Contents Chapter 1 Climate change and crop water productivity: opportunities for improvement 1 1.1 Climate change and crop water productivity (CWP) 2 1.1.1 Climate change and agricultural production 2 1.1.2 The potential evapotranspiration and meteorological drought 3 1.1.3 Water storage 5 1.1.4 The impact of climate change on crop yields 6 1.1.5 Crop water productivity 7 1.2 Context, objectives and outline of the book 9 1.2.1 Context 9 1.2.2 Objectives 10 1.2.3 Outline 11 1.3 Study region and data collection 12 1.3.1 Study region 12 1.3.2 Data collection 14 1.4 Methods 16 1.4.1 Calculation of potential evapotranspiration 16 1.4.2 DSSAT-CERES-Wheat model for yield simulation 17 1.4.3 Satellite-based actual evapotranspiration estimation using the SEBAL method 19 References 20 Chapter 2 Impacts of climate change on potential evapotranspiration under a historical period and future climate scenario in the Huang-Huai-Hai Plain, China 31 2.1 Introduction 32 2.2 Materials and methods 34 2.2.1 Study area 34 2.2.2 Meteorological data 36 2.2.3 Estimation of potential evapotranspiration 37 2.2.4 Time series analysis to quantify major trends 37 2.2.5 Sensitivity analysis and multivariate regression 38 2.3 Results 38 2.3.1 Historical and future trends of meteorological variables 38 2.3.2 Spatial and temporal characteristics of ET0 40 2.3.3 Temporal variation of sensitivity coefficients 45 2.3.4 Regional response of ET0 to climate change 48 2.4 Discussion 49 2.4.1 Spatio-temporal evolution of ET0 49 2.4.2 Impact of meteorological variables on ET0 50 2.4.3 Estimated precipitation deficit and impact on agriculture 51 2.5 Conclusions 52 References 53 Chapter 3 Spatio-temporal variation of drought characteristics in the Huang-Huai-Hai Plain, China under the climate change scenario 59 3.1 Introduction 60 3.2 Materials and methods 62 3.2.1 Study region 62 3.2.2 Climate data 62 3.2.3 Drought area data 63 3.2.4 Calculations of drought indices 63 3.2.5 Drought identification using run theory 64 3.3 Results 65 3.3.1 Selection of preferable drought index 65 3.3.2 Drought characteristics over the past 50 years 65 3.3.3 Drought prediction for 2010–2099 under RCP8.5 scenario 70 3.4 Discussion 73 3.4.1 Trend variations between different drought indices 73 3.4.2 Applicability of drought index 75 3.5 Conclusions 76 References 77 Chapter 4 Potential effect of drought on winter wheat yield using DSSATCERES-Wheat model over the Huang-Huai-Hai Plain, China 81 4.1 Introduction 81 4.2 Materials and methods 83 4.2.1 Study region and data description 83 4.2.2 Calculation of precipitation deficit for winter wheat 84 4.2.3 Crop model description 85 4.2.4 Statistical tests for trend analysis 85 4.3 Results 86 4.3.1 DSSAT evaluation 86 4.3.2 Trends and persistence of typical growth date and precipitation deficit 87 4.3.3 Variation of yield reduction rate 88 4.3.4 Cumulative probability of yield reduction rate 89 4.4 Discussion 91 4.5 Conclusions 92 References 92 Chapter 5 Investigation of the impact of climate change on wheat yield using DSSAT-CERES-Wheat model over the Huang-Huai-Hai Plain, China 97 5.1 Introduction 98 5.2 Materials and methods 100 5.2.1 Study region 100 5.2.2 CERES-Wheat crop model 101 5.2.3 Simulated scenarios: past, future and isolated variables 102 5.3 Results 104 5.3.1 Testing of CERES-Wheat model 104 5.3.2 Changes in growth duration and related climate variables 105 5.3.3 Changes in yield and the contributions of single climate variables 107 5.4 Discussion 109 5.4.1 Negative impact of increasing solar radiation 109 5.4.2 Positive impact of warming temperature and increasing precipitation 111 5.5 Conclusions 112 References 113 Chapter 6 The impacts of climate change on wheat yield based on the DSSATCERES-Wheat model under the RCP8.5 scenario in the Huang-Huai-Hai Plain, China 116 6.1 Introduction 117 6.2 Materials and methods 118 6.2.1 Study region 118 6.2.2 CERES-Wheat model 118 6.2.3 Simulation design 119 6.3 Results 121 6.3.1 Model calibration and validation 121 6.3.2 Simulated changes of the phenological phase 122 6.3.3 Changes of climatic variables during the wheat-growing period 123 6.3.4 Impacts of different climate variables on wheat yield 124 6.3.5 Impact of elevated CO2 on wheat yield 126 6.4 Discussion 127 6.4.1 The impact of warming temperatures 127 6.4.2 Uncertainties 128 6.5 Conclusions 129 References 130 Chapter 7 Water consumption in winter wheat and summer maize cropping system based on SEBAL model in the Huang-Huai-Hai Plain,China 133 7.1 Introduction 134 7.2 Materials and methods 135 7.2.1 Study area 135 7.2.2 Crop dominance map 136 7.2.3 Phenological data 136 7.2.4 MODIS products 137 7.2.5 Meteorological data 137 7.2.6 SEBAL model 137 7.3 Results 140 7.3.1 Crop ETa 140 7.3.2 Correlation among ETa, NDVI, and land surface temperature 141 7.3.3 Correlation between ETa and geographic parameters 143 7.4 Discussion 145 7.4.1 Assessment of regional crop evapotranspiration 145 7.4.2 Separation of evapotranspiration of the two crops 146 7.4.3 Possible uncertainty of results 146 7.4.4 Need for refinement 147 7.5 Conclusions 147 References 148 Chapter 8 An assessment of water consumption, grain yield and water productivity of winter wheat in agricultural sub-regions of Huang-Huai-Hai Plain, China 152 8.1 Introduction 153 8.2 Materials and methods 154 8.2.1 Study region description 154 8.2.2 Data collection 155 8.2.3 CWP estimation 155 8.3 Results 157 8.3.1 ET map 157 8.3.2 Wheat yield map 159 8.3.3 CWP map 159 8.3.4 Relations among yield, ETa and CWP 161 8.4 Discussion 163 8.5 Conclusions 165 References 165 Chapter 9 General discussion, conclusions, and prospects 170 9.1 Overview of results and hypotheses 171 9.1.1 ET0 and drought characteristics 171 9.1.2 Effects of climate change and drought on wheat yield 172 9.1.3 Spatial variability in crop water productivity 173 9.2 General discussion 175 9.2.1 Agricultural adaptations for CWP improvements 175 9.2.2 The uncertainties 178 9.2.3 Referable value from dataset and methodology of this book 179 9.3 Conclusions 180 9.4 Prospects and improvements 181 9.4.1 Increasing RCP scenarios alternatives 181 9.4.2 Increasing collection of irrigation and fertilizer management for DSSAT simulation 182 9.4.3 Increasing collection of observed CWP in agro-meteorological stations 183 9.5 Closing words 183 References 184