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<br />OD0485 <br /> <br />5 <br /> <br />Data Acquisition and Communication <br />A variety of data will need to be gathered and stored in the data ba~e on <br />real-time or near real-time basis during a flood event, For the most part <br />thi s data wi 11 be exchanged from computer-to-computer us i ng speci a 1 ut i 1 ity <br />programs called communication software, The watershed telemetry systems are a <br />good example of what is involved in acquiring and verifying data. Figure 2 <br />shows the tasks that are required in processing raw telemetry data. <br />To begin with the digital signal must be transformed and verified. These <br />tasks are accomplished by decoding and screening routines. The decoding <br />routine transforms' the digital signal into a recognizable data string and <br />sends the data on for further processing. If the signal cannot be <br />interpretted then it is discarded to an error log for later diagnostic eva- <br />luation. The data is then evaluated for other errors or alarm conditions. <br />This involves conditional testing to see if the data has exceed established <br />threshold values, For example, if the data exceeded the measurement range of <br />the remote sensor then the data would be logged to an error fi le. On the <br />other hand if the data showed an alarm condition then the screening routine <br />would initiate a system alarm. Further processing of the data may be <br />desirable before the data is stored in the data base. A typical example <br />would be conversion of river stage to discharge or a rainfall tipping bucket <br />count to inches of rainfall. <br />Higher level screening is necessary to check the overall performance of <br />the data collection network. For example, data may be missing from a station <br />due to a malfunction. Higher level routines identify this malfunction and <br />readjust the network to compensate for the missing station. Higher levels may <br />allow review and revision of forecast information by an interactive user when <br />human judgment is required to attain an accurate estimate of conditions. <br /> <br />Data Co 11 ect i on <br />The primary "real-time" data on which the forecast is based may consist <br />of forecast information from outside sources (typically NWS), weather radar, <br />and watershed telemetry. Since the watershed telemetry system is the opera- <br />tional responsibility of the flood control manager a description of this net- <br />work is given. The entire data collection task however, needs to consider all <br />data sources required to prepare an effective flood forecast. <br />