Time series trend analysis of temperature and rainfall in lake Tana Sub-basin, Ethiopia

Environmental Systems Research

Table 1 Mean monthly aggregated rainfall data in LTSB descriptive statistics for the last 3 decades (mm)

Rainfall level	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low Sub-basin
Min.	0.00	0.00	0.00	0.00	1.20	66.00	224.00	217.53	106.21	0.00	0.00	0.00
Max.	13.3	26.9	85.6	104.3	237.5	437.2	636.4	654.0	269.2	209.6	65.3	16.9
Mean	1.65	2.21	8.31	24.84	70.62	181.5	381.97	376.14	172.08	81.62	11.2	2.10
SD	3.22	5.87	16.60	27.27	55.88	72.95	117.06	112.30	46.48	53.56	13.9	3.99
CV	2.29	3.31	2.49	1.18	0.90	0.47	0.31	0.32	0.31	0.71	1.50	2.18
r	0.15	0.20	0.12	−0.09	0.01	0.01	−0.27	0.41	0.24	0.12	0.45	0.04
Slope	0.00	−0.04	−0.07	−0.27	0.40	1.34	−9.55	−5.36	−2.66	−0.65	−0.0	−0.03
Upper Sub-basin
Min.	0.00	0.00	0.00	5.50	10.30	73.00	234.00	190.20	80.10	2.90	0.50	0.00
Max.	81.4	81.1	98.00	118.30	211.50	345.00	592.10	628.50	321.00	305.0	76.20	82.50
Mean	5.46	7.99	34.65	49.94	92.49	151.70	396.59	375.94	188.53	74.90	22.78	11.86
SD	14.0	18.30	33.42	33.51	67.25	59.43	83.57	92.09	55.53	65.51	17.30	15.96
CV	2.56	2.29	0.96	0.67	0.73	0.39	0.21	0.24	0.29	0.87	0.76	1.35
r	0.26	−0.04	−0.23	0.22	0.32	0.19	0.17	0.40	0.33	0.21	0.05	−0.12
Slope	0.31	−0.37	−0.77	−0.51	−0.88	0.41	−4.46	−5.07	−0.84	−1.51	−0.19	−0.06