FFZ-01Z Digital Water Surface Evaporation Station

1 Overview
The FFZ-01Z Digital Water Surface Evaporation Station is manufactured in accordance with the Ministry of Water Resources and Electric Power's "Water Surface Evaporation Observation Specification" SD265-88 and the China Meteorological Administration's 2003 edition "Ground Meteorological Observation Specification." It is used for automatic observation of the water surface evaporation process.
The term "Digital Water Surface Evaporation Station" refers to an evaporation station where all components—the evaporimeter, rain gauge, overflow bucket, data acquisition control process, and water replenishment process—are fully digitized for observing water surface evaporation.
The resolution of both the evaporimeter and rain gauge in the FFZ-01Z Evaporation Station is 0.1mm, and the overflow resolution is 0.025mm, meeting the high-level requirements of relevant national standards. The data formats for precipitation and evaporation comply with the requirements for data storage and compilation. It can be used to equip various types of water surface evaporation observation stations, replacing tedious and complex manual observations and enabling automatic observation and recording of water surface evaporation.
The FFZ-01Z Evaporation Station can be connected to a GPRS data transmission device to form a telemetry station.
This station's equipment is limited to use during non-freezing periods.
Devices such as the evaporimeter, rain gauge, and overflow bucket in this station should undergo regular maintenance as required by the relevant product manuals.
2 Working Principle
This evaporation station system uses the evaporimeter, rain gauge, and overflow bucket as basic observation tools. The data logger automatically collects, processes, and displays information on evaporation, precipitation, and overflow processes, and automatically controls the water replenishment and drainage processes of the evaporation bucket and overflow bucket. The data logger connects to the upper computer system and data transmission communication equipment (RTU) via RS485/232 communication interfaces. Using the system's supporting application software, remote monitoring of water surface evaporation process information and data compilation for storage can be achieved.
During operation, the water level in the evaporation bucket should be maintained at the water level marker line. On non-precipitation days, the data logger automatically collects changes in the water surface height in the evaporation bucket to calculate evaporation. Whenever the water surface height in the evaporation bucket drops to a predetermined value (10mm below the water level marker line), the data logger controls the replenishment pump B3 to operate at the observation day boundary time (hydrological boundary at 8:00, meteorological boundary at 20:00), automatically replenishing water to the evaporation bucket and water ring to restore the water level to the marker line height. The height after replenishment is then used as the starting point for measuring evaporation in the next period.
On precipitation days, when the water level in the evaporation bucket rises to a predetermined value (10 mm above the water level marker line), the data logger activates the overflow pump B1 to divert water from the evaporation bucket into the overflow bucket. When the water level in the overflow bucket reaches the predetermined value, the overflow process ends. After collecting and calculating the overflow data, the data logger starts the overflow bucket drainage pump B2 to drain water from the overflow bucket to the predetermined base water height.
According to the "Water Surface Evaporation Observation Specification" and the China Meteorological Administration's "Ground Meteorological Observation Specification," the formula for calculating evaporation is:
Evaporation = (Evaporation bucket water level measurement value - Evaporation bucket water level initial value) + Precipitation - Overflow
This formula can be simplified as:
QF = (Wt - W0) + Qj - Qy
Where: QF: Represents water surface evaporation, unit: mm
Wt: Represents the evaporation bucket water level at measurement time (t), unit: mm
W0: Represents the evaporation bucket water level at the initial time, unit: mm
Wt and W0 values are automatically measured by the FFZ-01 Digital Water Surface Evaporimeter.
Qj: Represents precipitation during the measured period. The Qj value is provided by the JFZ-01 Digital Rain Gauge, unit: mm
Qy: Represents overflow during the measured period. The Qy value is automatically measured by the overflow bucket, unit: mm