Soil erosion risk
Author: Fabian Becker
Date: February 2015
Document: Soil erosion risk assessment in the Upper Mefou subcatchment, Southern Cameroon Plateau [Master's Thesis]
Database:
Institue Géographique National 1956;
El-Swaify et al. 1982;
Nill et al. 1996;
Jarvis et al. 2008;
own data (2012–2014)
Classification
| Risk class |
(relative∗) soil loss |
| low |
0–10 t ha-1 yr-1 |
| high |
10–100 t ha-1 yr-1 |
| severe |
100–1000 t ha-1 yr-1 |
∗: values are relative and only qualitative estimates,
as USLE-models might overestimated soil erosion;
Actual soil erosion risk
Actual soil erosion risk (RUSLE3D) is a function of land use and land cover, soil erodibliy, rainfall erosivity and terrain characteristics (slope, flow accumulation).
Potential soil erosion risk
Potential soil erosion risk (RUSLE3D) is a function soil erodibility, rainfall erosivity and terrain characteristics (slope, flow accumulation). In contrast to the acutal soil erosion risk, land use and land cover is not important
for the potential risk. Using an RUSLE3D-approach, the C-factor is set to unity to model the potential risk
(cf.
Grimm
2001).
.
LULCC scenarios
Change of the soil erosion risk for five land use and land cover change (LULCC) scenarios. The scenarios are descriped in the table below,
the assumptions are based on literature research on LULCC in Cameroon
(
Kotto-Same
et al.
1997,
Sunderlin
et al.
2000
[cf.
Sayer
et al.
2012],
Imbernon and Branthomme
2001,
Lambin
et al.
2003,
).
Scenarios
| Scenario ID |
Description |
| 1 |
In Scenario 1, it is assumed that—possibly
driven by a higher demand for food for a growing population in rural or periurban areas—
food production in the area is expected to increase by forest clearance (1a) or a cultivation of
bush or fallows (1b). |
| 2 |
Scenario 2 takes account of the intensification of cropping, i. e. mixed-cropping systems will change to cassava or maize
mono-cropping. |
| 3 |
In addition to an intensification of food production, also
the production of cash crops might increase. In Scenario 3 it is therefore assumed that forest
or dense shrub is converted to plantations—either to coffee, cacao or palm oil plantations
for cash food production or to plantains for food production. |
| 4 |
The last scenario simulates the erosional impact of reforestation measures. |
Effect classification
Afforestation
| Class |
Change of relative soil loss |
| decrease |
<−15% |
| slight decrease |
−15–0% |
| no change |
0% |
Intensification
| no effect |
0% |
| slight effect |
0–15% |
| medium effect |
15–50% |
| heavy effect |
50–100% |
| severe effect |
>100% |