The Application Of Local Grid Refinement Technique In The Water Sources Numerical Model Along The Yellow River

The shared node Local Grid Refinement technique(LGR)based on MODFLOW is often applied to refine local areas of interest in numerical simulation of groundwater to accurately portray the head change,solute transport and so on.LGR is a more advanced local grid refinement technique,which can provide much of the accuracy achieved by global refinement with much smaller execution time.In this paper,by comparing LGR with other local grid refinement technologies and analyzing their advantages and disadvantages,the unique advantages of LGR when applied in numerical simulation of groundwater can be understood.At first,the influence of the distance between child models on the simulation accuracy and model execution time is discussed when refining areas of interest simultaneously.Through theoretical analysis and validation of the ideal model,it can be proved that refining multi areas simultaneously can not only attain a good result,but also reduce the run time.The error introduced on the interface boundary because of the abrupt change in grid resolution can be minimized by putting all the stress in the parent grid.By adding the budget of the shared boundary and that of the areas refined by LGR and providing the lateral flow from the simulation result of parent model,the budget of refined areas can be calculated totally.In the paper,LGR is applied in the water sources numerical model along the Yellow River,and the Puyang water source is refined individually.It can be found that the quantity of wells and recharge achieved by LGR and MODFLOW are equal,while the quantity of the river and evaporation is more or less the same.LGR can reflect the actual budget more precisely.Then ten water sources are refined simultaneously in the water sources prediction model along the Yellow River dated form 2010 to 2020.The results show that refining ten water sources at the same time can portray the water level in the vicinity of pumping well more accurately,reflect the budget of each refined area more truly,and shorten the run time.The study suggests that LGR can portray multi complex irregular models at the same time accurately.It can reflect the water level and water budget of refined areas of interest more truly,reduce the boring repetitive workload,and reduce the run time to a certain extent.LGR is a reasonable and efficient local gird refinement technique.