三江平原地下水资源潜力评价

Potential evaluation of groundwater resources of Sanjiang Plain in Heilongjiang Province

三江平原地区第四系松散堆积物厚度一般为100～200m,最厚达300m,为结构单一、大厚度的砂、砂砾石含水层,储存运移着巨量的孔隙水(部分为微承压水)。含水层疏导功能与富水性强,单井涌水量多在1000m3 d,且水质为矿化度小于1g L的淡水。依据含水层的地质时代和贮水介质类型,将三江平原地下水系统划分成第四系孔隙含水层亚系统、第三系孔隙裂隙含水层亚系统、基岩裂隙含水层亚系统。其中第四系孔隙含水层亚系统进一步分成更新统含水层次级亚系统和全新统含水层次级亚系统;第四系更新统含水层次级亚系统又细分为下、中、上更新统含水层。根据盆地浅部区域地下水分布的主要控制因素(流域水系、地质构造、地貌条件、含水层结构及地下水补、径、排条件),对三江盆地地下水系统进行了系统的描述;各地下水动力亚系统受外部动力条件(降水、蒸发、地表水、地下水)的制约,同时受内动力条件(含水介质循环条件)的控制,形成了独特的地下水动力场;论述了含水层系统的特征、边界条件、输入特征、输出特征、内部功能特征等。最后对三江平原的地下水资源潜力进行了计算与评价:依据水均衡原理,充分地考虑了计算区及计算单元在开采状态下多年补、排均衡的基础上,利用长系列的气象、水文资料,应用三维模型模拟计算了丰、平。

The loose Quaternary deposits of the Sanjiang Plain has the thickness of 100-200m, the thickest of 300m. The aquifers are uniform in composition: thick sand, sand with gravels which have great power to store and transfer pore water (some confined water). The aquifers have great transporting conditions and great power to contain water, single hole water yield is commonly 1000 m^3/d, and the water is fresh water with the salinity less than 1g/L. According to the age and form of containing water, the groundwater system of Sanjiang Plain is divided into Quaternary pore water subsystem, Tertiary pore water subsystem, and bed rock fracture aquifers subsystem. The Quaternary pore water subsystem can be further divided into upper, middle and lower Pleistocene aquifers. We described the ground water systems: their main control factors (catchments; structural geology, geomorphology, structures of aquifers, and supply, transport, drainage conditions). The subsystems are not only controlled by their exterior dynamical conditions (precipitation, evaporation, surface water, groundwater), but also controlled by the inner dynamical conditions (aquiferous medium circulation conditions); thus, they have unique ground water dynamic field. We also discussed the aquifers systems characteristics, limit conditions, supply characteristics, drainage characteristics, inner function characteristics, and so on. As the conclusion, we calculated and evaluated the ground water resource potential of Sanjiang Plain. In the calculation, we followed the law of water equilibrium, considered the supply-drainage equilibrium due to the water mining, made use of long time climate and hydrology records, and applied 3-D model to calculate the supply and yield of each cell at the abundant, average and dry years. Thus, we got the amount of ground water resource that can be used of long time equilibrium.