или даже "plopper tape"

In case of instrument failure, depth to water will be measured by a plopper tape, which is a bell- or
cup-shaped stainless-steel weight (plopper) attached to a nylon-clad, stainless-steel or fiberglass
tape. When lowered into the well, a "plopping" or "popping" sound is made when the weight
strikes the surface of the water. The depth to water can be determined by lifting and lowering the
weight in short strokes, and reading the tape when the weight just strikes the water.
https://semspub.epa.gov/work/05/346834.pdf

и здесь стр. 9: http://www.davidson.com.au/Uploads/file/Environmental-Indust...

еще ссылки: https://in-situ.com/product-category/water-level-monitoring/...

на русском: https://studopedia.ru/17_137621_pribori-dlya-izmereniya-i-re...