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- 1. Soil and Water AssessmentTool NATHANIEL R. ALIBUYOG MMSU, Batac, Ilocos Norte
- 2. Model Philosophy Readilyavailable input – Physically based Computer efficient Comprehensive – Process interaction Simulate Management
- 3. Modeling History: TimeLine USLE CREAMS (Clean Water Act) EPIC SWRRB SWAT 1960’s 1970’s 1980’s 1990’s GLEAMS WEPP AGNPS ANN AGNPS USLE – plot scale EPIC – field scale WEPP – Hillslope scale APEX – Farm scale SWAT – watershed scale APEX
- 4. What is SWAT SWATis a physically-based, river basin-scale, continuous event hydrologic model developed to quantify the impact of land management practices on water, sediment, and agricultural chemical yields in large, complex watersheds with varying soils, land use, and management conditions Major model components describe processes associated with water movement, sediment movement, soils, temperature, weather, plant growth, nutrients, pesticides and land management.
- 5. SWAT General Description ContinuousTime Daily Time step One Day -- Hundred of Years Distributed Parameter Unlimited Number of subwatersheds Comprehensive – Process Interactions Simulate Management
- 6. Upland Processes o Weather oHydrology o Sedimentation o Plant Growth o Nutrient Cycling o Pesticide Dynamics o Management o Bacteria
- 34. Some Applications of SWATin Water Resources Planning and Management
- 35. Digital Elevation Model Land use Map Soils Map GIS- SWAT Climatic Database Landsat 2005 StreamFlow Erosion Rate SWAT- CUP Stream Flow Data Erosion Hotspot NGP Targeted Areas Calibration Identifying Erosion Hotspot
- 38. Predicting the effectsof land use and climate change on watershed hydrology
- 39. Impacts of Landuse change on watershed hydrology
- 40. Impact of ClimateChange on Water Resources The four storylines developed by the IPCC which defines plausible emission scenarios
- 41. Comparison of Baselineand Projected Monthly Water Yield (mm) under Medium-Range Scenario (A1B)
- 43. Stream flow hydrographof Apayao-Abulug River
- 44. Stream flow- DependableFlow 1960 – 1970 (NWRB) 7.55 MCM/day 1980 – 2010 (Present Study) 5.62 MCM/day
- 45. Some Applications ofSWAT SWAT has been extensively used worldwide for various applications. Among the common applications of SWAT includes: o Simulation of watershed hydrologic balance o Estimation of soil water, recharge, tile flow, and groundwater level o Runoff, erosion and sediment studies o Comprehensive water quality assessments o Pesticide fate and transport studies o Assessment of climate change impacts on hydrology and on pollutant loss
- 46. Some Applications ofSWAT • Evaluation of overland or stream/river flow changes as a result of: Retention/detention structures Wetland restoration BMPs or changes in land use/land cover (such as no-till farming or conversion of farmland to grassland) • Drought planning • Water supply options • Regional impacts of climate change on groundwater recharge and on water supplies
- 47. Some Applications ofSWAT • Evaluation of best/better management practices (BMPs) to control sediment and nutrient loading to waterways: Buffer strips No-till or reduced-till farming Fertilizer application rates Wetland restoration • Assessment of regional water endowments, crop water productivity, and implications for intra-country virtual water trade
- 48. Some Applications ofSWAT • Catchment scale water quality impact analysis related to life cycle assessment for forestry and agriculture • Coastal watershed assessment • Evaluation of economic and environmental benefits of soil and water conservation measures • Estimation of water quality, air quality, and soil carbon benefits from conservation program • Use of swat to determine flow and chemistry variables for development of ecological indicators in stream ecosystems
- 49. SWAT is aproduct of Research and offers various applications which can be used in the Philippines SWAT Model can be used for decision support on Water resources development and plan over the country Proven and widely used for water quality, water supply and climate change studies CONCLUSION
Editor's Notes
- #21 Flood routing using the Variable storage and Muskingum Transmission losses, evaporation Sediment Routing using degradation and deposition which computed simultaneously Nutrient process using the modified QUAL2E and WASP Pesticide using the toxic balance developed at University of Colorado
- #36 In this exercise, We used GIS together with SWAT (the Soil and Water Assessment Tool) to identify erosion hotspot within the Laoag River Watershed. We used GIS to prepare all spatial data required by the SWAT model. Specifically, GIS was used to delineate watershed boundary, derived river networks and slope maps from DEM. Likewise, we used GIS and RS (ENVI) produce our land use map from LandSat 2005. Spatial variation of soil physical and chemical properties were likewise mapped using GIS. After preparing all these parameters, we used GIS to overlay all the parameters to come up with unique hydrologic response unit that serve as our model unit. These data were then used by the SWAT model to simulate the stream flow and erosion rates in the watershed. From the simulated erosion rates, we then used GIS reclassification tool to identify erosion hotspots.
- #37 Using GIS, we could easily reclassify and present the simulated erosion rates into soil erosion susceptibility map. The red color erosion hotspot that may be considered priority areas for the National Greening program. The erosion hotspot area account about 6% of the total watershed area or about 8557 ha.
- #39 As part of the previous modeling exercises, we also use the calibrated model to predict the effects of land use and climate changes on watershed hydrology.
- #41 Climate change is one of the most fundamental challenges ever to confront humanity. Its adverse impacts are already being seen and may intensify exponentially over time if nothing is done to reduce further emissions of greenhouse gases. Meanwhile, detailed information on plausible future climates, such as changes in temperatures, rainfall and frequency of extreme weather events are important basis for planning for and implementing climate change adaptations. In 2011, PAGASA generated projections of temperature increase and rainfall change in the Philippines using PRECIS (Providing Regional Climates for Impact Studies) model in two time frames; 2020 and 2050. Three of the emission scenarios developed by the Intergovernmental Panel on Climate Change in its Special Report on Emission Scenarios (IPCC-SRES) were used to run the PRECIS model; namely, A2 (high range), A1B (mid-range), and B2 (low-range). These emission scenarios cover a range of demographic, societal, economic and technological storylines. Table 2.4 presents the four different storylines (A1, A2, B1, and B2) as defined in the IPCC-SRES.
- #42 Results of the simulation showed there would be likely increase in water yield (Figure 2.12) and surface runoff (Figure 2.13) in 2020 and 2050 time slices as a result of the increase annual rainfall amount in the basin. In spite of the overall increase of annual water yield, water yield during the summer months (MAM), would likely decrease by as much as 34% as consequence of less rainfall during the summer months. It is imperative therefore that water savings of excess rainfall during the rainy season be adopted to be used during the dry months.
- #43 Similarly, we were able to show that changes in precipitation may affect the watershed hydrology. Increased in precipitation may results to increase runoff, stream flow but may not significantly increase groundwater recharge. This is considering the present land use of the watershed.