Table 5.

Performance metrics (RMSE, MAE, R²) of XGBoost, RF, and SVM models across hydrogeological zones Z1–Z5 during training and testing.

Model	Index	Training					Testing
		Z1	Z2	Z3	Z4	Z5	Z1	Z2	Z3	Z4	Z5
XGBoost	RMSE	0.82	0.81	1.64	1.09	0.35	0.85	2.37	2.87	1.25	0.43
	R 2	0.93	0.95	0.94	0.90	0.95	0.91	0.80	0.85	0.76	0.92
	MAE	0.21	1.01	1.5	0.38	0.15	0.32	1.8	2.4	0.67	0.21
	WI	0.98	0.99	0.97	0.96	0.99	0.97	0.92	0.94	0.93	0.98
	PBIAS (%)	−0.8	1.2	−1.5	0.6	−0.5	−1.1	2.4	1.8	−1.7	−1.2
RF	RMSE	0.74	1.43	2.14	1.08	0.68	0.77	2.77	2.93	1.23	0.83
	R 2	0.82	0.88	0.86	0.70	0.9	0.78	0.75	0.77	0.59	0.85
	MAE	0.42	1	1.7	0.41	0.2	0.72	1.5	2.8	0.66	0.48
	WI	0.96	0.94	0.92	0.91	0.95	0.94	0.89	0.90	0.87	0.95
	PBIAS (%)	1.5	3	2.8	−2.4	1.1	2.8	4.5	5.1	−3.2	1.7
SVM	RMSE	0.79	1.23	2.34	1.13	0.23	0.87	2.05	4.16	1.26	0.44
	R 2	0.91	0.94	0.92	0.85	0. 97	0.86	0.82	0.80	0.70	0.93
	MAE	0.40	1.4	2	0.51	0.12	0.51	2.5	3.2	0.75	0.19
	WI	0.97	0.96	0.91	0.93	0.99	0.96	0.91	0.86	0.90	0.98
	PBIAS (%)	−1.2	2.1	3.4	−1.8	0.4	−0.7	3.7	7.9	−2.5	0.8