- Title
- Study on the changes of groundwater storage based on GRACE data in northern China
- Creator
- Yin, Wenjie
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2021
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Many environmental geological problems have occurred due to the irrational exploitation of groundwater. Therefore, the knowledge of groundwater storage (GWS) anomalies is essential for reliable water resource assessment. The traditional method to measure groundwater level mainly relies on groundwater monitoring wells. However, knowledge about GWS temporal and spatial variations is generally lacking due to scarcity of groundwater monitoring networks and uneven spatial distribution. The launch of GRACE satellites provides the measure of terrestrial water storage (TWS) changes at basin scales for the first time. This dissertation first evaluates the accuracy of GRACE data in quantifying GWS in Northern China. Then, two extended applications are developed by use of GRACE data: one is to detect the flux change pattern over basin boundaries, and the other is to reconstruct long-term time series of TWS anomalies. However, the applicability of GRACE data to local water resources management is constrained due to the coarse spatial resolution. Both statistical and dynamical downscaling approaches are presented to overcome the limitation. The main contents and findings of this dissertation are summarized as follows: (1) Groundwater storage anomalies of Northern China are isolated from GRACE-derived TWS anomalies using GLDAS data, then validated against two Chinese official datasets to verify the accuracy of GRACE-based GWS in the Northern China. In six river basins of Northern China, the correlation between GRACE-based GWS and annual groundwater resource anomalies is strengthened with the increase of study area. Moreover, there is a good match between yearly measured and GRACE-based GWS in Huang-Huai-Hai Plain and the Song-Liao Plain of China In terms of provinces where the Central Route of the South-to-North Transfer Project located, Jing-Jin-Ji region has a higher yearly depletion rate of groundwater storage, with -0.70 cm/yr Equivalent Water Height (EWH), and Henan province has the decreasing rate of -0.21 cm/yr EWH from 2003 to 2012. (2) An innovative method is developed to detect the flux change patterns over the boundaries of the Heihe River Basin in China using GRACE data, water balance and Darcy’s law, and the trend of the changes is investigated using Mann-Kendall and Sen’s slope. During the period from 2003 to 2015, there are generally decreasing trends in TWS anomalies and GWS anomalies over the Heihe River Basin (HRB). The water resources, recharging the HRB from the eastern and western boundaries, show negative trends from 2003 to 2015, while increasing trends on the other two boundaries. To sum up, the summation of flux change coefficient is -152.35 mm among four boundaries, indicating that the total amounts of water resources, recharging the HRB from the outside areas, generally decrease from 2003 to 2015. (3) In order to overcome the short lifetime of GRACE-derived TWS, the water balance method is used to reconstruct monthly and annual TWS changes from 1980 to 2015 in the Beishan area of China by use of GRACE data and multi-source remote sensing products. A decreasing trend is found from GRACE-filtered and mascon solutions during the period 2003-2015. TWS anomalies independently computed from the water balance method also show a similar decreasing trend with the GRACE observations, with a slope of -0.94 mm/yr. During these 35 years, TWS anomalies show a prolonged declining trend, and large decreasing trends emerge between 1982-1987 and 1993-2005. As a whole, the TWS anomalies almost remain stable since 2001. (4) In order to extend the application of GRACE data at local scales, a statistical downscaling approach is presented to improve the spatial resolution of GRACE-based GWS anomalies based on the close relationship between GWS and evapotranspiration (ET) over the North China Plain (NCP) of China. GWS anomalies are downscaled using three ET products from GLEAM, Noahv2 and MOD 16 to choose the best ET data. It can be found that GWS anomalies can be downscaled into a higher spatial resolution using MOD 16 ET than other products. Therefore, GWS anomalies are downscaled from 110 km to 2 km based on MOD ET, and further validated using 111 observation wells in the Beijing Plain. The results indicate that the in situ groundwater level agree with the GRACE downscaled results for the Beijing Plain in both interannual and monthly scales. (5) In order to overcome the coarse spatial resolution of GRACE data, a dynamical downscaling (data assimilation) approach is implemented by assimilation GRACE TWS changes into the Community Atmosphere Land Exchange (CABLE) model via ensemble Kalman filter in the NCP. The procedure can improve the estimates of water storage components at the model resolution, as well as disaggregate the GRACE large-scale terrestrial water storage changes vertically. The spatial pattern of simulated TWS and simulated GWS are mainly influenced by that of precipitation. After assimilating GRACE data into CABLE model, the spatial pattern of TWS and GWS become closer to the GRACE patterns. The downscaled results are further validated against in situ groundwater level in the NCP. The simulated GWS are negatively correlated with observations in several pixels, while assimilation greatly improves the correlation coefficient and reduce root mean square error.
- Subject
- GRACE; terrestrial water storage change; groundwater storage variation; statistical downscaling; data assimilation; water resources management
- Identifier
- http://hdl.handle.net/1959.13/1476730
- Identifier
- uon:49851
- Rights
- Copyright 2021 Wenjie Yin
- Language
- eng
- Full Text
- Hits: 760
- Visitors: 942
- Downloads: 226
| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 7 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 630 KB | Adobe Acrobat PDF | View Details Download |