home    land degradation    project outcome    Gallery Flooding Flood Hazard Assessment Pilot Area • The Pilot Areas • Climate • Cover factor (C) estimation • Digital terrain analysis • Relationship between soil properties • Relationship of soil properties with different land use/cover types Methodology • Methodologies • LISEM Results • Result Soil Properties and Land Use • Runoff rate for different land cover types • Model calibration and validation • Sensitivity analysis • Land use scenarios • Rainfall size scenarios • Flooding Scenario - 2 years return period • Flooding Scenario - 10 years return period • Flooding Scenario - 20 years return period • Flooding Scenario - 50 years return period • Summary tables for each flood characteristic • Flood hazard mapping • Conclusions and Recommendation Erosion Erosion Assessment Pilot Area • The Pilot Areas • Climate • Cover factor (C) estimation • Digital terrain analysis • Relationship between soil properties • Relationship of soil properties with different land use/cover types Methodology • Methodologies • Erosion Models Result • Results • C-Factor Mapping for erosion assessment • Soil erosion assessment • Assessment of land use/cover change effect on soil erosion • Assessing critical zones for ephemeral gully formation • Erosion Assessment by Different Models • The recommended erosion models • RMMF Landslide Case I • Landslide hazard assessment • The area (Pilot 3) • Landslide Mapping in Wang Chin using digital image analysis Techniques. • Results • Discussions Case II • Doi Ang Khang (Ang Khang) (Pilot area 4) • Landslide mapping in Ang Khang using aerial photos • Landslide Inventory Mapping • Landslide modelling and Susceptibility mapping • Landslide Susceptibility Maps from the three Scenarios (models) • Comparison between Ang Khang and Wang Chin (with respect to weights of evidence modelling using morphometric parameters) Salinization Case I • Pilot area II • Soil salinity • Salinization • Geomorphology • Soils • Geopedologic map • Results Case II • CASE II - The study of Yadav, R.D. (2005), • Methodology • Crop Simulation Model • PS 123 • Results • Mathematical (Regression) Model for Crop Yield Estimation • Conclusion Case III • Case III • Modeling Salinization • Geostatistics and Interpolation (GIS and Kriging) • Model Simulation and Prediction of Salinity • Simulated Depth to water table • Tenth Years Prediction • Twenty Years Prediction • Conclusion Runoff • Surface Runoff • Methodology • Modelling Runoff • Modelling Runoff Using Empirical Approach • Modelling runoff using the Semi-physical approach • Estimation with the Curve Number Method • Results and Discussion • Generation of Scenarios • Comparison of runoff rates with soil loss map • Conclusions • Presentation of papers based on project work at international • Workshop in Lomsak • Hua Hin seminar • Training of LDD staff • GIS and RS based predictive soil mapping • Soil erosion assessment • Landslide hazard assessment • Flood hazard assessment • Soil salinity study • List of completed MSc. theses on project LAND USE SCENARIOS Although the models might not be able to accurately predict future events they may be used to simulate different land use scenarios (Hessel et al., 2003; Jetten et al., 1999). In the case of scenario,the same uncertainty in input data applies to all scenarios and one can therefore assume that the differences produced for the different simulations are in fact a consequence of the applied scenariochanges. Therefore in order to evaluate the effects of the different land use scenarios, three land cover scenarios were developed: Scenario base: Present situation. Scenario A: Changing the entire catchment under forest, the values of all parameters used were converted to those used for representing forest area. Scenario B: Changing the land use to corn cultivation before harvest, the values of all the parameters used were converted to those used for representing cornfields before harvested. Scenario C: Changing the land use to corn cultivation after harvest, the values of all the parameters used were converted to those used to account for cornfields after harvest and the soil being bare. Table 1 : Summary of change in peak runoff and their arrival time for selected event (060905) due to different land use scenarios. Scenarios Peak discharge(m3/s) Change in peak discharge * SC SR Present situation 37.90 0 0.0 ** 593,152 Entire basin forested (A) 9.27 -76% 2.0 177,042 Change from forest to cornfield before harvest (B) 184.14 5X -2.0 2,183,872 Change from forest to cornfield after harvest (C) 193.93 6X -3.0 2,267,746 Note : *    Compared to present situation   **   Peak time of present situation is 3 1/2 hours Converting the results of the whole catchment into forest cover results in an overall decline in the amount of surface runoff and peak discharge from the watershed. It also increases the peak time of runoff from the catchment. The peak runoff predictions were found to be decreased by 76%, total discharge decreased by 70% and peak arrival time was delayed by two hour from present land use. In contrast, the effects of changing to corn cultivation show the opposite results of the previous scenario. For peak runoff, the predictions of the cornfield scenario before harvest were found to be 5 times greater than that of the present land use and in the case of the after harvest scenario, the peak runoff was found to be about 6 times greater than that of the present land use. The peak time decreased to 2 hour and 3 hour under cornfield before harvest and after harvest condition respectively. In scenarios B and C, total discharges were found to be about 4 times greater than that of the present land use.   Figure 1 : Predicted hydrograph for different land use scenarios. This indicates that the effect of cornfield cultivation brings about an increase in the amount of surface runoff that generated large water volumes flowing out of the catchment. The extent of the overall increase in both cases shows that expanding areas of agricultural practices in the watershed could result in an extensive increase in amount of surface runoff. The hydrographs shows the discharge pattern in the Nam Chun catchment as predicted by the present land use and the three case scenario studies. The hydrographs show significant changes on all scenarios. In forest scenario, the hydrograph reduced the peak runoff as well as the overall discharge pattern of the river. In contrast, the hydrographs show significant increase in the predictions of the scenario from the predictions of the present land use on changes to corn cultivation and also indicate a sharp increase in peak runoff. References Hessel, R., Jetten, V., Liu, B., Zhang, Y. and Stolte, J., 2003. Calibration of the LISEM model for a small Loess Plateau catchment. CATENA, 54(1-2): 235-254. http://www.sciencedirect.com/science/article/B6VCG-48SPBWM-1/2/ff6340f370a510d51967db7375eb9c66 Jetten, V.G., De Roo, A.P.J. and Favis-Mortlock, D., 1999. Evaluation of field-scale and catchment-scale soil erosion models. Catena, 37: 521-541. Development of Methodologies for Land Degradation Assessment Applied to Land Use Planning in Thailand ^go to top