High-Intensity Soil Survey and Hydropedologic Functional Map Units S. J. Indorante, J. A. Doolittle, H. S. Lin, M. A. Wilson, and B. D. Lee abstract The fundamental purposes of a soil survey are to show (cartographically) the geographic distribution of the soils and make land-use predicti o ns about those soi ls. A wide array of environmental , ecological , agricultural, geological , and natural resource issues have placed greater demands on soil survey information . Traditional soil maps , soil map units , and inter- pretations may be inadequate when confronting these complex issues , and in particular , issues that require detailed hydrologic information. Two soil-landscape case studies are presented to evaluate the utility I of traditional soil maps and high intensity soil maps in the map- ping and interpretation of hydropedological properties. The concept of a Hydropedological Functional Unit (HFU) will be introduced as a means of cartographically representing critical and more detailed hydropedological functions related to soil-landscape relationships. HFUs are unique map- pable areas at a particular scale of resolution, created through interaction of pedogenic features and hydrologic processes. A forested catchment and a cultivated catchment were selected for the study. Two levels of soil survey (first and second order) were evaluated at each site for their cartographic representation of soil-landscape hydrol- ogy. We evaluated the hydropedologic utility of a soil survey by analysis of intensive soil property pOint data, detailed soil-landscape and geomorphic analysis, and geophysical techniques. At both sites, the second-order soil survey captured soil variation, but had low spatial resolution and uniform attribute value (uniform spatial information as depicted within polygons) within map units delineated to have significantly different hydropedological utility. The first soil surveys showed higher spatial resolution, but were constrained by uniform attri- bute value within map units. The results of these two case studies suggest that traditional soil survey and even high intensity soil survey may not be adequate to map and interpret a soil landscape's hydropedological function. Another level of cartographiC data is needed to more accurately and precisely map the critical soil water processes that range from pedon scale to landscape and landform scale. This article introduces the concept of Hydropedologic Functional Map Units (HFU) as a cartographiC building block to increase knowledge, understanding, and utility of soil-landscape hydrology for var- ious applications. S.J. Indorante, USDA-NRCS, MLRA Office, 148 E. Pleasant Hill Rd., Car- bondale, IL 62903 (sam.indorante@il.usda.gov); J.A. Doolittle, USDA- NRCS, National Soil Survey Center, Newtown Square, PA, 19073; H.S. Lin, Dep. of Crop and Soil Sciences, The Pennsylvania State University, University Park, PA, 16802; MA Wilson, USDA-NRCS, National Soil Survey Center, Lincoln, NE, 68508; B.D. Lee, University of Kentucky, Plant and Soil Sciences Dep., Lexington, KY, 40546. Published in Soil Surv. Horiz. 50:79-82 (2009). Fall 2009 Study Objective The study was conducted to evaluate the utility of both traditional and high intensity soil maps in the mapping and interpretation of soil-land- scape hydro pedological properties. The focus is on evaluating the ability of first- and second-order soil surveys to depict soil-landscape hydrologi- cal processes (e.g., interception, runoff, infiltration, percolation, storage, evaporation, and transpiration). After the initial evaluations the concept of the HFU as a cartographic building block will be introduced to determine if a HFU map unit, and in turn a HFU data layer, will increase knowledge, understanding, and utility of soil-landscape hydrology. Traditional Soil Maps and their Interpretations The fundamental purposes of a soil survey are to show (cartographi- cally) the geographic distribution and make predictions about the soils (Soil Survey Staff, 1993). To this end, a soil survey includes soil maps, map unit descriptions, soil series descriptions, taxonomic classifications, and interpretations for the use and management of the soils. Published soil surveys are typically second and third order in the United States, which range in scale from 1:12,000 to 1: 31 ,680 and 1:20,000 to 63,360, respectively (Soil Survey Staff, 1993). These sur- veys commonly have 10 to 15 tables that include interpretations for plants, urban land use, rural development, recreational development, and for conservation and wildlife habitat planting (Soil Survey Staff, 1993). The soil survey interpretation tables are based on soil properties, qualities, and behaviors gathered at traditional soil survey scales of observation (Le., second and third orders). A wide array of environmental, ecological, agricultural, geological, and natural resource issues have placed greater demands for more accurate, precise, and problem-specific soil survey information. A few of these chal- lenges are nutrient management, sewage disposal, water resource plans, storm water management, and wetland protection (Lin et aI., 2006a). Many of these challenges also require detailed hydrologiC information. Traditional soil maps and their interpretations may be inadequate when confronting these complex issues (Indorante et aI., 1996; Lin 2003; Zhu et aI., 1997; Lin et aI. , 2006a,b). 79 Published August 4, 2015