1. Mid-Term Presentation
A thesis in partial fulfillment of the requirement for the
degree of Master of Science in Water Resources Engineering
Institute of Engineering, Pulchowk Campus
Presenter:
Sunil Basnet (066 MSW 419)
Supervisor:
Prof. Dr. Narendra Man Shakya
2. Introduction
Need for research
Study Area
Literature Review
Model Description
Methodology
Results
Conclusions and Recommendations
3. Includes the processes of detachment, transportation
and deposition
Kinds of soil erosion
• Sheet erosion
• Rill erosion
• Gully erosion
• Stream Channel erosion
4. For conservation, development and utilization of soil
and water resources
Entering of the sediment in the irrigation and
hydropower canals
Prediction of how much sediment passes by the outlet
of basin
Which part of the watershed what rate of soil
degradation
Field method of mapping time consuming and tedious
7. Empirical Model like USLE model, RUSLE
model, MUSLE model
Physically based models like CREAMS
model,ANSWERS model,Morgan model
etc
Conceptual model
8. USLE Model
Derived and tested from real field observations
Dependent on six factors
A = R×K×L×S×C×P
R –Rainfall Erosivity factor
K- Soil Erodibility factor
L – Slope Length factor
S – Slope Steepness factor
C- Crop management factor
P – Support control factor
10. Software used
Arc GIS 9.3
Arc Hydro (Arc GIS Extension)
Erdas Imagine
Visual Basic Environment in MS Excel
11. Acquisition and processing of data
Extraction of topographic data
Mean catchment rainfall using Thiesson
polygon analysis
Soil cover map by remote sensing
Division of the catchment into no of grids
Calibration and validation parameters for
each month
Calculation of sediment yield at each sub
catchment
12. Divide catchment into
no of grids
Generate remotely sensed
soil cover map
R factor
R =α (F.I)β
F.I =∑pi2/P
K factor
USDA
Classification
LS factor
A= R.K.LS.C.P
C factor P factor
Y=∑ SDRi . Ai
∑Residual Values= ∑ (|observed - simulated|)
If
n>100
Change
values of α
and β
1
2
N
Y
13. Calculate soil
detachment rate at
each grid running
USLE model after
validation
Adopt α and β
for minimum
values of ∑ R
Calculate R2 value
for adopted α and β (
calibration period)
If R2
>0.7
Calculate R2 value for
adopted α and β for
validation period
1
2
If R2
>0.7
2
Y
Y
N
N
14. Month α β
Jan 0.003 0.370
Feb 0.003 0.291
Mar 0.002 0.323
Apr 0.003 0.377
May 0.028 0.358
Jun 0.159 0.499
Jul 0.502 0.617
Aug 0.531 0.408
Sep 0.306 0.496
Oct 0.080 0.592
Nov 0.028 0.453
Dec 0.012 0.230
Calibrated and validated values of parameters α and β
15. Year R2
1974 0.82
Period of
Calibration
1975 0.8
1976 0.82
1977 0.77
1978 0.85
2001 0.73
Period of
validation2002 0.87
2003 0.75
Coefficient of determination (R2) for calibration and validation period
20. USLE model with GIS and remote sensing gives good
estimation of soil loss rate
An attempt to account for the distribution of rainfall
erosivity factor within every month is successful rather
than using R as lump sum factor for whole single year
R factor is the most promising factor for soil erosion
Average sediment yield at the outlet of the basin is
obtained as 21.94 tons hectare/annum
Sediment yield values ranges from 18.04 to 25.07 tons
hectare/annum
Few minutes interval precipitation data gives more
realistic and better results.
Projection of future erosion rates can be done
