| Terrestrial water storage(TWS)is an important component of water storages and basin water cycle.It is of great significance to accurately monitor the temporal and spatial changes of regional terrestrial water and its influencing factors to reveal the terrestrial water cycle.GRACE(Gravity Recovery and Climate Experiment)provides a new way to observe the variation of Terrestrial water storage anomaly(TWSA)and groundwater storage.The Huang-Huai-hai Plain is a large agricultural area in the north of arid area of China.However,existing studies mostly focus on the temporal and spatial variation of TWS and the influence of natural factors such as precipitation.Current studies lack quantitative analysis of factors affecting TWSA from the perspective of internal water layer changes.Meanwhile,there are few studies on the temporal and spatial evolution of groundwater drought caused by the drop of groundwater table and the identification of characteristic variables.Based on multi-source data such as GRACE satellite,this study uses Sen trend analysis and other methods to deeply understand the temporal and spatial evolution of TWS and their components in the study area,and uses the water balance formula to invert the changes of groundwater storages to explore the effects of different components of groundwater on TWS.At the same time,the temporal and spatial evolution of groundwater drought caused by groundwater is further analyzed by the run-distance theory.The main work and research results are reflected in the following five aspects:(1)The regional applicability of GRACE satellite data is high in the Huang-Huaihai Plain.The correlation between the mean TWS data of the study area from April 2002 to December 2021 and the TWS output of the WGHM hydrological model was the highest(r=0.92).The groundwater storage data of the study area from April 2002 to December2021 obtained by GRACE satellite and GLDAS were highly consistent with the groundwater storage data output by WGHM hydrological model(r=0.75).(2)During the study period,TWS in the study area decreased significantly(Trend=-9.89mm/yr,P<0.01),and all changes of groundwater storages played a leading role in TWSA.The spatial distribution was significantly different,ranging from-20 mm to 9mm,showing a "rapid decline in the middle,slow decline in the periphery".In terms of quality,the variation of groundwater storages in the study area as a whole and in the sub-zones accounts for 88.36%,90.14%,96.39% and 86.27% of TWSA.(3)During the study period,groundwater storages in the Huang-Huai-hai Plain decreased significantly(Trend=-9.58mm/yr,P<0.01).The spatial distribution was significantly different,with the overall variation range from-19mm/yr to 2mm/yr.The trend of groundwater reserves in the semiarid,dry-subhumid and humid zone were-12.67mm/yr(P<0.01),-7.13mm/yr(P<0.01)and-2.55mm/yr(P<0.01).(4)From 2002 to 2016,irrigation water consumption accounted for the highest proportion of total water consumption,reaching 76.89%.Among them,the irrigation water consumption in semiarid,dry-subhumid and humid zone accounted for 77.17%,69.63% and 82.76% of the total water consumption.It shows that the major factor leading to the serious decline of groundwater storages in the study area is the large amount of irrigation water consumption.(5)During the study period,groundwater drought in the Huang-Huai-hai Plain has the characteristics of high frequency,wide range and continuous drying.In terms of time,the GRACE Groundwater Drought Index(GGDI)showed a significant downward trend.The spatial distribution features of "the north becomes drier and heavier,while the south becomes drier and slower" are presented.Groundwater drought affects a wide range in early spring and summer,and its frequency is highest in spring.The spatial distribution of groundwater drought intensity is highly consistent with that of groundwater drought duration.In the future,groundwater drought will continue to dry in most areas of the Huang-Huai-hai Plain. |
