Optimizing the DRASTIC Method for Nitrate Pollution in Groundwater Vulnerability Assessments: a Case Study in China

Abstract

Groundwater vulnerability assessments, using DRASTIC, are important and useful tools for groundwater pollution prevention and control. The DRASTIC method, however, is not appropriate for accurate specifi c vulnerability assessments where nitrate concentrations are high. A new method has been developed that retains the basic structure of DRASTIC while adding or subtracting parameters, and modifying the parameter ratings and weightings. The resulting DRACILM model was used to assess vulnerability to nitrate pollution in the West Liaohe Plain and as a basis for vulnerability mapping. The accuracy, appropriateness, and reliability of the vulnerability mapping were analyzed using a group of integrated indicators, such as correlation, ANOVA F-statistics, and single-parameter sensitivity analysis. The correlation between vulnerability class and the concentration of NO 3 -N in the DRACILM model improved to 0.649, which was 40.6% higher than that obtained by DRASTIC. The ANOVA F-statistic was 27.71, which indicated a lower overlap between the mean values of nitrates in the different vulnerability classes. The single-parameter sensitivity analysis revealed that land use type exhibited the highest and hydraulic conductivity the lowest effective weighting values. The vulnerability maps by DRACILM model could assist planners and government decision-makers with preliminary investigations into planning water protection projects or establishing management scenarios for water resource quality.

Influence of Agricultural Irrigation Activity on the Potential Risk of Groundwater Pollution: A Study with Drastic Method in a Semi-Arid Agricultural Region of China

“…In this study, the water interception and absorption of crop was almost the same for the different cultivated areas, owing to the wide planting of maize in the study area. The net recharge in this cultivated area was discussed in light of the different soil media and irrigation methods [52], and the proposed comprehensive corrected coefficients were used for estimating the groundwater vulnerability in Scenario 3. The fractional area associated with relatively high-risk regions in Scenario 3 decreased by 14.55% and 21.38%, compared with Scenario 1 and Scenario 2, respectively.…”

Assessment of factors affecting the intrinsic vulnerability of groundwater rated by the mean residence time estimation method

“…Al though the results ob tained with the in dex meth ods are qual i ta tive, they are still com monly used world wide, es pe cially via the very ef fec tive DRASTIC method (e.g., Krogulec, 2006;Ró¿kowski, 2007;Saidi et al, 2011Saidi et al, , 2017Khemiri et al, 2013;Krogulec and Trzeciak, 2016). This method has been im proved and ad justed to com plex hydrogeological con di tions (Witkowski et al, 2003;Yu et al, 2012;Jiménez-Ma drid et al, 2013;Hernández-Espriú et al, 2014;Kazakis and Voudouris, 2015;Bonfanti et al, 2016;He et al, 2018). Com bined meth ods gen er at ing a qual i ta tive result are also used (Gemitzi et al, 2006;Civita, 2010).…”

Groundwater Pollution Risk Assessment Based on Vulnerability to Pollution and Potential Impact of Land Use Forms

“…However, reliable quantitative determination of groundwater pollution risk is difficult as it depends on many factors, some of the mhardly measurable, and thus assessments of groundwater pollution risk are usually qualitative instead quantitative. Some groundwater pollution risk assessments focus on the risk stemming from only one specific source of pollution, for example nitrates derived from agricultural fertilization [11][12][13][14][15][16][17][18][19], waste disposal sites [20,21], or even biofuel-related land use [22].…”

“…Locally measured nitrate concentrations are usually taken as an indicator of current degradation of groundwater quality, such as in [11][12][13][14][15][16][17][18][19]. In this way, a purely theoretical possibility of occurrence of an unwanted event is linked with real facts.…”

“…The approach to reducing the degree of uncertainty of groundwater pollution risk assessment is usually done by validation of data and factors affecting this risk. As a result of validation, researchers modify the primarily accepted original method of assessment of intrinsic vulnerability of groundwater to pollution, usually by changing the weights of selected factors or by introducing additional factors or parameters affecting this risk, such as in [11][12][13][14][15][16][17][18][19]. In this way, (i) there is an intentional or unintentional shift from the assessment of intrinsic vulnerability to a specific one, (ii) the result obtained by the modified method of groundwater pollution risk assessment becomes closer to the observations of the current concentrations of specific compounds, usually nitrates, but as a result it is an assessment of groundwater-pollution-specific risk instead of an assessment of the overall risk of groundwater pollution arising from any potential factor.…”