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

Table 3

The comparison of water in dam and relative errors of the two models from actual data gathering.

Year	Water in dam (MCM)	GM(1,1)		Grey Verhulst model		Comparison
		Forecasted	Relative error	Forecasted	Relative error	Precise model
2005	438	438.0000	0.0000	438.0000	0.0000	A	A^∗
2006	1627	1697.094408	0.043081996	1619.2925	0.004737247	A	A^∗
2007	1917	1999.758645	0.043170915	1886.765149	0.015771962	A	A^∗
2008	1690	1762.845604	0.043103908	1653.978051	0.021314763	A	A^∗
2009	882	919.5604189	0.042585509	850.516227	0.035695888	A	A^∗
2010	2274	2372.348758	0.043249234	2258.133293	0.006977444	A	A^∗
2011	2145	2237.715356	0.043223942	2101.732322	0.020171412	A	A^∗
2012	510	531.3152594	0.041794626	469.3646272	0.079677202	A^∗	A
2013	1469	1532.194582	0.043018776	1459.992114	0.006131985	A	A^∗
2014	634	660.7303126	0.042161376	606.8758104	0.042782633	A^∗	A
2015	230	239.08772	0.039511826	218.7315064	0.04899345	A^∗	A
		MAPE	0.042490211	MAPE	0.028225398	A	A^∗

Source: The Thai Royal Irrigation Department.