Landslide Susceptibility Mapping Using GIS and Bivariate Statistical Models in Chemoga Watershed, Ethiopia

Table 2

Spatial relationship between each conditioning factors and landslide occurrence using FR and IV models.

Conditioning factors	Classes	Class pixels	Class pixels (%)	Landslide pixels	Landslide pixels (%)	FR	IV
TWI	2.72–5.30	323,931	25.08	1594	49.64	1.98	0.297
	5.30–6.40	494,455	38.28	830	25.85	0.68	−0.171
	6.40–7.72	268,130	20.76	440	13.7	0.66	−0.18
	7.72–9.42	142,058	11	260	8.1	0.74	−0.133
	9.42–16.72	63,073	4.88	87	2.71	0.55	−0.256
Land use	Water body	582	0.05	3	0.09	2.07	0.317
	Forest	59,977	4.64	223	6.94	1.5	0.175
	Crops land	639,319	49.5	1,217	37.9	0.77	−0.116
	Grass/scrub/shrub	451,440	34.95	1730	53.88	1.54	0.188
	Settlements	139,820	10.82	9	0.28	0.03	−1.587
	Bare land	509	0.04	29	0.9	22.92	1.36
NDVI (ratio)	(−0.04) to 0.10	231,989	17.96	1,007	31.36	1.75	0.242
	0.10−0.12	458,792	35.52	945	29.43	0.83	−0.082
	0.12–0.18	367,141	28.42	692	21.55	0.76	−0.12
	0.18–0.23	180,380	13.97	410	12.77	0.91	−0.039
	0.23–0.48	53,345	4.13	157	4.89	1.18	0.073
Road (m)	0 −3,253	392,519	30.39	752	23.49	0.77	−0.112
	3,253–6,985	327,932	25.39	641	20.02	0.79	−0.103
	6,985–11,577	264,136	20.45	1,342	41.92	2.05	0.312
	11,577–16,936	174,099	13.48	380	11.87	0.88	−0.055
	16,936–24,399	133,032	10.3	86	2.69	0.26	−0.584
Rainfall (mm/yr)	1,484–1,519	196,729	15.23	647	20.15	1.32	0.122
	1,519–1,539	331,512	25.67	946	29.46	1.15	0.06
	1,539–1,563	438,126	33.92	1,343	41.82	1.23	0.091
	1,563–1,593	195,465	15.13	50	1.56	0.1	−0.988
	1,593–1,636	129,815	10.05	225	7.01	0.7	−0.157
River (m)	0–1,243	384,766	29.79	949	29.55	0.99	−0.003
	1,243–2,560	363,147	28.12	787	24.51	0.87	−0.06
	2,560–4,133	304,347	23.57	1,139	35.47	1.51	0.178
	4,133–6,072	160,917	12.46	306	9.53	0.76	−0.116
	6,072–9,327	78,320	6.06	30	0.93	0.15	−0.812
Slope (degree)	0–7	447,188	34.62	263	8.19	0.24	−0.626
	7–13	449,831	34.83	467	14.54	0.42	−0.379
	13–21	244,633	18.94	607	18.9	1.00	−0.001
	21–33	107,403	8.32	892	27.78	3.34	0.524
	33–67	42,592	3.3	982	30.58	9.27	0.967
Curvature (ratio)	Convex (−16.55 to (−0.98)	248,830	19.26	858	26.72	1.39	0.142
	Flat (−0.98 to 0.75)	721,286	55.84	1,253	39.02	0.7	−0.156
	Concave (0.75–20.22)	321,531	24.89	1,100	34.26	1.38	0.139
Elevation (m)	863–1,509	334,549	25.9	235	7.32	0.28	−0.549
	1,509−2,042	216,355	16.75	1,497	46.62	2.78	0.445
	2,042–2,513	482,883	37.39	1,190	37.06	0.99	−0.004
	2,513−3,059	169,167	13.1	172	5.36	0.41	−0.388
	3,059–3,946	88,693	6.87	117	3.64	0.53	−0.275
Aspect (direction)	flat (−1)	82,464	6.38	60	1.87	0.29	−0.534
	North (0–22.5 and 337.5–360)	213,107	16.5	195	6.07	0.37	−0.434
	Northeast (22.5–67.5)	123,845	9.59	210	6.54	0.68	−0.166
	East (67.5–112.5)	151,109	11.7	388	12.08	1.03	0.014
	Southeast (112.5–157.5)	158,025	12.23	629	19.59	1.6	0.204
	South (157.5–202.5)	131,648	10.19	407	12.68	1.24	0.095
	Southwest (202.5–247.5)	142,068	11	502	15.63	1.42	0.153
	West (247.5–292.5)	146,211	11.32	449	13.98	1.24	0.092
	Northwest (292.5–337.5)	143,170	11.08	371	11.55	1.04	0.018
Lithology	Tertiary extrusive and intrusive rocks	497,273	38.58	438	10.22	0.27	−0.576
	Cretaceous and Jurassic	323,705	25.11	804	18.77	0.75	−0.126
	Precambrian	391,465	30.37	2,460	57.42	1.89	0.278
	Triassic and permain	76,620	5.94	582	13.59	2.29	0.360