Spatiotemporal change of Vegetation and hydrology factors over North China Plain from 2002 to 2016

Groundwater pumping has caused marked aquifer storage declines and land subsidence in the North China Plain, which has the world's largest funnel of groundwater. In addition to threatening the viability of groundwater-dependent economic activities, groundwater storage serious losses reshape the hydrological landscape and ecological environment. A more comprehensive understanding of spatio-temporal dynamic changes of eco-hydrological elements in North China Plain is needed as we strive for more efficient water resources management and ecological environment project. Combining MODIS enhanced vegetation index (EVI) with precipitation, GRACE gravity satellite water storage (TWS), groundwater and soil moisture, in this study we investigated the spatial-temporal dynamics and trends of vegetation and its association with the changes in various hydrological factors over the North China Plain between 2002 and 2016. Our results showed that: (1) From 2002 to 2016, the vegetation in the North China Plain exhibited increasing trend while there was downward trend in the hydrological factors (TWS, soil moisture, groundwater) (2) Being mainly covered by crops, the vegetation in Huanghuai plain area was found increasing during the study period. Meanwhile, precipitation, TWS, groundwater, and soil moisture all significantly decreased. Over-exploitation of groundwater to irrigate crops is an important measure to ensure food security in the short term. (3) The contrasting trends in the decreasing vegetation coverage, TWS, soil moisture and groundwater with increasing precipitation over the urban and rural residential area in the Taihang-yanshan mountains piedmont plain and Ji-lu-yu low lying plain may present the influences from intense human activities. (4)The natural forest and grassland ecosystems located in Shandong hilly agroforestry region was found to be positively correlated with precipitation during the study period, both showing decreasing trends. Results from this research will generate a better understanding of vegetation dynamics in different ecological environments and its response mechanisms to the changes in different hydrological factors. This will guide the design of rational water-use strategies in the face of a changing climate and increasing anthropological activities.