The Original USDA-ARS Experimental Watersheds in Texas and Ohio: Contributions from the Past and Visions for the Future

Harmel, R. Daren; Bonta, J. V.; Richardson, C. W.

doi:10.13031/2013.23958

Cited by 23 publications

(9 citation statements)

References 44 publications

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“…1). Field data available at these sites include daily evapotranspiration (ET) and soil temperature ( (Harmel et al, 2007). The area is characterized by small-scale agricultural fields (grassland and arable crops).…”

Section: Study Sitesmentioning

confidence: 99%

“…The Riesel Y2 subwatershed (44.4 ha) is located within the Texas Blackland Prairies and is characterized by Houston Black soils (fine, smectitic, thermic Udic Haplusterts). More than 50% of the soil contains clay that shrinks or swells with changes in soil water(Harmel et al, 2007). Headwater subareas Y6, Y8, and Y10 are terraced, and crops including corn, wheat (Triticum aestivum L.), sorghum [Sorghum bicolor (L.) Moench], and oat (Avena sativa L.) are rotated.…”

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confidence: 99%

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The Variable Saturation Hydraulic Conductivity Method for Improving Soil Water Content Simulation in EPIC and APEX Models

Doro

Jones

Williams

et al. 2017

Vadose Zone Journal

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Core Ideas We propose VSHC for calculating soil water percolation in continuous models. VSHC relates permeability to daily hydraulic properties to estimate hydraulic conductivity. VSHC performed well at field scale and improved estimates of peak streamflows. Soil water percolation is a key process in the life cycle of water in fields, watersheds, and river basins. The Environmental Policy Integrated Climate (EPIC) and the Agricultural Policy/Environmental eXtender (APEX) are continuous models developed for evaluating the environmental effects of agricultural management. Traditionally, these models have simulated soil water percolation processes using a tipping‐bucket approach, with the rate of flow limited by the saturated hydraulic conductivity. This simple approach often leads to inaccuracy in simulating elevated soil water conditions where soil water content (SWC) levels may remain above field capacity under prolonged wet weather periods or limited drainage. To overcome this deficiency, a new submodel, the variable saturation hydraulic conductivity (VSHC) method, was developed for simulating soil water percolation processes using a nonlinear equation to estimate the effective hydraulic conductivity as a function of the SWC and soil properties. The VSHC method was evaluated at three sites in the United States and two sites in Europe. In addition, a numerical solution of the Richards equation was used as a benchmark for SWC comparison. Results show that the VSHC method substantially improves the accuracy of the SWC simulation in long‐term simulations, particularly during wet periods. At the watershed scale, results on the Riesel Y2 watershed indicate that the VSHC method enhances model performance in the high‐flow regime of channel peak flows because of the improved estimation of SWC, which implies that the improved SWC simulation at the field scale is beneficial to hydrologic modeling at the watershed scale.

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Section: Study Sitesmentioning

confidence: 99%

mentioning

confidence: 99%

The Variable Saturation Hydraulic Conductivity Method for Improving Soil Water Content Simulation in EPIC and APEX Models

Doro

Jones

Williams

et al. 2017

Vadose Zone Journal

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“…USDA-ARS Riesel Watersheds is a part of the Agriculture Research Service and managed by the U.S. Department of Agriculture and has been in operation since the mid-1930s (Harmel et al, 2003;Harmel et al, 2006;Harmel et al, 2007). Riesel is 29 km southeast of Waco, TX (Figure 1) for the 47-mm filters and 82 L min À1 for the 90-mm filters, with a total of 132.48 m 3 of air sampled from midnight to midnight each day.…”

Section: Sampling Sitementioning

confidence: 99%

Urban impacts on regional carbonaceous aerosols: Case study in central Texas

Barrett

Sheesley

2014

Journal of the Air & Waste Management Association

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Rural and background sites provide valuable information on the concentration and optical properties of organic, elemental, and water-soluble organic carbon (OC, EC, and WSOC), which are relevant for understanding the climate forcing potential of regional atmospheric aerosols. Implications: Background concentration and absorption measurements are essential in determining regional potential radiative forcing due to atmospheric aerosols. Back trajectory, chemical, and optical analysis of PM 2.5 was used to determine climatic and air quality implications of urban outflow to a regional receptor site, representative of the central United States. Results indicate that central Texas organic carbon has mixed urban and rural sources, while elemental carbon is controlled by the transport of urban emissions. Analysis of aerosol absorption showed black carbon as the dominant absorber, with less brown carbon absorption than regional studies in California and the southeastern United States.

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“…It was focused at the field scale on watersheds up to roughly 10 ha employing paired watershed analyses (Kelly & Glymph, 1965;Richardson & King, 1995). In 1935, there was an expansion in scope to examine fields and watersheds up to several square kilometers in size (Harmel et al, 2007). The experimental watershed studies included both management control and improved observations of the water budget, including installation of large weighing lysimeters to measure evapotranspiration (ET).…”

Section: Background and Historymentioning

confidence: 99%

The USDA‐ARS Experimental Watershed Network: Evolution, Lessons Learned, Societal Benefits, and Moving Forward

Goodrich

Heilman

Anderson³

et al. 2021

Water Resources Research

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The U.S. Department of Agriculture‐Agricultural Research Service's (ARS) Experimental Watershed Network grew from Dust Bowl era efforts of the Soil Conservation Service in the mid‐1930s with the establishment of small experimental watersheds. In the 1950s, five watershed research centers with intensively instrumented watersheds at the scale of 100 to 700 km2 were established. Primary network research objectives were to quantify on‐site and downstream effects of conservation practices and develop rainfall‐runoff relationships for design of water conservation structures. With passage of the Clean Water Act in 1972, research objectives have evolved to add a variety of observations relevant to the water quality issues. Many of the watersheds within the network have served, and continue to serve, as core validation sites for satellite sensors. As a result of the network's long history and intensive monitoring, coupled with mission‐driven research, a deep knowledge base of watershed processes has been developed. This has led to the extensive development and validation of numerous watershed models that are in widespread use today. The visionary investments in building and maintaining this network and associated scientific investigations for more than half a century have not only resulted in numerous high‐impact research accomplishments but also a wide array of accomplishments that directly benefit society. The ARS Experimental Watersheds formed the core of the Conservation Effects Assessment Project (CEAP) as well as the recently established Long‐Term Agroecosystem Research (LTAR) network. LTAR will expand the mission of the ARS Watersheds Network to include agricultural intensification, maintaining or improving ecosystem services while enhancing rural prosperity.

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The Original USDA-ARS Experimental Watersheds in Texas and Ohio: Contributions from the Past and Visions for the Future

Cited by 23 publications

References 44 publications

The Variable Saturation Hydraulic Conductivity Method for Improving Soil Water Content Simulation in EPIC and APEX Models

The Variable Saturation Hydraulic Conductivity Method for Improving Soil Water Content Simulation in EPIC and APEX Models

Urban impacts on regional carbonaceous aerosols: Case study in central Texas

The USDA‐ARS Experimental Watershed Network: Evolution, Lessons Learned, Societal Benefits, and Moving Forward

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