Change Trends And Attribution Analysis Of Green Water Footprints Of Main Grain Crops In Ningxia

In recent years,climate change has a impact on agriculture in Ningxia,and the green water footprint(GWF)of crops is an effective indicator to quantify the impact of climate change on agricultural production.Therefore,it is of great significance to study the spatial-temporal evolution of the GWF of major grains in Ningxia,and to ensure the efficient utilization of agricultural water resources and food security under climate change.On the basis of extensive data collection and reference literature reading,based on water footprint theory,Mann-Kendall trend and mutation point test,Sen slope,path analysis and other research methods,combined with ArcGIS and SPSS platform,The spatial-temporal evolution of GWF of maize,wheat and rice in Ningxia and the main driving factors affecting the change were analyzed,and the following conclusions were drawn:(1)The mean of GWF of maize,wheat and rice production in Ningxia was 0.182,0.360 and 0.180 m3/kg,respectively(1993-2019).There was no obvious trend of change in GWF of maize production in the whole Ningxia and its three sub-regions.The change rates of GWF of maize,wheat and rice production were very small.In terms of spatial distribution,the GWF of maize and wheat production decreased from southeast to northwest,while the GWF for rice production decreased from north to south in the northern Yellow River irrigation area and the central arid zone.(2)The mean values of regional GWF of maize,wheat and rice were 184.1 million m3,1662 million m3 and 0.976 million m3.respectively;The regional GWF of maize increased significantly in Ningxia and its three sub-regions(P<0.01);The regional GWF of wheat decreased significantly in the whole region and the southern mountainous area(P<0.05);The GWF of rice region decreased significantly in the whole region and the northern Yellow River irrigation area(P<0.01).The change rates of GWF of m aize,wheat and rice in the whole region were 0.125,-0.029 and 0.019 billion m3/a,respectively.In terms of spatial distribution,the variation range of maize and wheat GWF decreased from south to north,while the high value of rice GWF was mainly distributed in the north Yellow River irrigation area.(3)According to the calculation process of GWF,green water consumption per unit area of crops,crop water requirement,effective precipitation during growth period and planting area were selected as the driving factors affecting the change of GWF.The change tends of driving factors for com,wheat and rice in the green water consumption per unit area,effective rainfall and the planting area were increase.The water dem and was significantly decrease;The yield per unit area of maize and wheat showed a significant upward trend.(4)Linear regression and path analysis were used to quantify the effects of driving factors.The results showed that the most significant direct and indirect factors were green water consumption per unit area and precipitation for maize and rice production,respectively.For the GWF of wheat production,the direct and indirect factors were yield per unit area and precipitation,respectively.For the regional GWF of the three crops,green water consumption per unit area was the most direct factor,and rainfall was the most indirect factor.