Development of a Digital Recording System for Automation of Class A Evaporation Pan Measurement
Abstract
Adapting a sensor for automation of pan evaporimeters will increase reliability and accuracy of evaporation measurements especially in areas where data reliability is questionable. This research was aimed at developing and calibrating a digital recording (water level sensing device) system for use with Class A pan. A simple quadratic equation (calibration curve) was fitted between the sensor’s recorded depth and manually recorded depth (R2 > 0.98; F = 4388; P < 0.0001). The system performance was evaluated on the basis of its accuracy in measuring water depth when compared with readings from manual observations. Two accuracy parameters, correlation coefficient (R) and mean bias error (MBA) were used to indicate this accuracy. A high R > 0.97 and MBA of 0.19 mm/day was obtained between the digital sensor values and manual readings of pan evaporation for the months of March while R > 0.97 and MBA of 0.15 mm/day was estimated for the month of April. The high correlation coefficient between pan evaporation values from digital sensor and the Manual method is an indication of the accuracy and sensitivity of the developed digital recording system for Class A pan evaporation measurement. The result of this study offers an opportunity for a near real-time evaporation measurement.
