The Assessment Of Shallow Groundwater Vulnerability Based On Uncertainty Parameter System In The Lower Reaches Of Liaohe River Plain

The lower reaches of Liaohe River Plain is the production center of the industrial and agricultural in Liaoning province.The proportion of industrial and agricultural output value of the lower reaches of Liaohe River Plain in the total industrial and agricultural output value of the Liaoning province can reach up to 60%and 68%respectively.With the rapid development of economy,the demand of water resources is increasing,and the status of groundwater pollution is very seriously.Groundwater vulnerability assessment can provide an important and foundational reference value for such work as the groundwater pollution prevention,land use planning,exploit and utilize rationally and protect ground water resource effectively.Groundwater environment is a complex open system,it have many variables which are influencing and interacting with each other.Distributional characteristic of the parameters in the groundwater environment have temporal and spatial heterogeneity under the influence of many subjective and objective factors.According uncertainty theory,parameters can be divided into some uncertainty types such as randomness,fuzziness,grayness and so on.Because the vulnerability of groundwater is restricted by the influence of regional hydro geological conditions and many factors of human activities,the results of groundwater vulnerability assessment are uncertain.Therefore,in order to explore the uncertainty and vulnerability distribution characteristics of shallow groundwater in different areas,the uncertainty theory was introduced into the evaluation of groundwater vulnerability.Taking full account of the impact on the evaluation results of the uncertainty characteristic of parameters can provide more scientific basis for the management of groundwater environment.In this paper,take the low reaches of Liaohe River Plain as the research objective.It's vulnerability an uncertainty distribution characteristic were analyzed based on the uncertainty theory.In view of the DRASTIC model limitations and the effect of uncertainties on the groundwater resource evaluation,combined with RS technology,a DRASTICL model based on fuzzy pattern recognition was established.The model was applied to assess the groundwater vulnerability in the lower reaches of Liaohe River Plain.The sub-watershed information was extracted by DEM with using the hydrologic analysis tool of ArcGIS.According to the uncertainty characterization of the parameters,the stochastic parameters and fuzzy parameters were simulated under different a-cut of triangular fuzzy parameters by Monte Carlo.As the results of the calculating of simulation under different a-cut by the DRASTICL model which was based on fuzzy pattern recognition and the cumulative distribution,the different groundwater vulnerable values under different a-cut and percentile were obtained.In order to analyze groundwater uncertainty and vulnerability,the groundwater vulnerability distribution map under different a-cut of the lower reaches of Liao River Plain was visualized by ArcGIS.Finally,the sensitivity analysis was used to identify the actual contribution that each parameter makes to the simulation results.The results show that:(1)The two level fuzzy pattern recognition model generates a continuous vulnerability index and describes the groundwater vulnerability of contamination transit continuously from the easiest to the most difficult in the form of nonlinear.(2)Adding the parameter of land use type is better to reflect the groundwater vulnerability degree which is higher in paddy field area than that in dry land.(3)This study deal with the uncertainty issues of parameter effectively from three layers:alpha level,different percentile,and different sensitivity coefficient.This article reflects the vulnerability degree of groundwater in different regions and under different possibility,combining the subjectivity of decision makers with the objectivity of the actual hydrogeological condition in research region,which has important significance to the local groundwater development and protection.