Research papersComparative analysis of water budgets across the U.S. long-term agroecosystem research network
Introduction
Intensification of agriculture can affect water availability by increasing land under crop and forage production (Raymond et al., 2008, Schilling et al., 2008, Tomer and Schilling, 2009) or by increasing land productivity (Zeri et al., 2013). Simultaneously, climatic changes in temperature and precipitation can alter available water resources in several ways by: 1) increasing the rate and timing of evapotranspiration through elevated temperatures (Flerchinger et al., 2019, Kingston et al., 2009) and changes in crop planting times (Gautam et al., 2018), 2) altering the amount, timing, and form of seasonal or annual precipitation (i.e., rain or snow [US Global Change Research Program, 2017]), and 3) altering precipitation intensity, which could lead to greater runoff and reduced percolation (Gautam et al., 2018, Groisman et al., 2001).
Key to the adaptation of agriculture across varying climates is the management of water, the natural availability of which ranges from deficit to excess for crops and rangelands. In water-limited environments, agriculture competes with other water users. Conversely, water-replete environments may be challenging because of poorly drained soils. Extreme precipitation events are challenging everywhere because of erosion and loss of water to runoff. Agricultural activities can affect the availability and quality of surface and ground waters, making careful management a fundamental requirement for sustainability.
Conflicts arising from agricultural water management such as water availability for municipal, industrial, or recreational uses (e.g., water shortages in Brazil in 2017, South Africa in 2018, and in India in 2019), and contamination of water bodies from agricultural pollution are becoming more frequent and threaten the well-being of future generations and the environment (United Nations Convention to Combat Desertification, 2017). In the United States, recent droughts (e.g., 2016 in Georgia or 2011–2017 in California) and floods (2008 in Iowa, 2011 and 2019 along the Mississippi and Missouri Rivers) have significantly impacted agricultural production, as well as water quality of receiving water bodies. Understanding the balance between precipitation, evapotranspiration, runoff, and groundwater recharge is critical to evaluating local, regional and global water resources (Healy et al., 2007).
A balanced water budget accounts for all of the major water inputs and outputs over an annual cycle in a defined area. Water budgets depend on topography, climate, soils, land use, and land management. In small catchments, a water budget provides an overview of the fate of water inputs. Evapotranspiration is commonly the main output, with the remaining balance going to groundwater recharge or streamflow generation. Water budgets describe the water pathways through the farm and rangeland management systems. Accurate water budgets for small catchments can also inform integrated land and water management in larger catchments and contribute to the analysis of potential trade-offs between water allocations for agriculture and other uses. Understanding how each budget component may shift as a function of management informs the optimal use of available water resources under varying climate, land use, and agricultural production. Optimization of water resources at the watershed or regional scale may in turn result in specific recommendations for the management of agricultural land in those regions.
Our current knowledge of water fluxes across agricultural landscapes in the United States is largely incomplete. For areas the size of a field, studies in agroecosystems focus on individual components of the water budget, often overland or subsurface runoff, or evapotranspiration (e.g., Bosch et al., 2012, Buckley et al., 2010). For large watersheds, water budget estimates are often based on models, which are calibrated with streamflow data measured at the outlet of the watershed (Afinowicz et al., 2005, Green et al., 2006, Schilling et al., 2008), or not calibrated if the modeling objective is to understand the primary hydrologic processes (Abatzoglou and Ficklin, 2017, Gobin et al., 2017). Regional research networks provide an opportunity to benefit from long-term ecological and hydrologic process site studies across a gradient of climatic conditions, land use, and land management. For example, data from the U.S. Long-Term Ecological Research network as well as other North American networks have helped identify forest-type susceptibility to climate warming (Creed et al., 2014).
The Long-Term Agroecosystem Research (LTAR) network is a partnership of 18 long-term research sites maintained by the U.S. Department of Agriculture (USDA) Agricultural Research Service (ARS) and academic institutions (Spiegal et al., 2018, Walbridge and Shafer, 2011). The LTAR network was established in 2014 to provide information in support of research for improved sustainability and intensification of U.S. agriculture over the next 20 to 50 years (Kleinman et al., 2018). The LTAR network includes 18 experimental watersheds (11 USDA-ARS) and ranges where precipitation and other hydro-meteorological variables have been systematically measured and archived for decades.
The LTAR network offers an opportunity to estimate and compare water budget components across a gradient of agroecosystems and climatic conditions as a baseline from which to evaluate the impacts and sensitivity of management in a changing climate. These water budgets provide a mechanism to identify deficiencies in monitoring instrumentation, the availability of data for additional comparative studies, and the identification of aspirational goals for regional watershed management. These data also provide an opportunity to evaluate the uncertainty of water budget components for accurate cross-site and regional analysis.
The objectives of this study were to: 1) characterize the hydrologic variability across the LTAR network; 2) identify data gaps in the water budgets across the LTAR network; and 3) identify opportunities to leverage the LTAR network to improve understanding of water budgets across agricultural landscapes. Analyses were conducted for 13 small catchments (< 50 ha) and 13 large catchments (> 400 ha) distributed among the 18 LTAR site locations.
Section snippets
Study sites
A water budget assessment was conducted at 26 study areas across 18 LTAR sites (Fig. 1). Each LTAR site was responsible for selecting one or more representative study areas, determining a period for which data were available, and calculating the mean and standard deviation of annual values for each water budget component. The assessments cover a range of soil, land use (Supplemental Table S1), and climatological conditions (Supplemental Fig. S1). The 26 locations were divided based on the size
Water budgets across the LTAR network
The magnitudes and uncertainty of each water budget component are described for each catchment in Supplemental Tables S16 and S17 and are summarized in Fig. 3, Fig. 4 and Table 1, Table 2. The LTAR network covers a gradient of precipitation from 240 mm yr−1 at JER to 1400 mm yr−1 at LMRB. Precipitation was the component measured with the smallest relative uncertainty (5%-17%, Table 1, Table 2). However, it was also the largest component and the absolute uncertainties related to precipitation
Opportunities for reducing uncertainties
These results highlight opportunities to reduce measurement uncertainties and to improve closure of the water budgets. Longer datasets and concurrent measurements for all the components, which is one objective of the LTAR network, will produce more accurate annual mean values. However, greater measurement accuracy is achievable as well. We discuss here opportunities for reducing errors and setting achievable goals.
Given that precipitation is the largest component of the water budget, improving
Conclusions
Water budgets were developed using multi-annual data from small and large catchments at the 18 LTAR sites in the United States by estimating precipitation, evapotranspiration, surface outflows (surface and subsurface flow), percolation, and change in water storage. Hydrologic characterization of each catchment was performed using indicators such as evapotranspiration and surface outflow. A Budyko plot of all the sites illustrates the spectrum of network sites across gradients of water and
CRediT authorship contribution statement
Claire Baffaut: Conceptualization, Methodology, Formal analysis, Writing - original draft, Writing - review & editing. John M. Baker: Writing - original draft, Writing - review & editing. Joel A. Biederman: Writing - review & editing. David D. Bosch: Investigation, Data curation, Writing - review & editing. Erin S. Brooks: Writing - original draft, Writing - review & editing. Anthony R. Buda: Investigation, Data curation. Eleonora M. Demaria: Visualization, Data curation, Writing - review &
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
This research was a contribution from the Long-Term Agroecosystem Research (LTAR) network. LTAR is supported by the United States Department of Agriculture.
References (96)
- et al.
Evapotranspiration information reporting: 1. Factors governing measurement accuracy
Agric. Water Manag.
(2011) - et al.
Assessing FAO-56 dual crop coefficients using eddy covariance flux partitioning
Agric. Water Manag.
(2017) The use of the aridity index to assess climate change effect on annual runoff
J. Hydrol.
(2002)Estimating the bankfull velocity and discharge for rivers using remotely sensed river morphology information
J. Hydrol.
(2007)- et al.
Tillage and slope position impact on field-scale hydrologic processes in the South Atlantic Coastal Plain
Agric. Water Manag.
(2012) - et al.
Long-term water balance and conceptual model of a semi-arid mountainous catchment
J. Hydrol.
(2011) - et al.
Can conservation trump impacts of climate change on soil erosion? An assessment from winter wheat cropland in the southern Great Plains of the United States
Weather Clim. Extremes
(2015) - et al.
Water scarcity, data scarcity and the Budyko curve—An application in the Lower Jordan River Basin
J. Hydrol. Regional Studies
(2017) - et al.
Variability and uncertainty in reach bankfull hydraulic geometry
J. Hydrol.
(2008) - et al.
Estimating storm discharge and water quality data uncertainty: A software tool for monitoring and modeling applications
Environ. Model. Software
(2009)
Reflections on the surface energy imbalance problem
Agric. For. Meteorol.
Long-term trends in climate and hydrology in an agricultural, headwater watershed of central Pennsylvania, USA
J. Hydrol.: Reg. Stud.
Precipitation: Measurement, remote sensing, climatology and modeling
Atmos. Res.
Uncertainty in water quality data
Dev. Water Sci.
Estimation of error in bankfull width comparisons from temporally sequenced raw and corrected aerial photographs
Geomorphology
Development of a global evapotranspiration algorithm based on MODIS and global meteorology data
Remote Sens. Environ.
Improvements to a MODIS global terrestrial evapotranspiration algorithm
Remote Sens. Environ.
Effect of timing of a deficit-irrigation allocation on corn evapotranspiration, yield, water use efficiency and dry mass
Agric. Water Manag.
Crop evapotranspiration estimation with FAO56: Past and future
Agric. Water Manag.
Analysis of localized unsaturated flow in fissured sediments in the Chihuahuan Desert, Texas: implications for contaminant transport
J. Hydrol.
The accuracy of sequential aerial photography and SAR data for observing urban flood dynamics, a case study of the UK summer 2007 floods
Remote Sens. Environ.
Assessment of measurement errors and dynamic calibration methods for three different tipping bucket rain gauges
Atmos. Res.
A simple approach to distinguish land-use and climate-change effects on watershed hydrology
J. Hydrol. (Amsterdam)
Correcting eddy-covariance flux underestimates over a grassland
Agric. For. Meteorol.
On the spatio-temporal dynamics of soil moisture at the field scale
J. Hydrol.
Climatic and physiographic controls of spatial variability in surface water balance over the contiguous United States using the Budyko relationship
Water Resour. Res.
Modeling effects of brush management on the rangeland water budget: Edwards Plateau Texas
J. Am. Water Resour. Assoc.
SWAT: Model use, calibration, and validation
Trans. ASABE
A methodology to reduce uncertainties in the high-flow portion of a rating curve
Trans. ASABE
Field Manual for Research in Agricultural Hydrology. USDA Agriculture Handbook No. 224
Effect of tillage on the hydrology of a claypan Soil in Kansas
Soil Sci. Soc. Am. J.
Changing forest water yields in response to climate warming: results from long-term experimental watershed sites across North America
Glob. Change Biol.
The influence of soil texture on the soil water dynamics and vegetation structure of a shortgrass steppe ecosystem
Plant Ecol.
Impact of climate change and variability on irrigation requirements: a global perspective
Clim. Change
More frequent intense and long-lived storms dominate the springtime trend in central US rainfall
Nat. Commun.
Water and carbon fluxes along a climate gradient in a sagebrush ecosystem
Ecosystems
The energy balance closure problem: an overview
Ecol. Appl.
Impact of weather and climate scenarios on conservation assessment outcomes
J. Soil Water Conserv.
Uncertainty of climate change impacts on soil erosion from cropland in central Oklahoma
Appl. Eng. Agric.
Soil erosion from winter wheat cropland under climate change in central Oklahoma
Appl. Eng. Agric.
Climate change and observed climate trends in the Fort Cobb Experimental Watershed
J. Environ. Qual.
Assessing long-term hydrological impact of climate change using an ensemble approach and comparison with global gridded model – a case study on Goodwater Creek Experimental Watershed
Water
Cited by (24)
Climate and breeding determined below-ground biomass allocation strategy in wheat
2023, Field Crops ResearchEvaluation of the storage and evapotranspiration terms of the water budget for an agricultural watershed using local and remote-sensing measurements
2023, Agricultural and Forest MeteorologyHow much water is stolen by sewers? Estimating watershed-level inflow and infiltration throughout a metropolitan area
2022, Journal of HydrologyCitation Excerpt :The two other large terms, besides P, were AETB and QT, and, similar to P, small changes in those terms would have large impacts on I&I. Those two terms most likely had uncertainties of at least 10% (Baffaut et al., 2020; McMillan et al., 2012). E definitely had an uncertainty larger than 10% due to uncertainties in evaporation rates from impervious surfaces; thus, the impact of E on I&I totals was much larger than what is shown in Table S4.
Ecohydrology of irrigated silage maize and alfalfa production systems in the upper midwest US
2022, Agricultural Water ManagementCitation Excerpt :These water inputs and outputs from a given land-area comprise a water budget. Quantifying its components can help determine the fate of water inputs, which can inform management decisions and help minimize offsite environmental impacts (Baffaut et al., 2020). Further, climate change is expected to alter regional hydrology, including warmer and wetter winters, greater spring precipitation, and hotter summers with longer dry periods (Pryor et al., 2014; Harding and Snyder, 2015; Liess et al., 2021).
- 1
Present address: Pima County Regional Flood Control District, Tucson, AZ 85701, USA.