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 THE PILOT AREAS Pilot area I In Nam Chun sub-watershed land degradation due to soil erosion and flooding are the main land degradation problems. Deforestation on steep mountain slopes and cultivationof field crops down slope has led to accelerated soil losses. In the low lands, floodingtakes place almost every year, which is caused not only by excessive rain but also due tosediment rich overland flow. The Nam Chun sub-watershed area consists of a narrow valley bordered by sloping and steep hilly and mountainous land. It lies between 16° 44/ and 16°48/ latitudes and between 101° 02/ and 101°09/ longitudes and covers 67 sq.km surface area . Elevation varies from 240 to 1,509 m asl. Climate is characterized by tropical monsoon climate with annual average rainfall of 1,000 mm, most of the rain falls during rainy season. Rainy season occurs during May to October months. In the hilly and mountainous areas rainfall amount may be more than in the low lands. Natural vegetation consists of mainly fallow grass lands, dominated by Imperata cylindica. Land use in the steep mountain slopes is mainly forest; the low lands are traditionally used for growing rice in the wet season. Where irrigation water is available, such crops as mung beans, soybean and tobacco are grown after the rice is harvested. Most of the sloping and steep lands have been deforested in the last 25 years and are now used for annual crop production, predominantly maize, and locally groundnuts, as a single cash crop, sometimes followed by mung beans as a second crop.   Figure 1 : Pilot area 1: Namchun watershed in Lomsak, Phetchabun province Mechanised downslope ploughing is the dominant land preparation practice that causes severe erosion in many areas. As a consequence, the yield has declined since the farmers started cultivating. Yields of many crops such as maize and rice have decreased. To increase the earnings of the farmers credit is given to switch to the alternative crop (sweet tamarind), which requires five to seven years to bear its first harvest. Due to heavy rain this year lots of damage to land (soil loss through landslides), peoples’ properties and even human lives occurred which raises concern among land use planners and development organisations. Geology and Geomorphology The area mainly composed of uplifted sedimentary rocks of the Korat group in the upper catchment area. The oldest rocks are of the Huai Hin Lat formation which consists of conglomerate, sandstone and shale, partly intercalated with andisitic tuff and aggromorate. The next formation is Nam Phong which contains raddish-brown cross-beded sandstone and conglomerate. Both formations were formed during the upper Triassic period. The formation next in age is the Phu Kradung formation which consists of shale, siltstone and sandstone. This was formed in the Jurassic period and occurs along the scarp in the study area. The youngest formation of the Korat group that occurs in the study area is Pha Wihan which consists of white and pink, cross-bedded sandstone with pebbly layers in the upper beds with some intercalations of the reddish-brown and grey shale. The lower plain consists of the Quaternary colluvial and alluvial terrace deposits .   Figure 2 : Geological map of the area Soils Figure 3 : Geo-pedplogical map of the area   The area mainly composed of uplifted sedimentary rocks of the Korat group in the upper catchment area. The oldest rocks are of the Huai Hin Lat formation which consists of conglomerate, sandstone and shale, partly intercalated with andisitic tuff and aggromorate. The next formation is Nam Phong which contains raddish-brown cross-beded sandstone and conglomerate. Both formations were formed during the upper Triassic period. The formation next in age is the Phu Kradung formation which consists of shale, siltstone and sandstone. This was formed in the Jurassic period and occurs along the scarp in the study area. The youngest formation of the Korat group that occurs in the study area is Pha Wihan which consists of white and pink, cross-bedded sandstone with pebbly layers in the upper beds with some intercalations of the reddish-brown and grey shale. The lower plain consists of the Quaternary colluvial and alluvial terrace deposits . Table 1 Landscape Relief Lithology Land form Soil Map Unit Pateau(P) Cuesta(P1) Sandstone Scarp Lithic Udorthents P11     Colluvium Very steep talus Lithic Haplustalfs P121       Steep talus Ultic Hapludalfs P122   Escarpment(P2) Siltstone Slope facet complex Typic Paleudalfs P2 Mountain(HM) High Ridge(HM1) Andesitic tuff Slope facet complex Ultic Hapludalfs HM1   Moderate High Ridge(HM2) Andesitic tuff Middle slope Lithic Haplustalfs HM21       Foot slope Typic Paleustalfs HM22   Erosional Glacis(HM3) Andesitic tuff Middle slope Ultic Haplustalfs HM31       Foot slope Lithic Haplustalfs HM32 Low Mountain(LM) High Ridge Andesitic tuff Slope facet complex Ultic Haplustalfs LM1   Moderate High Ridge Andesitic tuff Slope facet complex Typic Haplustalfs LM2   Low Ridge Andesitic tuff Undulating Ultic Paleustalfs LM3 Valley   Alluvial Side slope Fluventic Haplustalfs V1     Colluvial Bottom complex     Vegetation and Land Use Figure 4 : Land use/cover map of the area   The dominant land use types in the study area include forest, agricultural land, shrub, grassland and residential area. Agricultural lands include rainfed annual crops, paddy rice fields with secondary crops, and orchard/ tree plantation areas such as tamarind, mango, litchi, etc. On the upper catchment area, the forest type is mixed deciduous. Owing to deforestation, degraded and disturbed forests are found on higher sloping areas. Most of the area is used for agricultural and human settlements. Farmers have encroached forest areas for cultivation of maize and other food crops. The major land use types are maize cultivation followed by beans or cabbage in the mountains and tamarind in the hilland. Most of the upper part of the catchment is covered by fallow grasslands which are dominated by the species Impecata cylindica. At the lowland, farmers mainly grow rice in rainy season followed by various crops such as tobacco, cucumber and maize in the dry period, locally being irrigated. On the levees, coconut palm, mango and tamarind are grown, which are also occupied by settlements. 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