Spatiotemporal dynamics of soil erosion response to land use land cover dynamics and climate variability in Maybar watershed, Awash basin, Ethiopia

Figures & data

Figure 1. Location map of Maybar watershed.

Figure 2. Soil types of the Maybar watershed.

Figure 3. Mean annual rainfall and maximum/minimum/mean temperatures for the study area.

Figure 4. Mean monthly rainfall and maximum/minimum/mean temperatures for the study.

Table 1. Data used and source.

No	Input data	Source	Tool for analysis	Purpose
1	Climate (Rainfall)	Ethiopian Metrological agency http://www.nmie.gov.et/	Microsoft Excel	To calculate the R-factor from mean annual RF data
2	Soil data	Field survey	ArcGIS 10.8.2	To calculate the Soil erodibility factor and other maps (LULC, study area)
3	Google image	Google Earth	Arc Map	Land use land cover classification and C _factor determination
4	DEM_2m	WLRC	ArcGIS 10.8.2	To delineate the watershed and to calculate the Length and Slope factor

Table 2. Land use Description of the study area (Tesfaye et al. 2017).

Land Use type	Description of Land Use type
Cultivated land	This category refers to land areas that have been tilled and made ready for the cultivation of crops, whether through rain-fed or irrigation methods.
Forest Area	Natural forests and woodlands with a diverse tree species composition.
Settlement	Human-made constructions and small rural settlements
Bare land	Areas with degraded lands and bare ground.
Shrub land	This land type is characterised by perennial woody shrubs and bushes with varying densities across different locations. It is typically found in hilly areas.
Grazing land	Land designated for grazing purposes
Water body	This category pertains to areas covered by bodies of water, such as ponds, lakes, and rivers.

Table 3. C-factor value based on Hurni (1985) and Nigussie et al. (2017).

Land Use Type	C_factor value
Cultivated land	0.18
Forest land	0.001
Grazing land	0.05
bare land	1
Settlement land	0.15
Waterbody	0.0
Shrub land	0.014

Figure 5. Slope class of the study area.

Figure 6. Flow chart of the analysis.

Table 4. Land use type in Maybar watershed for 2004, 2012, and 2020.

Land use type	Year
	2004		2012		2020
	Area(ha)	Area (%)	Area(ha)	Area (%)	Area(ha)	Area (%)
Cultivate Land	36	31.9	56.4	49.8	40	35.3
Forest land	18	15.9	26	22.9	40.9	36.1
Bare land	38	33.6	14.4	12.7	9.1	8.1
Grazing land	4	3.5	4.2	3.7	11.8	10.4
Shrub land	13	11.5	7.8	6.9	6	5.3
Settlement	4	3.5	4	3.5	4.2	3.7
Waterbody	0	0.0	0.6	0.5	1.3	1.1
Total	113.4	100	113.4	100.0	113.4	100

Figure 7. Land use and land cover of the study area (2004).

Figure 8. Land use and land cover of the study area (2012).

Figure 9. Land use and land cover of the study area (2020).

Table 5. Trend of LULC 2004 – 2020.

LULC type	Year
	2004		2012		2020		2004–2012	2012–2020	2004–2020
	Area(ha)	Area (%)	Area(ha)	Area (%)	Area(ha)	Area (%)	Area(ha)	Area(ha)	Area(ha)
Cultivated land	36	31.9	56.4	49.8	40	35.3	−20.4	16.4	−4
Forest land	18	15.9	26	22.9	40.9	36.1	−8	−14.9	−22.9
Bare Land	38	33.6	14.4	12.7	9.1	8.1	23.6	5.3	28.9
Grazing land	4	3.5	4.2	3.7	11.8	10.4	−0.2	−7.6	−7.8
Shrub land	13	11.5	7.8	6.9	6	5.3	5.2	1.8	7
Settlement	4	3.5	4	3.5	4.2	3.7	0	−0.2	−0.2
Waterbody	0	0	0.6	0.5	1.3	1.1	−0.6	−0.7	−1.3
Total	113.4	100	113.4	100	113.4	100

*- sign indicates that there is land use change (the specific land use is increasing).

Table 6. Mean annual rainfall and erosivity factor of the study area.

Year	Mean Annual Precipitation(mm)	R_factor		Source
1996– 2004	1402.0	776.987	R=(0.56*P)-8.12	(Hurni 1985)
2005–2012	1097.4	606.42
2013– 2020	1322.8	732.64

Figure 10. Soil sample distribution (left) and soil erodibility (K) factor map (right).

Table 7. Statistically summary of soil parameters in the watershed.

Soil Parameter	Minimum	Maximum	Mean	STDEV	CV
Organic Matter	2.66	3.45	3.2	0.3	0.1
Percentage of clay	27	43.25	35.05	6.56	0.2
Percentage of silt	22.5	31.5	27.82	3.67	0.14
Percentage of sand	27.75	47.75	37.1	9.86	0.29

*CV-Coefficient of Variation, STDEV-Standard Deviation.

Table 8. Soil type and corresponding erodibility factor of the watershed.

Soil mapping code	Soil Name	Description	Textural Class	K_factor	Area coverage
					(ha)	(%)
GM	Mollic Gleysols	Within shallow water table	Clay	0.053	3.03	2.7
Hh1	Haplic Phaeozems	very shallow (10–25 cm deep)	Sandy clay loam	0.098	46.41	40.9
Hh2	Haplic Phaeozems	shallow (25–50 cm deep)	Clay loams	0.114	25.6	22.3
Hh3	Haplic Phaeozems,	moderately deep (50–100 cm)	Sandy clay loams	0.850	16.89	14.9
Hh4	Haplic Phaeozems,	deep to very deep (>100 cm)	Sandy clay loams	0.098	15.29	13.5
Je	Eutric Fluvisols,	>100 cm deep	Clay loams	0.114	4.43	3.9
Re	Eutric Gleysols	10–100 cm deep	Clay	0.101	2.08	1.8
Total					113.4	100

*Where K value is in Mg ha⁻¹ MJ⁻¹ mm⁻¹

Figure 11. Slope in degree (left) and ls _factor value (right).

Table 9. Estimated soil loss with slope gradient in 2004 and 2020.

Slope Class (%)			Soil loss in 2004		Soil loss in 2012		Soil loss in 2020		Net change
	Area(ha)	Area (%)	t ha^−1 year^−1	t year^−1	t ha^−1 year^−1	t year^−1	t ha^−1 year^−1	t year^−1	%
0–5	1.5	1.3	0.04	5.13	0.03	3.5	0.1	8.9	−0.09
5–10	3.5	3.14	1.5	167.6	0.38	43.9	0.4	39.83	0.72
10–20	17.9	15.8	2.5	281.2	0.79	88.6	0.8	95.3	0.91
20–30	16.08	14.18	8.09	918.02	1.7	192.3	3.0	334.6	3.39
30–50	39.5	34.8	15.7	1775.9	6.0	688.7	3.1	347.01	6.6
50–100	34.85	30.7	21.9	2485.7	8.25	936.07	6.0	683.73	7.65
>100	0.027	0.024	1.4	162.7	0.079	9.0	0.1	9.73	1.22

*-sign indicates soil erosion is reducing within this slope.

Figure 12. Cover management factor (C-Value) for the three study years.

Figure 13. P _factor map for Maybar watershed for the years 2004,2012 and 2020.

Table 10. Support practices (P) factor based on (Wischmeier and Smith 1978a).

Land Use	Slope (%)	P Factor
Agricultural land	0–5	.1
	5–10	.12
	10–20	.14
	20–30	.19
	30–50	.25
	>50	.33
Nonagricultural land use	All	1

Figure 14. Annual soil loss map in 2004, 2012 and 2020 of the watersheds.

Table 11. Temporal variation of soil erosion with land use dynamics.

Result descriptions	Soil loss in different years
	2004	2012	2020
Soil loss Range (tons ha−1 yr−1)	0–879.44	0–169.02	0–295.4
Total soil loss (tons/yr.)	99728.4	19167.3	33500.1
Mean soil loss (tons ha−1 yr−1)	12.8	4.8	3.21

Table 12. Distribution of annual and mean soil loss between different types of land use during (2004, 2012, and 2020).

LULC type	2004					2012					2020
	Soil loss (t/y)	Mean soil loss (t/ha/yr)	Area		Soil loss (t/yr)		Mean soil loss (t/ha/y)	Area (ha) (%)		Soil loss (t/y)		Mean soil loss (t/ha/y)	Area
			(h)	(%)									(ha)	(%)
Bare land	4234	37.34	38	33.6	3176.8		28.0	14.4	12.7	3429.2		30.2	9.1	8.1
Shrub land	85.7	0.755	13	11.5	87.24		0.8	7.8	6.9	67.17		0.6	6	5.3
Cultivated land	380.6	3.35	36	31.9	311.79		2.7	56.4	49.8	300.3		2.6	40	35.3
Forest land	48.37	0.42	18	15.9	36.74		0.3	26	22.9	20.17		0.17	40.9	36.1
Grazing land	127.0	1.12	4	3.5	42.86		0.4	4.2	3.7	37.75		0.33	11.8	10.4
Settlement	11.42	0.10	4	3.5	13.74		0.1	4	3.5	17.42		0.15	4.2	3.7
Waterbody	0	0	0	0	73.59		0.6	0.6	0.5	124.87		1.10	1.3	1.1

Figure 15. Variation in mean soil loss in different land use classes and years.

Table 13. Soil erosion across different soil types during 2004, 2012, and 2020.

Soil type	Area		2004			2012			2020
			Total annual soil loss(ton/year)		Soil loss (t ha ^-1 yr^-1)	Total annual soil loss(ton/yr)		Soil loss (t ha ^-1 yr^-1)	Total annual soil loss(ton/yr)		Soil loss (t ha ^-1 yr^-1)
	(ha)	(%)	(t)	(%)		(t)	(%)		(t)	(%)
Mollic Gleysols	3	2.6	58.2	0.7	0.5	19.7	0.3	0.2	18.1	0.3	0.2
Haplic Phaeozems	103.9	91.6	1508.9	17.2	13.3	493.5	7.4	4.4	325.1	6.1	2.9
Eutric Fluvisols	4.4	3.9	2987.4	34.0	26.3	388.7	5.8	3.4	354.8	6.6	3.1
Eutric Gleysols	2.1	2.6	4231.0	48.2	37.3	5785.4	86.5	51.0	4652.3	87.0	41.0
Total	113.4	100

Table 14. Soil erosion classification based on Morgan (2005a).

Soil erosion rate (t ha^−1 year^−1)	Coverage of the erosion-affected area (%)
	2004%)	2012%)	2020%)	Severity Class
0–5	62.2	82.6	88.5	Low
5–10	6.2	5.3	3.9	Moderate
10–50	22.3	9.4	5.4	High
50–100	7.0	0.9	0.6	Severe
>100	0.8	0.6	0.4	Very severe
Total	100	100	100

Figure 16. Soil erosion severity map.

Table 15. Prioritized part of watersheds for conservation planning purposes.

2020
Soil loss t ha^−1 yr^−1	Area coverage (ha)	Area (%)	Priority Class	Class of Watershed	Description
0–5	100.3	88.5	V	SW5	Low
5–10	4.4	3.9	IV	SW4	Moderate
10–50	6.2	5.4	III	SW3	High
50–100	0.6	0.6	II	SW2	Severe
>100	0.5	0.4	I	SW1	Very Severe
2012
0–5	93.7	82.6	V	SW5	Low
5–10	6.0	5.3	IV	SW4	Moderate
10–50	10.6	9.4	III	SW4	High
50–100	1.0	0.9	II	SW3	Severe
>100	0.6	0.6	I	SW1	Very Severe
2004
0–5	70.5	62.2	VI	SW6	Low
5–10	7.0	6.2	V	SW5	Moderate
10–50	25.2	22.3	IV	SW4	High
50–100	8.0	7.0	III	SW3	Severe
100–500	0.8	0.7	II	SW2	Very severe
>500	0.1	0.1	I	SW1	Catastrophic

Figure 17. Annual soil loss and severity class map of the Maybar watershed.

Figure 18. Current priority class of the watershed for soil and water conservation.

Tesfaye, G., Assefa, A., & Kidane, D. (2017). Runoff, sediment load and land use/cover change relationship: The case of Maybar sub-watershed, South Wollo, Ethiopia. International Journal of River Basin Management, 15(1), 89–101. https://doi.org/10.1080/15715124.2016.1239625

 Web of Science ®Google Scholar

Hurni, H. (1985). Erosion-productivity-conservation systems in Ethiopia.

 Google Scholar

Nigussie, Z., Tsunekawa, A., Haregeweyn, N., Adgo, E., Nohmi, M., Tsubo, M., Aklog, D., Meshesha, D. T., & Abele, S. (2017). Farmers’ perception about soil erosion in Ethiopia. Land Degradation & Development, 28(2), 401–411. https://doi.org/10.1002/ldr.2647

 Web of Science ®Google Scholar

Wischmeier, W., & Smith, D. (1978a). Predicting rainfall erosion losses: a guide to conservation planning Beltsville, Maryland. U.S. Department of Agriculture, Agriculture Handbook No. 537.

 Google Scholar

Morgan, R. P. C. (2005a). Soil erosion and conservation (3rd ed.). Blackwell Publishing company.

 Google Scholar