Measurement of evapotranspiration in a winter wheat field

Zhang, Yongqiang; Liu, Changming; Shen, Yanjun; Kondoh, Akihiko; Tang, Changyuan; Tanaka, Takafumi; Shimada, Jun

doi:10.1002/hyp.1072

Cited by 40 publications

(23 citation statements)

References 21 publications

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“…The measurement at Luancheng was from the depth of 20 to 160 cm with 20 cm measurement intervals, and that at Yucheng was from 10 to 150 cm depth with 10 cm intervals. Actual ET was measured daily with large-scale weighing lysimeters with a 0.02 mm precision at Luancheng and Fengqiu and a 0.04 mm precision at Yucheng Zhang et al 2002).…”

Section: Experimental Data and Model Testingmentioning

confidence: 99%

Quantifying the effects of climate trends in the past 43 years (1961–2003) on crop growth and water demand in the North China Plain

et al. 2009

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This paper explores changes in climatic variables, including solar radiation, rainfall, fraction of diffuse radiation (FDR) and temperature, during wheat season (October to May) and maize season (June to September) from 1961 to 2003 at four sites in the North China Plain (NCP), and evaluates the effects of these changes on crop growth processes, productivity and water demand by using the Agricultural Production Systems Simulator. A significant decline in radiation and rainfall was detected during the 43 years, while both temperature and FDR exhibit an increasing trend in both wheat and maize seasons. The average trend of each climatic variable for each crop season from the four sites is that radiation decreased by 13.2 and 6.2 MJ m −2 a −1 , precipitation decreased by 0.1 and 1.8 mm a −1 , minimum temperature increased by 0.05 and 0.02• C a −1 , maximum temperature increased by 0.03 and 0.01• C a −1 , FDR increased by 0.21 and 0.38% a −1 during wheat and maize season, respectively. Simulated crop water demand and potential yield was significantly decreased because of the declining trend in solar radiation. On average, crop water demand was decreased by 2.3 mm a −1 for wheat and 1.8 mm a −1 for maize if changes in crop variety were not considered. Simulated potential crop yields under fully irrigated condition declined about 45.3 kg ha contribute to the increase in actual crop yield for the wheat-maize double cropping system, contrasted to the decline in the potential crop yield. Further research on how the improvement in crop varieties and management practices can counteract the impact of climatic change may provide insight into the future sustainability of wheat-maize double crop rotations in the NCP.

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Section: Experimental Data and Model Testingmentioning

confidence: 99%

Quantifying the effects of climate trends in the past 43 years (1961–2003) on crop growth and water demand in the North China Plain

et al. 2009

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“…Root depths of winter wheat and maize were reported by Zhang (1999) as a function of the number of days since planting. Leaf-area index was measured by Zhang et al (2002) and Wang et al (2001).…”

Section: Field Site Descriptionmentioning

confidence: 99%

“…The lysimeter was weighed approximately daily 1 October 1998 through 12 January 2001. The lysimeter, which weighs about 2 t empty and about 14 t when full of soil, has a waterdepth measurement precision of 0Ð02 mm (Zhang et al, 2002). Although the measurements were precise, their accuracy was affected by the non-vegetated surroundings (the 'oasis effect'), which enabled vegetation in the lysimeter to transpire more than if surrounding plants had reduced wind advection (Burman and Pochop, 1994).…”

Section: Field Site Descriptionmentioning

confidence: 99%

“…Although the measurements were precise, their accuracy was affected by the non-vegetated surroundings (the 'oasis effect'), which enabled vegetation in the lysimeter to transpire more than if surrounding plants had reduced wind advection (Burman and Pochop, 1994). Also, Zhang et al (2002) noted that this effect may have been exacerbated by the lysimeter's metal and concrete frame, which extends above the soil surface and concentrates heat. Owing to the enhanced evapotranspiration, drainage from the lysimeter occurred only in July-August 2000.…”

Section: Field Site Descriptionmentioning

confidence: 99%

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A soil‐water‐balance approach to quantify groundwater recharge from irrigated cropland in the North China Plain

Kendy¹,

Gerard-Marchant²,

Walter³

et al. 2003

Hydrological Processes

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Abstract:Rapidly depleting unconfined aquifers are the primary source of water for irrigation on the North China Plain. Yet, despite its critical importance, groundwater recharge to the Plain remains an enigma. We introduce a one-dimensional soil-water-balance model to estimate precipitation-and irrigation-generated areal recharge from commonly available crop and soil characteristics and climate data. To limit input data needs and to simplify calculations, the model assumes that water flows vertically downward under a unit gradient; infiltration and evapotranspiration are separate, sequential processes; evapotranspiration is allocated to evaporation and transpiration as a function of leaf-area index and is limited by soil-moisture content; and evaporation and transpiration are distributed through the soil profile as exponential functions of soil and root depth, respectively. For calibration, model-calculated water contents of 11 soildepth intervals from 0 to 200 cm were compared with measured water contents of loam soil at four sites in Luancheng County, Hebei Province, over 3 years (1998)(1999)(2000)(2001). Each 50-m 2 site was identically cropped with winter wheat and summer maize, but received a different irrigation treatment. Average root mean-squared error between measured and model-calculated water content of the top 180 cm was 4Ð2 cm, or 9Ð3% of average total water content. In addition, model-calculated evapotranspiration compared well with that measured by a large-scale lysimeter. To test the model, 12 additional sites were simulated successfully. Model results demonstrate that drainage from the soil profile is not a constant fraction of precipitation and irrigation inputs, but rather the fraction increases as the inputs increase. Because this drainage recharges the underlying aquifer, improving irrigation efficiency by reducing seepage will not reverse water-table declines.

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“…Ongoing research is attempting to quantify the potential water savings (e.g. Zhang et al, 2002). However, irrigated crop plantings are extremely dense, so most of the water savings occur during the brief periods between crops, when dry surficial soil layers naturally minimize evaporation.…”

Section: Implications For Sustainable Water Managementmentioning

confidence: 99%

Groundwater recharge from irrigated cropland in the North China Plain: case study of Luancheng County, Hebei Province, 1949–2000

Kendy¹,

Zhang

Liu

et al. 2004

Hydrological Processes

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191

145

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Abstract:Effective management of limited water resources in the North China Plain requires reliable calculation of historical groundwater balances at local, sub-watershed scales. These calculations typically are hindered by poorly constrained recharge estimates. Using a simple soil-water balance model, we independently calculated annual recharge from irrigated cropland to unconfined alluvial aquifers underlying Luancheng County, Hebei Province, in the western part of the North China Plain, for 1949-2000. Model inputs include basic soil characteristics and daily precipitation, potential evapotranspiration, irrigation, crop root depth, and leaf-area index; model outputs include daily actual evapotranspiration and areal groundwater recharge. Results indicate that areal recharge is not a constant fraction of precipitation plus irrigation, as previously assumed, but rather the fraction increases as the water inputs increase. Thus, model-calculated recharge rates range from 5 to 109 cm year 1 , depending on the quantity of precipitation and irrigation applied. The important implication is that, because this drainage recharges the underlying aquifer, improving irrigation efficiency by reducing seepage does not save water. This explains why successful efforts to reduce groundwater pumping for irrigation have had no effect on water-table declines. So long as crop cover is extensive and all crop-water requirements are met-which has been the case in Luancheng County since the 1960s-groundwater levels will continue to decline at a steady rate. Potential solutions include reducing the irrigated area, reintroducing fallow periods, and shifting water from agriculture to other, less consumptive uses.

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Measurement of evapotranspiration in a winter wheat field

Cited by 40 publications

References 21 publications

Quantifying the effects of climate trends in the past 43 years (1961–2003) on crop growth and water demand in the North China Plain

Quantifying the effects of climate trends in the past 43 years (1961–2003) on crop growth and water demand in the North China Plain

A soil‐water‐balance approach to quantify groundwater recharge from irrigated cropland in the North China Plain

Groundwater recharge from irrigated cropland in the North China Plain: case study of Luancheng County, Hebei Province, 1949–2000

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