Dutch water utility computerizes groundwater measuring system
The Dutch water company Waterleiding Maatschappij Limburg (WML) recently made a decision to computerize fully its groundwater monitoring and measuring instrumentation network. It is the first water utility in Holland to upgrade its system in this way, and contracted with two Dutch companies, Van Essen Instruments and IWACO, to undertake the project.
Waterleiding Maatschappij Limburg's management had been looking for a suitable monitoring system for some time. What they sought was instrumentation of advanced design that would monitor the groundwater level accurately, and also have the capability to function for about 10 years without maintenance. In addition, the information system to be acquired by WML for monitoring the network, known as DAWACO, had to be able to read and process the data easily.
The practice until recently has been to measure manually the groundwater levels in the aquifer the water utility uses as its source of raw water. The twice-a-month procedure involved reading a large number of gauges, a method that is very labor-intensive and prone to errors due to the inconsistencies in the manual measurements.
After extensive review of available products and discussions with the manufacturers, the WML management decided to select an instrument called the Diver that met the requirements. Developed by Van Essen Instruments, the unit is small and fits easily into the existing 1-in. gauge sleeves. It has a proven ability to provide readings of high accuracy, and the life of its built-in battery is at least 10 years.
Groundwater levels are measured using an adjustable frequency signal, and the collected data are stored in the device's memory. The instrument then can be read out at any chosen time. Since in addition to the groundwater level reading being stored the exact time of the measurement also is registered, WML staff members now have the ability to compare the groundwater levels across the water utility's entire extraction area at exactly the same time. As a result, much more accurate and reliable accurate information is available than was previously the case.
Modified data loggers will process information immediately
Under the terms of the contract, Van Essen Instruments are supplying 900 of the Diver groundwater data loggers, and the IWACO organization is modifying these modules so that once installed in the DAWACO measuring network information system they can process the collected groundwater data immediately. In addition, complementary software has been developed which speeds up and simplifies the fieldwork considerably. This software also has been modified to allow handheld computers to be used at the measuring locations rather than laptops if so desired. The completed measuring network of Diver units is expected to be fully functional this year.
The entire package has a modular structure and has a built-in versatility that will be used in the future to incorporate the ability to measure water quality parameters, and to adapt the system for telemetry. The latter is a recent development which Van Essen Instruments currently is demonstrating as a participant in the Waterstad 2000—or Watercity 2000—project.
Watercity 2000 is a Dutch pilot project intended to test and implement an innovative, technically advanced system of measurement that will produce an integrated water management program in the Delft region. The objective of the project is to use advanced technology to gain knowledge about the quality and quantity of the various types of water resources within the hydrologic cycle of the area. This information would be readily accessible so that water and wastewater managers can integrate their operational functions and predict water supply situations.
For further information please contact Martin Haasjes of Van Essen Instruments in Holland at Tel. 015-275 5012; or via e-mail at vanessen@vanessen.com.
Edited by Ian Lisk
Editor Emeritus, Water Online