Understanding agricultural water footprint variability to improve water management in Chile
Graphical abstract
Introduction
Climate variability and competing water intake flows or demands make water a scarce, vulnerable resource (Hejazi et al., 2014; Hoekstra et al., 2016; Miglietta et al., 2018). The water footprint (WF) is an indicator of water resources use that allows the volume of water directly or indirectly consumed or polluted for the production of a good or service to be determined (De Miguel et al., 2015; Pellicer-Martínez and Martínez-Paz, 2018). Thus, it is a useful tool for addressing the imbalance between the supply of and demand for various water flows (Chukalla et al., 2017; Qian et al., 2018).
The water footprint (WF) requires information on water flows, vegetation dynamics and human needs. River runoff and groundwater infiltration are known as the blue water flow. The green water flow is the precipitation that is temporarily stored in the soil and on top of vegetation. The gray water flow is the water necessary to replenish the environmental carrying capacity after a human intervention (Hoekstra, 2014; Liu et al., 2017). Globally, it is estimated that around three fifths of precipitation takes the green path and two fifths the blue (Lovarelli et al., 2016). Consequently, the three components of the WF are: 1) WFblue, which is the volume of blue flow water taken up for industrial, domestic and agricultural irrigation purposes; 2) WFgreen, which is the consumption of green flow water that sustains the production of crops, pasture land, forestry plantations and ecosystems; and 3) WFgray, which is the volume of water required to assimilate or dilute pollutant or fertilizer inputs (Cazcarro et al., 2015; Hoekstra et al., 2016; Hoekstra, 2017).
The WFcrop is defined as the water consumed as a result of evapotranspiration, irrigation requirements and fertilizers applied during the growing period, according to climate and soil characteristics and crop parameters; the sum of the water consumption of each crop ultimately determines the WFagricultural of the basin (Salmoral et al., 2011; Schyns et al., 2015; Chukalla et al., 2018).
Establishing water consumption in a river basin contributes to the sustainable and efficient management of water resources. The unconsumed portion of the extracted water returns to the system and remains available for downstream use; thus, water quality and the destination of the returned water are important (Hoekstra et al., 2012). Nonetheless, there are few studies that address the assessment of the WFagricultural in river basins, particularly in the case of mediterranean regions, where agriculture requires irrigation to compensate for drought periods (Billib et al., 2009; Cortés et al., 2012; Pellicer-Martínez and Martínez-Paz, 2018). In such areas, blue and green water availability is variable, due precisely to rainfall irregularity; thus, agriculture in these areas is the greatest water consumer (Ercin et al., 2013). Switzerland (Hoekstra, 2015) and California (Fulton et al., 2012) are examples.
In the last 25 years of research on water management in agriculture, the greatest efforts have been made mainly in Asia (China, India), North America (United States), Oceania (Australia) and Europe (Germany), while in Latin America the field is still emerging (Velasco-Muñoz et al., 2018).
The economy of Chile, a Latin American country rich in mediterranean landscapes, is based on the use and extraction of natural resources, including water (Donoso, 2006; Cortés et al., 2012). Agriculture accounts for 80% of consumptive extractions of water, allowing the irrigation of over 1.1 million hectares; the irrigated area has increased annually, especially into previously unused areas, an expansion aided by the application of technology (Donoso et al., 2016; DGA, 2016). Global climate change trends will also produce greater vulnerability as increasing water demands become more difficult to meet, with projections for 2040 indicating general water reduction in central Chile (32°S to 33°S), where the largest amount of cropland is concentrated (Iglesias and Garrote, 2015; Pino et al., 2015; Chartzoulakis and Bertaki, 2015). Added to these trends is the drought period that began on 2007, with a precipitation deficit of 30% and temperature increases between 0.5 °C and 1.5 °C above the historical average (Boisier et al., 2016; Valdés-Pineda et al., 2016).
The foregoing suggests the need for public policies that ensure efficiency and equity in water resources (Jaramillo and Destouni, 2015). Water regulation in Chile is a major challenge. It is based on a market model governed by the Water Code of 1981 (DFL 1.122), which entails a combination of a (centralized) distribution system and (freely transferable) water use rights (Hearne and Donoso, 2014; Rivera et al., 2016). In this model, water is a “national good of public use,” but water use rights are private property (Guiloff, 2012; Hearne and Donoso, 2014). Thus, Chile is an example of an extreme unitary legal system, as the state has limited power to intervene and promote the maintenance of continental aquatic systems, with minimum environmental protections incorporated belatedly and independent of local ecosystems and a large percentage of water already allocated (OECD – UN ECLAC, 2016). This last situation has led to over-granting of water use rights in many agricultural regions in the central macro zone (30°–35° S), with consumptive and non-consumptive surface flows of 7271.932 m3/s granted (DGA, 2016).
Thus, this study contributes to water-use planning in a region of the Southern Hemisphere that, due to its geographical particularities, exhibits high-value, high-quality agricultural production (Aguilera et al., 2019; Fernández et al., 2018), and where regional fruit exports increased 33% in 2018 and are estimated at 1609.4 MMUS$, in contrast to other agricultural exports, which decreased by 22%, to 8.7 MMUS$ (INE, 2018). These changes are attributed to instances of climate change, droughts and fires (Henríquez et al., 2016), in addition to decreases in sales to China, Brazil and Japan (INE, 2018).
It is therefore a priority to calculate indicators that assess agricultural water demands and allow the impacts of climate phenomena to be quantified and change processes to be interpreted (Lathuillière et al., 2018), through a holistic approach that includes technical, environmental, and socio-economic aspects in an innovative and manner, as achieved by water footprint assessment (Zhang et al., 2018).
Current basin-level water management practices make agricultural production dependent on irrigation type and climate characteristics (Billib et al., 2009; Cortés et al., 2012; Valdés-Pineda et al., 2016), leading to questions such as the following: What component of the WFagricultural (WFblue,WFgreen, WFgrey) explains the greatest water consumption? Does the area in which crops are grown influence the water requirement? Is it possible to determine the differences in agricultural water consumption as a function of local climate variability? What percentage of water consumption of crops is given by WFblue, WFgreen and WFgrey?
The hypothesis is that the greatest WFagricultural will occur in dry periods, even though water resources are diminished then. The primary objective of this study is to determine the water consumption of the main crops produced in a central Chilean river basin by calculating the water footprint of agriculture considering climate variability (dry, wet and normal years) and the green, blue and gray water footprint indicators in order to modify future water allocation plans and complement them with more rational water management models.
Section snippets
Materials and methods
To analyze the WF, the Cachapoal River basin was selected as representative of a central Chilean basin because it accounts for 78% of the cropland in one of the administrative regions of the area. Agribusinesses are located along its banks, contributing to water pollution (Novoa et al., 2016, Novoa et al., 2019). There is increasing soil erosion (moderate, severe and very severe) in 44% of the total basin area, environmental damage resulting from poor practices in the forestry, farming and
Agricultural water footprint
The analysis of the climatic behavior of the Cachapoal River basin in the 34 years studied and at the weather stations selected as a reference showed that precipitation and effective precipitation revealed higher values in 2005 (representative of a wet year), with 969 ± 3.1 mm and 625 ± 8.1 mm, respectively. The opposite was observed in 2007 (representative of dry conditions), in which precipitation (420 ± 3.4 mm) and effective precipitation (212 ± 8.2 mm) were lower, with a decrease of 43%
Discussion
The study of the water footprint on a drainage-basin scale is carried out through the development of increasingly complex indicators, allowing a large variety of factors that determine the water cycle to be considered and their dynamics to be simulated, in addition to permitting spatial variations to be included as input data (Chukalla et al., 2018; Vanham et al., 2018). Multiple climate variables, soil characteristics and crop properties, as well as evapotranspiration estimates and irrigation
Conclusions
Climate variations are determinant in the water requirements of agricultural activities, particularly in a Latin American basin with a mediterranean climate, since the water flow is related to various types of consumption, that is, in a year with drought conditions (this is, 43% decrease in precipitation relative to 34 years of records) the greatest WFagricultural and WFblue were estimated, while in normal conditions the greatest WFgreen was determined. The WFgray, however, was directly
Nomenclature
Symbol Unit Explanation AR kg/ha/mass/area Application rate of a chemical (fertilizer or pesticide) per unit of land Α – Leaching-run-off fraction, i.e. fraction of applied chemicals reaching freshwater bodies AWP $/m3 Apparent water productivity CWUblue m3 ha−1/volume/area Blue crop water use CWUgreen m3 ha−1/volume/area Green crop water use CWR mm month−1/length/time Crop water requirement Cmax kg m3/mass/volume Maximum acceptable concentration of a chemical in a receiving water body Cnat kg m3
Acknowledgements
The authors express their gratitude to the Conicyt National Commission for Scientific and Technological Research for the funding provided through the CRHIAM Conicyt/Fondap/15130015 project, the Conicyt Advanced Human Capital Program of the Government of Chile, the National Doctorate Grant-2011, and FONDECYT projects 11150424 and 1150459. Dr. Ahumada-Rudolph expresses his gratitude to the post-doctoral program of the Directorate of Research, University of Bío-Bío.
References (76)
- Aguilera, M.A., Aburto, J.A., Bravo, L., Broitman, B.R., García, R.A., Gaymer, C.F., Gelcich, S., López, B.A.,...
- et al.
Incorporating the water footprint and virtual water into policy: reflections from the Mancha Occidental region, Spain
Water Resour. Manag.
(2010) - et al.
Integrated water resources management for sustainable irrigation at the basin scale
Chil. J. Agric. Res.
(2009) - et al.
Anthropogenic and natural contributions to the Southeast Pacific precipitation decline and recent megadrought in central Chile
Geophys. Res. Lett.
(2016) - et al.
Evaluation of climate change impacts and adaptation strategies on rainfed rice production in Songkhram River Basin
Thailand. Sci. Total Environ.
(2019) - et al.
Evaluation of the grey water footprint comparing the indirect effects of different agricultural practices
Sustain.
(2018) - et al.
How sustainable is the increase in the water footprint of the Spanish agricultural sector? A provincial analysis between 1955 and 2005-2010
Sustain.
(2015) - et al.
Sustainable water management in agriculture under climate change
Agric. Agric. Sci. Procedia.
(2015) - et al.
Virtual water trade patterns in relation to environmental and socioeconomic factors: a case study for Tunisia
Sci. Total Environ.
(2018) - et al.
Marginal cost curves for water footprint reduction in irrigated agriculture: guiding a cost-effective reduction of crop water consumption to a permit or benchmark level
Hydrol. Earth Syst. Sci.
(2017)
Trade-off between blue and grey water footprint of crop production at different nitrogen application rates under various field management practices
Sci. Total Environ.
Application of the Watershed Sustainability Index to the Elqui river basin
North-Central Chile. Obras y Proy.
Sustainability of the water footprint of the Spanish pork industry
Ecol. Indic.
Atlas del Agua, in: Atlas Del Agua Chile 2016
Scenario development for water resource planning and management: a review
Technol. Forecast. Soc. Change.
Water markets: case study of Chile's 1981 Water Code
Cien. Inv. Agr.
Water footprints and irrigated agricultural sustainability: the case of Chile
Int. J. Water Resour. Dev.
System methodology application to make water resources management plan for unstudied rivers
Sustainability of national consumption from a water resources perspective: the case study for France
Trans. Costs Environ. Policy.
Implications of climate change for semi-arid dualistic agriculture: a case study in Central Chile
Reg. Environ. Chang.
California's Water Footprint About the Pacific Institute About the Authors
Climate change and food security
Philos. Trans. R. Soc. B
Análisis de la tendencia y la estacionalidad de la precipitación mensual en Venezuela
A pragmatic approach to multiple water use coordination in Chile
Water Int.
Updated high-resolution grids of monthly climatic observations - the CRU TS3.10 dataset
Int. J. Climatol.
Optimal allocation of water resources from the “wide-mild water shortage” perspective
Water.
Integrated assessment of global water scarcity over the 21st century under multiple climate change mitigation policies
Hydrol. Earth Syst. Sci.
Zonas de catástrofe por eventos hidrometeorológicos en Chile y aportes para un índice de riesgo climático
Rev. Geogr. Norte Grande.
Water scarcity challenges to business
Nat. Clim. Chang.
The water footprint: the relation between human consumption and water use, in: The Water We Eat: Combining Virtual Water and Water Footprints
Water footprint
The Water Footprint Assessment Manual
Global monthly water scarcity: blue water footprints versus blue water availability
PLoS One
Water footprints and sustainable water allocation
Sustain.
Adaptation strategies for agricultural water management under climate change in Europe
Agric. Water Manag.
Censo Agropecuario y Forestal 2007
Boletín de exportaciones Región de O'Higgins Edición n°31
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