Sustainable Yield of a Karst Aquifer System: a Case Study of Jinan Springs in Northern China

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Sustainable yield of a karst aquifer system: a case study of Jinan springs in northern China

Fengxin Kang & Menggui Jin & Pinrui Qin

Abstract Based on the long-term monitoring data of Keywords Karst . China . Sustainable yield . Maximum rainfall, groundwater levels, groundwater abstraction, allowable drawdown . Numerical model spring flow rates and groundwater quality, an assessment has been undertaken of the sustainable yield of a karst aquifer system in Shandong Province, northern China, to maintain perennial outflow of the karst springs while Introduction meeting water demands. One of the fundamental indica- tors for sustainable yield of groundwater is identified as There are numerous valuable karst springs in northern maximum allowable water-level drawdown. A regional China (Shandong, Shanxi, Hebei, Henan, Shanxi Prov- three-dimensional finite-difference numerical model has inces and Beijing), where 61% of the areas of the been developed to optimize the schemes associated with provinces are made up of Cambrian and Ordovician well fields and their locations and sustainable yields, in carbonate rocks (Li and Kang 1999). In these areas, the Jinan spring catchment and its adjacent karst ground- groundwater in karst aquifers is abundant, and has water catchments, with the aim of maintaining the water become the main water-supply sources for domestic, municipal and industrial uses, and agricultural irriga- level higher than the allowable lowest water level of fl 27.5m above sea level. Furthermore, measures necessary tion. The karst springs out ow at centralized discharge areas of karst aquifer systems. The free flow rate of to move towards sustainable use of the karst groundwater 3 3 are outlined, drawing on contingency plans of water- more than 50 springs is greater than 1 m /s (86,400m / source replacement and artificial recharge, dual water d) (Ma et al. 2004). These big karst springs present not supply (based in water quality), use of the spring waters only the most splendid scenery, but also the sources for themselves, and groundwater quality protection. the local rivers, lakes and water supply for regional water users, so that they are one of the primary elements of the local ecosystem. For instance, the famous karst springs in Jinan, Shandong Province, are thesourceofDa’ming Lake and Xiaoqing River, as well as one of the largest tourist attractions in Jinan and Received: 24 November 2009 /Accepted: 4 March 2011 Shandong Province. Published online: 6 April 2011 With the large-scale exploitation of karst groundwater and rapid urbanization, continuous lowering of * Springer-Verlag 2011 groundwater levels and groundwater-quality deterioration have occurred in these karst groundwater systems. fl F. Kang : M. Jin ()) Correspondingly, the free ow rates of the springs have MOE Key Laboratory of Biogeology and Environmental Geology decreased and some springs have even dried up. The & School of Environmental Studies, springs in Jinan City were selected as being representa- China University of Geosciences, tive of a system suitable for studying the sustainable Wuhan 430074, China e-mail: [email protected] karst groundwater yield under the prerequisites of Tel.: +86-276-7883461 maintaining perennial outflow of the springs and meet- Fax: +86-278-7436235 ing water supply demand. F. Kang The Jinan karst aquifer system lies at the northern edge Shandong Provincial Bureau of Geology and Mineral Resources, of Taishan Mountain (elevation of 1,545 m above sea 74 Lishan Road, Jinan 250013, China level (asl), the highest in Shandong Province), and is P. Qin bounded to the north by the Yellow River, the second Shandong Provincial Institute of Geo-engineering, largest river in China. For the purpose of spring protection Jinan 250014, China in Jinan, much research and numerous investigations have

Hydrogeology Journal (2011) 19: 851–863 DOI 10.1007/s10040-011-0725-2

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852 been done in the last 40 years (Li 1985; Li and Kang than the allowable lowest water level of 27.5 m asl and to 1999; Li et al. 2002, 2003; Wang et al. 2004; Qian et al. meet water demand in Jinan City. 2006; Wu et al. 2010). However, all of the previous studies have concentrated on the sole Jinan spring catchment, not the whole Jinan karst aquifer system. As shown in Fig. 1, the Jinan karst aquifer system is composed of Description of the study site Jinan spring catchment, White spring catchment, Chang- xiao karst water catchment and Dong’er karst water Jinan springs catchment, with areas of 1486, 784, 677, and 823 km2 Jinan, the capital city of Shandong Province, is famous for respectively. its springs, and is named “City of Springs”. There are 108 It is necessary to take into account all four catchments springs distributed within 2.6 km2 in the center of Jinan. as one karst aqufier system because the catchments are Flowing along the moat, the spring waters collectively hydraulically interconnected. On the basis of the long- flow into the Daming Lake, and then drain out into the term monitoring data of rainfall, groundwater levels, Xiaoqing River. The total discharge of the springs ranges groundwater withdrawals, and spring discharges, a three- from 300,000 to 400,000 m3/d in normal years, with the dimensional finite–difference groundwater numerical maximum of 502,000 m3/d observed in 1962. Among model has been developed to simulate sustainable ground- them, four spring groups are the most famous: Baotu water yield under different scenarios for the Jinan karst spring, Black-tiger spring, Pearl spring and Five-dragon aquifer system. The aim is to maintain water levels higher spring.

Fig. 1 Hydrogeology of Jinan Karst Aquifer System, consisting of Jinan spring catchment, White spring catchment, Changxiao karst water catchment and Dong’er karst water catchment. 1 karst groundwater abundant and discharge area, 2 karst groundwater recharge area, 3 karst groundwater buried below impermeable sandstone and shale, 4 impermeable igneous rock, 5 impermeable granitic gneiss, 6 permeable fault, 7 low permeability fault, 8 impermeable fault, 9 impermeable igneous dike, 10 surface and groundwater divide, 11 no-flow boundary, 12 lateral inflow boundary, 13 lateral outflow boundary, 14 karst spring, 15 general direction of karst groundwater flow, 16 karst groundwater well field and its number, 17 urban area of Jinan City, 18 towns, 19 Cambrian-Ordovician, 20 Carboniferous-Permian, 21 Archean, 22 magmatic rock

Hydrogeology Journal (2011) 19: 851–863 DOI 10.1007/s10040-011-0725-2 中国科技论文在线 http://www.paper.edu.cn

853 Over the last 40 years, due to over-exploitation of the between Jinan spring catchment and Changxiao karst karst groundwater and changes to the recharge conditions, water catchment, and Niujiaodian Fault between Chang- the discharge from the springs has been declining xiao karst water catchment and Dong’er karst water continuously, and the springs have dried up during dry catchment. Southern sections of these boundaries are seasons (March–June). For example, Baotu spring began impermeable, whereas northern sections are permeable. to dry up in the dry season from 1972 (Fig. 2); on The Upper Cambrian (€3) and Lower-Middle Ordovician occasions, there was no free flow in the whole year, like in (O1, O2) limestone and oolitic limestone are the main 1982, 1989, and 2000–2002. The “City of Springs” is in aquifers in the system. danger of being unworthy of its title, which could affect Precipitation is the predominant recharge source and the sustainable development of Jinan’ssocietyand streamflow seepage is another important recharge source. economy. The drying up of the springs is the biggest The major discharge has changed from natural spring cultural issue to all Jinan citizens, because springs are the outflows to artificial extraction. There are also some other soul and the most valuable treasure of Jinan. Therefore, it small discharges, such as lateral outflow through the is important to study the sustainable yield of the karst Quaternary aquifer at the northwest of Jinan City. aquifer system. As shown in Figs. 1 and 3, the karst groundwater is generally flowing from south to north, which basically coincides with the dip direction of karst strata and Geology and hydrogeology topography; when moving to Jinan City, the karst ground- The Jinan karst aquifer system is a monoclinic structure, water is obstructed by impermeable Mesozoic igneous with an area of 3,770 km2 and an average annual rocks (diorite and gabbro) or Carboniferous-Permian sand precipitation of 673 mm. Topographically, the Jinan karst and shale and then enriched around the contact zone aquifer system is gradually lowered in elevation from between impermeable rocks and permeable limestone. In — the suitable areas of topography and structure, the south to north from mountainous and hilly land to a fi fl piedmont inclined plain and to the Yellow River alluvial con ned karst groundwater ows out as ascending plain. Jinan is located in the conjunction between the two springs, and a typical monoclinic artesian structure is plains (Figs. 1 and 3). The Yellow, Xinzhaoniu, Xiaoqing, formed. Yufu and Beisha rivers run through the system. The Jinan karst aquifer system basement, consisting of metamorphic rocks of the Archean Taishan Group, is distributed in the south of the catchment. In the middle of Effects of historical over-extraction on the karst the catchment, the basement is covered by karstic groundwater carbonate strata of Cambrian and Ordovician. The Karst groundwater level and springs discharge Cambrian strata is characterized by the interbeds of limestone and shale while the Ordovician is composed Measurements of water levels in wells provide the most by thick-bedded limestone, argillaceous limestone and fundamental indicator of the status of groundwater and are dolomitic limestone, with the dip direction of NE20° and critical to meaningful evaluations of the quantity and dip angle from 5 to 10°. In the south of the Jinan City quality of groundwater and its interaction with surface proper, the limestone is buried under Quaternary sedi- water (Taylor and Alley 2001). Thus, the long-term ment; while the magmatic rocks (diorite and gabbro), monitoring data are used to evaluate the effects of karst which formed in the Mesozoic Yanshan Orogeny, are groundwater over-exploitation in Jinan spring catchment. distributed in the north, most of them are covered by It can be seen from Fig. 4 that although the rainfall data Quaternary sediment. from 1959 to 2008 displayed strong variations, they do As shown in Fig. 1 the Jinan karst aquifer system is not show a systematic trend, i.e. neither have an composed of four catchments. These four catchments have increasing nor decreasing trend, with the average annual rainfall of 673 mm. On the other hand, the groundwater such boundaries as Dongwu Fault between Jinan spring fl fl catchment and White spring catchmen, Mashan Fault level and spring ow rate uctuations from 1959 to 2000 were in a declining trend in response to the increasing trend of groundwater withdrawals. From 2000 to 2008, the groundwater levels and spring flow-rate fluctuations were in an increasing trend due to the decrease of groundwater withdrawals. In general, the groundwater withdrawal is controlling the long-term trend of karst groundwater levels and spring discharges, and precipitation is superimposing its signa- ture in the short-term. This pattern suggests that the essential study should be focused on sustainable yield development of karst groundwater for the purpose of Fig. 2 Average number of days per year in which Baotu spring has maintaining perennial outflow of the springs and meeting dried up water-supply need.

Hydrogeology Journal (2011) 19: 851–863 DOI 10.1007/s10040-011-0725-2 中国科技论文在线 http://www.paper.edu.cn

854

Fig. 3 Hydrogeological cross-section of Jinan spring catchment (north–south) 1 Soil(Q4), 2 Limestone(O2), 3 Dolomitic limestone(O1), 4 Limestone and shale(€3), 5 Oolitic limestone(€2), 6 Limestone and shale(€1), 7 Granitic gneiss(Ar3), 8 Diorite(Mz), 9 Fault, 10 Baotu and Five-dragon spring

Karst groundwater quality deterioration the spring water was 200 mg/L in 1958, whereas it The main chemical types of the Jinan springs and karst increased up to 550 mg/L in 2008, with an annual increase of 7 mg/year. The concentration of NO increased from groundwater are of HCO3–Ca and HCO3–Ca–Mg. Before 3 the 1960s, the Jinan springs not only flowed without fail 1.06 mg/L in 1958 to 43.93 mg/L in 2008, which is very but also had good water quality with low total dissolved close to the upper limit of the Chinese national standards solids (TDS). Corresponding to the intensification of of drinking water (GB5749-2006). Accordingly, the future human activities and groundwater level decrease, the study should concentrate on karst water quality, including conditions of groundwater recharge, runoff and discharge vulnerability and contamination risk mapping (Ravbar and have also been changed significantly. The natural chem- Goldscheider 2007), tracer testing for contaminated ical balance in the groundwater system has been disrupted. recharge simulation (Mahler and Garner 2009), and The groundwater quality is severely threatened by sewage countermeasures simulating for karst groundwater quality draining, garbage deposition, and the use of chemical protection. fertilizer and pesticides in the southern mountainous recharge area. All these drive the groundwater quality towards deterioration (Fig. 5). For instance, the TDS of Sustainable yield development Sustainable yield The concept of sustainable development, which emerged in the early 1980s, centered on the idea of limiting resources use to levels that could be sustained over the long term (Alley and Leake 2004). There are various definitions on sustainable or safe yield of groundwater (Alley et al. 1999; Brown et al. 1999; Kalf and Woolley 2005;Sharp1998; Sophocleous 1997, 2000, 2005). In view of the actual conditions of groundwater recharge, runoff and discharge, together with their long- term behavior in response to exploitation in northern

Fig. 4 Relation among observed a karst groundwater withdrawal, – b annual rainfall, c karst groundwater level and d springs discharge, Fig. 5 Total dissolved solids (TDS) and NO3 concentrations for from 1959 to 2008 Baotu spring water, from 1958 to 2008

Hydrogeology Journal (2011) 19: 851–863 DOI 10.1007/s10040-011-0725-2 中国科技论文在线 http://www.paper.edu.cn

855 China, ‘sustainable groundwater yield’ is here defined as groundwater levels from 1959 to 2008 is determined as groundwater exploitation over a specified timeframe (Fig. 6): without causing harmful environmental, economic, or social consequences. These consequences include: lower Qspring ¼ 4:57 H lowest water level, below the designed level; impact on the ÀÁ normal operation of existing groundwater extraction wells; 107 Coefficient of determination; R2 ¼ 0:803 water-quality deterioration and temperature exceeding allowable limits; and induced environmental harm. Water 4 3 resources cannot be developed without altering the natural where Qspring is spring discharge (10 m /d) and Hlowest is environment and harmful impacts are to be avoided the lowest groundwater level elevation (m asl). (Barlow et al. 2004). It can be calculated from this equation that when the Although many people have expressed concerns karst groundwater level equals the allowable lowest ‘ ’ groundwater level (27.5 m asl), the lowest spring flow about the ambiguity of the term sustainability ,the 3 fact remains that prudent development of a groundwater rate is 187,000 m /d. When the karst groundwater level is basins in today’s world is a complicated undertaking. A lower than 27.5 m, the Baotu and Black-tiger springs will dry up, but the other springs with outflow elevations less key challenge for sustained use of groundwater resour- fl ces is to frame the hydrologic implications of various than 27.5 m will still have some free ow. alternative development strategies in such a way that their long-term implications can be properly evaluated. Each hydrologic system and development situation is Development of regional groundwater model unique and requires an analysis adjusted to the nature of the water issues faced, including the social, eco- Numerical modeling is the preferred method for determin- nomic, and legal constrains that must be taken into ing the basin sustainable yield (Kalf and Woolley 2005), account (Alley and Leake 2004). and it is the best available tool to simulate the impacts of The author believes that the most fundamental indicator proposed groundwater exploitation scenarios (Zhou 2009). for sustainable yield of groundwater, particularly when Thus, several numerical models have been built in the last taking account of environmental issues, is the maximum 20 years for Jinan spring catchment (Wang et al. 2009; allowable water level drawdown. The reason for this is that Wu et al. 2003;Wu2004; Xing et al. 2009; Xu et al. most of the environmental groundwater problems are 2004); however, all of these models are limited to the induced by excessive drawdown of the groundwater level. Jinan spring catchment, and do not apply to the whole These environmental issues include: the drying up of famous Jinan karst aquifer system. Thus, it is necessary to springs, streams and wet lands; intrusion of water with establish a numerical model covering the four catchments undesirable quality into the aquifer; depression cone of in the Jinan karst aquifer system, because the four groundwater level and land subsidence; karst collapse; and catchments have hydraulic connection. groundwater contamination, etc. To be simplistic, the sustainable yield of groundwater is the maximum allowable yield for which the actual drawdown does not exceed the Conceptual model maximum allowable drawdown within a specified time The proposed model covers the whole Jinan karst aquifer frame. Accordingly, the prerequisite to determine the system, including Jinan spring catchment, White spring sustainable yield is to determine the maximum allowable catchment, Changxiao karst water catchment and Dong’er drawdown (Kang 2005). So, the importance of long-term 2 karst water catchment, with a total area of 3,770 km . measurements of groundwater levels should be highlighted. Hydrogeologically, the study area is generalized as a three-layer aquifer system. The first layer is a Quaternary Maximum allowable drawdown determination sand aquifer, with free water surface. The second layer is a The drying up of springs is the biggest environmental issue in Jinan, so that the sustainable groundwater yield should be based both on maintaining the perennial outflow of the springs and on meeting the water supply demand. In view of the critical outflow elevation of the Baotu spring (27.5 m asl), the maximum allowable drawdown is determined as the difference between the actual groundwater level and 27.5 m asl.

Lowest spring discharge calculation Based on the long-term observation of spring discharges and groundwater levels in Jinan spring catchment, the Fig. 6 Correlation between spring ﬂow rates and lowest ground- ﬁtted equation between spring discharges and the lowest water levels in Jinan spring catchment, from 1959 to 2008

Hydrogeology Journal (2011) 19: 851–863 DOI 10.1007/s10040-011-0725-2 中国科技论文在线 http://www.paper.edu.cn

856 Fig. 7 Comparison of calculated and measured groundwater level elevation hydrographs in representative monitoring wells in the calibration period (from October 1, 2005 to September 30, 2006). For locations of monitoring wells, see Fig. 12

Quaternary clay layer (that permits leakage), between the where the main aquifer media are dissolution pores but not first layer and the third layer (which, in turn, is the well- caves and channels. For example, the equivalent porous- developed karst aquifer). The karst aquifer constitutes the media models have been successfully established for most main water-supply source in the Jinan karst aquifer of the karst aquifer systems in northern China. system, and the recharge source of Jinan springs. The use of equivalent porous media models in high- permeability karst aquifers presents some problems Governing equations (Worthington 2009), where the larger channels in aquifers The governing equations for a three-dimensional transient display turbulent flow and which are termed ‘conduits’(- groundwater flow model are extensively documented in White 1988). Nevertheless, these equivalent porous-media many publications (e.g. Harbaugh et al. 2000) and, models could be used to simulate the water balances and therefore, are not repeated in this report. trends of regional groundwater flow in highly karstified aquifers (Dufresne and Drake 1999; Scanlon et al. 2003) Boundary condition As shown in Fig. 1, the southern boundary is the water divides of both surface water and groundwater, which act as no-flow boundaries. The northern boundary is formed by impermeable faults and impermeable igneous rocks except in the northwest section of Jinan City, where there is a lateral outflow boundary. The east boundary is an impermeable fault, sandstone and shale. The west boundary is a lateral inflow boundary. The rivers in the study area are treated as mixed boundaries.

Model construction A regional three-dimensional finite-difference groundwater numerical model has been constructed for the whole Jinan karst aquifer system, based on the hydrogeological investigation, long-term monitoring data of groundwater withdrawals, spring flow rates, groundwater levels, rainfall recharge and surface-water seepage. The US Geo- logical Survey flow code, MODFLOW, was used to Fig. 8 The hydraulic conductivity and specific yield zones for the produce the numerical model. The model consists of 3 first layer, the Quaternary sand aquifer (see Table 1) layers; each one has 254 rows and 170 columns. MOD-

Hydrogeology Journal (2011) 19: 851–863 DOI 10.1007/s10040-011-0725-2 中国科技论文在线 http://www.paper.edu.cn

857 Calibration of the model The purpose of calibration is to establish that the model can reproduce the ﬁeld measured groundwater levels. The calibration period is from October 1, 2005 to September 30, 2006. The model was considered to be a calibrated base model by adjusting the hydraulic parameters of the aquifers until the calculated groundwater levels were reasonably well matched with the observed groundwater levels (Fig. 7). This optimization process yields the best-ﬁt hydraulic parameters, which are shown Figs. 8, 9, 10 and Tables 1, 2, 3.

Verification of the model To check whether the calibrated model has the required predictive power, the calibrated model was applied to another period where a second set of field data are available. The measured data from October 1, 2006 to September 30, 2007 were used to verify the accuracy of the hydraulic parameters optimized from the calibration period. When generally good agreement was obtained — Fig. 9 The hydraulic conductivity for the second layer the between measured and calculated groundwater levels in Quaternary clay layer (that permits leakage; see Table 2) the verification period, the numerical model with optimized hydraulic parameters (including hydraulic conduc- FLOW simulated recharge, evapotranspiration, well with- tivity, specific storage, leakance, precipitation recharge drawals, and surface-water/groundwater interactions using coefficient, evapotranspiration coefficient, etc.) can be hydraulic parameters obtained from hydrogeological anal- used to predict water level response over different future yses conducted throughout the study area. production scenarios (Fig. 11).

Fig. 10 The hydraulic conductivity and speciﬁc storage zones for the third layer—Cambrian and Ordovician karst aquifer (see Table 3)

Hydrogeology Journal (2011) 19: 851–863 DOI 10.1007/s10040-011-0725-2 中国科技论文在线 http://www.paper.edu.cn

858 Table 1 Optimized hydraulic conductivity and specific yield for the being maintained above 27.5 m asl and the spring fi — rst layer the Quaternary sand aquifer discharge not less than 187,000 m3/d. Zone No. Hydraulic conductivity Specific yield The lowest precipitation series in Jinan history— kx, ky, kz (m/d) continuous four dry years and one rainy year— are used 1 22 0.03 to predict water level response. Groundwater levels are 2 28 0.082 estimated for the following pumping scenarios. 3 22 0.051 4 21 0.035 5 23 0.041 6 31.5 0.095 Scenario 1 7 16 0.017 This scenario is to retain the well field locations and their 8 19 0.011 abstraction rates before 2003 (Table 4). The predicted 9 25 0.07 10 26.5 0.09 water level of Baotu spring will be lower than 27.5 m asl, 11 28.5 0.13 and the Baotu and Black-tiger springs will run dry in dry 12 31 0.15 seasons. Therefore, this exploitation scheme is not 13 15 0.08 sustainable because it could not meet the required criteria. 14 29 0.125 15 20 0.092 16 10 0.05 17 24 0.075 Scenario 2 18 22 0.025 This scenario requires that the city does not use the urban 19 26 0.025 well fields near the springs in Jinan urban area—Pulimen, 20 35 0.045 21 45 0.081 Quanchenglu and Jiefangqiao. The predicted water level 22 31 0.083 of Baotu spring will also be lower than 27.5 m asl, and the 23 31 0.07 Baotu and Black-tiger springs will run dry in dry seasons. 24 20 0.01 Therefore, this exploitation scheme is not sustainable because it could not meet the required criteria.

Estimate of sustainable yield Scenario 3 The calibrated model after verification with optimized This scenario requires closure of the urban well fields hydraulic parameters was used to predict water-level (scenario 2) and also closure of the western suburb well response over different pumping scenarios, and to opti- fields in Jinan spring catchment (Qiaozili, Emeishan, mize sustainable yield under the prerequisite of meeting Dayangzhuang and Lashan), together with reduction in water demand while maintaining the perennial outflow of the pumping rates of well fields Lengzhuang and Gucheng the springs, i.e. with the constrains of groundwater level (Table 5). Meanwhile, for the purpose of meeting the drinking-water demand of Jinan citizens, three newly fi — Table 2 Optimized hydraulic conductivity for the second layer— investigated well elds Caolou, Guodian and Zhaoguan the Quaternary clay layer (that permits leakage) (in Changxiao karst water catchment)—should supply groundwater to Jinan City. Zone No. Hydraulic conductivity fi k (m/d) The optimized well eld distribution and their z sustainable yields (scenario 3) are shown in Table 5 – 11e5 and Fig. 12, and the predicted water-level responses of 2 0.00023 3 0.0015 BaotuspringareshowninFig.13. It is obvious that 4 0.001 the water level of Baotu spring will be maintained 5 0.00012 above 27.5 m asl, and the springs will flow perennially. 6 0.00041 The optimized well fields supplying water to Jinan 7 0.0001 – include (6), (7), (8), (11), (12), and (19), with total 85e5 3 9 1.5e–6 sustainable yields of 290,000 m /d, which can meet the 10 0.0015 drinking-water needs of Jinan citizens. 11 0.008 12 0.011 13 0.006 14 0.009 Measures taken towards sustainable use of karst 15 0.035 groundwater 16 0.001 17 0.07 Measures implemented 18 0.12 19 0.00085 20 0.03 Pumping scheme adjustment 21 0.021 Based on the outcomes of the numerical model, the well 22 0.0013 fields of Qiaozili, Emeishan, Dayangzhuang, Lashan, 23 0.001 Pulimen, Quanchenglu and Jiefangqiao in Jianan spring

Hydrogeology Journal (2011) 19: 851–863 DOI 10.1007/s10040-011-0725-2 中国科技论文在线 http://www.paper.edu.cn

859 Table 3 Optimized hydraulic conductivity and specific storage for the third layer—Cambrian and Ordovician karst aquifer Zone No. Hydraulic conductivity (m/d) Specific storage (m–1) Zone No. Hydraulic conductivity (m/d) Specific storage (m–1)

kx ky kz kx ky kz 1101515e–6 45 0.2 0.1 0.02 7e–5 2 3 6 0.6 1.5e–5 46 5 15 0.2 6.3e–5 3 0.125 0.25 0.0125 0.0003 47 0.3 1 0.05 7.5e–5 4 25 30 2.5 4.5e–5 48 0.15 0.2 0.015 7.5e–5 5 0.12 0.17 0.025 6.6e–5 49 0.05 0.1 0.005 7e–5 6 0.3 0.5 0.03 5.25e–5 50 100 100 10 5e–6 7 0.3 0.5 0.03 8.25e–5 51 0.8 8 0.08 3.8e–5 8 0.8 2.2 0.08 0.0002 52 0.5 5 0.03 0.00015 9 5 15 0.5 7.5e–5 53 0.1 0.8 0.03 0.0003 10 4 20 0.4 6.7e–5 54 0.2 1.5 0.02 0.0003 11 10 50 1 3e–5 55 80 160 8 6.6e–7 12 22 45 5 5.6e–5 56 20 15 3 1.8e–6 13 2.25 4.5 1 1.6e–6 57 2 2 0.2 3e–6 14 2 4.2 0.8 1.2e–5 58 1.5 1.5 0.15 1.3e–5 15 3 5 1.5 1.15e–5 59 0.3 0.5 0.03 0.00017 16 6 8 2.5 6.32e–5 60 0.3 0.5 0.03 0.0002 17 10 20 0.5 3e–5 61 0.8 1 0.08 0.00015 18 1 2 0.1 4.5e–5 62 1 5 0.3 8e–6 19 0.05 0.1 0.005 0.0001 63 1 1 0.2 0.0002 20 0.15 0.2 0.02 0.00055 64 15 10 1.5 0.00015 21 0.2 0.3 0.03 0.0004 65 6 4 1.5 2.2e–5 22 0.6 0.8 0.05 6e–5 66 40 110 10 1.8e–5 23 1 1.5 0.1 6e–5 67 50 120 12 2e–5 24 14 30 4 0.0001 68 60 15 3 3e–5 25 15 15 2.5 1.1e–5 69 10 2.2 0.4 8e–6 26 120 120 8 5.2e–6 70 1 5 0.1 8.2e–5 27 30 5 2 3e–6 71 0.4 0.8 0.04 0.0008 28 120 120 3.5 8e–6 72 0.2 0.4 0.02 0.001 29 120 120 3.5 1e–5 73 15 4 0.6 5e–6 30 1 6 0.3 5.5e–5 74 0.3 3 0.05 4e–5 31 0.5 1 0.05 5.3e–5 75 5 15 0.5 3e–5 32 0.25 0.5 0.03 0.0001 76 60 60 12 3e–5 33 65 130 3.8 0.00015 77 0.6 6 0.3 3.5e–6 34 65 130 3.8 5.2e–5 78 25 5 1.5 1.5e–5 35 30 20 1.1 5.2e–5 79 15 4 0.6 5e–6 36 10 10 1 1.3e–5 80 0.3 0.5 0.03 5e–5 37 80 160 4 7e–5 81 2 2 0.2 3e–5 38 80 160 4 0.0002 82 15 15 1.5 3e–5 39 50 130 2.5 7e–6 83 0.25 0.5 0.025 0.0009 40 120 120 5 4.3e–5 84 0.1 0.2 0.01 5e–5 41 90 90 9 1.7e–6 85 0.3 0.6 0.03 0.00088 42 60 30 3 8.5e–5 86 0.2 0.45 0.02 0.00088 43 50 25 2 2e–5 87 0.4 0.8 0.04 0.0001 44 4 2 0.4 3e–5

catchment have been closed, and the abstraction rates of 27.5 masl of Baotu spring, the plan is divided into three Lengzhuang and Gucheng have been reduced. Moreover, warning levels: the three newly investigated well fields in Changxiao karst water catchment—Caolou, Guodian and Zhaoguan, with – Yellow warning: when the groundwater level in Jinan the individual optimized sustainable yields of 50,000, down to 28.15 m asl, the 3rd level of the contingency 50,000 and 100,000 m3/d, respectively—are in construc- plan will be carried out, i.e. preparing for the tion and are scheduled to supply groundwater to Jinan implementation of water-supply-source replacement City in 2012. and artificial recharge. – Orange warning: when the groundwater level in Jinan is down to 28.00 m asl, the 2nd level of the Contingency plan contingency plan will be implemented, i.e. decrease For the objective of maintaining the perennial outflow of groundwater withdrawal by 100,000 m3/d, and increase the springs in Jinan City, a contingency plan of water- reservoir water withdrawal by 100,000 m3/d; using supply-source replacement and artificial recharge has been 300,000 m3/d of reservoir water to recharge the aquifer implemented to control the maximum allowable draw- artificially. down, i.e. the lowest groundwater level (Fig. 14). In view – Red warning: when the groundwater in Jinan down to of the maximum allowable drawdown, outflow elevation 27.60 m asl, the 1st level of the contingency plan will

Hydrogeology Journal (2011) 19: 851–863 DOI 10.1007/s10040-011-0725-2 中国科技论文在线 http://www.paper.edu.cn

860

Fig. 11 Comparison of calculated and measured groundwater level elevation hydrographs in representative monitoring wells during the veriﬁcation period (from October 1, 2006 to September 30, 2007)

be carried out, i.e. decrease groundwater withdrawal by Up to now, Jinan municipal government has built two 130,000 m3/d, and increase reservoir water withdrawal reservoirs for storing the Yellow River water: one is by 130,000 m3/d; using 400,000 m3/d of reservoir Queshan Reservoir with a capacity of 46 million m3, and water to recharge aquifer artiﬁcially. the other is Yuqinghu Reservoir with a capacity of 48.5 million m3. It is obvious that diverting water from the Yellow River to Jinan would be a signiﬁcant measure. However, the Yellow River water contains too much sediment, and the ecological environment will be More key steps to move towards sustainable impacted when large quantities of the Yellow River water use of karst groundwater are diverted and utilized for a long term. More impor- tantly, the quality of Yellow River water is not good Water quality-divided water supply enough for drinking due to the large amounts of drainage The citizens in Jinan put a great premium on water along its upper reaches; thus, drinking water for Jinan quality. The groundwater and spring water with high citizens cannot be based on excessive diversion of water quality should be used for drinking water, while surface from the Yellow River. water, especially the Yellow River water with low A large amount of domestic and industrial sewage is quality should be used for industrial, agricultural and poured into ditches and rivers in Jinan, which has ecological purposes. seriously impacted the environment and sanitation. Thus,

Table 4 Well field locations and their abstraction rates (×104 m3/d) before 2003. AR abstraction rate Dong’er karst water catchment Changxiao karst water catchment Jinan spring catchment White spring catchment Well fielda AR Well field AR Well field AR Well field AR Dong’er (1) 0.8 Xiaoli (5) 3.5 Qiaozili (10) 8.16 SujiaZhangma (20) 1.7 Xiamatou (2) 4.9 Caolou (6) 5.0 Lengzhuang (11) 4.32 Zhongli (21) 2.0 Qianzhai (3) 1.9 Changxiao (9) 1.6 Gucheng (12) 6.72 Peijiaying (22) 1.5 Pingyin (4) 0.8 Emeishan (13) 4 Wujia (23) 4.0 Dayangzhuang (14) 4 Huangtuya (24) 3.5 Lashan (15) 5 Pulimen (16) 1.5 Quanchenglu (17) 2 Jiefangqiao (18) 6.5 East suburb (19) 5.0 Subtotal 8.4 Subtotal 5.1 Subtotal 47.2 Subtotal 12.7 a Locations of well fields are shown in Figs. 1 and 12. The locations of well fields and their abstraction rates are determined by detailed hydrogeological survey for each catchment

Hydrogeology Journal (2011) 19: 851–863 DOI 10.1007/s10040-011-0725-2 中国科技论文在线 http://www.paper.edu.cn

861 Table 5 Optimized well field schemes and their sustainable yields (×104 m3/d). SY sustainable yield Dong’er karst water catchment Changxiao karst water Jinan spring catchment White spring catchment catchment Well fielda SY Well field SY Well field SY Well field SY Dong’er(1) 0.8 Xiaoli(5) 3.5 Qiaozili(10) 0 SujiaZhangma(20) 1.7 Xiamatou(2) 4.9 Caolou(6) 5.0 Lengzhuang(11) 1.0 Zhongli(21) 2.0 Qianzhai(3) 1.9 Guodian(7) 5.0 Gucheng(12) 3.0 Peijiaying(22) 1.5 Pingyin(4) 0.8 Zhaoguan(8) 10.0 Emeishan(13) 0 Wujia(23) 4.0 Changxiao(9) 1.6 Dayangzhuang(14) 0 Huangtuya(24) 3.5 Lashan(15) 0 Pulimen(16) 0 Quanchenglu(17) 0 Jiefangqiao(18) 0 East suburb(19) 5.0 Subtotal 8.4 Subtotal 25.1 Subtotal 9.0 Subtotal 12.7 Self-supplied wells 2.4 Self-supplied wells 1.5 Self-supplied wells 5.8 Self-supplied wells 5.3 Mine drainage —— Mine drainage —— Mine drainage —— Mine drainage 7.5 Agriculture exploitation 6.3 Agriculture exploitation 7.1 Agriculture exploitation 10.0 Agriculture exploitation 5.1 Total 17.1 Total 33.7 Total 24.8 Total 30.6 Sum of the sustainable yield of entire Jinan karst aquifer system: 106.2×104 m3/d The well fields supplying water to Jinan include (6), (7), (8), (11), (12), and (19), with total sustainable yields of 29×104 m3/d a Location of the well fields are shown in Figs. 1 and 12. The locations of well fields are determined by detailed hydrogeological survey for each catchment, and their sustainable yields are determined by numerical model optimization with the principle of maintaining water level above 27.5 m asl

Fig. 12 Optimized well field schemes and their sustainable yields. 1 permeable fault, 2 low permeability fault, 3 impermeable fault, 4 impermeable igneous dike, 5 surface and groundwater divide, 6 no-flow boundary, 7 lateral inflow boundary, 8 lateral outflow boundary, 9 streamflow seepage section, 10 local well field, well field number/sustainable yield (×104 m3/d), 11 well field for Jinan City, 12 closed well field, 13 karst springs, 14 karst groundwater monitoring well, 15 monitoring well for Quaternary sand aquifer, 16 urban area of Jinan City

Hydrogeology Journal (2011) 19: 851–863 DOI 10.1007/s10040-011-0725-2 中国科技论文在线 http://www.paper.edu.cn

862 northern China. Karst groundwater level and quality, together with spring flow rates, have been declining in most of the famous spring catchments since the 1980s and, as such, are the biggest eco-environmental issue in northern China. Sustainable yield is defined as groundwater exploitation over a specified time frame without causing harmful environmental, economic, or social consequences, including decrease in water level below the designed level, impact on existing groundwater extraction wells, water Fig. 13 Predicted water level response for optimized well field quality deterioration, water temperature exceeding allow- schemes and their sustainable yields at Baotu spring (scenario 3) able limits, and induced environmental harm. Sustainable groundwater yield determination should be based on the long-term monitoring data of rainfall, groundwater levels fl the sewage should be treated and reused as water for and withdrawals, spring ow rates and groundwater quality, with the prerequisites of maintaining the perennial industrial, agriculture and ecological purposes. The reus- fl able amount of treated sewage is estimated to be out ow of the springs and meeting water supply demand. approximately 280,000–400,000 m3/d in Jinan. The most fundamental indicator for sustainable yield of In view of the aforementioned, the authors suggest groundwater is maximum allowable water level draw- implementing quality-divided water supply, i.e. supply down. The sustainable yield of groundwater is the high-quality groundwater for drinking purposes and use maximum allowable yield when the actual drawdown the surface water, including Yellow River water and does not exceed the maximum allowable drawdown treated sewage, for industrial, agricultural and ecological within a given time frame. purposes–watering trees, grass, flowers, and washing Numerical modeling is the preferred method for roads, etc. calculating karst aquifer sustainable yield, which is best determined in the context of entire karst aquifer systems with clear hydraulic boundaries. The first regional numerical model has been constructed to optimize well- Drinking spring waters field schemes and their sustainable yields in Jinan spring After all the spring conservation measures have been catchment and its three adjacent karst groundwater catch- put into practice and the springs continue to spout out ments. A total of 24 well fields and their sustainable yields perennially, it would be a waste to let clean spring fl have been optimized in Jinan karst aquifer system, with waters simply ow away. Therefore, it would be the aim of meeting water-supply demand and maintaining advisable to drink the spring waters after the tourists the perennial outflow of the springs. Six well fields are have enjoyed seeing them. That is to say, at a point optimized to supply water to Jinan, with total sustainable beyond the tourist locations, the spring waters can be yields of 290,000 m3/d, which can meet the drinking need collected, treated and channeled into the water-supply of Jinan citizens. pipeline for Jinan citizens to drink. The available spring 3 The example of water-supply management schemes waters are estimated to be 100,000 m /d. Some water from Jinan illustrates that both the objective of water would be put into the water supply and the rest would fl fl supply and perennial out ow of the springs can be still ow into the Daming Lake and Xiaoqing River to achieved based on long-term observation data, detailed realize their ecological value. numerical modeling and science-based management. In the future, more emphasis should be focused on protection of the karst groundwater quality. Karst groundwater quality protection As mentioned in the preceding, although the groundwater levels and spring discharges have been rehabilitated since September 6, 2003, the water quality still has a trend of deterioration. Therefore, more investigations, research and management strategies should be highlighted with respect to water-quality protection.

Conclusions

The key ﬁndings from this study can be summarized as follows. Groundwater in karst aquifers in the region is the biggest water-supply source, and karst springs provide one Fig. 14 Critical elevations in the water-supply management plan of the most attractive types of scenery for tourists in with respect of perennial outﬂow of the springs in Jinan City

Hydrogeology Journal (2011) 19: 851–863 DOI 10.1007/s10040-011-0725-2 中国科技论文在线 http://www.paper.edu.cn

863 Acknowledgements This study was supported in part by the 973 Qian JZ, Zhan HB, Wu YF, Li FL, Wang JQ (2006) Fractured-karst Program (2010CB428802) and the National Natural Science spring-flow protections: a case study in Jinan, China. Hydrogeol Foundation of China (40772155). The authors also wish to express J 14:1192–1205 heartfelt thanks to Z. Sheng, V. Post, P. Renard, S. Schemann, N. Ravbar N, Goldscheider N (2007) Proposed methodology of Goldscheider, J. Meiman and two anonymous reviewers for their vulnerability and contamination risk mapping for the protec- constructive comments and suggestions for improvement of the tion of karst aquifers in Slovenia. Acta Carsologica 36 manuscript. (3):397–411 Scanlon BR, Mace RE, Barrett ME, Smith B (2003) Can we simulate regional groundwater flow in a karst system using equivalent porous media models? Case study, Barton Springs References Edwards aquifer, USA. 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Hydrogeology Journal (2011) 19: 851–863 DOI 10.1007/s10040-011-0725-2