Modification of erosion potential method using climate and land cover parameters

Figures & data

Figure 1. Soil type distribution and category description for the Dubračina catchment.

Figure 2. Distribution of the Dubračina catchment sub-catchments.

Table 1. Characteristics of Dubračina catchment and its sub-catchments.

Catchment/ Sub-catchment	Area (km^2)	River length (km)	Average elevation (m n.m.)	Average slope (°)	Max slope (°)
Dubračina	43,5	13.7	213	17	89
Duboki	0.67	0.96	342	23	89
Bronac	0.99	1.62	293	20	89
Cigančica	1.49	3.0	298	21	89
Leskovnik	1.62	0.87	384	22	89
Sušik	1.93	0.78	418	21	89
Ričina Tribaljska	2.74	1.71	428	18	89
Pećica	2.23	2.32	385	15	89
Kostelj	0.82	1.04	128	10	83
Slani Potok	2.21	3.22	358	17	89
Mala Dubračina	2.09	3.0	341	15	89
Kučina	3.29	1.52	437	13	89
Malenica	5.54	4.0	341	14	89

Figure 3. Flow chart of the model based on the EPM.

Table 2. Descriptive evaluation of the method parameters (de Vente and Poesen 2005; Haghizadeh et al. 2009) and the numerical and descriptive evaluation for the erosion coefficient Z applicable in the Mediterranean area (de Vente and Poesen 2005).

Soil protection coefficient (Xa)
Mixed and dense forest	0.05–0.2
Low density forest with grove	0.05–0.2
Coniferous forest with little grove, scarce bushes, bush prairie	0.2–0.4
Damaged forest and bushes, pasture	0.4–0.6
Damaged pasture and cultivated land	0.6–0.8
Areas without vegetal cover	0.8–1.0
Soil erodibility coefficient (Y)
Hard rock, erosion resistant	0.2–0.6
Rock with moderate erosion resistance	0.6–1.0
Weak rock, schistose, stabilised	1.0–1.3
Sediments, moraines, clay and other rock with little resistance	1.3–1.8
Fine sediments and soils without erosion resistance	1.8–2.0
Coefficient of type and extent of erosion ($\mathit{\phi }$)
Little erosion on watershed	0.1–0.2
Erosion in waterways on 20–50% of the catchment area	0.3–0.5
Erosion in rivers, gullies and alluvial deposits, karstic erosion	0.6–0.7
50–80% of catchment area affected by surface erosion and landslides	0.8–0.9
Whole watershed affected by erosion	1.0
Erosion coefficient ($\mathit{Z}$)
Excessive erosion	>1.00
Severe erosion	0.70–1.00
Medium erosion	0.40–0.70
Slight erosion	0.20–0.40
Very slight erosion	0–0.2

Figure 4. Soil protection coefficient according to numerical evaluation of different land cover/use maps: (a) Landsat 4 and 5 data source, (b) Landsat 8 data source.

Figure 5. Land cover for the Dubračina catchment based on Landsat 8 images: (a) winter; (b) spring; (c) summer; (d) autumn.

Figure 6. Erosion coefficient Z for the Dubračina catchment based on the EPM: (a) past time 1961–1990, (b) present time 1991–2020.

Figure 7. Total annual volume of the detached soil W_a in m³/cell/year for the Dubračina catchment based on the EPM: (a) past time 1961–1990, (b) present time 1991–2020.

Figure 8. Actual sediment yield $G_y$ in m³/cell/year for the Dubračina catchment based on the EPM: (a) past time 1961–1990, (b) present time 1991–2020.

Table 3. Descriptive statistics for the derived past and present model outputs ($Z$, $W_a$,$\mathrm{ }{G}_y$) for the entire catchment of Dubračina.

Time-series	Statistical parameter	$\mathit{Z}$(-)	${\mathit{W}}_{\mathit{a}}$(m^3/cell/year)^a	${\mathit{G}}_{\mathit{y}}$(m^3/cell/year)^a
1961–1990	Minimum	0.0009	0.044	0
	Mean	0.274	16	1
	Maximum	4.163	257	18
	Sum^b	/	67 073^b	5573^b
	Standard deviation	0.297	11	2
1991–2020	Minimum	0.0009	0	0
	Mean	0.250	15	1
	Maximum	4.189	280	22
	Sum^b	/	64,811^b	5332^b
	Standard deviation	0.219	13.701	1.908

^acell size is 100 m × 100 m or 0.01 km².

^b (m³/catchment/year).

Table 4. The minimum, mean and maximum change in sub-catchments between the time series for all three model outputs (Z, W_a, G_y).

Sub-catchments	ΔZmin^a	ΔZmean^a	ΔZmax^a	Zmean.present^a	ΔWamin^b	ΔWamean^b	ΔWamax^b	Wa mean.present^b	ΔGymin^b	ΔGymean^b	ΔGymax^b	Gy mean.present^a
Duboki	–0.4	0	0.4	0.3	–2003	3	1899	1194	–437	–32	44	94
Bronac	–0.5	0	0.3	0.3	–2661	–33	1617	1626	–377	–15	376	133
Cigančica	–0.5	0	0.4	0.3	–2890	–36	2312	2576	–666	–16	573	205
Leskovnik	–0.4	0	2.0	0.4	–1959	182	13997	3968	–281	–1	267	105
Sušik	–0.5	0	0.5	0.3	–2706	12	3878	4141	–432	5	458	135
Ričina Tribaljska	–0.7	0	1.1	0.2	–4314	57	7299	3800	–477	5	411	139
Slani Potok	–1.2	0	1.1	0.3	–6251	243	6619	4045	–155	57	2026	560
Mala Dubračina	–1.0	0	1.0	0.3	–4966	106	5657	3229	–122	20	1449	513
Kučina	–0.6	0	2.0	0.2	–3405	64	14254	3893	–466	3	464	218
Pećica	–0.6	0	0.8	0.2	–3514	122	5136	2413	–455	0	354	191
Malenica	–0.5	0	0.6	0.2	–2807	175	3258	7769	–435	6	807	455
Kostelj	–0.5	0	0.5	0.2	–2510	16	3088	1005	–248	5	382	124

^a(-)

^b (m³/km²/year)

Figure 9. Erosion coefficient$:$ (a) winter, (b) spring, (c) summer, (d) autumn.

Table 5. Descriptive statistics obtained using the EPM model and the representative model outputs.

Season	Statistical parameter	$Z_s$ (-)	$W_{a.s}$ (m^3/cell/season)^a	$G_{y.s}$ (m^3/cell/season)^a
Winter	Minimum	0.0009	0	0
	Mean	0.243	2	0
	Maximum	4.189	42	3
	Sum^b	/	9908	702
	Standard deviation	0.213	2.0	0.25
Spring	Minimum	0.0009	0.009	0
	Mean	0.226	3	0
	Maximum	4.189	54	3
	Sum^b	/	11352	854
	Standard deviation	0.204	2.50	0.30
Summer	Minimum	0.0009	0.011	0
	Mean	0.250	4	0
	Maximum	4.189	65	5
	Sum^b	/	14990	1233
	Standard deviation	0.219	3.17	0.44
Autumn	Minimum	0.0009	0.019	0
	Mean	0.204	5	0
	Maximum	4.189	99	7
	Sum^b	/	19902	1514
	Standard deviation	0.204	4.67	0.65

^acell size is 100 m × 100 m or 0.01 km².

^b(m³/catchment/season).

Figure 10. Estimation of erosion coefficient ($Z_s$), redistribution of the soil loss ($W_{a.s}$) and transported sediment yield ($G_{y.s}$) within the seasons and comparison with annual soil loss for present time ($W_a,\mathrm{ }Z,\mathrm{ }{G}_y$).

Figure 11. Observation points on the land cover representing the present time and the summer season from 6.8.2013.

Table 6. EPM and field survey erosion coefficient estimation on 20 different locations.

Location No.	Longitude	Latitude	ZEPM	Zobserved
1	14.617047E	45.256260N	Very slight erosion	No signs of erosion
2	14.620763E	45.255129N	Slight erosion	Small signs of erosion, angled trees
3	14.623636E	45.253210N	Slight erosion	Small signs of erosion
4	14.627808E	45.248859N	Very slight erosion	No signs of erosion
5	14.630030E	45.247128N	Slight erosion	Signs of erosion, some sediment
6	14.639420E	45.243460N	Slight erosion	No signs of erosion
7	14.647677E	45.241608N	Very slight erosion	Sediment detained in the river bed
8	14.656109E	45.237249N	Slight erosion	Signs of erosion, upper part sediment detention
9	14.661799E	45.233687N	Slight erosion	Sediment detention
10	14.665060E	45.230546N	Very slight erosion	No signs of erosion
11	14.669548E	45.228518N	Very slight erosion	No signs of erosion
12	14.677426E	45.220309N	Very slight erosion	No signs of erosion
13	14.682978E	45.211081N	Very slight erosion	Sediment detention in river bed
14	14.702010E	45.189780N	Severe erosion	Signs of erosion, angled trees, sediment detention, sediment in the river bed
15	14.703040E	45.193659N	Very slight erosion	Sediment in the river bed
16	14.713250E	45.198127N	Very slight erosion	No signs of erosion
17	14.711116E	45.211073N	Medium erosion	Sings of erosion, sediment detention, road damages
18	14.707866E	45.207751N	Excessive erosion	Signs of excessive erosion, gullies, soil detachment, visible erosion processes, angled trees
19	14.696372E	45.216285N	Very slight erosion	No signs of erosion
20	14.696946E	45.198502N	Very slight erosion	Sediment in the river bed

Figure 12. Chosen location for surface soil loss observations: (a) the location in the Dubračina catchment, (b) photograph of the location taken in June 2014, (c) photograph of the location taken in June 2015 and (d) photograph of the location taken in July 2016.

de Vente J, Poesen J. 2005. Predicting soil erosion and sediment yield at the basin scale: scale issues and semi-quantitative models. Earth Sci Rev. 71(1–2):95–125.

 Google Scholar

Haghizadeh A, Teang Shui L, Godarzi E. 2009. Forecasting sediment with erosion potential method with emphasis on Land use changes at basin, electronic. J Geotech Eng. 14:1–12.

 Google Scholar