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 MODEL SIMULATION AND PREDICTION OF SALINITY The model has been run for a period of twenty years at each location using the input parameters. The land use and agricultural practices are assumed to remain the same throughout the simulation period and the spatial extent of the study area. The prediction outputs of salinity in terms of EC are given for each season (2 seasons) of every year. The simulated variables include root-zone, transition zone and ground water salinities and also prediction of depth to groundwater table. The results are averaged on the basis of landform units for the third, tenth and twentieth year. The time scale interval considered is decadal but the third year has been included in the table for purposes of validation as it correspond to the time of the current field measured values. The output file starts at year zero which reflects the original input values as was into fed into the model, and this ca be regarded as the spin off period of the model. Soil Salinity in the Root zone The root-zone refers to the first two upper soil depth (0-30 and 30 -60cm) of which the average values have been used for input as these layers were measured separately. The results of the predicted root-zone salinity (EC_dS/m) are given in table 1. with the trend showing an increase in salinity from the first year through to the twentieth year. However, some of the landform units show some kind of decrease in the third year (notably Pe111, Va211 & Va311) but finally increased for the tenth and twentieth year. In general the model projects an increase in soil salinity for all the land forms provided that the current land use practices are maintained. Graphical presentation of these results based on relief units is given in figure. Table 1 : Average predicted root-zone salinity (EC-dS/m)/landform GP YEAR_0 YEAR_3 YEAR_10 YEAR_20 Pe111 3.50 3.09 9.24 17.55 Pe112 0.78 0.72 0.92 1.23 Pe113 4.77 7.65 12.37 19.73 Pe114 2.52 3.78 7.60 13.05 Pe115 2.3 2.85 6.77 15.73 Pe211 1.6 2.63 5.64 8.95 Pe311 1.61 2.73 5.43 12.20 Pe412 9.6 11.24 19.15 22.00 Pe413 2.12 2.84 5.74 9.85 Va111 2.96 4.22 6.33 9.90 Va211 3.98 4.28 5.43 6.37 Va311 3.50 3.87 10.64 20.56 Figure 1 : Average predicted root-zone salinity (EC-dS/m)/landform Soil Salinity in the Transition zone These results of the predicted salinity in the transition zone are given in tablend figure which basically show a different trend from the root-zone salinity. The EC values predicted by the model for this zone tend to either slightly decrease or remain almost the same for the entire period. In general there is no significantly noticeable change in the salinity in this zone except for only one landform (Va311) where it has increased from an initial value of 4.5 dS/m at the beginning to around 7.5 dS/m at the end of the second season of the twentieth year. The non-changing or slightly decreasing situation in the transition layer can be attributed to mobilization of salts from this zone and aquifer through capillary rise effects to the root-zone. Consequently salts tend to be removed from here and accumulate in the root-zone hence increase in the latter zone but no noticeable changes in the zone below it. Table 2 : Average predicted salinity in the transition zone (EC-dS/m)/landform GP YEAR_0 YEAR_3 YEAR_10 YEAR_20 Pe111 0.47 0.46 0.47 0.36 Pe112 0.83 0.82 0.78 0.69 Pe113 0.59 0.59 0.57 0.52 Pe114 0.09 0.05 0.04 0.04 Pe115 2.35 2.34 2.19 2.60 Pe211 2.52 2.36 2.18 2.08 Pe311 1.77 1.74 1.39 1.19 Pe412 0.30 0.31 0.30 0.28 Pe413 2.74 2.80 2.78 2.88 Pe511 0.65 0.63 0.75 1.01 Va111 2.64 3.65 3.72 4.12 Va211 3.53 3.52 3.24 2.64 Va311 4.50 4.48 4.80 7.53 Figure 2 : Average predicted salinity in the transition zone (EC-dS/m)/landform Salinity in the Aquifer These results for the predicted salt content changes over time in the aquifer zone are given in table and figure . The behaviour is quite similar to the transition zone whereby there is no really serious change in the salt content, i.e. the salinity tends to remain almost the same throughout the simulated 20 year period. This observed stability of the soil water salinity concentration in the aquifer (Cqf) suggests a lack salt leaching from root and transition zones into the aquifer. Another factor that can be highlighted is the horizontally incoming groundwater that was not taken into consideration due to lack data. Thus only the horizontally outgoing water was considered which was estimated through the calibration process of the natural drainage. The suggested procedure for the calibration of the natural drainage (Gn) is to set the incoming groundwater (Gi) as zero[30, 31, 46, 49]. Then arbitrary changes for outgoing ground water (Go) are made to get the best possible the value that better predicts the observed water table. In this the total natural drainage (Gn = Go – Gi) is equal to the horizontally outgoing groundwater. Table 3 : predicted salinity in the aquifer (dS/m)/landform GP YEAR_0 YEAR_3 YEAR_10 YEAR_20 Pe111 0.23 0.23 0.21 0.20 Pe112 0.52 0.38 0.35 0.43 Pe113 1.42 1.19 1.11 1.18 Pe114 0.13 0.10 0.09 0.06 Pe115 2.73 0.08 0.08 2.31 Pe211 1.15 0.58 0.55 1.05 Pe311 2.04 1.96 1.83 1.70 Pe412 0.30 0.30 0.28 0.25 Pe413 1.02 0.37 0.36 0.96 Pe511 0.20 0.20 0.19 0.17 Va111 3.56 0.61 0.59 0.37 Va211 1.93 0.29 0.27 1.68 Va311 2.60 2.57 2.45 2.31 Figure 3 : Average predicted salinity in the aquifer (dS/m)/landform Development of Methodologies for Land Degradation Assessment Applied to Land Use Planning in Thailand ^go to top