Document Type


Date of Degree

Summer 2013

Degree Name

PhD (Doctor of Philosophy)

Degree In

Interdisciplinary Studies in Water Quality Monitoring and Policy

First Advisor

Rajagopal, Rangaswamy

Second Advisor

Skopec, Mary P.

First Committee Member

Osterberg, David

Second Committee Member

Schnoor, Jerald

Third Committee Member

Stensvaag, John-Mark

Fourth Committee Member

Wichman, Michael

Fifth Committee Member

Zhang, You Kuan


High frequency water quality monitoring presents unique and unlimited opportunities of exploring spatio-temporal variation in water quality. Knowledge gained from analyzing high frequency water quality data can provide more clarity regarding transportation and processing of water constituents over time and space and scale. This study analyzes high frequency discharge, nitrate load and concentration data for three watersheds of different sizes - Cedar River Watershed, North Raccoon and Middle Raccoon. Each of these sites were monitored for 2-3 calendar years.

Sudden spikes in discharge, nitrate concentration and load data, also defined as "events" were analyzed in great detail to understand the patterns in event occurrence and event intensity. Smaller watersheds seemed to have sharper and "flashier" events compared to bigger watersheds. Nitrate concentration events were flatter in shape compared to discharge and nitrogen load events. The relationship between nitrogen concentration and discharge was found to be varying over time, unlike the relationship between nitrate load and discharge, which were almost perfectly correlated for most site-year combinations.

Based on more than 40,000 simulations, it was determined that high frequency water quality sampling is not only efficient in capturing minute spatio-temporal variations but can also capture nitrate exceedances to a greater degree. High frequency sampling was also associated with higher yield ratio in nitrate load estimates, not only during high flow periods, but also during the non-high-flow period.


Clean Water Act, high-frequency monitoring, Iowa, nitrate, River, Safe Drinking Water Act


xvi, 204 pages


Includes bibliographical references (pages 186-204).


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Copyright 2013 Malini Banerjee