Spatial-temporal characteristics of water demand, water surplus and deficit of potato in northern Hebei Province in the past 50 years

In order to efficiently use water resources and increase the agricultural production efficiency, the data from 23 meteorological stations in the main potato growing areas of Hebei Province (northern Hebei Province) were analyzed to calculate the water demand and water shortage during the growing period of potato from 1969 to 2018. The analyses involved the reference crop evapotranspiration calculation method and the related crop coefficient method recommended by the Food and Agriculture Organization of the United Nations. The changing trend of precipitation, effective precipitation, water demand, and water shortage during the 50-year potato growing period, and the changing characteristics of water demand and water shortage in different regions and different growing periods were analyzed. There were three main results. Firstly, the annual variation of precipitation and effective precipitation during the growing period of potato in northern Hebei Province in the past 50 years could be divided into two stages. In one stage, there was a decreasing trend from 1969 to 2003. The climatic tendency rates of precipitation and effective precipitation were -15.68 mm·(10a)^-1 and -6.61 mm·(10a)^-1. In the stage from 2004 to 2018, the tendency rates was significantly increased, which were 60.07 mm·(10a)^-1 and 9.68 mm·(10a)^-1. The average precipitation and effective precipitation in recent 50 years were 356.5 mm and 148.6 mm, respectively. Their spatial characteristics showed the zonal feature of decreasing gradually from west to east. Secondly, the interannual variation of water demand and water shortage during the growth period of potato in the past 50 years also showed a decreasing trend from 1969 to 2003 and an increasing trend from 2004 to 2018. In years of high water demand, there was also a great shortage of water. In the past 50 years, the average water requirement and water shortage were 497.8 mm and 349.1 mm, respectively. The spatial distribution showed an increase from Bashang plateau to the Baxia mountain area. In the region of high water demand, there was also a great shortage of water. Thirdly, the water demand of potato was largest during the expansion period, when the water shortage also reached its maximum. The water resources of potato in northern Hebei Province have been in a serious deficit state during the past 50 years. It is necessary to fully consider the response of potato water demand to the changes of meteorological factors in order to strengthen water management and ensure the efficient utilization of water resources.