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Climate change impacts on food supply and water use efficiency have become an urgent issue for the agricultural researchers and governments. With climate change, water resources will be a restricting factor for agriculture, especially in arid and semi‐arid areas. This paper mainly discusses the changing tendency of water balance components, maize yield and water use indices under rainfed and irrigated conditions in subareas of the Loess Plateau under the A2 and B2 scenarios with the SWAGMAN® Destiny model. The results show that evapotranspiration will increase in future for both rainfed and irrigated maize under both scenarios. The water use indices mentioned in this paper have the same tendency under both scenarios in the same subareas, but variability under the A2 scenario is higher than that under B2. The crop yield and water use indices will decrease for rainfed maize production in the whole Loess Plateau. With irrigation, crop yield will increase in Clay Loam‐2 and Clay Loam‐1 while it will decrease in Light Loam and Sandy Loam under the A2 scenario and B2 scenarios in 2020, 2050 and 2080 respectively. The evapotranspiration efficiency and ratio of evapotranspiration and irrigation under irrigated maize will increase in Clay Loam‐2, Clay Loam‐1, Light Loam and Sandy Loam under both scenarios. Crop water use efficiency, irrigation water use efficiency and total water use efficiency will decrease under the A2 and B2 scenarios during irrigated maize growth. Therefore, for the rainfed crop, it is necessary to improve water harvesting technology so as to meet the increasing crop water requirements with climate change; while, for the irrigated crop, it is vital to enhance soil water capacity in order to make good use of the irrigated water. Copyright © 2013 John Wiley & Sons, Ltd.

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Aiming to analyse the variation of seasonal reference crop evapotranspiration (ET 0 ) and show the impact of meteorological factors on ET 0 across Sichuan Province, this study mainly discussed the variation of ET 0 during the periods of 1967-2016 in three subregions of Sichuan Province with the Mann-Kendall test (MK), Morlet wavelet analysis and path analysis. Meanwhile, future ET 0 trend variation characteristics at different timescales were evaluated by Hurst exponents based on the rescaled range analysis (R/S) method. The results indicated that over the past 50 years, annual ET 0 had a decreasing trend with a rate of À0.64 mm per10 years, confirming the existence of an 'evaporation paradox'. Through spatial analysis, the distribution of average annual ET 0 exhibited a declining trend from south to north over the study region. On the seasonal scale, the highest values of ET 0 in summer were distributed in the Sichuan central basin while the highest values in other seasons were in the south-western mountain area. The Hurst exponents showed that the trends of annual and seasonal ET 0 in the future are consistent with past ones in the whole region (H > 0.5). The annual ET 0 showed the obvious periodic variation of 28 years in the study regions based on Morlet wavelet analysis. The decreases in ET 0 were mostly attributed to the decline in sunshine hours.These findings can help water managers in better water planning and irrigation scheduling for local agricultural production.

Climate change impacts on food production and water use efficiency are becoming more and more important. This paper mainly discusses the climate change effects on water use indices and maize yield under rainfed and irrigated conditions projected by three climate models in the Murray Darling Basin, Australia in 2020, 2050 and 2080 under A2 and B2 scenarios. The climate prediction results show that it is similar to the future precipitation and temperature projected by three climate models for the same time slices. For rainfed and irrigated maize, the crop yield, the potential and actual evapotranspiration will increase by 3–32, 3–12, 30–45 and 32–45, 3–15, 6–15% under both scenarios in the future during the maize growth period compared with the baseline respectively. Water use indices of maize under rainfed conditions will decrease and the variable increment will gradually be larger in the future, including evapotranspiration efficiency, crop water use efficiency and total water use efficiency. However, all the water use indices analysed under irrigated conditions will increase. The variation for evapotranspiration efficiency, ratio of evapotranspiration and irrigation is around 20%, but the variation for the other three indices is more than 30%. The projection results also indicate that the indices under the B2 scenario are smaller than those under A2 although the variable tendency and range are consistent. The conclusions suggest that it is significant to develop irrigated agriculture so as to mitigate climate change effects on crop production in the Murray Darling Basin. Copyright © 2015 John Wiley & Sons, Ltd.

In this paper, the long-term dynamics of water balance components in two different contrasting ecosystems in Australia were simulated with an ecohydrological model (WAter Vegetation Energy and Solute modelling (WAVES)) over the period 1950–2015. The selected two ecosystems are woodland savanna in Daly River and Eucalyptus forest in Tumbarumba. The WAVES model was first manually calibrated and validated against soil water content measured by cosmic-ray probe and evapotranspiration measured with eddy flux techniques. The calibrated model was then used to simulate long-term water balance components with observed climate data at two sites. Analyzing the trends and variabilities of potential evapotranspiration and precipitation is used to interpret the climate change impacts on ecosystem water balance. The results showed that the WAVES model can accurately simulate soil water content and evapotranspiration at two study sites. Over the period of 1950–2015, annual evapotranspiration at both sites showed decreasing trends (−1.988 mm year−1 in Daly and −0.381 mm year−1 in Tumbarumba), whereas annual runoff in Daly increased significantly (5.870 mm year−1) and decreased in Tumbarumba (–0.886 mm year−1). It can be concluded that the annual runoff trends are consistent with the rainfall trends, whereas trends in annual evapotranspiration are influenced by both rainfall and potential evapotranspiration. The results can provide evidence for controlling the impacting factors for different ecosystems under climate change.