The aim of this paper is to analyse the influence of a groundwater pumping rate on nitrate concentrations at the Bartolovec wellfield, which is part of a water supply system of the town of Varaždin, Croatia. Over the past 16 years both the pumping rate and nitrate concentrations have increased at the wellfield. The nonlinear models that describe the pumping rate to nitrate concentration levels were developed on the basis of Logistic, Gompertz, and Richards growth functions. For each function, three different types were established regarding the initial lower contamination limit parameter. The conditions that models have to meet were defined and their reliability was established. The models were implemented on the experimental data collected during the period under consideration. The models were validated and mutually compared using Akaike’s Information Criteria (AIC_c), while the data fitting was estimated by using a coefficient of determination. After the results were obtained by using different models, they were compared to the maximum allowable nitrate concentrations (MAC) in water for human consumption. The dependence of nitrate concentrations on a pumping rate was confirmed and the reliable model for nitrate concentration on pumping rate was created. The model was calibrated and tested on the experimental data. The model exhibits asymptotic behavior and result shows that with the further increase in the pumping rate of groundwater drainage at the Bartolovec wellfield, nitrate concentrations will not exceed the MAC value providing there are no new sources of contamination in the zone of a pollutant influence.

中文翻译：

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硝酸盐浓度对供水系统抽水速度的依赖性的非线性模型

本文的目的是分析Bartolovec井场的地下水抽水率对硝酸盐浓度的影响，该井场是克罗地亚Varaždin镇供水系统的一部分。在过去的16年中，井场的抽水速率和硝酸盐浓度均增加了。在Logistic，Gompertz和Richards生长函数的基础上，开发了描述泵送速率至硝酸盐浓度水平的非线性模型。对于每种功能，针对初始污染下限参数建立了三种不同的类型。定义了模型必须满足的条件，并确定了它们的可靠性。这些模型是根据所考虑期间收集的实验数据实施的。AIC _c），同时使用确定系数估算数据拟合度。使用不同的模型获得结果后，将其与人类食用水中的最大允许硝酸盐浓度（MAC）进行比较。证实了硝酸盐浓度对抽速的依赖性，并建立了硝酸盐浓度对抽速的可靠模型。对该模型进行校准并根据实验数据进行测试。该模型表现出渐近行为，结果表明，随着Bartolovec井场地下水排水抽水速率的进一步提高，如果在污染物影响区域内没有新的污染源，则硝酸盐浓度不会超过MAC值。