Study on Construction and utilization of a comprehensive lake water quality database system

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Monitoring is a fundamental step to understand water quality conditions in lakes, and many lakes have been storing a huge amount of water quality data. However, these past records are not effectively used. This research project aims to develop a new water quality database system, which possesses almost all data recorded in a target lake with functions to use them skillfully, and satisfies not only the general public, but also specialists. Lake Biwa was chosen as the research lake.Then, past and present investigation projects in Lake Biwa were surveyed and their water quality data were collected and analyzed.The results indicate these investigations have various and different patterns on their investigation methods; the number of sampling stations ranges 1 to 5, that of depths ranges 1 to 12, that of times in a year ranges 1 to 365, and that of measured items ranges 8 to 100 more. The whole projects identified 86 different sampling stations and 44 different depths in the lake. The variety of investigation methods suggested that simple spread sheet can not handle the whole data systematically, and that the use of a relational database application software is needed. Then, Access 2000 was introduced to organize all of the data.The constructed database consists of one main table, two sub-main tables and seven minor explanatory tables, and has stored 670,000 WQI data for 50,000 samples from 15 survey projects. Its application softwares were also developed with the help of VBA (Visual Basic for Application) for general users who are not familiar to Access. This system has high flexibility on the data management and application, so that further extension of the system can be easily achieved.