Assessing soil erosion and conservation with various methodologies at different scales Symposium Assessing benefits of SLM-Key for success Rabat 2009 MOROCCAN DESIRE TEAM

Sehoul is located between Oued Bouregreg and Grou is part of the natural geographic unit " Plateau Central Marocain". Marginal land with a high rate of poverty and important indicators of degradation Land degradation, characterized by high variability and chronic shortage in term of natural resources.

Crop rotation Cereal / leguminous Fodder cultivation: e.g. the lupine Rainfed tree plantation: olive associated with annual cultivation Assisted regeneration of cork oak The assessed approaches

METHODOLOGY

Results

Crop rotation: Cereal / Leguminous 1- Increased soil protection by providing better cover 2- Maintaining and improving soil fertility Cereal / leguminous rotation  vegetation cover reached 65,5% Cereal / Cereal rotation  vegetation cover is < 50 %

3- Improving soil structural stability Crop rotation (cereal/leguminous): Improves soil resistance to compaction and limits surface crusting.

4- Soil moisture

The Rainfed fruit tree plantation associated with annual cultivations 1- Protecting the soil surface (vegetation cover) In the olive grove (15 years), we recorded the most important herbaceous cover (66%). However, the average cover of herbaceous in the rotation Cereal / Cereal does not exceed 52,5%. 2- Improvement of soil fertility and surface characteristics

Fodder cultivation: (the lupine) Lupin: offers the best vegetation cover Offers a medium organic matter content in the soil.

Assessment of soil erosion by 137 Cs measurements barley/wheat rotation leguminous/ wheat rotation vine monoculture

barley/wheat rotation Wheat / leguminous rotation Vine monoculture Mean erosion (tha -1 yr -1 ) Less erosion for wheat /leguminous crop rotation Medium term assessment of Erosion rates ~50 years

Rainfall simulation technique: Soil loss and runoff coefficient under different land use Novembre 2007Avril 2008 Coefficient Ruissellement en % Taux d'érosion (g/m²) Coefficient Ruissellement en % Taux d'érosion (g/m²) Sol fersialitique Labour1,52,5*** Chaume pâturé8,617,6*** Jachère annuelle*** 3,31,76 Jachère longue65,86,32,6 Céréale*** 1,70,2 Nu très caillouteux*** Sol Calcimagnésique Jachère6,624955,4 Parcours*** 17,837,8

HYDROLOGIC MEASUREMENTS/ THE Hannanat catchement Water balance in rainfall 726,7mm Runoff coefficient : 10%

Follow-up of the vegetation growth and effect on runoff Autumn Winter Spring Rainy events with important runoff Rainy events without runoff 14208

Hydrologic behaviour at the experimental micro catchment : Autumn winter In autumn: the flood hydrograph shows a quick response. The peak discharges are around several hundreds of liters per second (469 l/S) with a Runoff coefficient up to 54%. In winter : rainfall events are longer and complicated compared to the autumnal period. Most of rainfall events shows a runoff coefficient lower than 5%.

The high content of suspended load during the intense rain events

Surface runoff and erosion modelling  Our will is to model the Surface runoff, using a Model (for example the LISEM).  This modelling will permit to imagine scenarios of functioning of the watershed in relation with the global changes expected to be recorded in the area, first the scenario of success of the WSC actions our team is implementing, but also other scenarios of change like climatic change or land use and land cover transformations.

Conclusion Study of vegetation cover, soil fertility, soil texture and moisture. Use of 137Cs measurements Soil loss and runoff coefficient Crop rotation Cereal / Leguminous seems to be a good strategy to use in Sehoul But there is need for providing fodder

Study of Water balance Hydrologic behavior Enable to understand the soil behaviour at the catchment scale and to evaluate the global soil loss

Thank you