Document Type


Date of Degree

Fall 2015

Degree Name

MS (Master of Science)

Degree In

Civil and Environmental Engineering

First Advisor

Larry J. Weber

Second Advisor

Antonio A. Amado

First Committee Member

A Allen Bradley


This thesis explores the potential impacts of the implementation of best management practices (BMPs) in Upper Roberts Creek (URC) watershed in northeast Iowa as part of the Iowa Nutrient Research Center (INRC). The INRC was formed in response to the United States Environmental Protection Agency (EPA) requirement that the states along the Mississippi River develop and implement strategies for reducing the nutrient load leaving their states and entering the Gulf of Mexico. The impacts of BMP implementation in URC were evaluated through the use of HydroGeoSphere which was used to develop a three dimensional, coupled surface/subsurface model of the watershed.

The URC model was used to evaluate the hypothetical impacts of the widespread implementation of cover crops on agricultural land within the watershed, the construction of eight Iowa Conservation Enhancement Reserve Program (CREP) style wetlands, and the combination of these two BMPs. Through the comparison of these simplified, hypothetical scenarios to a baseline condition, potential nitrate load reduction estimates were made for each practice or combination of practices. These estimates indicate that neither of the individual practices would be likely to achieve the nitrogen reductions targeted by the EPA and in order to achieve these goals a combination of practices would likely be required.

Public Abstract

Excess nutrients in waterways and waterbodies can cause significant problems for the aquatic life which live in them and the people who live nearby. In the Gulf of Mexico each year a large area develops that is devoid of aquatic life, colloquially called the “Dead Zone”. This area is a result of the nutrients which flow from the agricultural Midwest. In an effort to reduce the amount of nutrients flowing out of Iowa into the Gulf of Mexico, this thesis seeks to understand how much of an impact a single watershed plays and what could theoretically be done to ensure more of these nutrients stay on the landscape. The two practices explored in this thesis are the use of cover crops which are grown between fall harvest and spring planting and the construction of new wetlands in the watershed.


publicabstract, HydroGeoSphere, Hydrology, Nitrate Modeling, Watershed Modeling


xii, 138 pages


Includes bibliographical references (pages 132-138).


Copyright 2015 Karl Hoover Brauer