A water level measurement using an interdigital capacitive sensor with low-cost, low-energy, good
repeatability, high linearity, and ease of installation is proposed with a support of experimental results.
This sensor comprises a printed circuit board (PCB) with configuration of two interpenetrating comb
electrodes. The comb electrode is 70–80 mm width, 300 mm height with 1–2 mm spacing between each
comb. This configuration of electrode causes the capacitance between comb electrodes to vary by the
water level. Microcontroller is used to calculate the capacitance between comb electrodes in terms of a
discharge time correlated to the water level. A practical water level measurement technique using two
comb electrodes designated as level and reference sensors is presented. This technique can directly be
applied to water with different conditions without recalibration. This sensor is able to measure absolute
levels of water with 0.2 cm resolution over 30 cm range. In addition, it is also sensitive enough to trace the
variability of water level. A flood monitoring simulation is carried out in wave flume where this sensor
is used to detect the rising wave.