Shallow groundwater dynamics and its driving forces in ... · Shallow groundwater dynamics and its...

HYDROLOGICAL PROCESSESHydrol. Process. 28, 1539–1553 (2014)Published online 1 February 2013 in Wiley Online Library(wileyonlinelibrary.com) DOI: 10.1002/hyp.9682

Shallow groundwater dynamics and its driving forces inextremely arid areas: a case study of the lower Heihe River in

northwestern China

Ping Wang,1 Jingjie Yu,1* Sergey P. Pozdniakov,2 Sergey O. Grinevsky2 and Changming Liu1,31 Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese

Academy of Sciences, 11A Datun Road, Chaoyang District, Beijing 100101, China2 Department of hydrogeology, Moscow State University, GSP-1, Leninskie Gory, Moscow 119899, Russia

3 College of Resources and Environment, Beijing Normal University, Beijing 100875, China

*CRelNaRoE-m

Co

Abstract:

Shallow groundwater is an important source of water for themaintenance and restoration of ecosystems in arid environments, whichnecessitates a deeper understanding of its complex spatial and temporal dynamics driven by hydrological processes. This studyexplores the dominant hydrological processes that control the shallow groundwater dynamics in the Gobi Desert-riparian-oasissystem of the lower Heihe River, a typical arid inland river basin located in northwestern China. The groundwater level andtemperature weremonitored in 14 shallowwells at 30-min intervals during the 2010–2012 period. After combining this informationwith meteorological and hydrological data, a comprehensive analysis was conducted to understand the dynamic behaviour of theshallow groundwater system and to determine the dominant factors that control the groundwater flow processes. The results of thestudy indicate notably large temporal and spatial variations in both the groundwater level and temperature. Noticeable fluctuationsin the groundwater level (0.5–1 m) and temperature (4–8 �C) were observed in the riparian zone, evidencing a clear river influence.In comparison, the groundwater fluctuations in the Gobi Desert were more stable (the annual variations of the water table were lessthan 0.5 m, and the water temperature varied by no more than 2 �C). Strong variations in the groundwater table (1.5–5.0 m/year)and temperature (1.5–6.5 �C), mainly caused by surface flood irrigation and groundwater pumping, were observed in the oasisarea. The investigated sites were categorized into three types that reflect the dominant hydrological processes: (1) the riparianzone, dominated by riverbank filtration and groundwater evapotranspiration; (2) the Gobi Desert area, controlled by groundwaterevaporation and lateral recharge; and (3) the oasis area, dominated by groundwater evapotranspiration as well as surface–groundwater interactions caused by human activities. Copyright © 2012 John Wiley & Sons, Ltd.

KEY WORDS groundwater dynamics; riverbank filtration; evapotranspiration; arid region; Heihe River

Received 6 June 2012; Accepted 11 December 2012

INTRODUCTION

Over the past several decades, land desertification andrehabilitation in arid and semiarid regions, whichrepresent approximately 30% of the global terrestrialsurface area (Dregne, 1991), have been influencedprimarily by climate variation and human activities(Goudie and Middleton, 1992; Wang et al., 2008; Hircheet al., 2011; Mertz et al., 2012). In these regions,groundwater is an essential water resource for environ-mental protection (Naumburg et al., 2005; Newman et al.,2006), and the groundwater-dependent ecosystems aremainly distributed in areas where water can be extractedby natural plants from aquifers or the capillary fringeabove the water table (Lite and Stromberg, 2005; Orellanaet al., 2012). Therefore, the groundwater table depth isone of the most important parameters in the study of arid

orrespondence to: Jingjie Yu, Key Laboratory of Water Cycle andated Land Surface Processes, Institute of Geographic Sciences andtural Resources Research, Chinese Academy of Sciences, 11A Datunad, Chaoyang District, Beijing 100101, China.ail: [email protected]

pyright © 2012 John Wiley & Sons, Ltd.

ecosystems (Le Maitre et al., 1999; Naumburg et al.,2005; Soylu et al., 2011) and is often used as animportant indicator of land desertification and soilsalinization in arid and semiarid regions (Cui and Shao,2005). In the last few decades, declines in the regionalgroundwater level have threatened many riparian ecosys-tems in the arid and semiarid regions of the world(Stromberg et al., 1996; Amlin and Rood, 2003).Therefore, an understanding of the hydrological processesthat control regional groundwater dynamics is crucial forthe sustainable improvement of current ecosystems inthese regions.Changes in the groundwater table can be caused by

many factors. Certain changes are caused by humanactivities, and others occur because of natural phenom-ena. Generally, the groundwater recharge from rainfall orsurface water and groundwater flow into the basin causethe water table to rise (Healy and Cook, 2002); however,the diurnal fluctuations of the groundwater level aremainly caused by evapotranspiration (Lautz, 2008;Martinetet al., 2009; Gribovszki et al., 2010). Other causes ofgroundwater fluctuations that are not related to rechargeand discharge include earth tides (Bredehoeft 1967; Cutillo

1540 P. WANG ET AL.

and Bredehoeft, 2011), ocean tides (Townley, 1995) andatmospheric tides (Palumbo, 1998). The Lisse effect and theWieringermeer effect are other types of rapid fluctuations ofthe groundwater table that are not caused by groundwaterrecharge or discharge (Heliotis and DeWitt, 1987). In aridregions with scarce rainfall, the groundwater dynamicsdepend mainly on the groundwater and surface waterinteraction processes (Besbes et al., 1978) in addition to therate of groundwater evapotranspiration (Abdalla, 2008).Groundwater level measurement is a direct instrument

for investigation of the dynamic behaviour of ground-water systems. In addition to the groundwater level, watertemperature measurements are another typical parameterused as a tracer in the study of hydrological processes(Duque et al., 2010). The water temperature is influencedby numerous natural phenomena, including solar radia-tion, air temperature, precipitation, surface water inflow,and groundwater exchange (Constantz, 1998; Constantz,2008). Recently, many studies and applications of thermalmeasurements (Anderson, 2005) have been conducted toanalyse the flow patterns in groundwater systems(Conant, 2004), the interchanges with surface water(Anibas et al., 2009), and the recharge and discharge rates(Taniguchi, 1994; Ferguson et al., 2003).This paper examines the dynamics of the shallow

groundwater systems of an extremely arid area, the lowerHeihe River in northwestern China, and the processes thatcontrol these dynamics. In the last 50 years, the regionalgroundwater level declines in the lower Heihe River haveled to an environmental deterioration of the oasisecosystem, which plays a protective role in blockingsandstorms in northwestern China (Guo et al., 2009).Attempts to explain the pattern of water table variationand forecast its future tendencies under various popula-tion pressures and climate change scenarios represent aresearch focus related to declining regional groundwaterlevels. However, although the importance of water tablefluctuation as a mechanism that affects desertification andrehabilitation is well recognized, water table dynamicsand the associated hydrological processes have not yetbeen studied extensively. The main objectives of thispaper are to determine the typical patterns of thegroundwater level and temperature variations and todelineate the main factors that influence each pattern ofgroundwater dynamics in this ecologically sensitive area.This study will provide important insight into thehydrological processes that control the groundwaterdynamics in the arid region of northwestern China, alocation where monitoring data are limited.

STUDY AREA

The study area is located in the lower reaches of the HeiheRiver Basin, the second largest inland river in north-western China, extending between 41�000 and 42�400 Nlatitude and between 100�100 and 101�200 E longitude(Figure 1A). This region is characterized by a continentalclimate that is extremely hot in the summer and severelycold in the winter. According to observational data from

Copyright © 2012 John Wiley & Sons, Ltd.

1957 to 2005 gathered at the Ejina weather station(Figure 1A), the mean annual precipitation was only42 mm, and the mean annual pan evaporation (20 cm indiameter and 11 cm in depth) was 3755 mm (Xi et al.,2010b). The topography of the study area inclines fromthe southwest to the northeast, with an average slope of1–3%, and the surface elevation varies from 1050 m to820 m above sea level.The Heihe River, which originates from rainfall and

snow melt in the Qilian Mountains (Figure 1A), branchesinto two broad rivers at Langxinshan: the Donghe Riverand the Xihe River, which ultimately flow into the EastJuyan Lake and the West Juyan Lake (Figure 1A). Thetotal length of these two branches is approximately 240 km.During the last 10 years, many hydraulic structures havebeen built in the study area, including several main canalsfor water conveyance, hundreds of lateral channels extend-ing from the main canals for irrigation and several diversionprojects (Zhang et al., 2011). Most of the main canals werebuilt on natural river courses, and a few are independent ofnatural rivers, such as the Dongganqu canal (Figure 1A).The streamflow entering the study area was first divided intothe Donghe River, the Dongganqu canal and the Xihe Riverthrough the LangxinshanDiversion Structure (Figure 2A); itsubsequently runs into the lower reaches of the DongheRiver via integrated natural–artificial water channels (Zhanget al., 2011).The study area represents a regional geo-tectonic basin,

the bedrock of which is composed of Late Jurassic (J3)formations. The basin is filled with unconsolidatedQuaternary (Q) sediments with a depth of several hundredmetres (Figure 1B) that form an independent aquifersystem (Xie, 1980; Wu et al., 2002). The regionalQuaternary aquifers vary from a zone of unconfinedgravel and pebbles to a multilayered zone that consists ofsand and silt (Xie, 1980; Wen et al., 2005). Thedepositional construction and a variety of lithofaciescontrol the distribution characteristics of the aquifersystems. From the southwest to the northeast of the studyarea, the lithologic features of the aquifer systemgradually vary from gravel to fine sand (Wen et al.,2005; Xi et al., 2010a).The Heihe River is the main recharge source for the

groundwater system. On the basis of the regional water-budget analysis, approximately 66% of the groundwaterrecharge in this area occurs through vertical percolationfrom the Heihe River (Wu et al., 2002). In general, thephreatic aquifer is recharged by river water in thesouthwestern portion of the study area, and the ground-water flows towards the area of the East and West JuyanLakes, where it is currently lost to evaporation (Xie,1980; Wen et al., 2005; Si et al., 2009). Furthermore,groundwater from adjacent basins is another importantrecharge source for the shallow aquifers in the study area(Wu et al., 2003). Additionally, according to hydro-chemical and isotopic investigations, the localizedrecharge of shallow groundwater may occur from theleakage of the underlying confined aquifer (Zhu et al.,2004; Zhang et al., 2005; Wang et al., 2013).

Hydrol. Process. 28, 1539–1553 (2014)

Figure 1. Location of the study area (1A) and geological cross section (1B) (modified from Xi et al., 2010a)

Figure 2. Photographs of (A) Langxinshan Diversion Structure, (B) groundwater pumping, (C) flood irrigation, (D) typical Gobi Desert, (E) DongheRiver and riparian zone and (F) part of the Juyan Oasis

1541HYDROLOGICAL PROCESSES CONTROLLING GROUNDWATER DYNAMICS IN ARID AREA

By the 1960s, the surface water was abundant in thestudy area (Wu et al., 2002), and the shallow aquifer wasreplenished by direct infiltration from the Heihe River.However, from 1960 onwards, as the surface water fromthe Heihe River decreased because of increased irrigationin its middle reaches, the groundwater level declined in itslower basin, and the West and East Juyan Lakes became


dry in 1961 and 1992, respectively (Jin et al., 2010).According to observations at the Dongjuyanhai Hydro-logical Station (Figure 1A), the Heihe River water flowedinto the East Juyan Lake again in 2002 as a result ofenvironmental flow controls aimed at delivering a setamount of surface water to the East Juyan Lake and theoasis ecosystem after 2000 (Wang et al., 2011a; Zhang

Hydrol. Process. 28, 1539–1553 (2014)

1542 P. WANG ET AL.

et al., 2011). The total volume of water transported intothe East Juyan Lake was nearly 0.36� 109 m3 from 2002to 2011, and it reached a maximal water surface ofapproximately 40 km2.As shown in Figure 3, the dominant landscape is that of

the Gobi Desert, which is composed of wind-eroded hillyareas, desert, and alkaline soils (Xie, 1980; Akiyamaet al., 2007). Natural oasis ecosystems, which representanother typical landscape, consist of two zones that arelocated along the Xihe River and the Donghe River.Several narrow strip-shaped oases have formed alongseveral relatively independent tributaries within theseareas. These green belts follow the southwest-northeastdirection and serve as multilevel shelters against sand-storms from the northwest. A flat oasis known as theJuyan Oasis (Figure 3) formed in the lower reaches of theDonghe River where the tributaries spread radially(Zhang et al., 2011). The predominant natural vegetation,which is characterized by phreatophytes (e.g. Populuseuphratica and Tamarix ramosissiman), relies on ground-water for survival. The other natural vegetation that existsin this region, such as Haloxylon ammodendron andSophora alopecuroides, is distributed along the rivers andmainly depends on surface water for sustenance (Zhaoet al., 2004; Wang et al., 2011b; Zhu et al., 2012).

Figure 3. Map showing the location of the monitoring wells and thespatial distribution of the oasis and desert regions (modified from Zhang

et al., 2011)


The cultivated land is mainly distributed within thenatural oasis ecosystem (Figure 3). Hami melon is themajor crop in this area, and other important crops includecorn and cotton. The growing season of these crops isapproximately 140 days, extending from early May to theend of September. Flood irrigation, which relies onextensive groundwater withdrawal (Figure 2B) with apumping rate of 40–80 m3/h from the phreatic aquifer byirrigation wells (50–100 m depth), is still the mostcommon method of crop irrigation. Generally, cropirrigation requires groundwater withdrawals that occur5–6 times in a typical growing season, and eachgroundwater withdrawal lasts for 2–5 days. During thelast 10 years, groundwater withdrawals for agriculturalneeds have caused significant water level declines in theJuyan Oasis area of up to 2 m (Wang et al., 2011a). Inaddition, flood irrigation using river water (Figure 2C)during the spring and autumn period is primarily intendedto maintain and enhance the agricultural and naturalecosystem in the study area.

MATERIAL AND METHODS

Data

The groundwater levels and water temperatures in 14monitoring wells (ø4–6 cm, with depths less than 15 m),constructed specifically for the monitoring programme in2001 by the Water Resources Research Institute of theInner Mongolia Autonomous Region, were chosen forthe quantitative analysis of the shallow groundwaterdynamics (Figure 3 and Table I). According to our fieldinvestigation and multiscale remotely sensed data (Zhanget al., 2011), wells a3, a4, a8 and a9 are located in theGobi Desert (Figure 2D); wells a1, a2 and a5–a7 areconstructed in the riparian zone of the Donghe and Xiherivers (Figure 2E); and wells a10–a14 are located in theJuyan Oasis (Figure 2F), which is associated with anatural ecosystem and irrigated agriculture. The ground-water levels and water temperatures were recorded at30-min intervals by Schlumberger Mini-Diver pressuretransducers located at a depth of 4.5–9.0 m (Table I).The groundwater level measurements were compensatedfor barometric changes, which were measured with theSchlumberger Baro-Divers. The uncertainty of the Mini-Diver measurements was �5 mm and �0.1 �C. Thegroundwater level depth and water temperature in 14wells from April 2010 to April 2012, except for wells a10and a13 (April 2010–August 2011), are shown in Figure 4.The mean, median (50th percentile), 25th percentile and75th percentile values of the groundwater level andtemperature are presented using boxplots. In addition, thegroundwater level monitoring data were analysed both todetermine the hydraulic head distribution in the aquiferusing the simple Kriging method in ArcGIS 9.2 and toassess the significance of trends in the time series of thegroundwater levels using the Mann-Kendall trend test(Wen and Chen, 2006; Novotny and Stefan, 2007; Barcoet al., 2010).

Hydrol. Process. 28, 1539–1553 (2014)

Table

I.Characterizationof

the14

monito

ring

wells

Wellno.

a1a2

a3a4

a5a6

a7a8

a9a10

a11

a12

a13

a14

Welllocatio

nRiparian

Riparian

Gobi

Desert

Gobi

Desert

Riparian

Riparian

Riparian

Gobi

Desert

Gobi

Desert

Juyan

Oasis

Juyan

Oasis

Juyan

Oasis

Juyan

Oasis

Juyan

Oasis

Wellelevations,m

1007.10

1015.45

1010.18

1009.68

1006.79

1008.08

962.57

953.13

946.12

932.45

915.11

919.27

918.78

914.16

Welldiam

eter,cm

44

44

44

44

64

44

44

Welldepth,

m15.0

12.0

15.0

15.0

15.0

4.8

4.8

15.0

14.0

12.0

14.5

5.5

6.5

8.4

Measureddepth,

m8.71

8.74

8.62

8.69

8.73

4.57

4.54

8.71

8.65

8.75

8.75

4.49

6.16

7.72

Distanceto

riverbank,

m190

2200

5950

8900

5200

7550

2860

4950

15220

90740

750

Distanceto

cultivatedland,m

~1000

<500

~1500

<500

<500



Daily streamflow data from the Langxinshan Hydro-logical Station (Figure 1A) were used in this study, and thedata are available for the period 1988–2011.Meteorologicaldata from the Ejina weather station (Figure 1A), includingprecipitation and air temperature, were selected for analysisfor the period 1960–2011. In addition, daily maximum andminimum air temperatures, relative humidity, sunshinehours and wind speeds were used to calculate the potentialevapotranspiration (ET0) using the simplified version of thePenman-Monteith (FAO56) approach (Allen et al., 1998).To determine the most influential factors affecting thegroundwater level and temperature variations, a compara-tive analysis was carried out with other parameters,including the air temperature, the runoff from the HeiheRiver and its tributaries, and the distance from the river.

Nonparametric trend test

The rank-based nonparametric Mann-Kendall (MK)statistical test (Mann, 1945; Kendall, 1975) is based onthe test statistic S, defined as follows:

S ¼Xn�1

i¼1

Xnj¼iþ1

sgn xj � xi� �

(1)

where

sgn θð Þ ¼1 if θ > 00 if θ ¼ 0�1 if θ < 0

8<: (2)

For a time series x= [x1,x2, . . .,xn] in which n> 10, thestatistic S is approximately normally distributed, with themean and the variance defined as follows:

E S½ � ¼ 0 (3)

Var Sð Þ ¼n n� 1ð Þ 2nþ 5ð Þ �

Xni¼1

tii i� 1ð Þ 2iþ 5ð Þ

18(4)

where ti is the number of ties of extent i. The standardizedtest statistic Z is estimated by

Z ¼

S� 1ffiffiffiffiffiffiffiffiffiffiffiffiffiffiVar Sð Þp S > 0

0 S ¼ 0Sþ 1ffiffiffiffiffiffiffiffiffiffiffiffiffiffiVar Sð Þp S < 0

8>>>><>>>>:

(5)

The standardized MK statistic Z follows the standardnormal distribution with a mean of zero and a variance ofone. At a significant level of 0.05, the null hypothesis ofno trend is rejected if |Z|> 1.96. A positive value of Zdenotes an increasing trend, and a negative value of Zcorresponds to a decreasing trend.

Correlation analysis

The Spearman rank correlation coefficient was used toidentify the relationship between the runoff dynamics and

Hydrol. Process. 28, 1539–1553 (2014)

Figure 4. Groundwater level depth and groundwater temperature variation in monitoring wells a1–a14

1544 P. WANG ET AL.

the groundwater levels (Seibert et al., 2003). The Spear-man rank correlation coefficient (rs) is defined by thefollowing expression:

rs ¼ 1� 6X

d2in n2 � 1ð Þ (6)

where d is the difference in statistical rank of thecorresponding variables. The values of rs vary from �1 to+1; values close to +1 or �1 indicate a strong correlation,and values close to zero indicate a lack of correlation.

Water table fluctuation method

The groundwater evapotranspiration rate (ETGW) is animportant term in the water budgets for arid and semiaridinland river basins (Lautz, 2008). However, ETGW is hard tomeasure directly because of the difficulties involved in


quantifying the atmospheric evaporative demand, the soiltexture and the plant transpiration (Loheide et al., 2005;Orellana et al., 2012). In arid environments, the water tablefluctuation (WTF) method is usually applied to estimateevapotranspiration fluxes, in which distinct water leveldeclines occur in unconfined aquifers (White, 1932; Healyand Cook 2002). The groundwater evapotranspirationderived from groundwater (ETGW) may be expressed as

ETGW ¼ SyΔh=Δt (7)

where Sy is the specific yield of the aquifer and Δh is thechange in the groundwater table during the periodΔt.White(1932) assumed that ETGWwas negligible from midnight to04:00 h, and the hourly rate of the water level increase was rduring this period. According to this method, the followingdaily ETGW is obtained:

Hydrol. Process. 28, 1539–1553 (2014)

Figure 5. Basic principle of ET estimation using the White method (afterHealy and Cook 2002; Gribovszki et al. 2008)


ETGW ¼ Sy 24r þ sð Þ (8)

where s is the net rise or fall of the water table during the24-h period (Figure 5).

RESULTS

Hydro-meteorological conditions

Meteorological factors such as precipitation andevaporation have a direct influence on the characteristicchanges of the groundwater table and temperature.Figure 6 presents the daily distribution of the precipita-tion, potential evapotranspiration and mean temperatureover the period 1960–2011. The average annual pre-cipitation during this period was 34.5 mm, and the rainfallmainly occurred during the June–September period,accounting for approximately 75% of the total. Theaverage annual ET0 was 1413.6 mm, which was 40 timesgreater than the average annual precipitation. During theMay–September period, the amount of ET0 was 980.5 mm,which accounted for 70% of the total. The mean annual

Figure 6. Daily precipitation, potential evapotranspiration and meantemperature observed at the Ejinaweather station during the period 1960–2011


air temperature over the same period was 8.95 �C, witha range of �35.3 �C (09 February 1964) to +43.7 �C(28 July 2010).According to observations at the Langxinshan Hydro-

logical Station, the average annual runoff volume wasestimated to be approximately 0.58� 109 m3 during theperiod from 1988 to 2011. As shown in Figure 7, therunoff from the Donghe River and the Xihe Riveraccounted for approximately 71% and 28% of the totalrunoff, respectively. In addition, the average annualvolume of surface water flowing through the Dongganqucanal after its implementation in 2005 was estimated to be0.014� 109 m3.

Temporal variations of the groundwater level

A mean water table map for the shallow aquifers wasconstructed; the map indicates that the groundwater flowsfrom Langxinshan towards the Juyan Oasis with agradient of 0.0010–0.0012 (Figure 8). As shown inFigure 9, the shallow groundwater level fluctuatedbetween 0.16 m (well a4) and 4.67 m (well a13), andits variation was less than 1.1 m in wells a2–a9. Themaximum groundwater level depth ranged from 1.96 m to5.98 m, and the minimum groundwater level depth rangedfrom 0.20 m to 3.53 m. The daily groundwater level depthfor the 14 monitoring wells was tested using the MKmethod, and the results are shown in Table II. Five wells(a4–a6, a13–a14) showed significant decreasing trends inthe daily groundwater level depth, seven wells (a1–a3,a8–a9, a11–a12) displayed increasing trends and theremaining two wells (a7, a10) showed no trends. It is notedthat the decline in the groundwater level along the Xiheriverbank continues; however, rising trends in the ground-water level were observed along the Donghe riverbank. Thedifferent dynamic trends in the groundwater level could beexplained by the significant differences in the surface waterrunoff between the Xihe and Donghe rivers.The variations of the groundwater level in the 14

monitoring wells can be classified into three differentpatterns (Figure 10). Stable trends with groundwater level

Figure 7. Annual river flow into the lower Heihe River at the LangxinshanHydrological Station

Hydrol. Process. 28, 1539–1553 (2014)

Figure 8. Distribution of the mean groundwater level and groundwatertemperature during the period from April 2010 to April 2012

Figure 9. Boxplots of the groundwater level depth and the groundwatertemperature in the 14 monitoring wells

Figure 10. Typical patterns of groundwater table fluctuations

1546 P. WANG ET AL.

variations of 0.10–0.40 m/year (Pattern I) are observed inthe Gobi Desert (wells a3, a4 and a8). Generally, thegroundwater level declines slightly during the summermonths and subsequently rises steadily during the winter

Table II. Results of the trend test of the daily gr

Well no. a1 a2 a3 a4 a5 a6 a

MK 2.22 8.15 15.64 �12.50 �10.61 �12.28 �0.


months. A fluctuating trend (Pattern II) represents theperiodical variations in the groundwater level, with anannual fluctuation amplitude of 0.5–1.0 m (wells a2, a5,a6, a7 and a9). This pattern is most often observed in theriparian zone where the river water recharges the aquifersalong the Donghe and Xihe rivers, particularly in theupper reaches (Figure 8). The main influences on theobserved groundwater level fluctuation are most likelythe processes of surface–groundwater interaction duringthe river runoff period. Pattern III is characterized byerratic variation behaviours, unlike the two patternspreviously described. Strong variations in the ground-water table (1.5–5.0 m/year) were observed for wells a1,a10, a11, a13 and a14 in the stable oasis and riparianregions, and the range between the first (25th percentile)and third (75th percentile) quartiles for these wells wasmuch larger than that of the other wells (Figure 9),indicating a greater fluctuation of the groundwater level.

Temporal variations of the groundwater temperature

The groundwater temperature is primarily affected bythe ambient air temperature in cases of notably shallow

oundwater level depth in 14 monitoring wells

7 a8 a9 a10 a11 a12 a13 a14

040 21.56 10.05 �1.05 12.56 38.52 �17.12 �20.98

Hydrol. Process. 28, 1539–1553 (2014)


water tables (Lee and Hahn, 2006), and the groundwatertemperature at many sites in the study area was observedto track with the air temperature. During the period from 1January 2010 to 31 December 2011, the mean annual airtemperature was approximately 9.8 �C, and the airtemperature reached its highest value in July and itslowest value in January, as shown in Figure 11. However,the groundwater temperatures exhibited different beha-viour in the study area. The highest groundwatertemperatures in the monitoring wells occurred mostly inDecember–March (Figure 4), which are the coldestmonths in this region, whereas the lowest groundwatertemperatures were observed in June–July, immediatelybefore the hottest months of July–August. The temporaloccurrences of the highest and lowest groundwatertemperatures were the inverse of those of the airtemperatures. However, the groundwater temperatures inwells a6–a7 and a12 were observed to respond to the airtemperatures with time lags of only 3 months or less.The distribution of the mean groundwater temperatures

for the shallow wells (alluvial aquifers) is shown inFigure 8. The mean groundwater temperatures rangedfrom a minimum of 7.9 �C (well a13) to a maximum of

Figure 11. Typical patterns of groundwater temperature fluctuations


13.2 �C (wells a3 and a4). The variation in thegroundwater temperatures generally ranged from 1 to2 �C (wells a1–a5, a8, a9 and a14), and the largestvariation in the groundwater temperatures (>5 �C) wasobserved in monitoring wells a6, a12 and a13 (Figure 9).During the study period, the maximum groundwatertemperatures ranged between 9.0 and 15.1 �C, and theminimum temperatures ranged from 2.5 to 12.5 �C.The temporal variation of the groundwater tempera-

tures exhibited three major patterns in this study, asshown in Figure 11. Pattern I (periodical) representsperiodic annual repetition behaviours with an annualfluctuation amplitude of 1–2 �C and a lag time betweenthe air temperature and the groundwater temperature of5–6 months. As shown in Table I, fluctuations of this typewere observed in the monitoring wells located at adistance from 190 m to a few kilometres from the river(wells a1–a5 and a8–a9). Pattern II (strong periodical)describes periodic annual fluctuations with noticeableamplitudes greater than 4 �C and lag times between the airtemperature and the groundwater temperature of less than3 months. It must be noted that the range between the first(25th percentile) and third (75th percentile) quartiles forthis type (wells a6–a7 and a12) was much larger than thatof the other wells (Figure 9). This difference indicates thatgreater temporal groundwater temperature variations existin these wells, which are situated within 100 m of theriverbank (Table I) and are under the influence of directinfiltration from the river (Lubis et al., 2008; Duque et al.,2010). In addition, this pattern was identified in wells withmeasured depths of approximately 4.5 m, whereas thosedescribed by Pattern I are generally deeper (8.6–8.8 m). Thegroundwater temperature variations tend to be reduced inamplitude and show an increasing lag time with depth(Stonestrom and Constantz, 2003). Therefore, the measureddepth of the groundwater also may appear to be related tothese classifications. Pattern III describes the most erraticvariation behaviours (wells a10–a11 and a13–a14), differ-ing from Patterns I and II. In this pattern, the annual periodicfluctuation of the groundwater temperature is generallybroken, with an amplitude of 1.5–6.5 �C during the springand autumn. This pattern was mostly observed at monitor-ing wells located in oasis areas, where the groundwatertemperature is affected not only by air temperature but alsoby direct recharge from surface water.

DISCUSSION

Response of groundwater dynamics to river flows

Rapid changes in near-stream water table levels can beobserved during runoff events due to stream-stagefluctuations (Sklash and Farvolden, 1979; Chen andChen, 2003; Chen, 2007). As shown in Figure 12, thegroundwater levels in well a6 (at a distance of 75 m fromthe Donghe River) exhibited temporal dynamics similarto those of the river discharge and were stronglycorrelated with the river discharge and timing; thegroundwater levels in well a5 (at a distance of 5.2 km

Hydrol. Process. 28, 1539–1553 (2014)

Figure 12. Time series of the Donghe River discharge and the groundwaterlevels in the wells from section a4–a6

Figure 13. Time series of the Donghe River discharge and the Spearmanrank correlation between the groundwater levels and river discharge

1548 P. WANG ET AL.

from the Donghe River) showed a lower response to theriver discharge with a greater lag time. However,according to the field investigations, the sharp rise ofthe groundwater level in well a5 during the spring andautumn (up to 1 m) is connected to the flood irrigation ofgrassland by river water diverted from the Dongganqucanal (Figure 1A). For groundwater levels farther fromthe stream, such as the water level in well a4 (at a distanceof 8.9 km from the Donghe River), there was no obviousresponse to the runoff events observed. The effect of theriver recharge decreases with the distance from the watercourse because there is less mixing with infiltrated riverwater (Calvache et al., 2011).For hydraulically connected stream-aquifer systems, the lag

time of the hydrological response between the groundwaterlevel and the runoff primarily depends on the hydraulicconductivity of the streambeds; the transmissivity and storagecapacity of the aquifer; the regional hydraulic gradients; theduration, height and shape of the runoff hydrograph; andthe distance from the riverbank (Sophocleous, 2002; Chenand Chen, 2003). To quantify this delay, Spearman rankcorrelation coefficients were calculated between the ground-water levels and the river discharge for two typical runoffevents, and the groundwater level time series was shifted bydifferent time steps relative to the river discharge (Seibertet al., 2003). As shown in Figure 13, for the first runoff event(12–26 July 2010), the strongest rank correlation betweenthe groundwater levels and the river discharge for well a6(rs =�0.94) occurred 5 days after the peak river flow rate,indicating a five-day delay in the groundwater levelresponses to the river flow. During the second runoff event(from 15 September 2010 to 4 November 2010), the highestrank correlation between the groundwater level in well a6and the river discharge (rs =�0.77) occurred 7 days afterthe peak river flows. The peak flow for the first event was124 m3/s, and the second runoff event had a peak flow of108 m3/s. Clearly, the peak of the river flow is thecontrolling factor for the groundwater response to runoffin the near-stream zone (<100 m). Greater peak flows leadto a stronger correlation between the groundwater levels andthe runoff and a reduced delay in the groundwater levelresponse to the runoff.


Diurnal groundwater fluctuations and groundwaterevapotranspiration loss

Many studies have linked diurnal water table fluctua-tions to evapotranspiration resulting from groundwateruse by phreatophytes, particularly in arid and semiaridareas (White, 1932; Loheide et al., 2005; Gribovszkiet al., 2008; Lautz, 2008; Martinet et al., 2009; Zhu et al.,2011; Soylu et al., 2012). Analysis of the groundwaterlevels in wells from riparian/oasis systems in the studyarea showed that a diurnal fluctuation existed in the watertable throughout the year, particularly during the periodfrom May to September. Figure 14 shows examples of thediurnal groundwater level fluctuation in the riparian zoneand the Juyan Oasis during the typical growing season in2010 without precipitation and river runoff. The diurnalfluctuations in the groundwater table for well a6 in theriparian zone were approximately 2 cm, and the water tabledeclined in the daytime because of evapotranspiration,reaching a minimum at approximately 15:00–17:00 h.Subsequently, the groundwater table began to recover as aresult of groundwater flow to the riparian zone from theneighbouring areas (Gribovszki et al., 2010) and reached amaximum at approximately 22:00 h, at which timeevapotranspiration had nearly ceased. During the night-time hours (22:00–4:00 h), the water table fluctuatedslightly, with an average recovery rate of nearly 0mm/hfor the period 1–6 July 2010, indicating the absence ofgroundwater recharge at night. The groundwater levelfluctuations in the Juyan Oasis (well a12) exhibited a similardaily pattern to that of the wells in the riparian zone(well a6); however, the amplitude of the diurnal ground-water fluctuations varied from 1 to 3 cm, and the water tableelevations reached their minimum values at approximately12:00–14:00 h. Additionally, the water table elevations inwell a12 exhibited a slight increasing trend during the night-time hours with an average recovery rate of approximately0.75mm/hr. It must be noted that the decline in thegroundwater level in well a12 lasted from midnight to04:00 h and after 20:00 h on 6 July, when evapotranspirationhad nearly ceased. Therefore, the groundwater withdrawalin the Juyan Oasis area could be another important factorresponsible for the water table decline in well a12.

Hydrol. Process. 28, 1539–1553 (2014)

Figure 14. Diurnal fluctuation of the groundwater level during the summer period without precipitation and river runoff


The daily ETGW values were calculated for the twotypical wells described previously from the diurnal watertable fluctuations using the White method, as shown inEquation (8). The specific yield (Sy, the storage term forunconfined aquifers) must be estimated to calculate thevalue of ETGW. In this study, a value for Sy (=0.2) wasselected on the basis of the regional hydrogeologicalsurvey report (Xie, 1980) as well as on the results ofgroundwater flow modelling in the Ejina Basin (Wu et al.,2003; Xi et al., 2010a). Table III shows the calculatedETGW from the groundwater data at wells a6 and a12. Forthe typical growing seasons (early July), the calculatedETGW in well a6 (riparian zone) varied from 0.8 to1.4 mm/day, with an average value of 1.1 mm/day.During the same period, the calculated ETGW in well a12(Juyan Oasis area) fluctuated from 2.8 to 4.6 mm/day withan average value of 4.0 mm/day. As shown in Table III,the daily ET0 value during this period was relativelystable, varying from 6.5 to 8.2 mm/day. The daily ETGWfor well a6 was highly correlated with the daily ET0, as

Table III. Comparison of groundwater evapotranspiration rate(ETGW) from wells a6 and a12 with potential evapotranspiration

(ET0)

Date

ETGW, mm/day

ET0, mm/daya6

(riparian zone)a12

(Juyan Oasis)

1 July 2010 1.0 4.4 6.62 July 2010 1.2 4.2 7.73 July 2010 0.8 3.8 6.54 July 2010 – 4.6 6.85 July 2010 1.4 2.8 8.26 July 2010 1.0 – 6.8


evidenced by a Pearson’s correlation coefficient of 0.92;however, no obvious relationship was detected betweenthe daily ETGW for well a12 and the daily ET0. It isimportant to note that the White method is based on thepremise that declines in groundwater levels are onlycaused by the evapotranspiration of plants (White, 1932).However, the large values of the calculated ETGW in theoasis area are possibly connected with an inaccurateestimate obtained by the White method because ofadditional factors (e.g., pumping of nearby wells) thatcontribute to water table declines (Lautz, 2008). Anotherkey source of error in the estimation of groundwaterevapotranspiration using the White method results fromthe limited accuracy of the specific yield (Healy andCook, 2002; Loheide et al., 2005; Lautz, 2008; Soyluet al., 2012), which has a high spatial variability (Chenet al., 2010) and depends on the soil texture, the initialwater table depth and the rate of change in water table(Duke, 1972; Nachabe, 2002). Additionally, a constantrate of groundwater recovery obtained using a shortinterval of night-time hours can also lead to largeuncertainties in the estimation of groundwater evapo-transpiration (Soylu et al., 2012).

Lateral groundwater flow and human impacts on thegroundwater dynamics

In arid regions, direct recharge through the vadose zoneis an uncommon occurrence because the low rainfall fromindividual events may be subject to evapotranspirationbefore reaching the water table (Seiler and Gat, 2007).However, as discussed previously, indirect recharge viariverbed infiltration during the flooding of intermittentrivers is a major recharge mechanism in the study area.The other potential recharge sources for shallow aquifersinclude surface water from the west Mazong Mountains

Hydrol. Process. 28, 1539–1553 (2014)

1550 P. WANG ET AL.

and groundwater from the southwestern Dingxin Basin(Wu et al., 2002). The hydraulic head contours (Figure 8)indicate an average hydraulic gradient of approximately0.0011 during the study period, which accounts for agroundwater flux on the order of 0.66 m2/day whencombined with an average transmissivity of 600 m2/day(Wu et al., 2003). Averaging this flow rate along the flowpath from a recharge area (Langxinshan DiversionStructure) towards a discharge area (wells a11–a14) witha maximum length of approximately 150 km perpendi-cular to the head contours yields an overall lateral flowrate within the aquifer of approximately 1.6 mm/year.Despite the regional groundwater flow, a distinct zone

of lowered hydraulic head was observed in the region ofwells a11–a14 within the Juyan Oasis (Figure 8). For wella12, located in the natural oasis (at a distance ofapproximately 1500 m from cultivated land), a gradualdecline in the water table was observed during nearly theentire period from June 2010 to September 2011(Figure 4), and the rate of groundwater decline duringthe growing season (approximately 3.6 mm/day) washigher than that in the nongrowing season (approximately1.2 mm/day). The higher rate of groundwater declineduring the summer months is related to the loss of watervia groundwater transpiration during the period ofvegetation growth. This effect temporally dominates theobserved variance in the groundwater levels, but rapidlydeclining groundwater levels due to groundwaterwithdrawals (Wang et al., 2011a) during the growingseason (approximately 10 mm/day) were detected in wellsa10–a11 and a13–a14. The rapid response of thegroundwater level dynamics to groundwater withdrawalswas observed in well a11, located at a distance of 480 mfrom a pumped well. Field investigations indicated thatthe obvious decline and recovery of the groundwaterlevel, with an average amplitude of 20 cm, were mostlyobserved within 1–2 h as a result of short-term ground-water withdrawal from the nearby pumped well.In addition, most wells in the oasis area (wells a10–a11

and a13–a14) exhibited distinctly different dynamicsfor groundwater level and temperature behaviours, whichcan be explained by other human factors, such as thenotable large influence of the irrigation return flowfrom river water. The peak groundwater level in thewells near the stream occurred instantaneously, with awater table rise of up to 4 m, indicating that thisbehaviour was caused by a rapid recharge due to floodirrigation from river water. In addition, the dailyfluctuations in the groundwater temperature were gen-erally no more than 1 �C; however, in the oasis area, thegroundwater temperature fluctuated sharply (by up to6.5 �C). Warm surface water increases the groundwatertemperature during the autumn, and cold river waterdecreases the groundwater temperature during the spring.As shown in Figure 9, the lowest mean temperatures,below 10.5 �C, occurred in wells a10 and a13–a14, wherethe groundwater temperature was affected by the irriga-tion return flow from river water during the period ofFebruary–April 2011.


Conceptual model of the shallow groundwater recharge/discharge processes

Shallow groundwater level changes in unconfinedaquifers are caused by an imbalance between dischargeand recharge effects (Healy and Cook, 2002). Thegroundwater resource system in this area is characterizedby relatively simple recharge sources from rivers anddischarge mainly via evapotranspiration (Wang et al.,2013), with a large temporal-spatial distribution of therecharge and discharge rates (Wang and Cheng, 2000).River runoff is significant to the total recharge of theshallow aquifer, because of not only direct infiltrationfrom the riverbed (Akiyama et al., 2007) but also thereturn flow from irrigation previously diverted from theriver (Zhang et al., 2011). The irrigation return flow inthis region is also significant because of the use of thetraditional flooding technique, which applies much morewater than the amount required by the plants. Ground-water discharge by evapotranspiration from bare soil andphreatophytes in the arid regions is a principal mechanismfor water loss (Nichols, 1993). In the study area, thedischarge also includes groundwater extraction forirrigation, industry and domestic use. Extensive pumpingfrom shallow aquifers is known to cause local and rapiddeclines in the groundwater level within the Juyan Oasis(Wang et al., 2011a).The temporal variation of the groundwater levels in the

14 monitoring wells shows that the Gobi Desert, near-stream and oasis zones each display different dynamicbehaviour patterns (Figure 15). In the Gobi Desert, weakfluctuations exist in the groundwater level (<0.5 m) andtemperature (1–2 �C). Evaporation below the sand surfaceis a principal component of regional groundwaterdischarge in the Gobi Desert (Wang and Mitsuta 1992),and the regional groundwater level fluctuations aredirectly affected by seasonal evaporation. Previousstudies (Xie, 1980; Wen et al., 2005; Xi et al., 2010b)have also indicated that groundwater evaporationaccounting for less than 2 mm/day (Luo et al., 2012) isone of the most important mechanisms for groundwaterdischarge in the Gobi Desert. Therefore, although thelateral groundwater flow (Figure 8) can cause a slight risein the water table, evaporation from the shallow ground-water is still the dominant process that controls thegroundwater dynamics during the summer months in theGobi Desert.In the riparian zone (within 100 m of the stream

channel), the amplitude of the annual groundwatertemperature fluctuation was greater than 4 �C, and thelag time between the air and groundwater temperaturewas approximately 80 days. In addition, the groundwaterlevels in the shallow aquifer were highly correlated withthe river runoff, with a lag time of a few days. It issuggested that riverbank filtration is a primary cause ofthe apparent cyclic fluctuations in the groundwater levelin this area. The delay in the groundwater table’s responseto river flows is determined by the distance from thestream channel as well as the peak, duration and volume

Hydrol. Process. 28, 1539–1553 (2014)

Figure 15. Simplified sketch of the groundwater recharge and discharge processes and the typical pattern of groundwater dynamics


of the river flows (Sophocleous, 2002). In addition, thegroundwater level fluctuations in the riparian zone arestrongly linked to the seasonal consumptive use ofgroundwater by riparian vegetation, with a daily evapo-transpiration rate of approximately 1 mm/day for a typicalgrowing season.Human activities, such as hydraulic engineering

projects intended to transport surface water to terminallakes (Zhang et al., 2011), flood irrigation of surfacewater and irrigation pumping in groundwater-fed irrigatedareas (Wang et al., 2011a), are believed to have asignificant impact on the local variation of the ground-water level in the irrigated oasis area. Irrigation returnflow recharge from river water and groundwater dischargevia groundwater withdrawals are the main causes of theobserved sharp rises and declines, respectively, in both thegroundwater levels (1.5–6.0 m) and temperatures (1.5–6.5�C). However, in the nonirrigated oasis, the main mechan-isms that control the groundwater dynamics are seasonalgroundwater evapotranspiration and lateral groundwaterflow, with an average groundwater flow gradient ofapproximately 0.0011.

CONCLUSIONS

The results of this study show that notably large spatialand temporal variations exist in the shallow groundwaterlevel and temperature patterns of the lower Heihe River,which is a typical and extremely arid region of north-western China. The temporal pattern of the groundwatertemperature is most similar to that of the air temperature,with an annual fluctuation amplitude of 1–2 �C and a lagtime of 5–6 months between the air temperature and thegroundwater temperature. Relatively high amplitudes ofthe annual groundwater temperature fluctuations (4–8 �C)and short lag times between the air temperature and thegroundwater temperature (less than 2–3 months) wereidentified in the near-stream areas, which are mainly


affected by the river water–groundwater interaction.Nevertheless, the oasis areas showed distinctly differentdynamic behaviour patterns in the groundwater tempera-ture, which can be explained by human activities, such asirrigation return flows from the surface water.The dynamic behaviour patterns of the groundwater

level at most sites are characterized by a declining trendduring the period from spring to autumn and a slightlyincreasing trend in the winter months. The seasonalvariations of the water table in the Gobi Desert aredetermined by the rate of evaporation and lateralgroundwater influx. The high rank correlation betweenthe groundwater levels near the stream (within approxi-mately 100 m) and the river discharge implies that theriparian groundwater levels respond strongly to riverflows. However, the water table in the riparian zone isexpected to decline during the summer periods because ofseasonal groundwater evapotranspiration. In the oasisareas, the irregular dynamics in the groundwater levelsare characterized by a significant water level declineinduced by groundwater transpiration in addition to large-scale groundwater withdrawals during the vegetationgrowth season and an instantaneous rise in the water levelcaused by flood irrigation with river water.A variety of hydrological processes are associated

with shallow groundwater dynamics. A subset of thesenatural processes, for example, groundwater evapotran-spiration and riverbank filtration, have relatively slowresponse times but may cause long-term groundwaterlevel changes. However, the effect of human factors(e.g. groundwater pumping events and flood irrigationwith surface water) on groundwater dynamics isrelatively instantaneous. Full quantification of thehydrological impacts on the groundwater dynamics ofthese arid regions will require farther field investiga-tions as well as systematic testing of hydrologicalsimulation models to determine the water exchangesbetween the different compartments (atmosphere, sur-face, soil, aquifers, etc.).

Hydrol. Process. 28, 1539–1553 (2014)

1552 P. WANG ET AL.

ACKNOWLEDGEMENTS

This research was supported by the National BasicResearch Programme of China (973 Programme)(No. 2009CB421305), the National Natural ScienceFoundation of China (No. 91025023 and 41271049), theNSFC-RFBR Programme 2011–2012 (No. 41111120029)and the Visiting Professorship for Senior InternationalScientists, Chinese Academy of Sciences (No.2012T1Z0037). The authors are grateful to the anonymousreviewers for their invaluable comments and suggestions,which contributed to improving the manuscript. We alsothank Juntao Zhu, Leilei Min, Bingqi Zhu, Fei Ao,Yongliang Xu, Zhiyong Wang, Dandan Wang and LiliMao for their participation in the fieldwork.

REFERENCES

Abdalla OAE. 2008. Groundwater discharge mechanism in semi-aridregions and the role of evapotranspiration. Hydrological Processes 22:2993–3009. DOI: 10.1002/hyp.6872.

Akiyama T, Sakai A, Yamazaki Y, Wang G, Fujita K, Nakawo M,Masayoshi A, Jurhpei A, Yuki G. 2007. Surface water-groundwaterinteraction in the Heihe River basin, Northwestern China. Bulletin ofGlaciological Research 24: 87–94.

Allen RG, Pereira LS, Raes D, Smith M. 1998. Crop evapotranspiration:guidelines for computing crop water requirements. FAO Irrigation andDrainage Paper No. 56. FAO: Rome.

Amlin NM, Rood SB. 2003. Drought stress and recovery of ripariancottonwoods due to water table alteration along Willow Creek, Alberta.Trees – Structure and Function 17: 351–358. DOI: 10.1007/s00468-003-0245-3.

Anderson MP. 2005. Heat as a ground water tracer. Ground Water 43:951–968. DOI: 10.1111/j.1745-6584.2005.00052.x.

Anibas C, Fleckenstein JH, Volze N, Buis K, Verhoeven R, Meire P,Batelaan O. 2009. Transient or steady-state? Using vertical temperatureprofiles to quantify groundwater–surface water exchange. HydrologicalProcesses 23: 2165–2177. DOI: 10.1002/hyp.7289.

Barco J, Hogue TS, Girotto M, Kendall DR, Putti M. 2010. Climate signalpropagation in southern California aquifers. Water Resour. Res. 46:W00F05. DOI: 10.1029/2009wr008376.

Besbes M, Delhomme JP, De Marsily G. 1978. Estimating recharge fromephemeral streams in arid regions: a case study at Kairouan, Tunisia.Water Resour. Res. 14: 281–290. DOI: 10.1029/WR014i002p00281.

Bredehoeft JD. 1967. Response of well-aquifer systems to earth tides.J. Geophys. Res. 72: 3075–3087. DOI: 10.1029/JZ072i012p03075.

Calvache ML, Duque C, Gomez Fontalva JM, Crespo F. 2011. Processesaffecting groundwater temperature patterns in a coastal aquifer. Int. J.Environ. Sci. Tech. 8: 223–236.

Chen X. 2007. Hydrologic connections of a stream–aquifer-vegetationzone in south-central Platte River valley, Nebraska. Journal ofHydrology 333: 554–568. DOI: 10.1016/j.jhydrol.2006.09.020.

Chen X, Chen X. 2003. Stream water infiltration, bank storage, andstorage zone changes due to stream-stage fluctuations. Journal ofHydrology 280: 246–264.

Chen X, Song J, Wang W. 2010. Spatial variability of specific yield andvertical hydraulic conductivity in a highly permeable alluvial aquifer.Journal of Hydrology 388: 379–388. DOI: 10.1016/j.jhydrol.2010.05.017.

Conant B. 2004. Delineating and quantifying ground water dischargezones using streambed temperatures. Ground Water 42: 243–257. DOI:10.1111/j.1745-6584.2004.tb02671.x.

Constantz J. 1998. Interaction between stream temperature, streamflow,and groundwater exchanges in alpine streams. Water Resour. Res. 34:1609–1615. DOI: 10.1029/98wr00998.

Constantz J. 2008. Heat as a tracer to determine streambed water exchanges.Water Resour. Res. 44: W00D10. DOI: 10.1029/2008wr006996.

Cui Y, Shao J. 2005. The role of ground water in arid/semiaridecosystems, Northwest China. Ground Water 43: 471–477. DOI:10.1111/j.1745-6584.2005.0063.x.

Cutillo PA, Bredehoeft JD. 2011. Estimating aquifer properties from thewater level response to earth tides. Ground Water 49: 600–610. DOI:10.1111/j.1745-6584.2010.00778.x.


Dregne HE. 1991. Global status of desertification. Annals of Arid Zone 30:179–185.

Duke H. 1972. Capillary properties of soils – influence upon specificyield. T. Am. Soc. Agr. Eng. 15: 688–691.

Duque C, Calvache ML, Engesgaard P. 2010. Investigating river–aquiferrelations using water temperature in an anthropized environment(Motril-Salobreña aquifer). Journal of Hydrology 381: 121–133. DOI:10.1016/j.jhydrol.2009.11.032.

Ferguson S, Woodbury AD, Matile GLD. 2003. Estimating deep rechargerates beneath an interlobate moraine using temperature logs. GroundWater 41: 640–646. DOI: 10.1111/j.1745-6584.2003.tb02402.x.

Goudie AS, Middleton NJ. 1992. The changing frequency of dust stormsthrough time. Climatic Change 20: 197–225. DOI: 10.1007/bf00139839.

Gribovszki Z, Kalicz P, Szilágyi J, Kucsara M. 2008. Riparian zoneevapotranspiration estimation from diurnal groundwater level fluctuations.Journal of Hydrology 349: 6–17. DOI: 10.1016/j.jhydrol.2007.10.049.

Gribovszki Z, Szilágyi J, Kalicz P. 2010. Diurnal fluctuations in shallowgroundwater levels and streamflow rates and their interpretation – areview. Journal of Hydrology 385: 371–383. DOI: 10.1016/j.jhydrol.2010.02.001.

Guo Q, Feng Q, Li J. 2009. Environmental changes after ecological waterconveyance in the lower reaches of Heihe River, northwest China.EnvironmentalGeology 58: 1387–1396.DOI: 10.1007/s00254-008-1641-1.

Healy RW, Cook PG. 2002. Using groundwater levels to estimaterecharge. Hydrogeology Journal 10: 91–109. DOI: 10.1007/s10040-001-0178-0.

Heliotis FD, DeWitt CB. 1987. Rapid water table responses to rainfall in anorthern peatland ecosystem. Journal of the American Water ResourcesAssociation 23: 1011–1016. DOI: 10.1111/j.1752-1688.1987.tb00850.x.

Hirche A, Salamani M, Abdellaoui A, Benhouhou S, Valderrama J. 2011.Landscape changes of desertification in arid areas: the case of south-westAlgeria. Environmental Monitoring and Assessment 179: 403–420. DOI:10.1007/s10661-010-1744-5.

Jin X, Schaepman M, Clevers J, Su Z, Hu G. 2010. Correlation betweenannual runoff in the Heihe River to the vegetation cover in the EjinaOasis (China). Arid Land Research and Management 24: 31–41. DOI:10.1080/15324980903439297.

Kendall MG. 1975. Rank correlation methods. Griffin: London.Lautz L. 2008. Estimating groundwater evapotranspiration rates usingdiurnal water-table fluctuations in a semi-arid riparian zone. Hydro-geology Journal 16: 483–497. DOI: 10.1007/s10040-007-0239-0.

Le Maitre DC, Scott DF, Colvin C. 1999. A review of information oninteractions between vegetation and groundwater. Water ResearchCommision 25: 137–152.

Lee J-Y, Hahn J-S. 2006. Characterization of groundwater temperatureobtained from the Korean national groundwater monitoring stations:implications for heat pumps. Journal of Hydrology 329: 514–526. DOI:10.1016/j.jhydrol.2006.03.007.

Lite SJ, Stromberg JC. 2005. Surface water and ground-water thresholds formaintaining Populus–Salix forests, San Pedro River, Arizona. BiologicalConservation 125: 153–167. DOI: 10.1016/j.biocon.2005.01.020.

Loheide SP, II, Butler JJ, Jr., Gorelick SM. 2005. Estimation ofgroundwater consumption by phreatophytes using diurnal water tablefluctuations: a saturated-unsaturated flow assessment. Water Resour.Res. 41: W07030. DOI: 10.1029/2005wr003942.

Lubis R, Sakura Y, Delinom R. 2008. Groundwater recharge anddischarge processes in the Jakarta groundwater basin, Indonesia.Hydrogeology Journal 16: 927–938. DOI: 10.1007/s10040-008-0278-1.

Luo X, Wang K, Jiang H, Sun J, Zhu Q. 2012. Estimation of land surfaceevapotranspiration over the Heihe River basin based on the revisedthree-temperature model. Hydrological Processes 26: 1263–1269. DOI:10.1002/hyp.8182.

Mann HB. 1945. Nonparametric tests against trend. Econometrica 13:245–259.

Martinet MC, Vivoni ER, Cleverly JR, Thibault JR, Schuetz JF, DahmCN. 2009. On groundwater fluctuations, evapotranspiration, andunderstory removal in riparian corridors. Water Resour. Res. 45:W05425. DOI: 10.1029/2008wr007152.

Mertz O, D’haen S, Maiga A, Moussa I, Barbier B, Diouf A, Diallo D, DaE, Dabi D. 2012. Climate variability and environmental stress in theSudan-Sahel zone of West Africa. AMBIO: A Journal of the HumanEnvironment 41: 380–392. DOI: 10.1007/s13280-011-0231-8.

Nachabe MH. 2002. Analytical expressions for transient specific yield andshallow water table drainage. Water Resour. Res. 38: 1193. DOI:10.1029/2001wr001071.

Naumburg E, Mata-gonzalez R, Hunter RG, McLendon T, Martin DW.2005. Phreatophytic vegetation and groundwater fluctuations: a review

Hydrol. Process. 28, 1539–1553 (2014)


of current research and application of ecosystem response modelingwith an emphasis on great basin vegetation. Environmental Manage-ment 35: 726–740. DOI: 10.1007/s00267-004-0194-7.

Newman BD, Wilcox BP, Archer SR, Breshears DD, Dahm CN, DuffyCJ, McDowell NG, Phillips FM, Scanlon BR, Vivoni ER. 2006.Ecohydrology of water-limited environments: a scientific vision. WaterResour. Res. 42: W06302. DOI: 10.1029/2005wr004141.

Nichols WD. 1993. Estimating discharge of shallow groundwater bytranspiration from greasewood in the Northern Great Basin. WaterResour. Res. 29: 2771–2778. DOI: 10.1029/93wr00930.

Novotny EV, Stefan HG. 2007. Stream flow in Minnesota: indicator ofclimate change. Journal of Hydrology 334: 319–333. DOI: 10.1016/j.jhydrol.2006.10.011.

Orellana F, Verma P, Loheide SP, II, Daly E. 2012. Monitoring andmodeling water-vegetation interactions in groundwater-dependentecosystems. Rev. Geophys. 50: RG3003. DOI: 10.1029/2011rg000383.

Palumbo AG. 1998. Atmospheric tides. Journal of Atmospheric and Solar-Terrestrial Physics 60: 279–287. DOI: 10.1016/s1364-6826(97)00078-3.

Seibert J, Bishop K, Rodhe A, McDonnell JJ. 2003. Groundwaterdynamics along a hillslope: a test of the steady state hypothesis. WaterResour. Res. 39: 1014. DOI: 10.1029/2002wr001404.

Seiler KP, Gat JR. 2007. Mechanisms and processes of recharge. InGroundwater Recharge from Run-off, Infiltration and Percolation.Springer: Netherlands; 31–68.

Si J, Feng Q, Wen X, Su Y, Xi H, Chang Z. 2009. Major ion chemistry ofgroundwater in the extreme arid region northwest China. EnvironmentalGeology 57: 1079–1087.

Sklash MG, Farvolden RN. 1979. The role of groundwater in stormrunoff. Journal of Hydrology 43: 45–65. DOI: 10.1016/0022-1694(79)90164-1.

Sophocleous M. 2002. Interactions between groundwater and surfacewater: the state of the science. Hydrogeology Journal 10: 52–67. DOI:10.1007/s10040-001-0170-8.

Soylu ME, Istanbulluoglu E, Lenters JD, Wang T. 2011. Quantifying theimpact of groundwater depth on evapotranspiration in a semi-aridgrassland region. Hydrol. Earth Syst. Sci. 15: 787–806. DOI: 10.5194/hess-15-787-2011.

Soylu ME, Lenters JD, Istanbulluoglu E, Loheide SP, II. 2012. Onevapotranspiration and shallow groundwater fluctuations: a Fourier-basedimprovement to the White method.Water Resour. Res. 48: W06506. DOI:10.1029/2011wr010964.

Stonestrom DA, Constantz J. 2003. Heat as a tool for studying themovement of ground water near streams. In: U.S. Geological SurveyCircular 1260. USGS.

Stromberg JC, Tiller R, Richter B. 1996. Effects of groundwater declineon riparian vegetation of semiarid regions: the San Pedro, Arizona.Ecological Applications 6: 113–131. DOI: doi:10.2307/2269558.

Taniguchi M. 1994. Estimated recharge rates from groundwatertemperatures in the Nara basin, Japan. Hydrogeology Journal 2: 7–14.DOI: 10.1007/s100400050031.

Townley LR. 1995. The response of aquifers to periodic forcing. Advances inWater Resources 18: 125–146. DOI: 10.1016/0309-1708(95)00008-7.

Wang G, Cheng G. 2000. The characteristics of water resources and thechanges of the hydrological process and environment in the arid zone ofnorthwest China. Environmental Geology 39: 783–790.

Wang J, Mitsuta Y. 1992. Evaporation from the desert: some preliminaryresults of HEIFE. Boundary-Layer Meteorology 59: 413–418. DOI:10.1007/BF02215461.

Wang X, Chen F, Hasi E, Li J. 2008. Desertification in China: anassessment. Earth-Science Reviews 88: 188–206. DOI: 10.1016/j.earscirev.2008.02.001.


Wang P,Yu J, ZhangY, FuG,Min L, Ao F. 2011a. Impacts of environmentalflow controls on the water table and groundwater chemistry in the EjinaDelta, northwestern China.Environmental Earth Sciences 64: 15–24. DOI:10.1007/s12665-010-0811-0.

Wang P, Zhang Y, Yu J, Fu G, Ao F. 2011b. Vegetation dynamicsinduced by groundwater fluctuations in the lower Heihe River Basin,northwestern China. Journal of Plant Ecology 4: 77–90. DOI: 10.1093/jpe/rtr002.

Wang P, Yu J, Zhang Y, Liu C. 2013. Groundwater recharge andhydrogeochemical evolution in the Ejina Basin, northwest China.Journal of Hydrology 476: 72–86. DOI: 10.1016/j.jhydrol.2012.10.049.

Wen F, Chen X. 2006. Evaluation of the impact of groundwater irrigationon streamflow in Nebraska. Journal of Hydrology 327: 603–617. DOI:10.1016/j.jhydrol.2005.12.016.

Wen X, Wu Y, Su J, Zhang Y, Liu F. 2005. Hydrochemical characteristicsand salinity of groundwater in the Ejina Basin, NorthwesternChina. Environmental Geology 48: 665–675. DOI: 10.1007/s00254-005-0001-7.

White WN. 1932. Method of estimating groundwater supplies based ondischarge by plants and evaporation from soil – results of investigationin Escalante Valley, Utah. In: US Geological Survey. Water SupplyPaper 659-A United States Department of the Interior. Washington D.C.pp: 105.

Wu X, Chen C, Shi S, Li Z. 2003. Three-dimensional numerical simulationof groundwater system in Ejina Basin, Heihe River, northwestern China(in Chinese with English abstract). Earth Science – Journal of ChinaUniversity of Geosciences 28: 527–532.

Wu X, Shi S, Li Z, Hao A, Qiao W, Yu Z, Zhang S. 2002. The study onthe groundwater flow system of Ejina basin in lower reaches of theHeihe River in Northwest China (Part 1) (in Chinese with Englishabstract). Hydrogeology and Engineering Geology 1: 16–20.

Xi H, Feng Q, Liu W, Si J, Chang Z, Su Y. 2010a. The research ofgroundwater flow model in Ejina Basin, Northwestern China.Environmental Earth Sciences 60: 953–963. DOI: 10.1007/s12665-009-0231-1.

Xi H, Feng Q, Si J, Chang Z, Cao S. 2010b. Impacts of river recharge ongroundwater level and hydrochemistry in the lower reaches of HeiheRiver Watershed, northwestern China. Hydrogeology Journal 18:791–801. DOI: 10.1007/s10040-009-0562-8.

Xie Q. 1980. Regional hydrogeological survey report of the People’sRepublic of China (1:200 000): Ejina K-47-[24] [R] (in Chinese).

Zhang Y, Wu Y, Su J, Wen X, Liu F. 2005. Groundwater replenishmentanalysis by using natural isotopes in Ejina Basin, Northwestern China.Environmental Geology 48: 6–14. DOI: 10.1007/s00254-004-1214-x.

Zhang Y, Yu J, Wang P, Fu G. 2011. Vegetation responses to integratedwater management in the Ejina basin, northwest China. HydrologicalProcesses 25: 3448–3461. DOI: 10.1002/hyp.8073.

Zhao W, Chang X, He Z. 2004. Responses of distribution pattern of desertriparian forests to hydrologic process in Ejina oasis. Science in China(Series D: Earth Sciences) 47: 21–31.

Zhu J, Young M, Healey J, Jasoni R, Osterberg J. 2011. Interference ofriver level changes on riparian zone evapotranspiration estimates fromdiurnal groundwater level fluctuations. Journal of Hydrology 403:381–389. DOI: 10.1016/j.jhydrol.2011.04.016.

Zhu J, Yu J, Wang P, Yu Q, Eamus D. 2012. Distribution patterns ofgroundwater-dependent vegetation species diversity and their relationshipto groundwater attributes in northwestern China. Ecohydrology: n/a-n/a.DOI: 10.1002/eco.1258.

Zhu Y, Wu Y, Drake S. 2004. A survey: obstacles and strategies for thedevelopment of ground-water resources in arid inland river basins ofWestern China. Journal of Arid Environments 59: 351–367.

Hydrol. Process. 28, 1539–1553 (2014)

Shallow groundwater dynamics and its driving forces in ... · Shallow groundwater dynamics and its...

Documents

Transcript of Shallow groundwater dynamics and its driving forces in ... · Shallow groundwater dynamics and its...