Pingzhai Reservoir dam was built in a deep canyon of the southern tributary of the Wu River and is the main water resource used in the Hydro-junction Project to satisfy the water requirements of Central Guizhou Province in southwestern China. The interval basin (i.e., subbasin, encompassing lower reaches between the dam and the backwater end of the main stream contributing to the dam reservoir) of Pingzhai Reservoir is characterized by thick karstified carbonate strata. Hydrological and hydrogeochemical data, including the inflow of the main stream to the interval basin, the reservoir water level, rainfall, reservoir discharge, and concentrations of major ions and stable isotopes of oxygen and hydrogen in water, were collected and analyzed. A conceptual model was constructed using the back-propagation artificial neural network approach and the water balance equation was used to calculate the total storage capacity of the karst underground reservoir associated with the Pingzhai surface reservoir. The results showed that the intensively karstified Lower Triassic Yongningzhen Formation carbonate strata resulted in the creation of a karst groundwater reservoir with a macroscopic volumetric karst rate of ~5.0%. The total storage capacity of the karst underground reservoir is (311 ± 108) × 106 m3, and it accounts for 29% of the total capacity of the Pingzhai surface reservoir. The reliability of the total storage capacity value of the karst underground reservoir was assessed by hydrochemical and stable isotopic methods. These results will aid in the joint management of surface reservoirs and associated underground reservoirs in karst canyon areas.

The Pingzhai Reservoir, a water source project of the Central Guizhou Province hydro-junction project, is located in the deep canyon karst area of the Sancha river in the Guizhou Plateau. It is an important water conservancy infrastructure to ensure the safety of water resources in central Guizhou. In this paper, the hydrological and hydrochemical automatic monitoring technology is used to study the hydrological and hydrochemical regime of the Santang underground river system, an important tributary in the interval basin of the Pingzhai Reservoir, which lacks the early basic research of hydrogeology. On this basis, the karst development and conduit model of the deep canyon karst subterraneous river system are preliminarily discussed. The results show that the hydrochemical regimes are mainly controlled by the cover CO2 effect, effective rainfall dilution effect and opening effect of runoff-discharge channels. In different time scales and atmospheric precipitation conditions, the variation characteristics of hydrochemical regime are different, and the corresponding dominant effect is also different. The annual variation of water temperature is high in summer and low in winter, and the daily variation is high in day and low at night. The annual variations of electrical conductivity and partial pressure of CO2 of the groundwater is high in normal-water level period and low in high-water level period because of the combined effects of land cover CO2 and rainfall dilution. On the monthly scale, the cover CO2 effect can be observed during the initial stage of rainfall, but after rainfall the dilution effect control the variation of electrical conductivity and Pco2. On the daily scale in the dry season, the daily hydrochemical regime controlled by the opening effect of the runoff-discharge channels can be observed. The identified opening effect of the runoff-discharge channels can provide a hydrochemical basis for judging the pressure state of karst conduit in the modeling study of the karst water system. This study provides a hydrogeological basis for the joint scheduling of surface and underground reservoirs and the reasonable utilization of water resources in this area in the future.

冀中坳陷地热资源潜力巨大,对其热储水化学特征及成因进行研究可为其下一步开发利用提供依据.通过对研究区的地热地质条件、水化学特征、同位素特征进行研究分析,确定了地热水的补给来源,热储温度及地热水的循环深度,并明确了研究区的地热水成因机制.结果表明,研究区地热水主要来自于西部太行山区大气降水补给,通过断裂由西北向东南对地热水进行补给,补给高程范围在585.7～1361.8 m,热储温度范围在30.2℃ ～93.2℃,循环深度范围在955.0～2579.7 m.

The coal-dominated energy structure in the Beijing–Tianjin–Hebei region has caused serious air pollution and contradicts the construction of a clean, low-carbon, safe and efficient energy system. Substituting geothermal energy for fossil energy such as coal can effectively alleviate this problem. Located in the hinterland of the Beijing-Tianjin-Hebei region, the Jizhong Depression is rich in geothermal resources and has great development potential, though the degree of current development and utilization is not high. Vigorously developing geothermal energy can not only effectively alleviate the air pollution problem in the Beijing–Tianjin–Hebei region, but also optimize the regional energy structure. Geothermal reservoir temperature determines the development and utilization value of geothermal resources, and accurate evaluation of the geothermal reservoir temperature of geothermal resources can provide a reliable basis for the subsequent development of geothermal resources in the Jizhong Depression. Aiming at the commonly used sandstone geothermal reservoir and carbonate geothermal reservoir in the Jizhong Depression, this paper collected 24 sandstone geothermal reservoir geothermal fluids and 14 carbonate geothermal reservoir geothermal fluids in the central-southern area of the Jizhong Depression and a water chemistry test was carried out. According to the test results of water chemistry, the temperature of the geothermal reservoir is estimated by using the cation geothermometer, the SiO2 geothermometer and the multi-mineral equilibrium method, and it is compared with the actual temperature measurement results of the boreholes. The results show that the direct use of a geothermal geothermometer for calculation will cause large errors. Through water–rock balance analysis, the use of a Na-K-Mg balance diagram, SiO2 and 1000/T relationship diagram and Na/K and 1000/T relationship diagram can determine whether the geothermal fluid is suitable for the geothermometer, which can effectively reduce the error. The chalcedony geothermometer in the central and southern part of the Jizhong Depression is the most suitable. The multi-mineral balance method, the Na-K geothermometer and the K-Mg geothermometer have also achieved good results, while the quartz and Na-K-Ca geothermometers are not suitable for the south-central Jizhong Depression area.

选取贵州乌江南源上的平寨水库作为研究对象,对其伴生的岩溶地下水库的库容进行计算.平寨水库是贵州省黔中水利枢纽工程的控制性水源工程,总库容达10.89亿m3.该地表水库位于云南高原向黔中高原过渡斜坡带上的深切峡谷区,峡谷两侧碳酸盐岩地层广泛分布,其中的三叠系下统永宁镇组碳酸盐岩地层岩溶化程度较高,为平寨水库伴生的岩溶地下水库的形成提供了重要条件.采用水库运营期水量反算法,对平寨水库大坝竣工后初始蓄水阶段(2015—2016年)进行水均衡计算,结果表明,与平寨水库相伴生的岩溶地下水库的总库容达3.11亿m3,约占平寨水库地表总库容的29％.