Sampling Description
Ultrasonic water level recorders are placed at each site. The recorders collect water level readings every hour. The data is collected from the water level recorder using an HP 48G+ calculator on a monthly basis. To make a daily water depth reading, all numbers are downloaded into Microsoft Excel, and all the readings from a day are averaged. Water depth data is then transformed from inches to centimeters by multiplying the numbers by 2.54. Data from 29-Aug-97 to 25-May-00 were collected using a Richards Type Water Level Recorder. From 31-Aug-00 to 12-Oct-00 both the Richards Type and Ultrasonic water level recorders collected water level data to calibrate data from the Richards Type Water Level Recorder. A regression of data from both recorders was performed to calibrate data from the Richards Type Water Level Recorder to the Ultrasonic water level recorder data. From June 2004, water levels are recorded using an Infinities Pressure water level gauge. The new device was calibrated to the values from the Acoustic before removal.
Method Step
Instrumentation
Infinities USA, INC Ultrasonic water level recorders Model #220 HP 48G+ calculator Dell 3800 notebookRichards Type Water Level Recorder Model 6511Infinities USA, INC Pressure water level recorders
Quality Control
Data that is downloaded from the Infinities water level gauges (WLG) is first checked for "Out of Range" values (they are deleted) (using the "Go To" command). Then the data is checked for negatives (values given especially during dry season). Negatives that are found are converted to zeros (modified Find and Replace). Next the data is checked for peaks and valleys (values that are found to be excessively high or low). Before the data is averaged per day the last data check is to see if a negative number (now a zero) causes a peak or valley (which are deleted as a peak or valley). The next several formulas are used for these checks, averaging the data set, and anomoly investigation: [=IF({time}=0,AVERAGE({24 values}),"")], [=IF(COUNT({24 values})>=22,"",{date at zero time})], [=IF(COUNT(D8:D10)>=2,IF(OR(ABS(D8-D9)<2,ABS(D9-D10)<2,D9=""),""),"")], [=IF(ISNUMBER(D9),IF(D9<>0,"",IF(AND(ABS(D9-D8)<2,ABS(D9-D10)<2),"")),"")].