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1、,Changes in groundwater induced by water diversion in the Lower Tarim River,Xinjiang Uygur, NW China: Evidence from environmental isotopes and water chemistry（由引水调度引起的塔里木河下游地下水变化的研究, 中国西北新疆维吾尔自治区 :基于环境同位素和水化学）,汇报人：导 师： 专 业：,Literatures Review,2,Literatures Source,Article structure,1、Introduction 2、B
2、ackground,1、Sampling 2、Analyses,1、Results and Discussion 2、Conclusions3、references,Summary,Contents,Introduction and Background,Sampling and Analyses,Results and Discussion,Conclusions,5,1. Summary,1、提出问题:The Lower Tarim River in NW China is under severe ecosystem degradation due to stopped stream f
3、low and diminished groundwater recharge. Since year 2000, eight water diversions from the upper streamand from the neighboring KaiduKongque River have been implemented to alleviate the ecosystem disaster.中国西北部塔里木河下游面临严重生态退化是由于河流断流和地下水补给减少造成的。自2000年以来, 通过从邻近的开都和孔雀河等河流上游的八次引水调度已经缓解塔里木河生态环境问题。,6,1. Sum
4、mary,2、研究方法:we sampled the riparian groundwater system in 2007 and 2008 along the 350 km-long river channel through the 40 monitoring wells situated along nine transects perpendicular to the river and three soil profiles. Measurements on the samples have included environmental isotopes (18O, H, H) a
5、nd water chemistry.我们沿河岸地下水系统在2007年和2008年沿着350公里河道,通过40个坐落在河流附近的监测井进行采样。测量样品项目包括环境同位素(18O, H, H)和水化学。,7,1. Summary,3、研究结果:Remarkable changes have been induced by the water diversions as follows：(1) The observed response of riparian groundwater system includes general decrease in total dissolved soli
6、d (TDS) and rise of water table. Greater rise of water table occurs near the river bank.沿河岸地下水系统观察结果包括:总溶解固体(TDS)减少和水位上升。更大的地下水位上升发生在河岸附近。(2) Tritium data show that the extent of modern recharge (since1960s), including that from the diverted water, is limited to 600m from the riverbank at the upper
7、segments and 200 m at the lower ones.氚数据显示,现代水补给范围(since1960s),包括从转移水,仅限于上游河岸600米内部分和下游200米内。,8,1. Summary,(3) Stable isotopes show that groundwaters are enriched in heavy isotopes and are plotted in parallel to the meteoric water line, attributed to evaporation during recharge.稳定同位素表明,地区地下水重同位素丰富,并
8、与大气降水线平行,归因于蒸发。(4) Groundwater is generally of NaMgClSO4 type and is formed by dissolution of minerals. The salinity of groundwater is mainly affected by that of the diverted water and of the local antecedent groundwater, salts in the unsaturated zone, evapotranspiration during recharge.地下水一般由Na-Mg-
9、Cl-SO4类型和溶解的矿物质组成。地下水盐度主要是受转移水和当地前期地下水,在非饱和区的盐度,蒸散发影响。,9,1. Summary,(5) As the zone of smaller groundwater depth (less than 5 m) suitable for the most existing Populus euphratica and Tamarix ramosissima, the main species targeted by the rescue effort.正如较小的一部分区域地下水深度(小于5米)适用于大多数现有胡杨和柽柳,它们是保护的主要目标。,10
10、,2、Introduction and Background,11,2、Introduction and Background,Introduction: Under the dual impacts of anthropogenic activities and climate change, a common scenario in arid and semiarid catchments, particularly in the lower reaches of them, is severe ecological degradation, such as death of vegeta
11、tion, intensified groundwater salinization, soil salinization and desertification, etc.介绍：人为活动和气候变化的双重影响下,一个常见的场景在干旱和半干旱区,特别是在下游,是严重的生态退化,如植被死亡,加剧地下水盐渍化、土壤盐渍化、沙漠化等。,12,Background:1、General settingThe Tarim River Basin is located in the south of Xinjiang, NW China. It has an area of 1.04x106 km2 and
12、is flanked by the Tianshan Mountains to the north and by the Kunlun Mountains to the south (Fig. 1).2、HydrogeologyThe occurrence of groundwater is similar between the Southern Tianshan watershed and Northern Kunlun watershed. The sink of the two groundwaters systems is centered in the south of the T
13、arim River. The diluvial aquifer from the northern mountains is composed of sand deposits some 100300 m thick forming an unconfined aquifer in which the present day water table ranges between 20 m and 200 m below surface (Fig. 2).,2、Introduction and Background,13,Fig.1 Sketch map of the Tarim River
14、Basin 1 Proterozoic; 2 Paleozoic; 3 Mesozoic; 4 tertiary; 5 granite; 6 quaternary; 7 river;8 surface water in the Upper Tarim River and the Aksu River; 9 regional groundwater flow.,14,Fig.2 Hydrogeological cross section in the Middle Tarim River, see Fig. 1 for the location,15,Background:3、ClimateTh
15、e Lower Tarim River is dominated by typical continental temperate arid climate.4、Ecosystem degradationUnder the impact of anthropogenic activities, runoff of three source streams (Aksu River, Hotan River and Yarkant River) to the Tarim River has decreased gradually in the last 50 years due to extens
16、ive oasis agriculture with increasing water utilization. With gradually decreased inflow to the Tarim River, proportion of water consumption in the upper and middle reaches increased gradually from 1970s to 1990s, while flow to the lower reaches reduced significantly (Table 1). The groundwater depth
17、 has increased to 812 m.,2、Introduction and Background,16,Table 1 Runoff changes at each station on the Tarim River (108 m3).,5、Water diversionTo protect the Green Corridor, the riparian vegetation restoration is imperative. Taking advantage of the wet period of the Kaidu River, the KuTa Channel (Yu
18、li to Qiala, Fig. 3) was constructed for diverting water from Kongque River to the Lower Tarim River.,17,Fig. 3 Sampling locations,18,Table 2 Statistics of eight water diversions,19,3.Sampling and Analyses,采样点布置及前期准备,稳定同位素测定方法及标准,18O, H, H 稳定同位素测量,八次引水后塔里木河流域下游地下水的物理化学变化规律及特征,水化学测定方法及标准,采样方法及具体实施步骤,
19、水化学离子色谱法测定,地下水位、位置,水温、pH值、TDS和电导率测定,20,Sampling：Groundwater samples were collected from boreholes at varying distances from the riverbed along nine groundwater monitoring transects, namely: Akdun (A), Yahopumarhan (B), Yengsu (C), Abudali (D), Karday (E), Tugmailai (F), Aragan (G), Yikanbujima(H), a
20、nd Kargan (I) (Fig. 3), respectively.Method：The soil samples were obtained using a hollow-stem hand auger with interchangeable 1.5 m aluminum rod from three profiles(5.87.7 m depth, SP1 and SP2 in section C and SP4 in section G, Figs. 3 and 4). Bulk soil samples of 400 g were collected at intervals
21、of 0.25 m. Samples were homogenized over the sampled interval and immediately sealed in polyethylene bags.,3.Sampling and Analyses,21,Method：Gravimetric moisture content was determined by drying a minimum of 80 g of soil at 110 C for 12 h. To determine chloride content, double deionisedwater (40mL)
22、was added to the oven-dried soil sample (40 g) . Samples were agitated on a reciprocal shaker table for 8 h. The supernatant was filtered through 0.45 lm filters. Chloride was then analyzed by ion chromatography.The chloride concentration of the soil solution is then calculated by dividing the measu
23、red concentration by gravimetric moisture content and by multiplying the mass ratio of solution to oven dry soil.,3.Sampling and Analyses,22,Table3 Site measurements and isotopic composition of surface waters.,Analyses：,23,Table 4 Chemical composition of the surface water and groundwater sections (m
24、g/L).,24,4.Results and discussion,Tritium and stable isotopeanalysis,Hydrochemical characteristics,Water table andTDS change,25,Fig.4 The precipitation tritium input from 1952 to 2007 and the decayed value for 2007.,The results show a tritium content decrease from 2586 TU (1963) to 2030 TU(2007). Us
25、ing an exponential decay equation, the decayed tritium contents for 2007 in precipitation, which would represent tritium concentrations in groundwater that had infiltrated between 1952 and 2007, ranges from 50 TU to 225 TU from 1962 to 1966, and ranges from 10 to 35 TU from 1957 to 2007 (Fig. 4). Th
26、erefore, groundwater with tritium content less than 10 TU is regarded as pre-modern water, or at least most part is pre-modern water when mixing with modern water is considered.,Tritium analysis,26,Fig. 5. Post map of Tritium content (TU) for groundwaters from the Lower Tarim River with a solid line
27、 showing the scope of modern recharge.,Fig. 5 shows the tritium contents in the riparian groundwater from the Lower Tarim River. The solid line in the figure is the boundary between groundwater that is recharged by modern water (19.146.3 TU) and that by pre-modern water (less than 4.1 TU).,Tritium a
28、nalysis,27,Fig. 6 The stable isotopes in the water reservoirs in the lower reaches are enriched in heavy isotopes due to evaporation: the Qiala Water Reservoir has the 18O of 4.6 and the Daxihaizi Water Reservoir has the 18O of 3.6 due to extended evaporation. The residual waters collected from the
29、river bed at the Lower Tarim River show 18O from 2.0 to 3.5 and 2H from 17.1 to 5.8, as a consequence of intensive evaporation.,Stable isotope analysis in surface waters,Fig. 6 Stable isotopic composition for surface waters and groundwaters,28,The modern and pre-modern groundwaters exhibit a similar
30、 behavior to fall in slight parallel to the meteoric water line, but enriched relative to the recharging river water. The phenomenon is commonly observed in dry climate and attributed to evaporation during river recharge to the riparian groundwater system in a rather uniform manner.,Fig. 7 Stable is
31、otopic composition for surface waters and groundwaters,Stable isotope analysis in groundwaters,Fig. 6 Stable isotopic composition for surface waters and groundwaters,29,iper三线图以三组生要的阳离子(Ca,Mg,Na和K)和阴离子(C1,S04 ,HCO3和CO3)的每升毫克当量的百分数来表示。每图包括三个部分，在左下方和右下方分别为二张等腰三角形域，中间上方夹着一张菱形域(图1)，每域的边长均按100等分读数。在左下方的等
32、腰三角形域，三个主要阳离子反应值的百分数按三线座标用一个单点表示。在右下方的等腰三角形域，阴离子亦用同样方法表示。这样，图上所作的二单点表示了地下水中某些溶解物质的相对浓度。然后通过这二个单点平行三角形外边作射线，于菱形域内相交一点。这一点通常可以说明地下水总的化学性质并用阴阳离子对表示地下水的相对成分。,Hydrochemical characteristics,30,The water type conversion from CaMgHCO3SO4 with low TDS in source stream to NaMgClSO4 with high TDS in the lower
33、reaches of the basin and fluoride concentration evolution show the one of the most typical water evolution of arid water system, going along with evaporation and dissolution.,Fig. 7 Piper trigraph for surface waters（a） and groundwaters（b）,Hydrochemical characteristics,（a）,（b）,31,TDS in the groundwat
34、er within 600 m to the river bed ranges from 0.8 g/L (E3) to 3.7 g/L. (C1) with an average of 1.6 g/L, except for section I, which is located in the terminal of the water flow and salt with very high TDS. Beyond the distance, TDS in groundwater is also high except for sample G5.,Fig. 8 TDS distribut
35、ion (g/L) in the Lower Tarim River,Hydrochemical characteristics,32,The strong correlations between Na and Cl (r = 1.00) and an approximately 1:1 trend (Fig. 9 a) suggest Na and Cl mainly comes from halite. Ca and Mg have strong correlations with SO4 (0.97,1.00) and relatively weak with HCO3 (0.77,
36、0.84). The equivalent ratios for (Ca + Mg) against HCO3 are more than 1 (Fig. 9b), suggesting that, besides dissolution of carbonates, dissolution of sulfate (CaXMg (1-X) SO4) contributes the additional (Ca + Mg) when concentration of (Ca + Mg) increases with that of SO4.Such a pattern indicates tha
37、t saturation of a relevant salt controls the concentration of the respective ions.,Fig. 9 Ionic ratio for the groundwaters.,Groundwater saliization mechanism,33,Fig. 10 shows the chloride concentration in dry soil,appearing to be highly variable. The SP1 has less chloride in the whole profile, rangi
38、ng from 24 to 862 mg/kg, compared to the SP2 and SP4, which show maximum chloride concentration of 4416 mg/kg (2.052.30 m depth) and 11,925 mg/kg (0.351.00 m depth), respectively.,Fig. 10 Moisture and chloride content for the three soil profiles,34,Fig.11 Water tables and TDS changes at certain grou
39、ndwater monitoring section in the Lower Tarim River under water diversions,35,The variations of water tables have the following characteristics:before the water diversion, the water tables were similar at each section and the flow field was stable; after the water diversion, the water tables rose to
40、 different extent. The closer to the river bed, the faster the groundwater table rose. The unstable infiltration takes place at river bed, as a result, the high groundwater hydraulic head moves towards both river-sides.Changes of TDS in groundwaters show the following characteristics:TDS in groundwa
41、ter from sections B and C has increased after the first diversion; after the second and third water diversions,TDS in groundwaters from all sections has decreased. The TDS for samples C7 (w8, 850 m away from the river) tempestuously increased from 4.57 g/L to 22.37 g/L after the fourth water diversi
42、on, to 15.32 g/L in August, 2007.,Water table and TDS change,36,Fig. 12 The variation of groundwater table (m) before water diversion and after the eighth water diversion (a) and groundwater depth (m) in the Lower Tarim River (August,2007).,The variation of groundwater table between that before wate
43、r diversion (05/2000) and after the eighth the water diversion (08/ 2007) and the groundwater depth (08/2007) are plotted in Fig. 15 using the Inverse Distance Weighting Method.,4.Results and discussion,37,The scopes of water tables rise are wider than modern recharge limit, due to water head pressu
44、re transfer. Since the vegetation coverage exhibits a continued declining trend with dropping water table and modern water recharge scope in the area, Niu and Li (2008) concluded there was 7345 hm2 increased vegetation area from 2000 to 2006 after water diversion based on satellite images of the mai
45、n area where vegetation distributed in the Lower Tarim River. However, the groundwater depth suitable for the growth of P. euphratica is less than 5 m in the Lower Tarim River, If the target of the ecological restoration is to maintain the vegetation dominated by P. euphratica, the optimal groundwat
46、er depth would be less than 5 m. However, the territory with the suitable groundwater depth is narrow, within 200 m from the river bed and becomes even narrower towards downstream,4.Results and discussion,38,1、The isotopic composition of shallow groundwater forms a trend line that is almost in paral
47、lel to the GMWL but is enriched in heavy isotopes compared with the recharging river water. This can be attributed to evaporation during the river recharge to the riparian groundwater system in a rather uniform manner.浅层地下水的同位素组成,形成一个趋势线,几乎是平行于GMWL，与河水相比重同位素值更大。归因于河水补给地下水系统过程间的蒸发作用。2、Tritium data sh
48、ow that the extent of modern recharge (since 1960) is limited to 600200 m from the river bank with a descending trend towards downstream.氚数据显示,现代(1960年以来)补给的程度是有限的,距离河岸600 - 200米范围内，往下游呈下降趋势3、Water table has risen after the eight water diversions except for three unusual boreholes where perched wate
49、r probably exists. The scope with more than 1 m of water table rise is from 700 m from the riverbank in the upper segments to 300 m in the lower segments.水位已经上升在八次引水之后,除了三个不同寻常的水井滞水现象可能存在。超过1米的水位上升的范围为从700米的上游河岸到300米的下游部分。,5. Conclusions,39,4、Groundwater salinity at certain locations is mainly affec
50、ted by the salinity of the diverted river water and of the local antecedent groundwater, salts in the unsaturated zone, evapotranspiration during the diverted water relocation. The TDS of groundwater has generally decreased after the water diversions.地下水矿化度在某些位置主要受转移水和当地前期的地下水的盐度,在非饱和区的盐度, 在转移水的过程中蒸
