The Comparison of Grey System and the Verhulst Model for Rainfall and Water in Dam Prediction

Table 2

The simulation value of rainfall and relative error from actual data of the two models.

Year	Value of rainfall (mm)	GM(1,1)		Grey Verhulst model		Comparison
		Forecasted	Relative error	Forecasted	Relative error	GM	GVM
2005	1,391.13	1,391.13000	0.000000	1,391.13000	0.0000000	A	A
2006	1,294.38	1160.639126	0.103320811	1268.777091	0.019780056	B	A
2007	1,127.55	1090.839652	0.032557623	1103.82589	0.021040407	A	A^∗
2008	1,273.20	1403.074098	0.102006046	1252.684884	0.016113035	B	A
2009	1,055.85	1040.43307	0.014601439	1032.535472	0.022081288	A	A^∗
2010	1,279.60	1481.163528	0.157520731	1260.451645	0.014964329	B	A
2011	1,622.40	1599.647364	0.014024061	1598.961774	0.014446639	A	A^∗
2012	1,184.70	819.8702634	0.307951158	1154.556153	0.025444288	C	A
2013	1,416.22	1488.707888	0.051184059	1394.610077	0.015258875	A	A^∗
2014	1,142.98	984.3991677	0.138743313	1116.887803	0.022828218	B	A
2015	1,082.38	1197.139254	0.106024921	1061.569763	0.019226368	B	A
		MAPE	0.102793416	MAPE	0.01911835	B	A

Source: Thailand Meteorological Department.