| 摘要 |
Processed measurements are provided by at least one pressure head sensor (SN) in a collecting drain (C1), and a plurality of flow velocity sensors obliquely arranged at various selected levels (L1, L2) in the drain. An acquisition unit (15) operates at a sampling rate of 1/30 to 1 Hertz. A processor (18) performs a selection among the velocity measurements on the basis of predetermined conditions, concerning velocity measurements at various levels and a pressure head measurement, at various times, whereby significant changes of a hydraulic nature may be recorded while variations such as random disturbances are ignored. The processor (18) advantageously selects at least some of the velocity measurements that indicate a substantial difference between two levels, and preferably further selects at least some of the velocity measurements that indicate a substantial instantaneous change at a single level. |
