Spatio-temporal patterns of crop planting structure and water requirement in the Zhangjiakou region, northern China

Zhangjiakou in northern China is a region with serious water shortage. Agriculture is the largest user of water resources; therefore, conserving water by changing planting structures is crucial. Here, we studied the changes in spatio-temporal patterns of crop planting structure and water requirement at different spatial scales in the Zhangjiakou region. The results showed that 1) from 2005 to 2015, the crop planting structure changed to high water-consuming crops. The planting area of high water-consuming crops increased by 24.75%, and the area of irrigated farmland increased by 6%. At the same time, the planting area of high water-consuming crops on Bashang plateau and Baxia area increased by 33.97% and 20.7%, respectively. The total planting area of rainfed crops decreased by 58.5% in Bashang plateau but increased by 48.51% in Baxia area. 2) Because of the increase in the planting area of high water-consuming crops in Zhangjiakou, the water requirement in 2015 was higher by 274 million～389 million·m^–3 than that in 2005. Although the structure of vegetable planting showed changes toward the direction of water saving and high income, the total planting area of vegetable crops increased, which led to a 6.84 million～6.85 million·m^–3 higher water requirement in 2015 than that in 2005. 3) In 2015, the water requirement of crops in Bashang and Baxia area increased by 22.36%～22.42% and 21.46%～21.81%, respectively. The water requirement of crops at Kangbao County, Guyuan County in Bashang and Zhangjiakou and, Chongli District in Baxia increased by 41.19%～41.59%, 38.86%～44.78%, 43.83%～52.42%, and 42.67%～45.26%, respectively, compared to that in 2005. The main reason for the increase in water requirement is increase in the planting area of high-water consumption crops.