Seifu A Tilahun School of Civil & Water Resources Engineering,BDU Storm Runoff and soil erosion processes on the Ethiopian highland

 Introduction  Field Experiments on the hydrology  Field Experiments on Erosion  PEER Science project at BDU Outline

 river sediment concentrations have not declined  runoff and erosion processes are not fully understood  investigating where they takes place in the landscape  used this information to model erosionIntroduction

Introduction 1 Automatic Rain Gauge 4 weirs installed & measured storm runoff ( events) 1 weir at the outlet (Adet Research Center) 19 piezometers to measure ground Water level 14 infiltration test Sediment concentration from 5 weirs ( events) Rill measurement from 10 agricultural fields 4 gully profile measurement

Infiltration Rate vs. Rainfall Intensity Debre Mawi Bayabil et al Ecohydrology

Saturated Areas A s = 10% Saturation Weir-1

Runoff

Runoff

{ Erosion

Sediment Concentration 8 Aug 2010

Sediment Concentration

Rill & Gully erosion – 120 ton ha -1 yr -1 in m 2 in m 2 in m 2 in 2011

Soil erosion with wetness

1. Saturated hydraulic conductivity generally greater than rainfall intensity for well vegetated watersheds 2. After a precipitation threshold is exceeded, discharge at outlet of watershed is linearly related to total precipitation 3. soil erosion was related to wetness through landscape position 4. Modelling should incorporate the above processes Conclusion

To propose more effective soil and water conservation practices by identifying those parts in the landscape that contributes most of the sediment and nutrients at the outlet. Project goal

 Measure stream flow and sediment concentrations  Measure shallow ground water level  Employ sediment tracers to locate sediment source areas  Focus group discussion and transect walk  Soil nutrient analysis  Modeling of runoff and sediment Activities

Thank You!!