INEXPENSIVE ELECTRONIC WATER-LEVEL RECORDERS FOR HYDROLOGIC STUDIES

Hydrologic investigations typically involve the collection of water le vel measurements at discrete points in space and time. The high cost o f commercial electronic recorders can be a burden. We have developed a n inexpensive ((similar to)$200) electronic water level recorder consi sting of a Motorola microcontroller, a clock. memory, pressure transdu cers, and associated circuitry. The instrument is powered by a 6-V bat tery. These devices. each capable of monitoring up to eight channels o f analog input, are presently providing continuous monitoring of neste d piezometers, tide gauges, and rain gauges in hydrologic studies at t he Savannah River site and the North Inlet (South Carolina) Long-Term Ecological Research (LTER) site. The instruments can be custom tailore d to record water levels at any specified time interval, or whenever t he water level changes by a specified amount, and can store up to 32,0 00 water level observations. These instruments have been used to condu ct slug tests and can be configured to monitor observation wells for p umping tests. Simplicity of construction and availability of component s offer hydrologists an inexpensive but reliable method of water level recording. Several examples of the use of this instrumentation in div erse hydrologic settings are described.