Sensitivity and uncertainty in crop water footprint accounting:  a case study for the Yellow River basin

Zhuo, La; Mekonnen, Mesfin; Hoekstra, Arjen Ysbert

doi:10.5194/hess-18-2219-2014

Cited by 141 publications

(86 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…For the irrigated fields, the larger WFs in the arid zone are caused by the relatively high ET 0 and ET. The results confirm the findings from previous studies that the WF of crops, especially rain-fed crops, is negatively correlated with precipitation and positively correlated with ET 0 (Zwart et al, 2010;Zhuo et al, 2014). The differ- Figure 6.…”

Section: Benchmark Levels For the Consumptive Wf For Different Climatsupporting

confidence: 82%

Benchmark levels for the consumptive water footprint of crop production for different environmental conditions: a case study for winter wheat in China

Zhuo

Mekonnen

Hoekstra

2016

Hydrol. Earth Syst. Sci.

Self Cite

View full text Add to dashboard Cite

Abstract. Meeting growing food demands while simultaneously shrinking the water footprint (WF) of agricultural production is one of the greatest societal challenges. Benchmarks for the WF of crop production can serve as a reference and be helpful in setting WF reduction targets. The consumptive WF of crops, the consumption of rainwater stored in the soil (green WF), and the consumption of irrigation water (blue WF) over the crop growing period varies spatially and temporally depending on environmental factors like climate and soil. The study explores which environmental factors should be distinguished when determining benchmark levels for the consumptive WF of crops. Hereto we determine benchmark levels for the consumptive WF of winter wheat production in China for all separate years in the period 1961-2008, for rain-fed vs. irrigated croplands, for wet vs. dry years, for warm vs. cold years, for four different soil classes, and for two different climate zones. We simulate consumptive WFs of winter wheat production with the crop water productivity model AquaCrop at a 5 by 5 arcmin resolution, accounting for water stress only. The results show that (i) benchmark levels determined for individual years for the country as a whole remain within a range of ±20 % around long-term mean levels over 1961-2008, (ii) the WF benchmarks for irrigated winter wheat are 8-10 % larger than those for rain-fed winter wheat, (iii) WF benchmarks for wet years are 1-3 % smaller than for dry years, (iv) WF benchmarks for warm years are 7-8 % smaller than for cold years, (v) WF benchmarks differ by about 10-12 % across different soil texture classes, and (vi) WF benchmarks for the humid zone are 26-31 % smaller than for the arid zone, which has relatively higher reference evapotranspiration in general and lower yields in rain-fed fields. We conclude that when determining benchmark levels for the consumptive WF of a crop, it is useful to primarily distinguish between different climate zones. If actual consumptive WFs of winter wheat throughout China were reduced to the benchmark levels set by the best 25 % of Chinese winter wheat production (1224 m 3 t −1 for arid areas and 841 m 3 t −1 for humid areas), the water saving in an average year would be 53 % of the current water consumption at winter wheat fields in China. The majority of the yield increase and associated improvement in water productivity can be achieved in southern China.

show abstract

Section: Benchmark Levels For the Consumptive Wf For Different Climatsupporting

confidence: 82%

Benchmark levels for the consumptive water footprint of crop production for different environmental conditions: a case study for winter wheat in China

Zhuo

Mekonnen

Hoekstra

2016

Hydrol. Earth Syst. Sci.

Self Cite

View full text Add to dashboard Cite

show abstract

“…In CUP1, irrigation occurs when the soil water content in the effective root zone is less than half of capacity. This assumption is in accordance with the management allowable depletion historically used by most irrigators [USDA SCS, 1993;Ozdogan et al, 2010]. Irrigation water is applied until the soil water content returns to field capacity.…”

Section: Crop Evapotranspirationmentioning

confidence: 66%

“…During the drought, urban water users in California were mandated to reduce their water use by 25%. California residential water users paid approximately $1630 per 1000 m 3 of water in 2013 [Gaur et al, 2013], while irrigators spent $22.19 in pumping cost per 1000 m 3 of on-farm water (surface water and groundwater) and paid $36.96 per 1000 m 3 for off-farm water supplies [USDA, 2014]. This highlights the high opportunity cost of water in agriculture in California, due to its heavy reliance on irrigation and proximity to urban areas.…”

Section: Drought Impacts To Food and Virtual Water Transfersmentioning

confidence: 99%

Drought impacts to water footprints and virtual water transfers of the Central Valley of California

Marston

Konar

2017

Water Resources Research

View full text Add to dashboard Cite

The Central Valley of California is one of the most productive agricultural locations in the world, which is made possible by a complex and vast irrigation system. Beginning in 2012, California endured one of the worst droughts in its history. Local impacts of the drought have been evaluated, but it is not yet well understood how the drought reverberated through the global food system. Here we quantify drought impacts to the water footprint (WF) of agricultural production and virtual water transfers (VWT) from the Central Valley of California. To do this, we utilize high‐resolution spatial and temporal data sets and a crop model from predrought conditions (2011) through 3 years of exceptional drought (2012–2014). Despite a 12% reduction in harvested area, the WF of agricultural production in the Central Valley increased by 3%. This was due to greater crop water requirements from higher temperatures and a shift to more water‐intensive orchard and vine crops. The groundwater WF increased from 7.00 km3 in 2011 to 13.63 km3 in 2014, predominantly in the Tulare Basin. Transfers of food commodities declined by 1% during the drought, yet total VWT increased by 3% (0.51 km3). From 2011 to 2014, groundwater VWT increased by 3.42 km3, offsetting the 0.94 km3 reduction in green VWT and the 1.96 km3 decrease in surface VWT. During the drought, local and global consumers nearly doubled their reliance on the Central Valley Aquifer. These results indicate that drought may strengthen the telecoupling between groundwater withdrawals and distant consumers of agricultural commodities.

show abstract

“…Daily crop evapotranspiration,

E T_{a, j}

, is calculated following Allen et al . [], a well‐established approach for the virtual water content assessment [ Mekonnen and Hoekstra , ; Siebert and Döll , ; Zhuo et al ., ].

E T_{a, j}

is defined as

E T_{a, j} = k_{c, j} \cdot E T_{0, j} \cdot k_{s, j} (\frac{mm}{normald}),

where

k_{c, j}

is the daily crop coefficient,

E T_{0, j}

is the daily reference evapotranspiration (mm d −1 ) from a hypothetical well‐watered grass surface with fixed crop height, albedo and canopy resistance, and

k_{s, j}

is the daily water stress coefficient depending on the available soil water content, with a value between 0 (maximum water stress) and 1 (no water stress).…”

Section: Methodsmentioning

confidence: 99%

“…Daily crop evapotranspiration, ET a;j , is calculated following Allen et al [1998], a well-established approach for the virtual water content assessment [Mekonnen and Hoekstra, 2011;Siebert and D€ oll, 2010;Zhuo et al, 2014]. ET a;j is defined as…”

Section: Crop Evapotranspiration Over a Single Growing Seasonmentioning

confidence: 99%

Global sensitivity of high‐resolution estimates of crop water footprint

Tuninetti

Tamea

D’Odorico

et al. 2015

Water Resources Research

104

View full text Add to dashboard Cite

Most of the human appropriation of freshwater resources is for agriculture. Water availability is a major constraint to mankind's ability to produce food. The notion of virtual water content (VWC), also known as crop water footprint, provides an effective tool to investigate the linkage between food and water resources as a function of climate, soil, and agricultural practices. The spatial variability in the virtual water content of crops is here explored, disentangling its dependency on climate and crop yields and assessing the sensitivity of VWC estimates to parameter variability and uncertainty. Here we calculate the virtual water content of four staple crops (i.e., wheat, rice, maize, and soybean) for the entire world developing a high‐resolution (5 × 5 arc min) model, and we evaluate the VWC sensitivity to input parameters. We find that food production almost entirely depends on green water (>90%), but, when applied, irrigation makes crop production more water efficient, thus requiring less water. The spatial variability of the VWC is mostly controlled by the spatial patterns of crop yields with an average correlation coefficient of 0.83. The results of the sensitivity analysis show that wheat is most sensitive to the length of the growing period, rice to reference evapotranspiration, maize and soybean to the crop planting date. The VWC sensitivity varies not only among crops, but also across the harvested areas of the world, even at the subnational scale.

show abstract

Sensitivity and uncertainty in crop water footprint accounting: a case study for the Yellow River basin

Cited by 141 publications

References 54 publications

Benchmark levels for the consumptive water footprint of crop production for different environmental conditions: a case study for winter wheat in China

Benchmark levels for the consumptive water footprint of crop production for different environmental conditions: a case study for winter wheat in China

Drought impacts to water footprints and virtual water transfers of the Central Valley of California

Global sensitivity of high‐resolution estimates of crop water footprint

Contact Info

Product

Resources

About