
irrigation areas in the Mambal irrigation area. The
problem in this research is what is the flow
coefficient applied to the existing measuring
building and what is the actual flow coefficient
based on the test results? The purpose of this study
is to determine the currently applied coefficient and
compare it with the actual flow coefficient of the
measurement results
2 METHOD
Calibration is one of the steps to determine the
stability of a measuring object to get the actual
measurement results. (Shock, Barnum, and Seddigh
1998), (Collectives n.d.), (Santos et al. 2021). The
research was designed for six months by conducting
research activities both in the field and analytically
involving a research team of lecturers and students.
Field research was carried out by coordinating with
several parties including the Bali Provincial Public
Works Service and irrigation observers based in
Lukluk Kapal. Coordination is carried out to
determine the timing of the implementation of the
instantaneous discharge measurement so that it does
not interfere with irrigation operations that are
already running. While the analysis is carried out by
analyzing the instantaneous discharge juxtaposed
with the flow formula in a measuring building. Field
surveys to determine the condition of the measuring
building include: the location of the measuring
building. difficulty level of measurement, temporary
method of measurement, physical condition of
measuring building, current flow formula and
problem of measuring accuracy of building
Measurement of instantaneous discharge is
carried out in several ways depending on the needs
and field conditions, for example with a current
meter, buoys and others (Setiawan and Purwanto
2018), (Indonesian National Standard 2015).
Instantaneous discharge measurement requirements
are carried out with the following requirements: in a
straight location, not affected by trees or roots,
evenly distributed and it is estimated that there is no
circular velocity distribution, there are no other
factors that can cause a sudden rise in water level,
the measurement depth should be 3 times to 5 times
the diameter of the propeller. Measurement
personnel requirements: have experience in taking
measurements at least in the same job and have
received instructions on how to measure before and
have a healthy body condition (Busscher 2009)
(Jaiswal et al. 2012) (Kroc and Zumbo 2018), (Liu
and Henze 2005)
Examination of the current meter includes that
the battery used is new, the panel is visible when the
measurement is taken, when taking the
measurement, it is expected to wear a life jacket,
there is a handle that can be used in an emergency
and a measurement form is available
Figure 1: Current Meter.
Calibration is an activity to test the current ar
flow formula by comparing the factual discharge
with the theoretical discharge. The series of
activities include determining the measurement
point, measuring the cross-sectional width,
determining the depth of the water, measuring the
instantaneous discharge, analyzing the instantaneous
discharge and calibration.
The steps of calibration activities start from
building inventory, instantaneous flow
measurement, discharge analysis and calibration.
Instantaneous discharge measurements are carried
out at least 10 times to obtain valid measurement
data. Complete calibration steps as shown in Figure
2.