Soil salinization risk assessments under future climate conditions: The case of central Huai Luang River Basin, Northeast, Thailand

Abstract

Salt-affected soil is one of the main problems decreasing the productivity of agriculture in Northeast Thailand. The Central Huai Luang Basin is the important rice producing areas of Udon Thani Province that is affected by saline soil. Regional and local groundwater flow systems are the major mechanisms responsible for spreading saline groundwater, waterlogging and the consequences of saline soils in this basin. Climate change may have an impact on groundwater recharge, on water table depth and the consequences of waterlogging, and on the distribution of soil salinity in this basin. A simulation model, in combination with groundwater models and the Geographical Information System (GISs), could be used to evaluate the risk of salinization. Five data, including soil salinity, soil group, irrigation area, groundwater salinity and waterlogging were used to input criteria data into a soil salinity risk model, which then calibrates the soil salinity simulation using field data. Three future climate conditions of RCPs from the CanESM2 models were downscaled to investigate the impact of future climate conditions on soil salinity risk. The impact of climate change was investigated by using a set of groundwater numerical models, namely HELP3 and SEAWAT, to estimate groundwater recharge and flow, and salt transport of the groundwater simulation, respectively. The results revealed that within the next 30 years (2045) the future average annual temperature and precipitation are projected to increase by 1.79^oC and 7.56% from current figures, respectively. The results showed that the impact of climate change on soil salinity distribution is projected to increase in every climate condition. By 2045 the salinity risk area will increase by about 216.90 km², or 23.62% from the current salt-affected area. The projected soil salinity assessment presented here is useful for targeting critical areas that may require special management for preventing or controlling soil salinization.