Mr Abdellah Laouina, Mohammed V University, Morocco. Global Symposium on Soil Erosion (GSER19), 15 - 17 May 2019 at FAO HQ.

1. Economic evaluation of water erosion and
Sustainable Land Management
A. Laouina, M. Chaker, N. Machouri, M. Alaktif, I. Machmachi
Mohammed V University, Rabat, Morocco
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2. 2
Introduction
2 main activities, annual crops for food production and livestock for immediate income
unsuitable forms of resources use : over-harvesting and over-grazing
land degradation and severe soil erosion in extension
over-harvesting on fragile soils over-grazing

3. 3
The watershed scale evaluation: The balance between water discharge and needs
At the scale of the big watershed, follow up of Solid transport and of the reservoir bathymetry vs the needs
of water = balance of water and siltation dynamics
increase of specific Degradation (185 t/km²/year in the 1970s;
270 after 2000),
negative evolution of the occupation and land management
practices
silting in the SMBA reservoir represents a threat to the future of
drinking water service
annual discharge : 530 Mm3, silting has already deprived the
storing ability about 112 Mm3 during 45 years
Demand for drinking water 300 Mm3 in 2000, 590 Mm3 in 2030.
Ecosystem accounting needs to be based on verified information
on services offered and benefits obtained by the local farmers
1
2
3
0
200
400
600
800
1000
1200
Annual discharge Reservoir Siltation 40 years Needs 2000 Needs 2030
Data of G. Mahé, 2013
Morocco
Bouregreg watershed

4. 4
Mapping LU changes and Erosion forms extension
At the level of the Korifla tributary watershed the work consisted in mapping land use and its
evolution from 1969 and 2016, using remote sensing.
The main part of siltation comes from the micro-watersheds dominating the dam, and namely
those of the low part of the Korifla.
1969 1996 2016
Sheet wash 6,7 10 15,9
Rills 1,7 6,7 13,1
Gullies 1,8 2,7 5,4
Total of eroded lands 10,2% 19,4% 34,4% (Alaktif, 2018)
Fast soil degradation over the past
50 years
The rills tend to become processes
of desertification and at the same
time of massive export of material. 1969
2016

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0
0,5
1
1,5
2
2,5
3
3,5
4
4,5
5-1,5
3,5
8,5
13,5
18,5
23,5
28,5
33,5
Hauteurpluie(mm)
Hauteurd'eau(cm)
Réponse hydrologique du bassin versant Hannanat aux évènements
pluvieux du 31/10/08 au 05/11/08
huateur d'eau (cm)
Hauteur pluie (mm)
Soil Erosion monitoring : plot level, process follow up and catchment scale
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10
20
30
40
50
60
16/12/20…
19/12/20…
22/12/20…
25/12/20…
28/12/20…
31/12/20…
03/01/20…
06/01/20…
09/01/20…
12/01/20…
15/01/20…
18/01/20…
21/01/20…
24/01/20…
27/01/20…
30/01/20…
02/02/20…
05/02/20…
08/02/20…
11/02/20…
14/02/20…
17/02/20…
20/02/20…
23/02/20…
26/02/20…
01/03/20…
04/03/20…
07/03/20…
10/03/20…
13/03/20…
16/03/20…
19/03/20…
22/03/20…
25/03/20…
28/03/20…
TDRs 30cm 16/12/09 au 28/3/10
Pluiel Station Aguibat-Ezziar, Sehoul
B-30cm(mulch/semis-direct) A
B-30cm(conventionnel tracteur)
hydro-meteorological monitoring over 3
years and analysis of the hydrologic
response of the rain events
Machmachi, 2018
Schwilch G. 2012

6. 6
Experiment the integration of new practices to mitigate the most aggressive dynamics, raise
agricultural production, increase the farmers income.
Rehabilitating the slope incised by deep
parallel gullies
Plantation of Fodder shrubs
Profits : more fodder availability, improved plant
cover, more moisture in the soil, healing of gullies
and less material export
18 months later
But, on the economic side, the management is expansive compared to the expected
environmental improvements. Some owners said in interviews that they are not willing
to invest that much money for a non immediate benefit.

7. 7
The gullied slope in May 2019
Ne remnant of the planted shrubs
More runoff on the slope, and progress of the incision along the main channel

8. Conclusions
• There is an effective potential for land rehabilitation,
fodder supply of the cattle and for evolution towards a
new semi-intensive breeding. But, the farmers are more
concerned by their immediate income than by
sustainability and the long term effects.
• The difficulty of intervention, proved by the number of
failures, needs a good knowledge of the social problems in
their diversity and complexity and efforts for
appropriation of the management proposals.
• The link between Upstream erosion and downstream
excess or deficit of water requires integrated
management; event if the cost could be very high, it can’t
be higher than the cost of non intervention.
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