Abstract: In order to reveal the spatiotemporal variability of surface water and groundwater with their interaction in Dengkou County, EMD algorithm and co-kriging model were used in this study based on four groups data divided by 17 experimental wells. The spatiotemporal variability between surface water and groundwater in Dengkou County were analyzed by 3S technology from east to west and south to north with spatial overlay and trend curve fitting. Results show that:(1)Groundwater depth in northern and eastern Dengkou County showed a decreasing trend in the period of 1990-2015, with an increasing trend in the center and southeast. The area of groundwater depression in southeastern Dengkou County has reduced by governance. (2)The area of surface water in Dengkou County had little change in the period of 1990-2015. It increased fist and then decreased, and at last increased again, which showed an increasing trend from both west to east and north to south. (3)The main recharging source of groundwater in Dengkou County is the Yellow River in the period of 1990-2005.

Key words: surface water, ground water, EMD, co-kriging, trend analysis