Physiographic Regions of Iowa

This map delineates regions and subregions of Iowa that share common landforms, geologic histories, and surface processes, providing a geographic framework for understanding how geomorphology (i.e., the physical form and evolution of landscapes) influences soil properties, hydrology, and land‑use patterns across the state. Each region represents a distinct geomorphic setting defined by its origin, surface materials, relief, and topographic structure, shaped over time by depositional and erosional processes driven by glacial, karst, eolian, and fluvial processes.

These landscape differences directly affect soil characteristics such as texture, drainage, and fertility, which in turn influence hydrologic behavior, including runoff, infiltration, and groundwater flow, ultimately guiding land‑use decisions as certain regions are better suited to specific agricultural systems, conservation practices, or resource management strategies. By distinguishing these interrelated attributes, the maps support land‑management planning, conservation assessment, environmental education, and scientific research, offering a unified spatial framework for interpreting Iowa’s environmental diversity and integrating geological, pedological, and hydrological information in both applied and academic contexts.

Purpose

Each region reflects a distinct geomorphology, defined by its origin, surface materials, relief, and topographic structure. Depositional and erosional processes, including those related to rivers, glaciers, wind, and karst activity, have formed these landscapes. These geomorphic variations affect soil properties, such as texture, drainage, and fertility, which in turn influence hydrologic dynamics, including runoff, infiltration, and groundwater flow. Consequently, landform and soil differences guide land use, with certain regions better suited for specific agricultural practices or conservation efforts.

By distinguishing these interrelated characteristics, the map supports land management, conservation planning, resource assessment, and education. It offers a unified spatial framework for interpreting Iowa’s environmental diversity and integrating geological, pedological, and hydrological data in both research and applied decision-making.

Description

The Geospatial Laboratory for Soil Informatics at Iowa State University created this spatial dataset, combining science and art to provide a unified perspective on the landscape, integrating geology, landforms, soil, water systems, and vegetation. To create the Physiographic Regions Map of Iowa, multiple lines of evidence were synthesized to delineate areas with similar landforms, geologic histories, soil characteristics, and hydrologic patterns. However, delineations were first created by evaluating patterns observed in terrain derivatives calculated from LiDAR-based elevation data (IDNR, 2020a). Interpretation of those areas was then made in consideration of a compilation of foundational maps – including the Outline Map of the Drift Sheets of Iowa (Calvin, 1904), Soils of Iowa (Brown, 1936), Principal Soil Associations (Simonson et al., 1952), Principal Soil Association Areas of Iowa (1965), Quaternary Geology of Iowa (Ruhe, 1969), Principal Soil-Association Areas of Iowa (Fenton et al., 1971), Landform Regions of Iowa (Prior, 1976), Iowa Soil Association Map (Iowa Agriculture and Home Economics Experiment Station, 1978), Highway Guide of Iowa Soil Associations ((Iowa Department of Agriculture and Land Stewardship et al., 2012), and Landform Regions of Iowa (Iowa Geological Survey, 2017). Newer maps carried the most weight.

Terrain derivatives, including slope gradient, profile curvature, and relative elevation, were computed from the LiDAR-derived digital elevation model (DEM) and integrated with a digital hillslope position classification (Miller and Schaetzl, 2015). Areas within Iowa’s state boundary (IDNR, 2020b) exhibiting similar topographic patterns were delineated and correlated with existing soil and landform knowledge. These subregions were grouped into regions by similarity. The naming of subregions utilized established nomenclature, first, and then referenced representative towns. Descriptive terms were added to subregion names based on relative relief.

The delineated regions were evaluated for differentiation of soil properties and hydrologic behavior. Spatial statistics were applied to summarize data from existing soils (NCSS, 2025), stream networks (IDNR, 2024c), and land cover maps (USDA-NASS, 2024).

GIS Data

Shapefiles for this data set are available on the Iowa State University Data Share website. The full package posted in that repository includes statistics for differentiating characteristics between subregions, complete metadata, and PDFs for high-quality printing.

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Terms of Use

CC BY-SA

This license enables reusers to distribute, remix, adapt, and build upon the material in any medium or format, so long as attribution is given to the creator. The license allows for commercial use. If you remix, adapt, or build upon the material, you must license the modified material under identical terms. CC BY-SA includes the following elements:

BY: credit must be given to the creator.

SA: Adaptations must be shared under the same terms.

Spatial Reference Information

Coordinate System: NAD 1983 UTM Zone 15N (WKID 26915)
Geographic Extent: -96.684901, -90.069432, 40.332776, 43.557019
Datum/Units: Meters; North American Datum 1983 (NAD83)

Credits

Authors: Bradley A. Miller (Associate Professor, Iowa State University) and C. Lee Burras (Morrill Professor, Iowa State University)

The Department of Agronomy at Iowa State University supplied the funding needed to create this map. Bradley A. Miller and C. Lee Burras are supported by Hatch Project IOW05772 (Geospatially Mapping the Soils and Land Use of Iowa).

This map and associated data have been published to Iowa State University’s DataShare repository, and may be cited as follows:

Miller, Bradley; Burras, C. Lee. 2026. Physiographic Regions of Iowa. Iowa State University. https://doi.org/10.25380/iastate.30836333.v1