Flood hazard analysis and risk assessment using remote sensing, GIS, and AHP techniques: a case study of the Gidabo Watershed, main Ethiopian Rift, Ethiopia

Figures & data

Figure 1. Study area map.

Figure 2. Methodology flowchart.

Figure 3. Slope (a), elevation (b), rainfall (c), LULC (d), drainage density (e), and soil map (f).

Table 1. Susceptibility level of sub-factors to flood hazard.

Factors	Susceptibility level of sub-factors to flood hazard
	1	2	3	4	5
	Very low	Low	Moderate	High	Very high
Slope	46–64	34–46	22–34	11–22	0–11
Elevation	2909–3032	2710–2908	2404–2709	2102–2403	1210–2101
Rainfall	<1060	1060–1090	1090–1120	1120–1150	>1150
LULC	Agroforest	Scrub forest	Agricultural land	Built-up and barren land	Wetland
Drainage density	47.6–55.6	42.3–47.5	35–42.2	26.4–34.9	8.8–26.3
Soil type	EC	EN, DG, & DN	CL & OA	CF	PV & CV

Note: EC -eutric cambisols, OA - orthic acrisols, PV – pellic vertisols, CV - chromic vertisols; DG - dystric gleysols, CF - calcic fluvisols, DN - dystric nitisols, CL - chromic luvisols, EN - eutric nitisols.

Figure 4. Population density map.

Table 4. Susceptibility level of sub-factors to flood risk.

Factors	Rank of sub-factors					Weight
	1	2	3	4	5
Flood hazard layer	Very low	Low	Moderate	High	Very high	0.3333
Population density	114–792	792–1566	1566–3405	3405–6647	6647–12454	0.3333
LULC	Agroforest	Scrub forest	Agricultural land	Built up & barren land	Wetland	0.3333

Table 2. Pairwise comparison matrix of parameters.

Factors	Slope	Elevation	Rainfall	LULC	Drainage density	Soil type
Slope	1	2	3	3	5	7
Elevation		1	2	3	3	5
Rainfall			1	2	3	4
LULC				1	2	3
Drainage density					1	2
Soil type						1

Table 3. Normalized weight of parameters.

Factors	Slope	Elevation	Rainfall	LULC	Drainage density	Soil type	Weight	Weight (%)
Slope	0.40	0.458	0.423	0.305	0.344	0.318	0.374	37.4
Elevation	0.20	0.229	0.282	0.305	0.206	0.227	0.241	24.1
Rainfall	0.132	0.114	0.141	0.203	0.206	0.181	0.162	16.2
LULC	0.132	0.075	0.070	0.101	0.137	0.136	0.108	10.8
Drainage density	0.08	0.075	0.046	0.050	0.068	0.090	0.068	6.8
Soil type	0.056	0.045	0.035	0.033	0.034	0.045	0.047	4.7

Figure 5. Flood hazard zone map.

Figure 6. Flood risk map.

Table 5. Area coverage of the flood hazard zone.

Flood hazard zone	Area (km²)	Percent
Very low	89.6	11.06
Low	162.4	20.05
Moderate	220.9	27.27
High	213.7	26.38
Very high	123.3	15.22

Table 6. Area coverage of flood risk.

Flood risk zone	Area (km²)	Percent
Very low	146.9	18.1
Low	230.7	28.4
Moderate	232.8	29
High	173.2	21.3
Very high	26.3	3.2

Figure 7. Flood risk zone area coverage in percentage.

Figure 8. Distribution of flooding risk sites.

Data availability statement

The datasets used and/or analyzed during the current study are available in the article/from the corresponding author on request.