Spatial differentiation of center pivot irrigation in a farming-pastoral ecotone of Northern China: A case study in Ulanqab

Agricultural production capacity in Farmingpastoral Ecotone of Northern China (FPENC) has been limited to long-standing water shortage and drought. In this context, the center pivot irrigation (CPI) exhibited a widespread adoption in recent years to increase utilization efficiency of agricultural water and crop yield. However, the high rate of groundwater extraction by CPI, reducing the aquifer saturated thickness, has large potential impacts on aboveground vegetation growth. And, we lack the knowledge of the temporal and spatial variations of CPI in FPENC. In this paper, taking Ulanqab as an example, we measured spatio-temporal patterns of CPI from 2008 to 2017 using Landsat TM/ETM+/OLI data and spatial autocorrelation methods. The results indicated that the number of CPI increased first and then decreased, reaching a peak of 1243 in 2015. There was a positive spatial autocorrelation in the spatial distribution of CPI, that is, it had a very obvious spatial clustering characteristics. The degree of spatial agglomeration increased from 0.283 in 2008 to 0.526 in 2017. The results of local spatial autocorrelation showed that the spatial agglomeration pattern of Ulanqab was dominated by High-High agglomeration. These obtained results can provide a strong basis for decision-making in formulating sustainable agricultural development strategies.