Abstract:
A rating evaluation method for groundwater pollution source intensity, including: determining pollution source characteristic indices, and weights and scores thereof, according to the type, the discharge mode, the existence time, and the like of a groundwater pollution source; determining an vadose zone antifouling property index and an vadose zone vulnerability index and scores thereof according to vadose zone characteristics; determining a rating evaluation index system for groundwater pollution sources by combining the pollution source characteristic indices with the vadose zone antifouling property index and the vadose zone vulnerability index; and establishing a rating evaluation method for groundwater pollution source intensity and evaluating the groundwater pollution source intensity. The evaluation method comprehensively considers pollution source characteristics and vadose zone characteristics to accurately reflect source intensities of groundwater pollutants and protect groundwater, and may provide a scientific basis to allow for more scientific and rational protection and management of groundwater.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present disclosure claims the priority of Chinese Patent Application No. 201610320234.3, filed on May 13, 2016, which is incorporated by reference herein in its entirety. 
       BACKGROUND 
     Field 
       [0002]    This disclosure relates to the field of water environment protection, and more specifically to a rating evaluation method for groundwater pollution source intensity. 
       Description of the Related Art 
       [0003]    As the society continuously develops, groundwater pollution becomes an unnegligible problem of pollution and brings about great health risk to the society and the public. Among others, how to scientifically and effectively manage groundwater resources becomes a particularly important problem. 
         [0004]    In order to be able to effectively manage groundwater resources, it is required to first determine groundwater pollution source intensity and the hazard level to which it contributes. Since groundwater pollution is greatly influenced by discharge of pollution sources, treatment measures, and different geological structures at various locations, the scientific and rational evaluation of groundwater pollution source intensity could be achieved only if comprehensive consideration is made. 
         [0005]    With respect to a rating evaluation method for groundwater pollution source intensity, an evaluation index system and a technical method for practical situations of groundwater pollution source intensity are required to be established, according to characteristics of groundwater pollution source types, distributions, pollutant compositions, hydrogeological conditions, and environmental influences. This would provide scientific bases for utilization and management of land resources, control of groundwater pollution, overall planning and management of economic regions, etc. At present, however, studies in these fields are still deficient. 
       SUMMARY 
       [0006]    In view of this, an object of this disclosure is to provide a rating evaluation method for groundwater pollution source intensity, so as to provide a scientific basis for classified prevention and control and overall management of groundwater pollution source. 
         [0007]    In order to achieve the object described above, this invention provides a rating evaluation method for groundwater pollution source intensity, comprising: 
         [0008]    step 1: determining pollution source characteristic indices as well as weights and scores thereof, wherein the pollution source characteristic indices measure the magnitude of the potential of a pollution source for outputting pollution, the weights of the pollution source characteristic indices are used to evaluate the relative magnitude of the “contribution” of the pollution source characteristic indices to groundwater pollution, and performing the evaluation of pollution source hazard using an overlay and index method; 
         [0009]    step 2: determining vadose zone characteristic indices and scores thereof, wherein the vadose zone characteristic indices include an vadose zone antifouling property index and an vadose zone vulnerability index, and performing evaluation of vadose zone resistance; 
         [0010]    step 3: with respect to an field not considering the vadose zone antifouling property, directly using the rating evaluation result of pollution source hazard obtained in step 1 as a rating evaluation result of the groundwater pollution source intensity, without performing step 2; with respect to an field considering the vadose zone antifouling property, performing the evaluation of pollution source hazard of step 1 and the evaluation of vadose zone resistance of step 2 respectively, and combining the two evaluation results by a matrix method, to obtain a result of rating evaluation of the groundwater pollution source intensity. 
         [0011]    In one embodiment, a modified. Nemerow index method is employed for the pollution factor comprehensive evaluation index in the evaluation of pollution source hazard, and the concentration, toxicity, mobility, and degradability of pollutants are comprehensively considered. 
         [0012]    In one embodiment, the vadose zone antifouling property of a polluted field is preferentially evaluated in the evaluation of vadose zone resistance, to predict whether the vadose zone effect is considered in the evaluation of groundwater pollution source intensity in the field or not. 
         [0013]    Based on the technical solutions described above, the pollution source characteristics and the vadose zone characteristics are comprehensively considered in the rating evaluation method for groundwater pollution source intensity of this disclosure, therefore, the method of this disclosure can provide a scientific basis to classify fields of groundwater pollution and allow for more scientific and rational protection and management of groundwater. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is the rating evaluation index system for groundwater pollution source intensity of this disclosure; and 
           [0015]      FIG. 2  is a schematic flow chart of the rating evaluation method for groundwater pollution source intensity of this disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    In order to enable objects, technical solutions, and advantages of this disclosure to be more clearly understood, this disclosure will be further illustrated in details in conjunction with specific embodiments and with reference to accompanying drawings. 
         [0017]    The rating evaluation of groundwater pollution source intensity is a key technique in establishing the whole process system of prevention and control of groundwater pollution, and is mainly applicable for analyzing and determining groundwater pollution source intensity. 
         [0018]    This disclosure provides a rating evaluation method for groundwater pollution source intensity, which constructs an evaluation index system for groundwater pollution source intensity comprehensively considering pollutant characteristics and vadose zone characteristics in an field, wherein, a modified Nemerow pollution index method and an improved DRMK model are used in evaluations of pollutant characteristics and vadose zone characteristics respectively, pollution source hazard and vadose zone resistance are rated by use of an overlay and index method, and finally a rating evaluation method for groundwater pollution source intensity is established. 
       1. Rating Evaluation Index System for Groundwater Pollution Source Intensity 
       [0019]    With respect to the evaluation index system for groundwater pollution source intensity, two aspects, which are pollution source characteristics and vadose zone characteristics, are mainly considered. The indices such as discharge amount, discharge mode, and the like of a pollution source are mainly considered for pollution source characteristics, and the indices such as antifouling property and vulnerability of vadose zone are mainly considered for vadose zone characteristics. A particular evaluation index system for groundwater pollution source intensity is shown in  FIG. 1 . 
       2. Rating Evaluation Method For Groundwater Pollution Source Intensity 
       [0020]    Based on the result of pollution source classification, and according to whether the fields where potential pollution sources and existent pollution sources are located have seepage prevention measures or not, the practical polluted fields are divided into four major types: potential pollution sources with seepage prevention, potential pollution sources without seepage prevention, existent pollution sources without seepage prevention, and existent pollution sources with seepage prevention. A rating evaluation system is established by using these four major types of pollution sources as basic objects for evaluation, and a particular process flow of evaluation is shown in  FIG. 2 . 
       3. Study on Groundwater Pollution Source Characteristics 
     3.1. Weights and Scores of Indices 
       [0021]    The pollution source characteristic indices measure the magnitude of the potential of a pollution source for outputting pollution. The weight of an index is the magnitude of the contribution of an evaluation factor to groundwater pollution, and a greater weight means a relatively greater risk of groundwater pollution by the evaluation factor. According to the analytic hierarchy process, a judging matrix is established by using a 9-level rating scale method proposed by Saaty, and weighted values of respective indices are rationally determined so as to achieve the ,object of accurate evaluation for pollution sources. Particular weights of groundwater pollution source indices are shown in Table 1. After the weights of groundwater pollution source indices are determined, respective indices are scored according to the practical situation of a field. 
         [0022]    The hazard of a pollution source is determined by comprehensive factors such as the type, the discharge mode, the existence time, and the like of the pollution source. The pollution factor comprehensive evaluation index (B 1r ) comprehensively considers the factors such as toxicities, mobilities, degradabilities, and the like of different pollution factors in a pollution source with respect to the environment. The discharge mode mainly depends on whether a pollution source is treated and the degree of treatment. The influence area proportion refers to a percentage of the area covered by an influence radius relative to the total area of the evaluation region. Influence area proportions of industrial residue piles and agricultural sources are calculated with actual polluted areas. Since the influence ranges of dot-like and linear potential pollution sources such as seepage pits, sewage rivers, etc., are difficult to be obtained in data collection and actual investigation, the influence radius of dot-like potential pollution sources such as seepage pits may be set to be 200 m. and the influence range of linear potential pollution sources such as rivers may be set to 100 m, according to literature research. 
         [0023]    Particular weights and scores of groundwater pollution source indices are shown in Table 2. 
         [0000]    
       
         
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Weights of groundwater pollution source indices 
               
             
          
           
               
                   
                 Pollution factor 
                   
                   
                   
                 Influence 
                   
                   
               
               
                   
                 comprehensive 
                 Discharge 
                 Discharge 
                 Discharge 
                 area 
                 Protective 
                 Existence 
               
               
                   
                 evaluation 
                 amount 
                 position 
                 mode 
                 proportion 
                 measure 
                 time 
               
               
                 Name 
                 (B 1r ) 
                 (B 2r ) 
                 (B 3r ) 
                 (B 4r ) 
                 (B 5r ) 
                 (B 6r ) 
                 (B 7r ) 
               
               
                   
               
               
                 Weight 
                 0.22 
                 0.17 
                 0.16 
                 0.1 
                 0.09 
                 0.12 
                 0.14 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Scores of groundwater pollution source indices 
               
             
          
           
               
                 Pollution factor 
                 Discharge 
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
             
          
           
               
                 comprehensive 
                 amount 
                 Discharge 
                   
                 Influence area 
                 Protective 
                 Existence 
               
               
                 evaluation 
                 (x10 4 m 3 /a) 
                 position 
                 Discharge mode 
                 proportion 
                 measure 
                 time 
               
               
                   
               
             
          
           
               
                 &lt;0.8  
                 2 
                 Q             1 
                 1 
                 Ground 
                 6 
                 Cyclically used 
                 1 
                             0.1% 
                 2.5 
                 Sealed 
                 1 
                 ≦1  
                 1 
               
               
                   
                   
                   
                   
                 surface 
                   
                 after water 
                   
                   
                   
                   
                   
                   
                   
               
               
                 0.80-2.50 
                 4 
                  1 &lt; q              10 
                 3 
                 Middle of 
                 8 
                 treatment or 
                 1 
                  0.1%~1% 
                 5 
                 Partly 
                 5 
                 1-5 
                 3 
               
               
                   
                   
                   
                   
                 vadose 
                   
                 discharged into 
                   
                   
                   
                 sealed 
                   
                   
                   
               
               
                   
                   
                   
                   
                 zone 
                   
                 municipal 
                   
                   
                   
                   
                   
                   
                   
               
               
                   
                   
                   
                   
                   
                   
                 pipelines 
                   
                   
                   
                   
                   
                   
                   
               
               
                 2.50-4.25 
                 6 
                 10 &lt; q              30 
                 5 
                 Bottom of 
                 10 
                 Discharged with 
                 4 
                   1%~10% 
                 7.5 
                 Exposed 
                 10 
                  5-10 
                 5 
               
               
                   
                   
                   
                   
                 vadose 
                   
                 standard met 
                   
                   
                   
                   
                   
                   
                   
               
               
                   
                   
                   
                   
                 zone 
                   
                 after treatment 
                   
                   
                   
                   
                   
                   
                   
               
               
                 4.25-7.2  
                 8 
                 30 &lt; q              60 
                 7 
                   
                   
                 Discharged with 
                 8 
                 10%~100% 
                 10 
                   
                   
                 10-20 
                 7 
               
               
                   
                   
                   
                   
                   
                   
                 standard not met 
                   
                   
                   
                   
                   
                   
                   
               
               
                   
                   
                   
                   
                   
                   
                 after treatment 
                   
                   
                   
                   
                   
                   
                   
               
               
                 &gt;7.20 
                 10 
                 Q &gt; 60 
                 10 
                   
                   
                 Directly 
                 10 
                   
                   
                   
                   
                 &gt;20 
                 10 
               
               
                   
                   
                   
                   
                   
                   
                 discharged 
                   
                   
                   
                   
                   
                   
                   
               
               
                   
               
             
          
         
       
     
       3.2. Pollution Factor Comprehensive Evaluation (B 1r ) 
       [0024]    At present, as for the evaluation of groundwater pollution sources, a method for averaging by equivalent standard pollution loading is typically used. For a case of groundwater in a region where the content of one pollutant is relatively high while the contents of other pollutants are all relatively low, evaluation results of the above-mentioned method cannot reflect the actual pollution condition of the groundwater environment. Nemerow pollution index method is a weighted-type multi-factor environment quality index method which takes the extremum (or referred to as the outstanding maximum) into account as well. This method can well highlight the effect of extremum, and the application thereof in the evaluation of groundwater pollution source intensity of a polluted field may effectively fill the blanks in studies. 
         [0025]    When the Nemerow index method is used in the evaluation of groundwater pollution source intensity, toxicities, mobilities, and degradabilities of different pollution factors with respect to the environment will be considered, and by adding a weighting factor, different pollution factors at the same quality level are differently treated. 
         [0026]    A conventional calculation equation of Nemerow comprehensive pollution index is as follows: 
         [0000]    
       
         
           
             
               
                 
                   
                     P 
                     i 
                   
                   = 
                   
                     
                       C 
                       i 
                     
                     
                       C 
                       
                         0 
                          
                         
                             
                         
                          
                         i 
                       
                     
                   
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
             
               
                 
                   
                     P 
                     comprehensive 
                   
                   = 
                   
                     
                       
                         
                           P 
                           
                             i 
                              
                             
                                 
                             
                              
                             ave 
                           
                           2 
                         
                         + 
                         
                           P 
                           
                             i 
                              
                             
                                 
                             
                              
                             max 
                           
                           2 
                         
                       
                       2 
                     
                   
                 
               
               
                 
                   ( 
                   2 
                   ) 
                 
               
             
           
         
       
     
         [0000]    in the equation, P i  is an evaluation value of an i th  kind of pollution factor; c i  is an actual concentration value of the i th  kind of pollution factor, mg/l; c 0i  is a standard value of a j th -class evaluation standard of the i th  kind of pollution factor, mg/l; P iave  is the average value of evaluation values of n kinds of pollution factors; P imax  is the maximum of the evaluation values of n kinds of pollution factors; and P comprehensive  is a Nemerow comprehensive index of the j th -class standard. 
         [0027]    A modified Nemerow pollution index method considers the weight a i  of each pollution factor in evaluation, and introduces P′ weighted average  to replace P iave . 
         [0000]    
       
         
           
             
               
                 
                   
                     P 
                     comprehensive 
                   
                   = 
                   
                     
                       
                         
                           P 
                           
                             weighted 
                              
                             
                                 
                             
                              
                             average 
                           
                           ′2 
                         
                         + 
                         
                           P 
                           
                             i 
                              
                             
                                 
                             
                              
                             max 
                           
                           2 
                         
                       
                       2 
                     
                   
                 
               
               
                 
                   ( 
                   3 
                   ) 
                 
               
             
             
               
                 
                   
                     P 
                     
                       weighted 
                        
                       
                           
                       
                        
                       average 
                     
                     ′ 
                   
                   = 
                   
                     
                       
                         ∑ 
                         
                           i 
                           = 
                           1 
                         
                         n 
                       
                        
                       
                           
                       
                        
                       
                         ( 
                         
                           
                             P 
                             i 
                           
                           × 
                           
                             a 
                             i 
                           
                         
                         ) 
                       
                     
                     n 
                   
                 
               
               
                 
                   ( 
                   4 
                   ) 
                 
               
             
           
         
       
     
         [0028]    Wherein, the weighted value a i  of pollution factor is determined as follows. 
         [0029]    Generally, the contributions of various pollution factors to the hazard level of groundwater are different, among others, toxicity (T), mobility (M), degradability (D), and the like of a pollution factor are mainly considered in the weight of each pollution factor. The weights of the three factors are 0.6, 0.2, and 0.2 respectively, as calculated by analytic hierarchy process, and the determination of sequential values of these three factors are shown in Table 3. By calculating the pollution factor attribute l i  (equation 5), the calculation of the weighted value a i  of the pollution factor is accomplished (equation 6). 
         [0000]    
       
         
               
             
               
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 Determination of sequential values of pollution factors  
               
             
          
           
               
                 Name  
                 Toxicity  
                 Mobility  
                 Degradability 
               
               
                   
               
               
                 Sequence  
                 C0i values of various pollution  
                 The mobility of a pollution  
                 The degradability of a  
               
               
                 description  
                 factors are arranged from small  
                 factor relies on lgKoc value. A  
                 pollution factor relies on the  
               
               
                   
                 to large, and are sequentially  
                 greater value means that the  
                 half-life. As the half-life  
               
               
                   
                 numbered. That is, as the C0i  
                 migration of this pollutant is  
                 becomes longer, the  
               
               
                   
                 becomes greater, the influence  
                 more difficult, the influence on  
                 influence on groundwater  
               
               
                   
                 on groundwater becomes  
                 groundwater becomes smaller,  
                 becomes greater and the  
               
               
                   
                 smaller and the sequential  
                 and the sequential value  
                 sequential value becomes  
               
               
                   
                 value becomes greater.  
                 becomes greater. (positive-  
                 smaller. (negative-sequence  
               
               
                   
                 (positive-sequence  
                 sequence arrangement)  
                 arrangement)  
               
               
                   
                 arrangement) 
               
               
                   
               
             
          
         
       
     
         [0000]        l   t =0.6 T   i +0.2 M   i +0.2 D   i   (5)
 
         [0030]    In the equation, T i , M i , and D i  represent sequential values of toxicity, mobility, degradability of an i th  kind of characteristic pollutant in the pollution source, respectively. 
         [0000]    
       
         
           
             
               
                 
                   
                     a 
                     i 
                   
                   = 
                   
                     
                       
                         l 
                         max 
                       
                       / 
                       
                         l 
                         i 
                       
                     
                     
                       
                         ∑ 
                         
                           i 
                           = 
                           1 
                         
                         n 
                       
                        
                       
                           
                       
                        
                       
                         
                           l 
                           max 
                         
                         / 
                         
                           l 
                           i 
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   6 
                   ) 
                 
               
             
           
         
       
     
         [0031]    In the equation, a i  is a weighted value of an i th  kind of pollution factor; l max  is a weighted evaluation value of the maximum characteristic pollutant in n kinds of pollution factors. 
       4. Study on Vadose Zone Characteristics 
     4.1. Vadose Zone Antifouling Property Index and Score 
       [0032]    For a built project without seepage prevention measures, according to rock (soil) single-layer thickness and permeability coefficient of vadose zone thereof, the vadose zone antifouling property is classed into three levels, which are strong, intermediate, and weak. Particular reference indices are shown in Table 4. 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                 TABLE 4 
               
             
             
               
                   
               
               
                 Rating of vadose zone antifouling property  
               
             
          
           
               
                 Rating  
                 Permeability of vadose zone rock (soil)  
                 Score 
               
               
                   
               
               
                 Strong  
                 Rock (soil) layer has a single-layer  
                 1 
               
               
                   
                 thickness Mb            1.0 m, a permeability  
                   
               
               
                   
                 coefficient K            10−7 cm/s, and the  
                   
               
               
                   
                 distribution is continuous and stable.  
                   
               
               
                 Intermediate  
                 Rock (soil) layer has a single-layer  
                   
               
               
                   
                 thickness 0.5 m            Mb &lt; 1.0 m, a  
                   
               
               
                   
                 permeability coefficient K            10−7 cm/s,  
                   
               
               
                   
                 and the distribution is continuous and  
                   
               
               
                   
                 stable. Rock (soil) layer has a single-layer  
                   
               
               
                   
                 thickness Mb            1.0 m, a permeability  
                   
               
               
                   
                 coefficient 10−7 cm/s &lt; K            10−4 cm/s,  
                   
               
               
                   
                 and the distribution is continuous and  
                   
               
               
                   
                 stable.  
                   
               
               
                 Weak  
                 Rock (soil) layer does not satisfy the 
                 0  
               
               
                   
                 conditions of “strong” and“ intermediate” 
                   
               
               
                   
                 described above. 
               
               
                   
               
             
          
         
       
     
       4.2. Vadose Zone Vulnerability Index and Score 
       [0033]    The DRASTIC method is proposed by EPA, U.S., and can be used to evaluate phreatic aquifers and confined aquifers. This method has been commonly used in Western countries such as the United States, Canada, South Africa, European Union countries, etc. According to practical situations in China, Zuoshen Zhong has proposed a DRTA model to evaluate the vulnerability of a phreatic aquifer and a DLCT model to evaluate the vulnerability of a confined aquifer, on the basis of DRASTIC. The main object to be evaluated in this disclosure is a shallow aquifer, and a DRMK model, which combines the DRTA model and study results of vadose zone antifouling property, is used as a vadose zone vulnerability evaluation tool. Particular weights and scores in this model are shown in Tables 5 and 6. 
         [0000]    
       
         
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 5 
               
             
             
               
                   
               
               
                 Evaluation indices and weights 
               
             
          
           
               
                   
                   
                   
                   
                   
                 Permeability  
               
               
                   
                 Burial depth  
                 Net  
                 Thickness  
                 Permeability 
                 coefficient of  
               
               
                   
                 of 
                 recharge 
                 of clayey  
                 coefficient of  
                 non-clayey  
               
               
                   
                 groundwater 
                 capacity  
                 soil media 
                 clayey soil  
                 soil media 
               
               
                 Index 
                 (D) 
                 (R) 
                 (M1)  
                 media (K1) 
                 (K2) 
               
               
                   
               
               
                 Weight 
                 1 
                 2 
                 4 
                 5 
                 3 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 6 
               
             
             
               
                   
               
               
                 Types and scores of various factors of DRMK model 
               
             
          
           
               
                   
                 Burial depth  
                 Net  
                 Thickness  
                 Permeability 
                 Permeability 
               
               
                   
                 of 
                 recharge 
                 of clayey  
                 coefficient  
                 coefficient of  
               
               
                 Evaluation 
                 groundwater  
                 capacity  
                 soil media  
                 of clayey soil  
                 non-clayey soil  
               
               
                 index 
                 (D) 
                 (R) 
                 (M1) 
                 media (K1) 
                 media (K2) 
               
               
                   
               
             
          
           
               
                 10 
                 ≦1.5 
                 &gt;254 
                 ≦1.6 
                  9 × 10 −7 ~12 × 10 −7   
                 &gt;2.2 × 10 −1   
               
               
                 9 
                 1.5~4.6 
                 235~254 
                 1.6~3.3 
                 8 × 10 −7 ~9 × 10 −7   
                 2.0 × 10 −1 ~2.2 × 10 −1   
               
               
                 8 
                 4.6~6.8 
                 216~235 
                 3.3~5.0 
                 7 × 10 −7 ~8 × 10 −7   
                 1.8 × 10 −1 ~2.0 × 10 −1   
               
               
                 7 
                 6.8~9.1 
                 178~216 
                 5.0~7.8 
                 6 × 10 −7 ~7 × 10 −7   
                 6.0 × 10 −2 ~1.8 × 10 −1   
               
               
                 6 
                  9.1~12.1 
                 147.6~178   
                   7.8~13.5 
                 5 × 10 −7 ~6 × 10 −7   
                 2.4 × 10 −2 ~6.0 × 10 −2   
               
               
                 5 
                 12.1~15.2 
                 117.2~147.6 
                 10.7~13.5 
                 4 × 10 −7 ~5 × 10 −7   
                 6.0 × 10 −3 ~2.4 × 10 −2   
               
               
                 4 
                 15.2~22.9 
                  91.8~117.2 
                 13.5~14.5 
                 3 × 10 −7 ~4 × 10 −7   
                 1.2 × 10 −3 ~6.0 × 10 −3   
               
               
                 3 
                 22.9~26.7 
                 71.4~91.8 
                 14.5~15.5 
                 2 × 10 −7 ~3 × 10 −7   
                 6.0 × 10 −4 ~1.2 × 10 −3   
               
               
                 2 
                 26.7~30.5 
                   51~71.4 
                 15.5~16.5 
                 1 × 10 −7 ~2 × 10 −7   
                 6.0 × 10 −5 ~6.0 × 10 −4   
               
               
                 1 
                 &gt;30.5 
                 ≦51 
                 &gt;16.5 
                 &lt;10 −7   
                 1.2 × 10 −6 ~6.0 × 10 −5   
               
               
                   
               
             
          
         
       
     
       5. Steps of Rating Evaluation 
     5.1. Rating of Evaluation of Pollution Source Hazard 
       [0034]    Pollution source hazard is evaluated by an overlay and index method, as particularly shown in equation (7), based on the calculation of pollution factors of groundwater pollution sources as well as the weights and the scores of respective parameters described above. With an unequal interval method, calculation results of the equation (7) in a value range of 0-10 are divided into 3 levels: level I when B≦4.0; level II when 4.0&lt;B&lt;7.0; and level III when B≧7.0. 
         [0000]        B= 0.22 B   1r +0.17 B   2r +0.16 B   3r +0.1 B   4r +0.9 B   5r +0.12 B   6r +0.14 B   7r   (7)
 
         [0035]    In the equation, B ir  is a score of each parameter. 
         [0036]    As the B value becomes greater, the groundwater pollution source hazard becomes higher and the evaluation level becomes higher. 
       5.2. Rating of Evaluation of Vadose Zone Resistance 
       [0037]    The rating of vadose zone comprehensive evaluation will comprehensively consider the factors in two aspects, which are antifouling property and vulnerability of vadose zone, in which, the vadose zone antifouling property of a polluted field is preferentially evaluated in the evaluation of vadose zone resistance, to predict whether the vadose zone effect is considered in the evaluation of groundwater pollution source intensity in the field or not. In the case where the vadose zone effect is considered, the score of vadose zone antifouling property (V), as a factor, is introduced to the calculation of vadose zone vulnerability index (DI), and the score of V is determined according to Table 4. In the calculation of the vadose zone vulnerability index, the score of vadose zone media thickness (T) is related to the thickness and the type of vadose zone media (R). It is not rational to give the same score value to different media with the same thickness, and thus the score value of T is multiplied by the score value of R in addition to being multiplied by the weight. The calculation of vadose zone comprehensive evaluation index (DI′) is shown in equation (8). The DI′ value ranges from 15 to 150, and the evaluation of vadose zone resistance is divided into 3 levels: level I when DI′&lt;70; level II when 70≦DI′&lt;120; level III when DI′&gt;120. 
         [0000]        DI′=V ×(1 ×D+ 2 ×R+ 4 ×M+ 5 ×K 1+3 ×K 2)  (8)
 
         [0038]    In the equation, V, D, R, M, K1 and K2 are score values of respective factors. 
         [0039]    As the DI′ value becomes higher, the vadose zone antifouling property becomes poorer, the vulnerability becomes higher, and the level becomes higher. 
       5.3. Rating of Evaluation of Groundwater Pollution Source Intensity 
       [0040]    The pollution source characteristic and the vadose zone characteristic are required to be comprehensively considered with respect to the evaluation result of groundwater pollution source intensity. This disclosure combines both of the characteristics using a matrix method, to concisely, briefly, and directly indicate the coupled effects of characteristic factors of pollution source and vadose zone on groundwater source intensity. Particular results of rating are shown in Table 7. The higher the level is, the greater the groundwater pollution source intensity is. 

 
       EXAMPLES 
     Field 1 
     An Informal Refuse Landfill, Which Has an Existent Pollution Source Without Seepage Prevention and Vadose Zone Antifouling Property Being “Weak” 
       [0041]    An informal refuse landfill was used as an object for study. This informal refuse landfill was an already built project without seepage prevention measures, and was rated for vadose zone antifouling property according to  FIG. 2 . The vadose zone of the field mainly consisted of sand gravel, and the permeability coefficient of the vadose zone was 0.006 cm/s so the vadose zone antifouling property of this field was “weak” according to Table 4. Therefore, when groundwater pollution source intensity was evaluated, only the groundwater pollution source hazard evaluation was performed, without considering the effect of the vadose zone. 
         [0042]    According to monitoring results of landfill refuse percolate, NH 3 —N 1810 mg/L, Cr 0.222 mg/L, Cd 0.045 mg/L, As 0.0444 mg/L, and Hg 0.00157 mg/L, among others, were selected as main factors in pollution factor comprehensive evaluation. By using class I water quality in the quality standard of groundwater as the standard, the sequences of toxicity, mobility, and degradability of related pollutants were determined. a i  values of NH 3 —N, Cr, Cd, As, and Hg were 0.09, 0.16, 0.26, 0.20, and 0.29 respectively, as calculated according to equation (5) and equation (6). P′ weighted average =7.40, P imax =362, and 
         [0043]    P′ comprehensive =256 were further obtained according to equation (3) and equation (4). 
         [0044]    The average annual rainfall in the region where this field was located was 480 mm, and the discharge amount of percolate was 3.84×10 4  m 3 /a. 
         [0045]    The landfill amount was 1550000 m 3 , and area in contact with ground was 100000 m 2 , and the influence area proportion was 79.6%. The service time was ten years, and it has been closed now. 
         [0046]    According to Table 2, P′ comprehensive , discharge amount, discharge position, discharge mode, influence area proportion, protective measures for pollution source, and existence time of pollution source had scores of 10, 3, 8, 10, 10, 10, and 5, respectively. 
         [0047]    The pollution source hazard B value was 7.79 as calculated according to equation (7). The rating of the evaluation of pollution source hazard resulted in level III by referring to Table 7. The rating of the evaluation of pollution source hazard was the rating of the evaluation of groundwater pollution source intensity according to  FIG. 2 . Therefore, the rating of the evaluation of groundwater pollution source intensity was level III. 
       Field 2 
     A Stockpile in a Rare Earth Mine Exploitation Project, Which Has a Potential Pollution Source With Seepage Prevention 
       [0048]    A rare earth mine exploitation project was used as an object for study. The waste disposal site of this exploitation project was a main pollution source of groundwater, and seepage prevention measures were going to be built in the waste disposal site. 
         [0049]    According to the results of a test for identifying the hazard of waste ores, Cu 0.354 mg/L, Cr 0.055 mg/L, Cd 0.0015 mg/L, As 0.0024 mg/L, Pb 0.227 mg/L, and Hg 0.0035 mg/L, among others, were selected as main factors in pollution factor comprehensive evaluation. By using “Identification standards for hazardous wastes—Identification for extraction toxicity” (GB5085.3-2007) and “Integrated wastewater discharge standard” (GB8978-1996) as the standards, the sequences of toxicity, mobility, and degradability of related pollutants were determined. a i  values of Cu, Cr, Cd, As, Pb, and Hg were 0.15, 0.08, 0.2, 0.15, 0.10, and 0.32 respectively as calculated according to equation (5) and equation (6). P′ weighted average =0.026326, P imax =0.708, and P′ comprehensive =0.5 were further obtained according to equation (3) and equation (4). 
         [0050]    The area of the waste disposal site was 10000 m 2 , the average annual rainfall in this region over several years was 1800 mm, and the discharge amount was 1.4×10 4  m 3 / a . 
         [0051]    This project had a total floor area of about 340000 m 2 , and the influence area proportion of the waste disposal site was 3%. The evaluation time was set to be 20a. 
         [0052]    According to Table 2, P′ comprehensive , discharge amount, discharge position, discharge mode, influence area proportion, protective measures for pollution source, and existence time of pollution source had scores of 2, 3, 6, 10, 7.5, 5, and 10, respectively. 
         [0053]    The pollution source hazard B value was 5.585 as calculated according to equation (7) and the rating of the evaluation of pollution source hazard resulted in level II. The rating of the evaluation of pollution source hazard was the rating of the evaluation of groundwater pollution source intensity according to  FIG. 2 . Therefore, the rating of the evaluation of groundwater pollution source intensity was level II. 
       Field Verification 
       [0054]    Evaluation results of groundwater pollution source intensities of three fields were compared to monitoring reports of groundwater of four fields. Particular results are shown in Table 8. 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                 TABLE 8 
               
             
             
               
                   
               
               
                 Field verification 
               
             
          
           
               
                   
                 Rating of 
                   
               
               
                   
                 evaluation of  
                   
               
               
                   
                 groundwater  
                 Monitoring report of groundwater (2013)  
               
               
                   
                 pollution  
                 Class I water quality in “Environment  
               
               
                 Field  
                 source intensity  
                 quality standard for groundwater” 
               
               
                   
               
               
                 1  
                 III  
                 Five pollutants including NH 3 —N, Cr, Cd, As,  
               
               
                   
                   
                 and Hg in the groundwater of the field exceeded  
               
               
                   
                   
                 the standard by 2.9-5 times.  
               
               
                 2 
                 II 
                 Six pollutants including Cu, Cr, Cd, As, Pb, and  
               
               
                   
                   
                 Hg in the groundwater of the field did not  
               
               
                   
                   
                 exceed the standard. 
               
               
                   
               
             
          
         
       
     
         [0055]    As seen from the table, the concentrations of pollutants involved in the evaluation of field 1 exceeded the standard, relatively complying with the result of level III in the rating of the evaluation of groundwater pollution source intensity; and none of the concentrations of pollutants involved in the evaluation of field 2 exceeded the standard, relatively complying with the result of level II in the rating of the evaluation of groundwater pollution source intensity in the field. Therefore, the results of the evaluation models established were acceptable. 
         [0056]    The objects, technical solutions, and advantageous effects of this disclosure are illustrated in details by the specific Example described above. It is to be understood that those described above are merely some specific Examples of the invention, but are not intended to limit the invention. All of modifications, equivalent replacements, improvements, and the like, which are within the spirit and the principle of the invention, should be encompassed in the scope protected by this invention.