Emergy Evaluation of a Production and Utilization Process of Irrigation Water in China

Table 5

Emergy indices and ratios for the integrated production system and for the separated production subsystems.

Number	Emergy indices and indicators	Expression	Quantity
			Irrigation water production	Irrigated agriculture production	Integrated production system
1	Renewable resources (sej/year)	R	1.09𝐸+17	4.60𝐸+17	1.24𝐸+17
2	Nonrenewable resources (sej/year)	N	1.26𝐸+17	1.09𝐸+15	1.27𝐸+17
3	Total environmental inputs (sej/year)	R + N	2.36𝐸+17	4.61𝐸+17	2.51𝐸+17
4	Purchased fuel and materials (sej/year)	M	1.92𝐸+17	3.52𝐸+17	5.44𝐸+17
5	Services and labor inputs (sej/year)	S	1.70𝐸+16	1.15𝐸+17	1.32𝐸+17
6	Total economy feedback emergy (sej/year)	M + S	2.09𝐸+17	4.67𝐸+17	6.76𝐸+17
7	Total emergy yield (sej/year)	Y = R + N + M + S	4.45𝐸+17	9.28𝐸+17	9.28𝐸+17
8	Proportion of total environment investment	(R + N)/Y	53.0%	49.7%	27.1%
9	Proportion of total feedback emergy	(M + S)/Y	47.0%	50.3%	72.9%
10	Renewability ratio	%R = R/Y	24.6%	49.6%	13.4%
11	Emergy yield ratio	EYR =Y/(M + S)	2.13	1.99	1.37
12	Emergy investment ratio	EIR = (M + S)/(R + N)	0.89	1.01	2.69
13	Environmental load ratio	ELR = (M + N +S)/R	3.07	1.02	6.47
14	Environmental sustainability index	ESI = EYR/ELR	0.69	1.95	0.21