Response And Evaluation Of Main Grain Water Footprint To Climate Change In Haihe River Basin

Spatial-temporal distribution of water resources is affected by climate change.Water footprint can be regarded as a comprehensive evaluation index of water resources.It is of great significance for regional agricultural water resources management that studies the effects of climate change on agricultural water footprint and puts forward effective countermeasures.In this paper,based on the software of Cropwat,ArcGIS10.0 and Matlab,we research the spatial-temporal distribution of main grain crop(winter wheat and summer maize)water footprint at the Haihe River Basin during 1990-2014,and simulate the yield in RCP2.6,RCP4.5 and RCP8.5 climate change scenarios of GFDL-ESM2M mode during 2020-2050,analyzes the contributions of various meteorological factors to water footprint.The main research contents and conclusions are as follows:(1)According to the measured meteorological data and crop yield during 1990-2014,based on Cropwat software,we calculate the per unit weight water footprint and total water footprint,studing the spatial distribution characteristics by ArcGIS10.0,researching the temporal characteristics by the time series analysis.Results show:To the water footprint per unit weight of summer maize,blue and green water is accounted for 36.21%and 63.79%respectively.And to the water footprint,blue and green water is accounted for 36.09%and 63.91%respectively.To the water footprint per unit weight of winter wheat,blue and green water is accounted for 76.52%and 23.48%respectively,and to the water footprint,blue and green water is accounted for 77.51%and 22.49%respectively.The high value area of blue and green water footprint per unit weight of winter wheat and summer maize is the northwest of basin and Bohai rim,and the characteristic of water footprint is that the high in the middle and southeast,the low on all side.During the period of1990-2014,the winter wheat water footprint and the blue and green water footprint per unit weight of two crops shows a declining trend,while the water footprint of summer maize upward.(2)Downscaling meteorological data of RCP2.6,RCP4.5 and RCP8.5 climate change scenarios of GFDL-ESM2M model during 2020-2050,we establish the fitting equation between 1990-2014 per unit area and the meteorological factors by Partial Least Squares Regression,aiming to simulate the yield per unit area of summer maize and winter wheat during 2020-2050.Results show:The average yield per unit area of summer maize of RCP2.6,RCP4.5,RCP8.5 during2020-2050 is 5581.1 Kg/hm~2,5706.8 Kg/hm~2,5723.5 Kg/hm~2 respectively;while the winter wheat is 4790.0 Kg/hm~2,average 4940.3 Kg/hm~2,4783.3 Kg/hm~2 respectively.At the same time,the analysis showed that there climate change scenarios were significant differences in yield and yield per unit area.(3)Based on Cropwat software,we calculate the water footprint per unit weight and water footprint during 2020-2050 under the different climate change scenarios.The spatial-temporal characteristics showed that:The spatial distribution of blue,green water per unit weight and water footprint of two crops is almost same as the distribution of 1990-2014.At the same time,compared with the average of 1990-2014,the blue and green water per unit weight of summer maize is decreased,while the winter wheat is increased,besides,the blue and green water footprints of the two crops are increased significantly.(4)According to the partial correlation analysis by Matlab software,we calculate the contribution of various meteorological factors on the water footprint,showed that the relative humidity,precipitation and sunshine hour is the mian meteorological factors to the summer maize water footprint,including that precipitation and relative humidity is negatively correlated with the blue water and positively to the green water,and the sunshine hour is all positively to the water footprint.Besides,the relative humidity is the most important meteorological factor to the winter wheat water footprint,with negatively to the blue water and positively to the green water.At the same time,to the various administrative divisions,water footprint of three scenarios at many areas are influenced by two main meteorological factors significantly,and the precipitation and humidity is negatively correlated to the water footprint per unit weight,while the sunshine hour,temperature and wind speed is positive.Besides,all the main meteorological factors are positively influence on water footprint.However,the main factors have significant difference for area scale.