Major Role of Surface-groundwater Interactions for Sustaining Spring Wetlands of the Great Artesian Basin, Australia

Groundwater is an essential resource for sustaining human life and associated ecosystems such as rivers and springs. Springs, fed by groundwater on the surface, regulate ecosystem services, including drought mitigation and support for biodiversity. However, climate variability and groundwater extraction for domestic and industrial use in the Great Artesian Basin (GAB) are contributing to groundwater stress, limited surface water in springs, and slowing groundwater recharge processes. Thus, an improved understanding of surface-groundwater interactions in springs is required in the GAB region. This study demonstrates the potential of the Gravity Recovery and Climate Experiment (GRACE) satellite observations to determine groundwater storage variation through validation with borewell monitoring data in the GAB. An important aspect of this study was to assess the surface-groundwater interactions to better explain the variability of spring extent in the GAB for the five spring supergroup sites: Springvale, Flinders, Eulo, Barcaldine, and Springsure. We used Partial Least Square Regression (PLSR) method to assess the response of groundwater storage to hydrological variables (e.g., surface water extent, rainfall, soil moisture storage, evapotranspiration, and surface water level) and vegetation greenness between 2002 and 2017 in the spring supergroups. The predicted and observed groundwater storage is well correlated with hydrological variables post La-Niña (2011-2017) compared to the pre La-Niña (2002-2010) period. This study revealed the importance of variations in climate in understanding how groundwater responds to predictors (vegetation greenness and soil moisture storage) in spring supergroups. Overall, groundwater responses to several predictors (NDVI, mNDWI, rainfall, SWL, ET, and SMS), even before the heavy rainfall season were the strongest in the Flinders spring supergroup. The preliminary results from this method provide information and directions that underpins sustainable groundwater management in the complex geological GAB region and associated ecosystem services such as nutrient recycling and sustaining biodiversity.