Many buried karst areas in Iran, and in other parts of the world have not yet been mapped using detailed geological or geophysical studies to delineate susceptibility to sinkhole development. The purpose of this paper is to investigate the possibility of using the results of hydrogeochemical analysis with routine measurements of physicochemical parameters to evaluate and detect areas prone to sinkhole develop. Sixteen spatial maps were prepared using analyzed data from 77 water samples from monitoring water wells in the Kabudar Ahang, Razan, and Qahavand (KRQ) sub-catchments of the Hamadan province, western Iran. By use of geographic information system tools 16 thematic maps for physicochemical parameters (EC, pH., TDS, and groundwater temperature), major cations (Ca²⁺, Mg²⁺, Na⁺, and K⁺), anions (HCO⁻₃, SO₄²⁻, NO₃⁻, and Cl⁻), and calcite, dolomite, gypsum, and partial pressure of CO₂ saturation indices (SIC, SID, SIG, and SIpCO₂) were prepared. It was hypothesized that the anomalies of each parameter concentration could be consistent with sinkhole prone areas. To evaluate this assumption, the area under the Receiver Operating Characteristic (ROC) curve was calculated by 100 points as a true sinkhole pixel (50 positive true) and non-sinkhole point (50 true negative). The areas under curve of ROC for these thematic maps were calculated for the 16 variables. Results show that the dolomite and calcite saturation indices (0.49 and 0.43, respectively) are poor indicators, whereas HCO⁻₃ and pCO₂ saturation indexes (0.83 and 0.78, respectively) are good indicators of sinkhole susceptibility in the study area. The result confirmed application of hydrogeochemical anomaly analyses and the ROC validation method in covered karst can be a useful tool for prediction of sinkhole prone zones forming in region, where sparse data are available.

伊朗和世界其他地区的许多地下岩溶地区尚未通过详细的地质或地球物理研究绘制地图，以描绘对天坑发育的敏感性。本文的目的是研究利用水文地球化学分析结果和物理化学参数的常规测量来评估和检测易于形成落水洞的区域的可能性。使用来自伊朗西部哈马丹省 Kabudar Ahang、Razan 和 Qahavand (KRQ) 子流域的监测水井的 77 个水样的分析数据绘制了 16 张空间图。通过使用地理信息系统工具 16 个物理化学参数（EC、pH.、TDS 和地下水温度）、主要阳离子（Ca ²⁺、Mg ²⁺、Na⁺、K ⁺ )、阴离子（HCO ^- ₃、SO ₄ ^2-、NO ₃ ^-和 Cl ^-）、方解石、白云石、石膏和 CO ₂饱和度指数的分压（SIC、SID、SIG 和SIPCO ₂) 准备好了。假设每个参数浓度的异常可能与天坑易发区域一致。为了评估这个假设，接收者操作特征 (ROC) 曲线下的面积计算了 100 个点，作为真正的天坑像素（50 正真）和非天坑点（50 真负）。这些专题地图的 ROC 曲线下面积是针对 16 个变量计算的。结果表明，白云石和方解石饱和度指数（分别为 0.49 和 0.43）是较差的指标，而 HCO ⁻ ₃和 pCO ₂饱和度指数（分别为 0.83 和 0.78）是研究区天坑敏感性的良好指标。结果证实，水文地球化学异常分析和 ROC 验证方法在覆盖岩溶中的应用可以成为预测在该地区形成的天坑易发带的有用工具，在那里可以获得稀疏数据。