System for realizing automatic-balancing sensing and control of water level of lysimeter

Abstract

The invention relates to the automatic control device for underground water level, particularly to a system for realizing automatic-balancing sensing and control of a water level of a lysimeter. The system is composed of a U-shaped tube with liquid mercury, adjustable screw rods, adjustable contacts, a fixed contact arranged at the bottom of the U-shaped tube, a control valve, a water supply and measuring device, and a draining and measuring device. The adjustable screw rods and the adjustable contacts enable the liquid mercury and normally-closed electromagnetic relays to be connected. An upward opening is formed in the bottom of the U-shaped tube; and the fixed contact is arranged inside the opening at the bottom of the U-shaped tube and is connected with positive electrodes of the electromagnetic relays by wires. Outward openings are formed in the middle of the vertical tube walls at the two sides of the U-shaped tube; the water supply and measuring device is connected with the openings at the two sides of the U-shaped tube by conduits and is connected with an inlet and drain pipe buried in field by a flow control valve. The input terminals of the electromagnetic relays employ 3-V voltages. The U-shaped tube, the lysimeter, and the water supply and measuring device are connected in sequence. A water level observation well is arranged inside the lysimeter.

Description

technical field [0001] The invention relates to an automatic groundwater level control device, in particular to a system for automatically balancing, sensing and controlling the water level of a lysimeter, and more specifically, to a system suitable for areas where the groundwater level is shallow and changes rapidly, and is based on communication The principle of the lysimeter ensures that the lysimeter and the groundwater level of the field change synchronously, and the automatic balance sensor and control system of the lysimeter water level. Background technique [0002] In areas with shallow groundwater levels, groundwater recharge is an important component of crop water demand, which can reach 15% to 95% in some cases; under irrigation conditions, deep seepage can also reach about 10% or even higher of water demand. Due to the difficulty in measuring the amount of groundwater recharge and deep seepage in the field, the use of bottom lysimeter is a common method to study...

AI Technical Summary

Problems solved by technology

Domestically, Liu Shiping was the first to design the method of moving the Martens jar up and down along the vertical guide rail to keep the internal and external water levels equal. However, manual observation of the water level and operation are still required. The workload is heavy, the equipment is complicated, and the investment is also high.

[0003] At present, when using lysimeters for research, the method of setting a fixed internal water level for a specific period of time is often used. The technology is also mature, but this does not match the reality of frequent changes in groundwater levels caused by rainfall and drainage in the southern region

It is technically feasible to measure and compare the internal and external water levels by using a water level sensor, and automatically control it through a microcomputer, but the construction and maintenance costs are high, and there are not many practical applications in China.

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