CONTINUOUS REAL-TIME WATER-QUALITY MONITORING OF KANSAS STREAMS

摘要

A continuous, real-time water-quality monitoring system was developed for 13 stream sites in Kansas thateliminates the waiting time inherent in chemical analyses reported by a laboratory and provides continuous estimates ofconstituent concentrations and loads. The U.S. Geological Survey (USGS) monitoring system is described, and itseffectiveness in characterizing water quality is evaluated using discrete water-quality samples collected from 1995 through2002 and continuous water-quality monitor data from the first 4 years of operation with examples from two stream sites onthe Little Arkansas River in south-central Kansas. Because sensor technology currently is not available to directly measuremany chemicals of interest in a stream, regression models are developed to relate constituents in laboratory-analyzed sampleswith in-stream continuous-sensor measurements. Concentration estimates traditionally have used continuous streamflow dataonly; however, most constituents are more accurately estimated with continuous specific conductance or turbiditymeasurements. As the hourly sensor measurements are transmitted from the stream sites to the USGS computers inLawrence, Kansas, the models are applied, and the computed estimates displayed on a Web page athttp://ks.water.usgs.gov/Kansas/rtqw/. Currently, continuous estimated concentrations and loads of sediment, major ions,select nutrients, atrazine, and indicator bacteria, and uncertainty of the estimates are displayed. Information from this systemis used by water suppliers to modify treatment of water, by State and local agencies in total maximum daily load (TMDL)programs, and to alert recreational water users of potential health risks.