seifu a tilahun school of civil & water resources engineering,bdu storm runoff and soil erosion...
TRANSCRIPT
Seifu A TilahunSeifu A TilahunSchool of Civil & Water Resources Engineering,BDUSchool of Civil & Water Resources Engineering,BDU
Storm Runoff and soil erosion Storm Runoff and soil erosion processes on the Ethiopian processes on the Ethiopian
highlandhighland
IntroductionIntroductionField Experiments on the Field Experiments on the hydrologyhydrology
Field Experiments on ErosionField Experiments on ErosionPEER Science project at BDUPEER Science project at BDU
OutlineOutline
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 erosion
IntroductionIntroduction
IntroductionIntroduction • 1 Automatic Rain Gauge
• 4 weirs installed & measured storm runoff (40 -50 events)
• 1 weir at the outlet (Adet Research Center)
• 19 piezometers to measure ground Water level
• 14 infiltration test• Sediment concentration
from 5 weirs (40 -50 events)
• Rill measurement from 10 agricultural fields
• 4 gully profile measurement
Infiltration Rate vs. Infiltration Rate vs. Rainfall IntensityRainfall Intensity
Debre Mawi
Bayabil et al. 2010 Ecohydrology
Saturated AreasSaturated Areas
As = 10%
Saturation
Weir-1
RunoffRunoff
RunoffRunoff1
2
3
4
5
{{
ErosionErosion
Sediment ConcentrationSediment Concentration
8 Aug 2010
Sediment Sediment ConcentrationConcentration
Rill & Gully Rill & Gully erosionerosion
– 120 ton ha -1 yr-1 in 2010
81m2 in 2005
321m2 in 2010
625m2 in 2011
Soil erosion with Soil erosion with wetnesswetness
1.1. Saturated hydraulic conductivity Saturated hydraulic conductivity generally greater than rainfall generally greater than rainfall intensity for well vegetated intensity for well vegetated watershedswatersheds
2.2. After a precipitation threshold is After a precipitation threshold is exceeded, discharge at outlet of exceeded, discharge at outlet of watershed is linearly related to watershed is linearly related to total precipitation total precipitation
3.3. soil erosion was related to wetness soil erosion was related to wetness through landscape position through landscape position
4.4. Modelling should incorporate the Modelling should incorporate the above processesabove processes
ConclusionConclusion
To propose more effective soil and To propose more effective soil and water conservation practices by water conservation practices by identifying those parts in the identifying those parts in the landscape that contributes most of landscape that contributes most of the sediment and nutrients at the the sediment and nutrients at the outlet.outlet.
Project goalProject goal
Measure stream flow and sediment Measure stream flow and sediment concentrationsconcentrations
Measure shallow ground water levelMeasure shallow ground water level Employ sediment tracers to locate Employ sediment tracers to locate
sediment source areassediment source areas Focus group discussion and transect Focus group discussion and transect
walkwalk Soil nutrient analysisSoil nutrient analysis Modeling of runoff and sediment Modeling of runoff and sediment
ActivitiesActivities
Thank You!!Thank You!!