| Author | Shrestha, Sangam |
| Call Number | AIT Thesis no.WM-03-11 |
| Subject(s) | Watersheds--Nepal
|
| Note | A thesis submitted in partial fulfillment of the requirements for the
degree of Master of Science |
| Publisher | Asian Institute of Technology |
| Abstract | Agricultural non-point source pollutants especially sediment and plant nutrients pose a
significant threat to water resources and management. Best Management Practices
(BMPs) can be used to reduce the impact of these pollutants, however this requires full
understanding and analysis of effectiveness of the alternative practices. Watershed
quality models are the most cost-effective tools to aid in decision making process of
selecting the BMPs that is most effective in reducing the pollutant loads. The main
objective of this study is to apply the Annualized Agricultural Non-Point Source
Pollution (AnnAGNPS) model to assess the watershed quality and evaluate the
effectiveness of BMPs for sediment and nutrients loading reduction in the Masrang Kho la
Watershed in the Siwalik Hills of Nepal.
AnnAGNPS simulations are compared with two years of field observations from the
study watershed. The model underestimates the runoff volume by 15% during calibration
phase and 22% during validation phase whereas the peak flow is overestimated by 2.5
times more during calibration phase and 4 times more during validation phase. However,
the relationships between simulated and observed runoff volume and peak flows are
highly correlated. Runoff underestimation is attributed to the method of land cover
discretization. The comparison of simulated and observed sediment yields demonstrate
that the model is not best suited for short-term individual event sediment production. This
is due to the use of Revised Universal Soil Loss equation (RUSLE) within AnnAGNPS,
and parameters associated with determining soil loss are derived from the long-term
average annual soil loss estimates.
The simulation results indicate the croplands are the most critical areas for soil erosion as
well as nutrient loading. Among the four BMPs (Mulch tillage, 2-year crop rotation of
Maize-Soybean-Maize-Soybean, Mulch tillage with 2-year crop rotation of Maize-Soybean-
Maize-Rice, and 2-year crop rotation of maize-Soybean-Maize-Millet)
analyzed, the results indicate that the 2-year crop rotation of Maize-Soybean-Maize-Millet
is most promising in reducing sediment and nutrients loading. |
| Year | 2004 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Water Engineering and Management (WM) |
| Chairperson(s) | Babel, Mukand S. ;Gupta, Ashim Das |
| Examination Committee(s) | Clemente, Roberto S. ;Zoebisch, Michael A. |
| Scholarship Donor(s) | Danish International Development Agency
(DANIDA) ;The Government of Denmark |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 2004 |