Spatial evaluation of surface water irrigation potential areas to improve rural crop productivity in the Gomma district, southwestern Ethiopia

Figures & data

Figure 1. Location and topography of the study area.

Table 1. Source, description and purpose of the data used in the study.

Types of data	Source	Resolution	Purpose
DEM	USGS	30 m	To generate slope, watershed, stream order
OLI_2019	USGS	30*30m spatial resolution	For LULC suitability
Digital Soil map	GIA	FAO (1986)	To generate soil suitability
Rainfall	NMA	–	For climate analysis
GCPs	Survey	–	Identification of suitable sites

Figure 2. Land cover map (a), LULC suitability status (b), Slope map (c), Slope suitability status (d), Soil map (e), and Soil suitability status (f). Where CF is coffee farm with shade trees; ICL: intensively cultivated land; MCL: moderately cultivated land; NFC: natural forest cover; NFCC: natural forest cover with coffee; OWL: open wood; RF: riverine forest; SGL: savanna grassland; St: settlement; AS: acrisols; AS-LS: acri-lixisols; CS: cambisols; FS-LS: Fluvial-lixisols; LS: leptosols; NS: nitosols; VS: vertisols; LiS: lixisols.

Table 2. Land cover evaluation suitability criteria description.

Category	Name	LULC types	Area (ha)	%
S1	Highly Suitable	Cultivated land	18,356.6	25.13
		Grassland
		Bush land
S2	Moderately Suitable	Woodland	15,235.64	20.86
		Dense bush land
		Forest
N	Not suitable	Dense woodland	52,874.35	54.0
		Bamboo forest
	Total		86,466.5	100

Table 3. Slope suitability status.

Slope in %	Area coverage (ha)	% of total area	Suitability classes
0–5	42,671.09	16.31	S1 (Highly Suitable)
5–8	29,687.62	49.36	S2 (Moderately Suitable)
>8	14,107.78	34.33	N (Currently not Suitable)
Total	86,466.5	100

Figure 3. Climate data in relation to the agro-ecological zones in the study area.

Table 4. Rainfall suitability status.

Factor	Value in mm	Raank in numbers	Rank in words
	1300–1555	1	Low
	1555–1688	2	Moderate
	1688–1920	3	High

Table 5. Drainage density suitability status.

Factor	KM/KM2	Rank in numbers	Rank in words
Drainage density	0–0.3	3	High
	0.3–0.5	2	Moderate
	0.5–1.4	1	Low

Table 6. Pair wise comparison matrix for irrigation suitability analysis.

Thematic map	WA	SL	RF	LULC	St	Dd	DWS	FD	Weight	Weight%
WA	1	2	3	4	5	6	7	8	0.334	33.4%
SL	0.5	1	2	3	4	5	6	7	0.23	23%
RF	0.33	0.5	1	2	3	4	5	6	0.15	15.7%
LULC	0.25	0.33	0.5	1	2	3	4	5	0.10	10.5%
ST	0.2	0.25	0.33	0.5	1	2	3	4	0.07	7%
Dd	0.16	0.2	0.25	0.33	0.5	1	2	3	0.04	4.7%
DWS	0.14	0.16	0.2	0.25	0.33	0.5	1	2	0.033	3.3%
SFD	0.12	0.14	0.16	0.2	0.25	0.33	0.5	1	0.024	2.4%
Total	1.7	1.58	1.44	1.28	1.08	0.83	0.5			100

WA: water supply; SL: Slope; RF: Rainfall; Dd: Drainage density; ST: Soil texture; LULC: Land Use/land cover; DWS: Stream flow direction.

Figure 4. Optimal suitable land for SWI potential for small holder farmers in the district.

Table 7. The overall SWI potential possibilities in the study area.

Suitable land class	Area coverage (ha)	% of total area
High	2,3811.47	15.76
Moderate	5,2552.21	7.17
Not suitable	5,6361.10	77
Total	86,466.5	100

Table 8. Irrigable and climatic zone of the study area.

River catchment	Station Used	Geographical location	Zone	Irrigable area (ha)	Suitability rank
Urgessa	Urgessa Nr. Gembe	36°35′30″E&7°58′30″N	Tropical climate III	910	5th
Tamssa	Temssa Nr. Agaro	36°33′0″E&7°50′30″N	Tropical climate III	1107	4th
Naso	Neso Nr.Beshasha	36°37′30″E&7°55′30″N	Tropical climate III	1626	2nd
Dedessa	Dedessa Nr.Limu shay	36°29′30″E &7°45′0″N	Warm Temperate Climate II	1838	1st
Awetu	Awetu Nr.Choche	36°29′0″E & 7°53′0″N	Tropical climate III	1484	3rd
Total				6965

Data availability statement

The data is included in the manuscript.