WINSCAR DAM - 24 YEARS OF MANUAL SEEPAGE MEASUREMENT REPLACED BY AUTOMATION

摘要

Winscar dam is a 53 metres high rockfill dam with an asphaltic concrete membrane. Seepage through the dam is collected into foundation drains that are piped to measurement chambers at the downstream toe. Seepage flows were recorded manually until 1999, and plotted against reservoir level and rainfall. On first filling the total seepage increased significantly when the water reached permeable sandstone. The reservoir was held down for grouting and then emptied for repairs to a hole in the membrane. By 1998 the seepage was 2 200 m~3/day and although this was lower than during the early years, there was nevertheless a rising trend. Loss of data and a change in measuring frequency hindered interpretation of behavioural patterns. Improvements to the seepage measurement system were put in place in 1999 with four new chambers and improvements to four others. The new system incorporates automated measurement of rainfall and flows. Ultrasonic instruments measure head over vee-notches at 15-minute intervals, which are then sent via telemetry to the owner's database. The original seepage measurement system has proved to be robust and invaluable in monitoring the performance of the dam. Advances in data handling and instrumentation mean that its usefulness can be maintained and improved.