Table 2.
Summary of Key Results From the Final, National‐Scale GRMa
| Covariates | Unit | Coefficient | Std. Error | LR Test P Value |
|---|---|---|---|---|
| Geological and Hydrogeological Variables | ||||
| Surface geology (n = 15)b | categorical | |||
| TSSC and its interaction with surface geologyc | m | −0.023 | 0.019 | 0.0013 |
| Hydraulic conductivity | m d−1 | −0.026 | 0.007 | 0.0089 |
| Sampling well depth and its interaction with surface geologyc | m | −0.012 | 0.009 | 0.0001 |
| Hydrodynamic and Groundwater Recharge Variables | ||||
| Mean groundwater recharge and its interaction with surface geologyc | mm yr−1 | −0.0006 | 0.004 | 0.0019 |
| Net changes in recharged | mm | −0.004 | 0.0009 | 0.0006 |
| Mean groundwater‐level trends | cm yr−1 | 0.034 | 0.012 | 0.0230 |
| Groundwater‐Fed Irrigation | ||||
| Irrigation trends (1985−1999) | mm yr−1 | −0.056 | 0.022 | 0.0635 |
a
Model coefficients represent the overall effect of a covariate excluding its statistical interactions; however, P values are for the main effect together with all associated interactions. Complete results from the national‐scale, final GRM are provided in supporting information.
b
Model coefficients, standard errors, and P values for categorical surface geology covariate listed in the supporting information.
c
Model coefficients are associated with the respective covariate only and not including their statistical interactions.
d
Net changes in mean recharge between PGI (1975−1980) and DGI (1995−1999) periods.