Dr. Niemann's research interests are in hydrology and geomorphology. His research includes analyzing and modeling the interaction of soil moisture and topography, characterizing river network properties, modeling the long-term evolution of river basin morphology, uncertainty estimation in geomorphic models, evaluating evapotranspiration from shallow groundwater, modeling the hydrologic response of urban and natural basins, and assessment of climate change impacts on regional hydrology. He has contributed to several projects to improve the drinking water, irrigation, and wastewater systems for rural communities in Kenya, Gabon, Guatemala, and El Salvador.