Srisuk K, Sriboonlue V, Buaphan C, Archvichai L, Youngme W, Satarak P, Jaruchaikul S
Department of Geotechnology, Faculty of Technology, Khon Kaen University, Thailand.
Water Sci Technol. 2001;44(7):157-64.
The objective of the project is to establish a conceptual groundwater model over the lower Nam Kam Basin in order to apply a numerical technique for the prediction of the impact of saline water transport due to the proposed weir across the Nam Kam River. Hydrogeological investigations including mapping, drilling, piezometer installations and monitoring were systematically conducted during 1997 to 1998. Brackish groundwater is saturated under the area with a depth of 30-60 m. Groundwater regionally flows from the south (the Phu Phan Range) to the north and discharges to the Nam Kam River. Another direction is from the northern region to the southern region, discharging to the central region. A two-dimensional model was constructed along the principal gradient in the NW-SE direction. There are several local recharge and discharge areas across the Nam Kam floodplain. A local groundwater flow is active within the depth of 2 m to 30 m below the ground surface within the sand and gravel unit. Simulations were calibrated with hydraulic heads and salinity of groundwater in the piezometers. It is found that the recharge and evapotranspiration rates are 1% to 40% of the rainfall and 10% to 15% of a pan evaporation, respectively. The ranges of horizontal hydraulic conductivity to vertical hydraulic conductivity are 0.1 to 0.01. The possible longitudinal dispersivity values of the hydrostratigraphic units are 20 m to 500 m, but the transverse dispersivity is less than the longitude by one order of magnitude. The comparison of calculated heads and measured heads give a root mean square error of less than 1 m. The different salinity concentrations are still in a range of 2000-5000 mg/l. Ten year simulation of saline water transport indicates that the reservoir ponding with water level at +140.5 m above mean sea level may divert groundwater flow and discharging to the northern boundary of the reservoir at Ban Don Kao.
该项目的目标是建立一个南甘河流域下游的概念性地下水模型，以便应用数值技术预测拟建的横跨南甘河的水坝导致的咸水输送影响。1997年至1998年期间系统地开展了包括测绘、钻探、安装测压仪和监测在内的水文地质调查。微咸地下水在该区域以下30 - 60米深度处饱和。区域地下水从南部（富潘山脉）向北流动，并排入南甘河。另一个方向是从北部地区流向南部地区，排入中部地区。沿西北 - 东南方向的主要梯度构建了二维模型。南甘河漫滩有几个局部补给和排泄区。在地表以下2米至30米深度范围内的砂和砾石单元内，局部地下水流活跃。利用测压仪中的水头和地下水盐度对模拟进行了校准。结果发现，补给率和蒸发散率分别为降雨量的1%至40%和蒸发皿蒸发量的10%至15%。水平水力传导率与垂直水力传导率的范围为0.1至0.01。水文地层单元的可能纵向弥散度值为20米至500米，但横向弥散度比纵向小一个数量级。计算水头与实测水头的比较给出的均方根误差小于1米。不同盐度浓度仍在2000 - 5000毫克/升范围内。咸水输送的十年模拟表明，水库蓄水水位在平均海平面以上140.5米时，可能会使地下水流转向，并排放到班东考水库的北边界。
