Automatic filling and emptying of a water evaporation pan

Abstract

The class A pan is used universally to estimate water evaporation for large reservoir water level control, for irrigation purposes, for predicting field drying of agricultural crops or simply for water budget calculations. Water level can be monitored automatically with a floating-type water level gage. However, it is important to re-establish the water level at a standard height each day. A control module with inflow and outflow solenoid valves was designed and adapted to a class A pan to correct the water level at a fixed time interval defined by the user. The water level was brought back to the standard level within 5 or 6 min after typical daily rainfall or evaporation. The system was stable provided the error tolerance was above the accuracy of the water level gage (±0.2 mm in the present system).