1996_Groundwater recharge estimation using chloride,stable isotopes and tritium profiles

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Contamination of groundwater under cultivated fields

Contamination of groundwater under cultivated ﬁelds in an arid environment,central Arava Valley,IsraelO.Oren a,*,Y.Yechieli a,1,J.K.Bo¨hlke b,2,A.Dody c,3aGeological Survey of Israel,30Malchei Yisrael Str.,Jerusalem 95501,IsraelbUSGS,431National Center,Reston,VA 20192,USA cNRCN,POB.9001,Beer Sheva 84190,IsraelReceived 7May 2003;revised 5December 2003;accepted 10December 2003AbstractThe purpose of this study is to obtain a better understanding of groundwater contamination processes in an arid environment (precipitation of 50mm/year)due to cultivation.Additional aims were to study the fate of N,K,and other ions along the whole hydrological system including the soil and vadose zone,and to compare groundwater in its natural state with contaminated groundwater (through the drilling of several wells).A combination of physical,chemical,and isotopic analyses was used to describe the hydrogeological system and the recharge trends of water and salts to the aquifers.The results indicate that intensive irrigation and fertilization substantially affected the quantity and quality of groundwater recharge.Low irrigation efﬁciency of about 50%contributes approximately 3.5–4million m 3/year to the hydrological system,which corresponds to 0.65m per year of recharge in the irrigated area,by far the most signiﬁcant recharge mechanism.Two main contamination processes were identiﬁed,both linked to human activity:(1)salinization due to circulation of dissolved salts in the irrigation water itself,mainly chloride,sulfate,sodium and calcium,and (2)direct input of nitrate and potassium mainly from fertilizers.The nitrate concentrations in a local shallow groundwater lens range between 100and 300mg/l and in the upper sub-aquifer are over 50mg/l.A major source of nitrate is fertilizer N in the excess irrigation water.The isotopic compositions of d 15N–NO 3(range of 4.9–14.8‰)imply also possible contributions from nearby sewage ponds and/or manure.Other evidence of contamination of the local groundwater lens includes high concentrations of K (20–120mg/l)and total organic carbon (about 10mg/l).q 2004Elsevier B.V.All rights reserved.Keywords:Groundwater;Arid environment;Nitrate;N isotope;Contamination;Agriculture1.IntroductionGroundwater is a signiﬁcant or sole source of waterin arid areas.Contamination of groundwater due to agricultural activities could therefore severely endan-ger survival in these harsh environments.This contamination is usually expressed in increasing salinity and nitrateconcentrations.*Corresponding author.Tel./fax:þ972-2-5380688.E-mail addresses:orly.oren@.il (O.Oren),yechieli@.il (Y.Yechieli),jkbohlke@ (J.K.Bo¨hlke),dodik@bgumail.bgu.ac.il (A.Dody).The quantities and qualities of the recharge water substantially inﬂuence the pumping potential from the aquifers in arid environments.The natural source is limited to inﬁltration duringﬂoods,which are characterized by low frequency and irregularity (Simmers,1997).The anthropogenic sources may be excess of irrigation water and leakage from sewage ponds.Agriculture has had profound effects on the rates and compositions of groundwater recharge (Albus and Knighton,1998;Rodvang and Simpkins, 2001;Bo¨hlke,2002).The effects of irrigation and fertilization in arid zones could be:(1)salinization of the soil and groundwater below theﬁelds(Stigter et al.,1998) and(2)increase of nitrate concentrations in ground-water(Singh et al.,1995;Oenema et al.,1998; Allaire-Leung et al.,2001).Irrigation in arid zones causes an increase of the salt concentrations in the root zone due to high evapotranspiration.In order to minimize soil salinization,excess amounts of water are required,much beyond that needed by the crops (Rhoads and Loveday,1990).The excess water causes the leaching of the salts to the groundwater.Hence,the presence of agricultural activities introduces a long-term risk of groundwater pollution by excess fertili-zers,salts and pesticides leached downward(Hadas et al.,1999).The fertilization efﬁciency(the fraction of applied N that is taken up by plants)in the study area was estimated to be about50%(Bar-Yosef et al., 1982).The average annual amount of applied N in the study area is55g/m2.Converting half of this amount to nitrate yields a potential annual nitrate load in recharging groundwater of approximately120g/m2.Agricultural activities,especially cultivation and fertilization,are principal causes of nitrate contami-nation on a regional scale(Hudak,2000;Nolan, 2001).Nitrate is very mobile in groundwater and tends not to adsorb or precipitate on aquifer solids (Hem,1985).High concentrations of nitrate constitute a health hazard and the American standard for drinking water is45mg/l NO3(EPA,1996).Agricultural application of K and P as plant nutrients commonly has less of a signature in groundwater(Bo¨hlke,2002).The fate of K is determined in part by ion exchange and sorption by clays hence K enrichment in groundwater is sporadic. P is sorbed strongly onto solid phases,hence no high values occur in groundwater.The purpose of this study is to obtain a better understanding of contamination processes of ground-water related to agriculture activity in an extremely arid environment.The word‘contamination’as used by Freeze and Cherry(1979)implies that human activities have increased the concentration of a constituent,though not necessarily harmful.Additional aims were to study the fate of N,K,and other ions along the whole hydrological system including the soil and vadose zone,to compare groundwater in its natural state with contaminated groundwater(through the drilling of several wells),among others,and to demonstrate the use of the15N isotope in nitrate.A combination of physical,chemical and isotopic analyses was used to explain the hydrological system and the trends of water and salt recharge.2.Study areaThe central Arava Valley is located in the southern part of Israel(Fig.1).The valley is drained to the north by Wadi Arava,which drains wadis from the east(Edom Mountains)and the west(Negev moun-tains)toward the Dead Sea.The area is characterized by desert climate.The average yearly precipitation is50mm and the potential evaporation exceeds3000mm.The average yearly temperature is258C.In the area there are several rural settlements with cultivatedﬁelds totaling18km2.Groundwater is the only source of water for the settlements.Since the 1960s agriculture developed above the formations of the upper aquifers,which contained in the past fresh water of good quality.Eighty percent of the irrigation and drinking water is drawn from the upper aquifers of the Hazeva and Arava formations and the other20%is drawn from deep aquifers,mainly from the Lower Cretaceous sandstones of the Kurnub Group(Yechieli et al.,1992;Naor and Granit,2000).The water from different wells mix before they reach theﬁelds.Over the years,increases in the salt concentrations,and especially nitrate were observed in the groundwater (Naor and Granit,2000).The research focused on theﬁelds around the En Yahav settlement as a representative case.This settlement was theﬁrst(founded in1967)and is the biggest,with a cultivated area of5.6km2.It was,O.Oren et al./Journal of Hydrology290(2004)312–328313O.Oren et al./Journal of Hydrology290(2004)312–328314Fig.1.Location map of the study area in the central Arava Valley.Coordinate in ITM grid.therefore,expected that contamination processes would be most notable there.3.The hydrologic systemThe upper aquifers include the Neogene Hazeva and the Plio-Pleistocene Arava formations.The Hazeva formation consists mainly of alternating clay and sand beds forming sub-aquifers of limited areal extension due to frequent lateral lithological changes.It is overlain by the Plio-Pleistocene Arava ﬁll aquifer consists of coarse clastic alluvial zones (Yechieli et al.,1992).Fig.2shows the typical ﬁeld relations inthe area.The general direction of groundwater ﬂow is NNE,toward the Dead Sea.The aquifer in the study area is divided by clay layers into two main sub-aquifers (Fig.3).The lower one is conﬁned whereas the upper is a semi-conﬁned aquifer.The hydraulic head of the upper sub-aquifer is about 2–10m higher than that of the lower one.Near the surface,at a depth of 2–5m there is a shallow groundwater lens that forms a perched aquifer (Fig.3)extending over an area of at least 2.5km 2.The hydraulic head of the perched aquifer is at least 2m higher than that of the upper sub-aquifer.The groundwater level measurements indicate that the ﬂow direction of all three aquifer units is to the NNE.4.Agricultural activityThe cultivation of the ﬁelds in the Arava Valley began in the late 1960s,and the area has evolved into an advanced technological center of agriculture.Agriculture is based on intensive irrigation and fertilization to improve the soils.In recent years most of the ﬁelds have been covered with green-houses.The crops include mainly seasonal crops such as vegetables and ﬂowers but also palmplantationsFig.2.Generalized stratigraphic column with indication of the main investigatedaquifer.Fig.3.Schematic geohydrological cross-section in the study area.O.Oren et al./Journal of Hydrology 290(2004)312–328315and vineyards.The growing season extends generally 10months a year.The irrigation regime begins with washing the soils by sprinklers with50m3of water per1000m2of land, equivalent to50mm/year.After that,the irrigation is accomplished by dripping.The entire amount of irrigation water ranges between1000and1500m3per 1000m2/year(1000–1500mm/year)depending on the crop type.The total amount of irrigation water is 7.5–8million m3/year.The fertilizers comprise three major nutrients: nitrogen,phosphorus,and potassium.The amounts applied average around50–60g N,5–6g P and40g K per m2/year,respectively.Moreover,at the beginning of the season,the farmers fertilize the ﬁelds with cattle manure,which adds about20g N, 10g P and20g K per m2.5.Methodology5.1.Unsaturated zoneSoil proﬁles were sampled to a depth of2–3m in cultivatedﬁelds,in theﬂood channel of Wadi Arava, and in undisturbed natural soils.The samples were collected at intervals of20cm.Salts were extracted from the soil samples by drying the soil at1058C,sifting it with a2mm sieve to remove the large fractions,dividing the sample randomly by splitter,dissolving the salts with distilled water by shaking for4h(approx,water/soil ratio¼10,by weight),andﬁltering the solution before the chemical analysis.The concentrations represent both the dissolved salts in1kg soil and the salts in the soil water.Irrigation water(in text ‘irrigation’)and irrigation water to which fertilizer has been added(in text‘irrigationþfertilizer’)were sampled in the cultivatedﬁelds and analyzed.Ceramic cups were used to sample the water in and below the root zone of cultivatedﬁelds.The sampler is a cylindrical ceramic chamber,6cm long with an external diameter of2cm and inner diameter of1.7cm;it has a maximum pore size of2–3m m. The ceramic cup is attached to a PVC pipe and the opposite end is sealed with a one-hole stopper with tubing and clamp so that air can be evacuated from the sampler.The buried porous cup collects a sample of soil water when the vacuum in the sampler exceeds the adjacent soil moisture tension(Hansen and Harris,1975).Nine samplers were inserted in the soil in three different greenhouses,and in each one,at different soil depths—20,40–60,80–120cm.Samples were collected every few days during the agriculture season.5.2.Saturated zoneEighteen shallow boreholes(2.5–5m depth)were drilled to the local groundwater lens between June and August2001(Fig.1).Anotherﬁve deeper boreholes were drilled in June2002to the local lens and to the upper sub-aquifer,at the center of the lens and at an upgradient location south of theﬁelds (Arava22well).Groundwater was also sampled from pumping wells located at three sites near theﬁelds(Fig.1);at every site there were two wells,one extracting from the upper sub-aquifer and the other from the lower sub-aquifer.The‘unpolluted wells’are wells that extract water from the same regional aquifer,some kilometers from the agricultural area and have low salt concentrations,similar to the natural composition before the settlement was built.Throughout the year(June2001–August2002)all the observation and pumping wells in the study area were sampled several times,and temperature and electrical conductivity were measured.Water levels in the shallow observation boreholes were measured regularly every2–3weeks.5.3.Chemical and isotopic analysesThe chemical analyses and d18O analyses in water were conducted at the Geological Survey of Israel. Major cations were analyzed on a Perkin Elmer Optima3300ICP AES.Anion concentrations were measured using a Dionex Series4000I Gradient Ion Chromatography and HPLC.Only analyses with charge balance,3%were used in this study.Oxygen isotope analyses of water were done by the VG SIRA II IRMS mass spectrometer with an analytical error of0.1‰.Tritium concentrations were determined at the Weizmann Institute following enrichment usingO.Oren et al./Journal of Hydrology290(2004)312–328 316an electrolysis system,by a low-level counting system,LKB1220Quantulus scintillation counter (Bowman and Hughes,1981).Tritium concentrations are expressed in Tritium Units(TU)with an analytical error of^0.2TU.Isotopic analyses of nitrogen(d15N)in nitrate were done at the USGS laboratory in Reston,Virginia. Nitrate samples and standards were prepared by freeze-drying and off-line combustion techniques for mass spectrometry,and the data were normalized to values ofþ0.4‰for IAEA-N1andþ180‰for USGS-32(Bo¨hlke and Denver,1995;Bo¨hlke and Coplen,1995;Bo¨hlke et al.,2002),with average reproducibility of^0.1to0.2.Analyses of total organic carbon(TOC)were done at the laboratory of the Israeli Ministry of Health.The analysis is based on the combustion-infrared method (Eaton et al.,1995),performed by the TOC analyzer, 5000A,Shimadzu.The precision of the method limits is5–10%.6.ResultsThe chloride,sulfate,and nitrate content in the soil proﬁles of natural soil,cultivatedﬁelds,and Wadi Arava(proﬁles A,C,D,respectively,Fig.1)are presented in Fig.4.The ionic concentrations are expressed in g/kg-dried soil.The ion concentrations in the natural soil are two orders of magnitude higher than the concentrations in the cultivatedﬁelds and Wadi Arava.The chloride and sulfate concentrations in the natural soil are around10g/kg while in the other proﬁles the chloride concentrations are below0.1g/kg and the sulfate concentrations are around 0.1g/kg.The nitrate concentration in the natural soil is about1g/kg while in the cultivatedﬁelds and Wadi Arava it is around0.01g/kg.Some of the excavations in the cultivatedﬁelds had water of the shallow lens at a depth of2–3m and their proﬁles were quite wet.The water table depth of the shallow lens rises by about30–40cm during the irrigation season,from September to March(Fig.5)and then drops again till August.Chemical and isotopic analyses of selected samples of irrigation water,irrigationþfertilizer water,soil water in and below the root zone(ceramic cups),and groundwater from the three sub-aquifers are presented in Table1.When plotting concen-trations of several ions versus Cl,the groundwater samples show a mixing line between groundwater from the local lens,which is highly contaminated,and groundwater from the lower sub-aquifer,which is mainly uncontaminated(Fig.6).The upper sub-aquifer is less contaminated and has intermediate values.In the upper sub-aquifer the salt concen-trations in the upgradient wells are lower than those of the downgradient wells(Table1).The Cl,SO4and other ionic concentration values of the water from the ceramic cups are in the same range as the local lens values.The irrigationþfertilizer water have the same concentrations of Cl,SO4,Mg,Na,Ca as theirrigation Fig.4.Ions proﬁles(Cl,SO4and NO3)in the unsaturated zone of the study area:in undisturbed natural soil(A),a cultivatedﬁeld(C)and in Wadi Arava(D)(locations in Fig.1).O.Oren et al./Journal of Hydrology290(2004)312–328317water but much higher concentrations of NO 3and K (Figs.6and 7,Table 1).The nitrate and chloride concentrations over a period of about 13years in three boreholes located at the southern side of the ﬁelds are presented in Fig.8.In the lower sub-aquifer (Marzeva 9),the nitrate and chloride concentrations are low and have been constant over the years.The nitrate concentrations are lower than 10mg/l and the chloride concentrations are about 250mg/l.In contrast,in Marzeva 10and 4,which extract water from the upper sub-aquifer,concentrations are higher and have increased for nitrate over the years,mainly since 1999.The chloride concentrations in Marzeva 4have also increased (corresponding with the nitrate increase)but in Marzeva 10,variations of the chloride concentrations were found.Fig.9presents the nitrate concentration ranges in the three aquifer units and in the ceramic cups.The nitrate values of the ceramic cups have the largest range,between 150and 700mg/l,depending on the fertilization efﬁciency and the variability in the soil.The nitrate concentrations in the local lens,between 100and 300mg/l,far exceed the standard for drinking water.The range in the lower sub-aquifer,between 5and 35mg/l,reveal the presence of nitrate at deeper groundwater levels.The potassium concentrations in the three aquifer units and in the ceramic cups are presented in Fig.10.There is a large variability of the potassium concentration in the ceramic cups and in the lens close to the surface.Another component with relatively high concen-trations in the local lens is the TOC.The TOC values in the groundwater in the local lens are around 10ppm while in the unpolluted wells they are about 0.4ppm (Table 1).Water in one of the boreholes to the local lens (Arava 16)has a value of about 200ppm,which probably represents a local source of organic matter.It also has exceptionally high concentrations of salts,TDS around 30,000mg/l,therefore it is not rep-resented as a sample of the local lens in Figs.6–7,9,and 10.The TOC value in the upper sub-aquifer is little higher than in the unpolluted wells;values of 0.6–0.8compared to 0.4ppm.The isotopic values of d 18O of the groundwater ranged between 24.3and 25.2‰(Table 1),similar to values found in former works,e.g.Gat and Galai (1982).The isotopic composition of nitrogen in nitrate was also measured in some of the samples (Table 1).The unpolluted wells,with low concentration of nitrate (below 10mg/l),have d 15N values of 6.7and 7.0‰.Nitrate leached from the virgin natural soilhasFig.5.Variation in water levels in selected boreholes of the shallow lens.Values of the water table are relative to the ﬁrst measurement.O.Oren et al./Journal of Hydrology 290(2004)312–328318somewhat higher d 15N values of 9.5and 12.0‰.This overall range of values (,7–12‰)is considered most likely to represent natural nitrate derived fromsoil organic matter (Densmore and Bo¨hlke,2000).In contrast,the fertilizer nitrates have d 15N values close to zero (0.9and 2.7‰)and nitrate in the drainage water from the root zone (ceramic cups,20–40cm depth)has an isotopic composition similar to that of the fertilizers used above (Table 1).The polluted boreholes have a wide range of d 15N values,between 4.9and 14.8‰.The boreholes upgradient from the sewage ponds (Fig.1)have lower values (4.9–6.2‰)than the natural nitrate,while the downgradient boreholes have d 15N values in the range of 5.5–14.8‰,some of which are higher than the values in unpolluted wells.There is no clear relation between d 15N values and either nitrate or chloride concentrations (Fig.11).7.DiscussionThe results of this study indicate that intensive irrigation in an arid environment signiﬁcantly affects the groundwater recharge.Low irrigation efﬁciency contributes large additions of water to the hydro-logical system.The recharge coefﬁcient of the irrigation water was estimated from the salt concen-tration factor.This was calculated by dividing the ion concentration in the local groundwater lens by the ion concentration in the irrigation water.The calculation was made only for ions that are considered con-servative and not uptaken by plants.Almost the same factor,of about 2.2,was found for Cl,Na,Mg and Sr,indicating that 55%of the water is lost by evapo-transpiration and the rest 45%inﬁltrates towards the groundwater.This means that from the 7.5–8million m 3of irrigation water per year,about 3.6million m 3inﬁltrates every year.Within the irrigated area,this is equivalent to about 0.65m per unit area.The inﬁltrating water from the ﬁelds is expected to raise the water table level.Indeed,there is a rise in the water table of the local lens of about 30–40cm from September to March (Fig.5).Although,this rise is much smaller than the expected value, 1.3m in September–March (calculation was done by dividing the excess irrigation water by porosity),it can be explained by down ﬂow of 70%of the rechargeT a b l e 1(c o n t i n u e d )N a m eD e s c r i p t i o nD a t eN a (m g /l )K (m g /l )C a (m g /l )M g (m g /l )C l (m g /l )S O 4(m g /l )H C O 3(m g /l )N O 3(m g /l )B r (m g /l )S r (m g /l )T D S (m g /l )T O C (m g /l )d 15N N O 3(‰)d 18O H 2O(‰)T r i t i u m (T U )N a /C l (e q ./e q .)K /C l (e q ./e q .)N O 3/C l (e q ./e q .)H a z e v a 15U n p o l l u t e d w e l l14/10/011679156702504352444,1.04.513407.01.030.030.01H a z e v a 13a 14/10/011649146702404402567,1.04.413366.71.050.030.02H a z e v a 1708/04/0224810192101422587245102.65.918230.4b0.910.020.01J -38s o i l ,A p r o ﬁl e eN a t u r a l s o i l25/06/0170131211702,0.020.07619.50.01,0.010.07O -96s o i l ,B p r o ﬁl e e18/07/01160702323010.037012.00.01,0.010.017-1-7F e r t i l i z e r s18/09/01172712.76-6-618/09/01203710.9aO -18s a m p l e d a t 6/12/01.bT O C s a m p l e d a t 8/4/02.cO -18s a m p l e d a t 10/9/01.4O -18a n d T r i t i u m s a m p l e d a t 18/6/01.eS a l t c o n c e n t r a t i o n s i n g r /k g d r y s o i l .O.Oren et al./Journal of Hydrology 290(2004)312–328320O.Oren et al./Journal of Hydrology290(2004)312–328321Fig.6.SO4,Mg,and NO3concentrations versus Cl concentrations for several water types(aquifers).Note that Cl,Mg,and SO4concentrationslens.fall on a mixing line between the lower sub aquifer,through the upper sub aquifer,and the local Array Fig.7.Ion equivalent ratios versus Cl concentrations for several water types(aquifers).amount towards the upper sub-aquifer.The water level drop from April to August can be explained by decrease of the irrigation amounts and increase of the evapotranspiration rate.The water level decrease means that the recharge rate is less than the downward ﬂow rate from the local lens to the upper sub-aquifer.The dependence of the water table on irrigation activity indicates that this is the main recharge source to the local lens.The natural recharge from ﬂoods depends on the rainfall in the whole basin each year.However,it is difﬁcult to estimate how much water reaches the water table from this source.The natural recharge seems negligible in comparison to the recharge from irrigation,at least in the period from September 2001to November 2002.In that period only two ﬂash ﬂoods crossed the study area in Wadi Arava for about 24–36h,above and along-side the shallow boreholes.According to the small decrease in groundwater temperature and to the temporary water level rise below the stream in the second ﬂow,it seems that waters from the ﬂoods reached the water table,but their contribution,relative to the recharge from irrigation,was insigniﬁcant.Recharge from excess irrigation water was also found to be most signiﬁcant in Sacramento Valley,California (80%of the recent recharge,Criss and Davisson,1996).Fig.8.Nitrate and chloride concentrations in the years 1987–2002in three wells:Marzeva 10and 4,upper sub-aquifer;Marzeva 9,lowersub-aquifer.Fig.9.Nitrate concentration ranges and average (squares)of the three aquifer units,unpolluted wells and ceramic cups.O.Oren et al./Journal of Hydrology 290(2004)312–328322Fig.11.d 15N values against NO 3and Cl of selected samples.The ion concentrations of the soils cannot be expressed in mg/l so they are out of the scale.Line A represents a hypothetical mixture between natural groundwater and excess “irrigation þfertilizer”water,and line B represents a hypothetical mixture between natural groundwater and sewage or manure source.O.Oren et al./Journal of Hydrology 290(2004)312–328323The tritium concentrations also conﬁrm that the main recharge comes from irrigation water,whose source is regional groundwater,and not from the ﬂoods.This is indicated by low tritium concentration in the shallow groundwater in the studied area(e.g.0.5–1.3TU in the local lens),which is similar to the values in the regional aquifers(Yechieli et al.,1997) but different from those in modernﬂood waters (4.1–6TU,Yechieli et al.,2001).Unlike the tritium,the stable isotopic composition of the water does not help to distinguish between the recharge sources.According to Yechieli et al.(2001) the d18O values of the rains in the Arava Valley ranges between22.8and27.5‰(average of 24.9‰)and those of theﬂoods,between25.1and 26.6‰.These values are close to the values of the irrigation and ceramic cups waters that were measured in this work(25.3to25.9‰).Therefore,the different sources cannot be distinguished by the d18O composition.The somewhat higher d18O values of the local lens (24.3to4.9‰)related to the recharge sources may indicate some evaporation during inﬁltration in the unsaturated zone.The correlation between d18O values and Cl,SO4and NO3concentrations(Oren, 2003)may indicate recharge of evaporative irrigation water,such as found in the Sacramento Valley by Davisson and Criss(1993).In the cultivatedﬁelds and Wadi Arava there is a ﬂushing process,indicated by the low salt concen-trations in the soil proﬁles,while in the undisturbed natural soil there is a salt accumulation process (Fig.4).Displacement of the salt below2–2.5m in the cultivatedﬁelds proves that the water inﬁltrates below this level towards the water table.Under a signiﬁcant part of theﬁelds,the shallow water table of the local lens is located2–5m below the surface; hence the salts reach the groundwater rapidly.It is, therefore,reasonable to maintain that irrigation water recharges the groundwater.The presence of salts, including gypsum and halite near the surface in the undisturbed natural soil,is typical in arid regions, whereﬂushing by rain is negligible.The effect of salinization in the Arava Valley due to recharge by excess irrigation water was previously reported in several preliminary works(Naor and Granit,1991,2000).The results of the present study indicate that intensive irrigation and fertilization signiﬁcantly affect the groundwater quality by two main contamination processes:(1)salinization due to circulation of salts dissolved in the irrigation water itself,mainly chloride,sulfate,sodium and calcium, and(2)direct input of nitrate and potassium from fertilizers and sewage ponds.The behavior of the main ions in the irrigation water(e.g.chloride,sulfate,magnesium,sodium and calcium)is conservative,while the fertilizer ions (nitrate and potassium)concentrations are reduced because they are uptaken by plants.Whereas the salt concentration factor due to evapotranspiration of the ‘irrigationþfertilizers’water is about 2.2,the nitrate and potassium concentration factors are less than1(0.7and0.5,respectively).This difference is consistent with selective uptake of nitrate and potassium by plants and also potassium sorption by clays.One of the most important problems related to irrigation in arid zones,where groundwater tends to be brackish or saline,is the recycling of salts.Salts in groundwater that is used for irrigation penetrate to the aquifer system again after evapotranspiration with higher concentration.The major salts are not taken up substantially by plants and therefore eventually reach the water table.It is possible to estimate the salt mass addition by multiplying the chloride concentration in the irrigation water(370mg/l)and the irrigation water volume(about1.4m3/m2),yielding about520g/m2of chloride per year.A similar calculation yields an addition of280g/m2sodium,740g/m2sulfate and 280g/m2calcium per year.The same process of salt circulation was found in a semi-arid area in Portugal, where the excess evaporative irrigation water caused chloride concentration increase,ion exchange and calcite precipitation(Stigter et al.,1998).These hydrochemical processes and possibly also dissol-ution might occur in the case herein too,but are not very signiﬁcantThe inverse relation between the depth of the aquifer units and the ion concentrations indicates that the contamination comes from the surface.This conclusion can be shown from the linear mixing lines between the major ions in the sub-aquifers(Fig.6). The lower sub-aquifer is interpreted to represent mainly natural water fromﬂoods,whereas in the groundwater closer to surface,the contaminant component is higher.O.Oren et al./Journal of Hydrology290(2004)312–328 324。

地下水科学专业英语

地下水科学专业英语地下水科学是研究地下水的起源、分布、运动、质量、利用和管理等方面的一门学科。

随着全球水资源的日益紧缺，地下水作为一种重要的水资源形式，其研究和管理变得越来越重要。

在这篇文章中，我们将介绍地下水科学中常用的英语词汇和表达方式。

1. 基本概念地下水：Groundwater地下水位：Groundwater level地下水文循环：Groundwater hydrological cycle地下水补给：Groundwater recharge地下水排泄：Groundwater discharge地下水流：Groundwater flow地下水流向：Groundwater flow direction地下水流速：Groundwater velocity渗透率：Permeability孔隙度：Porosity水头：Hydraulic head2. 地下水质量地下水质量是指地下水中包含的化学物质、微生物和其他物质的种类和浓度。

以下是一些常用的地下水质量相关术语：水质：Water quality污染：Pollution污染物：Pollutant水体污染：Water body pollution水质标准：Water quality standard水质监测：Water quality monitoring水质评价：Water quality assessment水质污染控制：Water quality pollution control3. 地下水利用地下水是一种重要的水资源形式，广泛应用于饮用水、农业灌溉、工业生产等方面。

以下是一些常用的地下水利用相关术语：地下水开采：Groundwater exploitation地下水抽取：Groundwater pumping地下水利用：Groundwater utilization地下水补给量：Groundwater recharge rate地下水可持续利用：Sustainable groundwater utilization 地下水资源评价：Groundwater resource assessment地下水资源管理：Groundwater resource management4. 地下水工程地下水工程是指利用地下水资源进行的各种工程活动，包括地下水开采、地下水治理、地下水调控等。

地下水模型Feflow介绍

PEST for parameter estimation, legend editor, improved map manager, reference distributions, DAVIS for 3D visualization
Extended zooming tools, improved coordinate handling, new mesh editor, non-linear dispersion, improved phreatic mode, new features in FEPLOT
12:00 午饭（Break for Lunch）
13:00 FEFLOW操作（Step by step using FEFLOW）
14:00 休息（Break）
14:15 FEFLOW建立二维地下水模型（Step by step set up 2D groundwater model ）
16:30 第一天培训结束
FORTRAN user-oriented batch program; implementations for IBM 370, EC 1055, BESM-6; limited pre- and postprocessing;
First interactive prototype for Sun workstations; rewritten in C for Sun-3 and Sun-4 workstations
Training program
Sa. 24th March 2007
8:30
建立二维地下水模型 (Step by step set up 2D groundwater model )
10:00 休息（Break）

等潜水位线数值的意思

等潜水位线数值的意思英文回答：The term "equilibrium water table" refers to the level at which the underground water pressure is equal to the atmospheric pressure. It is the imaginary line that represents the height to which water would rise in a well if it were drilled into the ground. The equilibrium water table is influenced by factors such as rainfall, groundwater recharge, and the geology of the area.The numerical value of the equilibrium water table represents the depth at which the water level is found below the ground surface. This value is typically measured in units of length, such as meters or feet. It is an important parameter in hydrogeology and groundwater management, as it helps determine the availability and sustainability of groundwater resources.Understanding the numerical value of the equilibriumwater table is crucial for various purposes. For example, it helps in determining the depth at which wells should be drilled to access groundwater. It also aids in assessing the potential for groundwater contamination and designing appropriate remediation strategies. Additionally, knowledge of the equilibrium water table is essential for understanding the movement of groundwater and its interaction with surface water bodies.中文回答："等潜水位线数值"是指地下水压力与大气压力相等的水平线。

groundwater for sustainable development

groundwater for sustainabledevelopmentIntroduction Groundwater is a vital source of water in many regions of the world, and its importance to the sustainability of development cannot be overstated. Groundwater is often the only source of drinking water for rural populations, and its availability is essential for food production and economic growth. As such, sustainable groundwater management is an important component of sustainable development.What is Groundwater? Groundwater is the water that exists below the ground surface in aquifers, or underground storage reservoirs. It is formed when precipitation infiltrates the soil and is stored in the pores and fractures of subsurface rocks and sediment. This water can remain stored in the ground for centuries, and it provides areliable source of water for many communities,especially in arid and semi-arid climates where surface water is scarce.Importance of Groundwater for Sustainable Development Groundwater is a critical resource for sustainable development. It provides a reliable source of water for basic needs like drinking, cooking, and sanitation, as well as foragricultural and industrial activities. In addition, groundwater is often used to supplement surface water supplies during times of drought or when surface water sources are polluted or depleted.Groundwater is also an important source of energy, as it can be used to generate electricity through geothermal power plants. Furthermore, groundwater helps to maintain stream flow and water quality, which is essential for aquatic ecosystems, recreation, and other activities.Challenges to Groundwater Sustainability Groundwater resources face a number of challenges that threaten their sustainability. These include population growth, urbanization, industrialization,climate change, pollution, and overexploitation. In particular, overexploitation of groundwater has become a major issue in many parts of the world. This is due to the fact that it is often easier and cheaper to extract large quantities of groundwater than to develop alternative sources of water. This has led to the depletion of aquifers and has put many communities at risk of water scarcity.Solutions to Improve Groundwater Sustainability Fortunately, there are a number of solutions that can be implemented to improve groundwater sustainability. These include improving water use efficiency, developing alternative sources of water, increasing public awareness, implementing regulations, and improving infrastructure. Additionally, watershed management strategies, such as recharge projects and artificial aquifer recharge, can help to replenish groundwater resources.Conclusion In conclusion, groundwater is avital resource for sustainable development. Its importance to the sustainability of developmentcannot be overstated. However, groundwater resources face a number of challenges that threaten their sustainability. Fortunately, there are a number of solutions that can be implemented to improve groundwater sustainability and ensure its availability for future generations.。

《水文地质基础》第六章地下水的补给与排泄

第1节地下水的补给
Groundwater recharge
补给方式：大气降水入渗、地表水入渗、凝
结水入渗、其他含水层或含水系统、人工补给
补给量(Incremeng of aquifer)的确定：
研究每一种补给方式的补给量大小
影响补给量大小的因素：讨论每一种补给
方式的影响因素
第1节地下水的补给—大气降水入渗补给
(Interaquifer flow; Flow across)
影响补给量大小的因素
两个含水层之间的水头差；裂隙、断层的透水性；弱透水层的透水性及厚度
越流补给量的确定：
K —— 弱透水层垂向渗透系数；
(Coefficient of permeability) I —— 驱动越流的水力梯度；
系：
地表水入渗补给量的确定
平原地区。选择符合下列条件的典型渗漏地段 ⑴ 无支流 ⑵ 无降水 ⑶ 无取水排水 ⑷ 河流两侧岩性均一
实测河段上、下游断面流量Q1和Q2
则渗漏量△Q为：
△Q = Q1 – Q2 根据△Q 的大小确定地表水与地下水的补排关系和渗漏量。
此法不适用于间歇性河流及侧向径流强烈，潜水位与河水位不相连的经常性河流。因为消耗于包气带的水量占相当比例，误差较大。
人工回灌
采用有计划的人为措施补充含水量的水量称为人工
补给地下水。其目的有：
补充、储存地下水资源；抬高地下水位以改善地下水开采条件；储存热源以用于锅炉用水；储存冷源用于空调冷却；控制地面沉降；防止海水倒灌与咸水入侵含水层；
第2节地下水的排泄
Groundwater discharge
按出露原因：侵蚀泉、接触泉、溢流泉——下降泉 (Destructional spring;boundary spring, Contact spring; Overflowing spring) 侵蚀泉、断层泉、接触带泉——上升泉 (Fault spring)

地下水循环井技术工艺流程

地下水循环井技术工艺流程Groundwater recharge wells, also known as groundwater replenishment wells, are an important technique used to augment and maintain groundwater levels. Through the process of injecting surplus water into the ground, these wells help replenish aquifers and ensure a sustainable supply of groundwater for various purposes. Often used in areas facing water scarcity or depletion, groundwater recharge wells play a crucial role in managing water resources and preventing overexploitation of groundwater reserves.地下水循环井，又称地下水补给井，是一种重要的技术，用于增加和维持地下水位。

通过将多余的水注入地下，这些井有助于补充含水层，确保各种用途的可持续地下水供应。

地下水循环井通常用于面临水资源匮乏或枯竭的地区，对于管理水资源、防止过度开采地下水储备发挥着至关重要的作用。

The process of groundwater recharge through wells involves various components and stages. Firstly, surplus water from sources such as stormwater runoff, treated wastewater, or excess surface water is collected and treated to remove impurities and contaminants. Next, the treated water is injected into the ground through recharge wells,where it percolates through the soil and replenishes the aquifers below. Monitoring and evaluation of groundwater levels, water quality, and recharge rates are essential to ensure the effectiveness and sustainability of the recharge process.通过井进行地下水充实的过程涉及各种组件和阶段。

基于U-D分解卡尔曼滤波地下水污染源溯源辨识

中国环境科学 2021,41(2)：713~719 China Environmental Science 基于U-D分解卡尔曼滤波地下水污染源溯源辨识贾顺卿1,2,卢文喜1,2*,李久辉1,2,白玉堃1,2(1.吉林大学地下水与资源环境教育部重点实验室,吉林长春 130012；2.吉林大学新能源与环境学院,吉林长春 130012)摘要：采用基于U-D分解的卡尔曼滤波与非线性规划优化模型相结合,溯源辨识出地下水污染源的个数､位置与释放强度.基于一个假想例子,建立地下水污染质数值模拟模型,运用灵敏度分析筛选出对模型影响较大的参数作为模型中的随机变量.然后,应用基于U-D分解的卡尔曼滤波辨识出污染源的个数与位置.在此基础上建立辨识污染源释放强度的优化模型,应用克里格插值法建立地下水污染质运移数值模拟模型的替代模型,代替模拟模型,作为约束条件嵌入优化模型中,运用遗传算法求解优化模型辨识出地下水污染源源强.结果表明:采用基于U-D分解的卡尔曼滤波方法能够保证滤波的稳定性,有效识别出污染源的个数和位置;非线性规划优化模型,可以辨识出污染源释放强度.在优化模型的求解过程中,应用克里格方法建立模拟模型的替代模型嵌入优化模型,能在保证一定精度的情况下,大幅度减少计算负荷和计算时间.关键词：地下水；污染源溯源辨识；U-D分解卡尔曼滤波；替代模型；遗传算法中图分类号：X523 文献标识码：A 文章编号：1000-6923(2021)02-0713-07Inversion identification of groundwater contamination source based on U-D factorization Kalman filter. JIA Shun-qing1,2, LU Wen-xi1,2*, LI Jiu-hui1,2, BAI Yu-kun1,2 (1.Key Laboratory of Groundwater Resources and Environment Ministry of Education, Jilin University, Changchun 130012, China；2.College of Environment and Resources, Jilin University, Changchun 130012, China). China Environmental Science, 2021,41(2)：713~719Abstract：This paper uses U-D factorization Kalman filtering and a nonlinear programming optimization model to identify the number, location, and release intensity of groundwater pollution sources. Based on a hypothetical example, a numerical simulation model of groundwater contamination was established, and the parameters having large influences on the model were selected as random variables in the model by using sensitivity analysis. Then, Kalman filtering based on U-D factorization was used to identify the number and location of pollution sources. On the basis of these processes, an optimization model for identifying the release intensity of contamination sources was established, and a Kriging interpolation method was used to establish an Surrogate model for the numerical simulation model of groundwater pollution transport, as an alternative of the simulation model, which was embedded in the optimization model as a constraint condition, and the genetic algorithm was applied to solve the optimization model. Finally, the source strength of groundwater pollution was identified. The results show that the Kalman filter method based on U-D factorization could ensure the stability of the filter and effectively identify the number and location of pollution sources; the nonlinear programming optimization model could identify the release intensity of pollution sources. In the process of solving the optimization model, a substitute model of the simulation model embedded the optimization model was built with the Kriging method, which could greatly reduce the calculation load and time under the condition of a certain accuracy.Key words：groundwater；contamination source identification；Kalman filter with UD factorization；Surrogate model;genetic algorithm地下水作为人类生存与社会发展必要的自然资源,近年来遭受的污染问题愈发严重.地下水污染难以监测,不易治理.地下水污染溯源识别是地下水污染修复与治理过程中的重要一环,能提供污染源空间分布、污染物释放历史等信息,为其治理提供参考依据.卡尔曼滤波是求解地下水污染反问题的一种有效方法[1].卡尔曼滤波作为一种最优状态估计方法,可以应用于受随机干扰的动态系统[2-3]. Herrera[4], Schmidt等[5]应用卡尔曼滤波对地下水水质监测网进行时空优化;Dokou[6]尝试使用卡尔曼滤波创建一个最优的搜索策略,使用最少的水质样本来识别DNAPL来源[6],Jiang等[7],江思珉等[8-9],顾文龙等[10]应用基于卡尔曼滤波技术和模糊集理论识别污染羽的方法.常规卡尔曼滤波可能出现矩阵协方差非对称或者负定的情况[11-12],崔尚进将卡尔曼滤波协方差矩阵进行U-D分解,提高了卡尔曼滤波的稳定收稿日期：2020-06-10基金项目：国家自然科学基金资助项目(41972252)* 责任作者, 教授,***************.cn714 中国环境科学 41卷性[13].Chen等[14], Xu等[15-16]使用集合卡尔曼滤波对二维确定性含水层中的污染源进行了溯源辨识[14-16];场地信息存在不确定性[17-18],白玉堃等[19]采用灵敏度分析筛选出灵敏度最高的参数作为随机变量进行污染源反演.结合前人研究,本文运用U-D分解卡尔曼滤波识别污染源的个数与位置,在此基础上建立优化模型,采用克里格插值法建立替代模型并嵌入优化模型,运用遗传算法求解优化模型得到污染源源强.1研究方法1.1技术路线图1 污染源反演技术路线Fig.1 Flow chart of contamination source identification首先应用U-D分解卡尔曼滤波反演污染源的个数与位置.在现场调查与动态监测的基础上,结合专家意见初步估计污染源潜在的个数､位置以及初始权重,构建地下水溶质运移模拟模型.考虑场地信息存在不确定性,对场地参数进行灵敏度分析,筛选出灵敏度最高的参数作为随机变量,其余参数作为确定型变量.给出随机变量一个取值范围,由拉丁超立方抽样生成参数随机场,采用蒙特卡罗法将参数随机场输入模拟模型生成溶质浓度场库,结合各潜在污染源初始权重计算得到初始综合浓度场与误差协方差矩阵.对误差协方差矩阵进行U-D分解,结合采样点数据运用U-D分解卡尔曼滤波对污染浓度场和潜在污染源权重进行更新,权重稳定后判断污染源的个数与位置.在识别出污染源个数与位置的基础上建立优化模型,进行污染源释放强度反演.以污染物监测浓度与模拟计算浓度拟合误差极小化为目标函数,污染源释放强度为待求变量,替代模型作为优化模型等式约束条件,同时考虑源强上下限等约束条件,建立非线性规划优化模型,运用遗传算法求解优化模型反演出污染源释放强度.为了减小求解优化模型时调用模拟模型产生的运算负荷,建立溶质运移模拟模型的克里格替代模型.1.2灵敏度分析与浓度场库建立灵敏度分析可反应模型输出对参数变化的敏感程度,本文采用Morris全局灵敏度分析方法评价参数变化对模型输出的影响,选出影响程度最大的参数进行研究.Morris设计采用“一次只改变一个参数”的抽样取值方法,轮流计算各参数的目标函数值,从而得到各个参数全局灵敏度及参数间相关性和非线性的定性描述[20-21]:11EE[(,...,,,,...,)()]/i i i i i i k iy x x x x x y x−+=+Δ−Δ (1)式中:EE i为第i个参数变化引起的变化效应, {}12,,,kX x x x=…为模型()y x的k个参数.采用文献[20]中的修正化方法进行评价,用影响值S i判断参数变化对模型输出值的影响1000()i ii iiy y y x xSx−−−=Δ=Δ(2)多次抽样取均值10011()11n niii iiy y yS Sn n−==−==Δ∑∑ (3) 把研究区用网格剖分,将筛选出的参数进行拉丁超立方抽样得到n组随机变量参数场,只考虑一个潜在污染源时,输入模拟模型得到对应的n组溶质浓度场,m个潜在污染源共m n×组.计算每个网格上参数场取不同值时浓度值的均值,就得到了该污染源的均值浓度场.在同一随机变量参数场下,m个污染源的溶质浓度场按照初始权重进行加权叠加得到叠加浓度场.将m个污染源的均值浓度场按初始权重进行加权叠加得到初始综合浓度场.1.3U-D分解卡尔曼滤波常规卡尔曼滤波存在数值稳定性较差,计算复2期贾顺卿等：基于U -D 分解卡尔曼滤波地下水污染源溯源辨识 715杂等问题,针对这一点可引入U -D 分解改进.常规卡尔曼滤波更新方程[8-9]:1[][][]T T r C C Z C I −−−+−−+−=×+=+−=−K P H HP H K H P KH P (4)式中:K 为卡尔曼增益矩阵,P 为n 阶误差协方差矩阵,C 为n 维状态向量,表示浓度估计值;-、+号表示先验估计与后验估计;Z 为采样值,r 是采样误差的方差,H 是1×n 阶量测矩阵,采样点处矩阵元素为1,其余位置为0,[00,1,00]H =K K ;I 是n 阶单位向量.P 矩阵更新时矩阵相减易导致矩阵稳定性降低,甚至引发滤波发散,将P 矩阵分解为P =UDU T 的形式,方程表示如下:1[]g a C C K Z A B−−+−−+−+=××=+−=×=K U HC U U D (5)其中1TTTTa g rg f fHa g g ABA−−−−−=××+=×=×−××=H U D U D (6) 式中:U 为单位上三角矩阵;D 为正定对角矩阵. 1.4 权重更新每个潜在污染源均值浓度场对应的污染羽为单个污染羽,综合浓度场对应的污染羽为综合污染羽.确定污染源的个数与位置需要通过污染源权重判断,将综合污染羽与单个污染羽标准化,用模糊集表示(所有浓度值除以最大浓度值),每个模糊集合的元素隶属度都大于等于给定的αi ,本文取值为0.2、0.4、0.6、0.8.将以模糊集形式表示的综合污染羽与各单个污染羽进行比较,记录二者的公共面积S i ,计算出全局相似度并用各污染源全局相似度除以各污染源全局相似度中的最大者,即可算得各污染源的权重.全局相似度为[7-9]:1ni i i g S α==∑ (7) 式中:g 为全局相似度;αi 为模糊集标准值,1,2,i =…;S i 为综合污染羽与单个污染羽在同一αi下的交叉面积.图2 污染羽对比示意Fig.2 Comparison of pollution plumes1.5 优化模型建立以污染物监测浓度与模拟计算浓度拟合误差极小化为目标函数,污染源释放强度为待求变量,替代模型作为优化模型等式约束条件,同时考虑源强上下限等约束条件,建立非线性规划优化模型目标函数:21ˆmin ()(-)nk k k Z q c c==∑ (8) 约束条件:min max q q q ≤≤ (9)()k c f q = (10)式中, q 为污染源释放强度,n 为采样点个数,c k 为替代模型输出的模拟值,ˆk c 为实测值,f 为替代模型. 1.6 替代模型应用遗传算法求解优化模型的过程中会大量调用溶质运移模拟模型,使用克里格方法建立溶质运移模拟模型的替代模型能有效减少运算负荷.替代模型回归方程为1ˆ()()()()()nT i i yx f x Z x f x Z x ββ=+=+∑ (11) 式中:ˆ()yx 为()y x 的估计值,()y x 为要求解的污染物浓度值;()T f x β是线性回归部分,()Z x 是随机部分;12()[(),()()]n f x f x f x f x =K 为模型的基函数,12[,]n ββββ=K 为基函数系数,可应用训练数据求出,()Z x 满足以下条件:22(())0(())cov[(),()](,)i j i j E Z x D Z x Z x Z x R x x σσ⎧=⎪⎪=⎨⎪=⎪⎩ (12) (,)i j R x x 为任意两点,i j x x 之间的关联函数,本文采用高斯型关联函数表示:716 中国环境科学 41卷1(,)exp(||)nij i j k k k R x x x x θ=−−∑ (13)式中:k θ为待定参数,ik x 为第i 个样本第k 维坐标.克里格模型中,点x 的响应值()y x 的估计值为1ˆ()()()T T y x f r x R y f ββ−=+− (14) 式中:()r x 为点x 与n 个采样点12(,,,)n x x x K 的相关向量, 12()[(,),(,),,(,)]n r x R x x R x x R x x =K ;y 为n 个采样点对应的响应值,为1n ×阶向量;β为待定参数,可以通过最优线性无偏估计求得:11()T T T f R f f R y β−−= (15)相关矩阵R 可表示为:1111(,)(,)(,)(,)n n n n R x x R x x R R x x R x x ⎛⎞⎜⎟=⎜⎟⎜⎟⎝⎠L M O M L (16) 方差2σ可表示为:21()()/T y f R y f n σββ−=−− (17)替代模型通过求解上面的非线性无约束优化问题来实现,待定参数k θ可通过一个无约束优化问题求得:2min{ln ln ||}n R σ+ (18)2 假想算例 2.1 问题概述图3 污染场地Fig.3 The plan of contaminated site假定研究区大小为1000m ×1000m,潜水含水层厚度为20m,介质为粗砂,含水层非均质各向同性.忽略非饱和带的影响.南北边界为已知水头边界,以含水层底板为基准面,北边界水位为16m,南边界水位为14m;东西边界为隔水边界.模型模拟时间长度为500d,分为5个时段,每个时段为100d.研究区接受降雨入渗补给,5个时段降水量分别为100,300, 100,50, 100mm.忽略研究区蒸发蒸腾作用的影响.结合场地信息与专家经验,估计潜在污染源个数为4个(图3),并给出潜在污染源的初始权重(权重表示潜在污染源为真实污染源的可能性大小,取值0~1之间),Ⅰ、Ⅱ、Ⅲ、Ⅳ号污染源分别为0.6、0.7、0.7、0.6.设定Ⅲ号为真实污染源,污染源泄漏流量为2000mg/d. 2.2 问题分析2.2.1 位置个数反演将研究区剖分成20×20的网格,应用GMS 软件的MODFLOW 和MT3DMS 模块建立溶质运移模拟模型,考虑场地信息的不确定性,对模型中的参数进行Morris 全局灵敏度分析,筛选出渗透系数K ､纵向弥散系数L d 、给水度S y ､降雨入渗补给系数α灵敏度最高的参数作为随机变量.共有15种组合方式,具体方法参照文献[21].表1 参数组合方式Table 1 Co mbinatio n -patterns of parameters组号 1 2 3 4 5 参数 K L dS y α K,L d组号 6 7 8 9 10参数 K,S y K,α L d ,S yL d ,α S y ,α组号 11 12 13 14 15参数K,L d ,S y K,L d ,α K,S y ,α L d ,S y ,α K,L d ,S y ,α0.20.40.60.811.21.41234567 8 9 10 11 12 131415组号灵敏度图4 参数灵敏度分析Fig.4 Sensitivity analysis of parameters从图4可以看出,渗透系数灵敏度最高,本研究将渗透系数作为随机变量,其余参数作为确定性变量,应用拉丁超立方抽样生成110组渗透系数随机场并进行相关性排序,场地存在4个潜在污染源,输2期贾顺卿等：基于U -D 分解卡尔曼滤波地下水污染源溯源辨识 717入模型得到4×110组溶质浓度场,计算得出初始综合浓度场和误差协方差矩阵,Ⅲ号污染源的均值浓度场作为真实浓度场.x (m)y (m )图5 真实污染羽 Fig.5 True po llutio n plume将采样点数据带入U -D 分解卡尔曼滤波更新方程对综合浓度场和污染源权重进行更新,图为浓度场和权重更新结果.图5为污染源真实污染羽,图6为初始综合污染羽.从图7可以看出,经过4次采样更新后,综合污染羽逐渐收敛于Ⅲ号污染源,与真实污染羽相似.4个污染源权重从0.6,0.7,0.7,0.6变为0,0.2,1,0.05,可以判断出Ⅲ号污染源为真实污染源,更新完成后污染羽中浓度最高处就是污染源位置.y (m )x (m)图6 初始综合污染羽Fig.6 Initial composite pollution plumex (m)y (m )x (m)y (m )a.1次更新b. 2次更新y (m )x (m)x (m)y (m )c. 3次更新d. 4次更新718中国环境科学 41卷0.20.40.60.811234污染源编号污染源权重0.20.40.60.811234污染源编号污染源权重e. 初始权重f. 4次更新后权重图7 污染羽与权重更新Fig.7 Update composite pollution plume and source location weight2.2.2 源强反演在运用U -D 分解卡尔曼滤波反演出污染源的个数和位置的基础上,建立优化模型并应用遗传算法求解.采用克里格插值法建立模拟模型的替代模型,应用拉丁超立方抽样获得80组源强,输入模拟模型得到4口采样井的输出,生成80组输入-输出样本,前60组作为训练样本,后20组作为检验样本,将平均相对误差(MRE)作为克里格替代模型近似精度的评价指标,结果见表2.表2 替代模型精度评价Table 2 Accuracy assessment of surrogate model采样点评价方法1 2 3 4 5平均相对误差 0.13% 0.08% 0.15% 0.17%0.24%确定性系数0.99 0.99 0.99 0.99 0.99由表2可知,误差精度不超过1%,替代模型符合精度要求.以污染物监测浓度与模拟计算浓度拟合误差极小化为目标函数,污染源释放强度为待求变量,替代模型作为优化模型等式约束条件,同时考虑源强上下限等约束条件,建立非线性规划优化模型.采用MATLAB 软件中的遗传算法工具箱求解优化模型,经过46次迭代求得源强1972mg/d,与真实值2000mg/d 接近,相对误差1.4%,源强反演精度较高. 3 结论3.1 将协方差矩阵进行U -D 分解,能够避免在迭代计算过程中卡尔曼滤波因为协方差矩阵可能出现不对称或者负定,导致迭代过程发散的情况,保证了卡尔曼滤波的数值稳定性,使迭代过程更容易收敛.算例表明基于U -D 分解的卡尔曼滤波,能够准确地辨识含水层中污染源的个数与位置.3.2 采用局部灵敏度分析方法筛选出渗透系数K 对模型输出影响最大,作为反映场地信息不确定性的随机变量输入模型建立浓度场库.3.3 针对污染源释放强度辨识问题,建立非线性规划优化模型.应用遗传算法求解非线性规划优化模型,能快速计算出污染源释放强度.应用克里格方法建立地下水污染质数值模拟模型的替代模型,将克里格替代模型代替模拟模型嵌入优化模型,能够在保证精度的同时减少大量的运算负荷和运算时间.参考文献：[1] 王景瑞,胡立堂.地下水污染源识别的数学方法研究进展 [J]. 水科学进展, 2017,28(6):943-952.Wang J R,Hu L T. 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Effects of the heterogeneity of multiple correlated random parameters on solute transport [J].Advances in Water Science, 2012,23(4):509-515.[19] 白玉堃,卢文喜,李久辉.卡尔曼滤波方法在地下水污染源反演中的应用 [J]. 中国环境科学, 2019,39(8):3450-3456.Bai Y K, Lu W X, Li J H,et al.Application of Kalman filter toidentify the groundwater contaminant sources [J].ChinaEnvironmental Science, 2019,39(8):3450-3456.[20] 鲁程鹏,束龙仓,刘丽红,等.基于灵敏度分析的地下水数值模拟精度适应性评价 [J]. 河海大学学报(自然科学版), 2010,38(1):26-30.Lu C P, Shu L C, Liu L H,et al.Adaptability evaluation of numericalsimulation accuracy of groundwater based on sensitivity analysis [J].Journal of Hohai University(Natural Sciences), 2010,38(1):26-30.[21] 束龙仓,王茂枚,刘瑞国,等.地下水数值模拟中的参数灵敏度分析[J]. 河海大学学报(自然科学版), 2007,(5):491-495Shu L C, Wang M M, Liu R G,et al.Sensitivity analysis of parametersin numerical simulation of groundwater [J].Journal of HohaiUniversity (Natural Sciences), 2007,(5):491-495.作者简介：贾顺卿(1997-),男,河南平顶山人,吉林大学硕士研究生,主要从事地下水污染源反演识别问题方面研究.。

地下水抽出回灌技术流程描述

地下水抽出回灌技术流程描述Groundwater extraction and recharge technology is an essential method for managing water resources, especially in regions where groundwater levels are declining due to overexploitation. This technology involves extracting groundwater from wells or boreholes, treating it if necessary, and then recharging it back into the ground through various means. The process aims to replenish the aquifer and maintain a sustainable water supply for various uses, such as irrigation, drinking water, and industrial purposes.地下水抽出和回灌技术是管理水资源的一种关键方法，特别是在由于过度开采而导致地下水位下降的地区。

这项技术涉及从井或钻孔中抽取地下水，必要时对其进行处理，然后通过各种方式将其重新充入地下。

这个过程旨在补给含水层，为灌溉、饮用水和工业用水等各种用途维持可持续的水源。

One of the main advantages of groundwater extraction and recharge technology is its ability to replenish depleted aquifers and prevent saltwater intrusion in coastal areas. By extracting groundwater and recharging it back into the ground, the natural balance of the aquifer can be restored, ensuring a continuous supply of clean water forcommunities and ecosystems. This technology also helps in managing water scarcity and reducing the reliance on surface water sources, which may be subject to pollution and seasonal variations.地下水抽出和回灌技术的主要优势之一是它能够补给枯竭的含水层，并防止海岸地区的盐水入侵。

湿地的作用和功能英语介绍

湿地的作用和功能英语介绍Wetlands, often referred to as the "kidneys of the Earth," play crucial roles in maintaining ecological balance and providing a myriad of benefits to both the environment and human populations. Here are some key functions and roles of wetlands: Biodiversity Support:Wetlands serve as unique habitats for a diverse range of plant and animal species, many of which are specially adapted to the wetland environment.They act as breeding and feeding grounds for numerous migratory birds, amphibians, and fish, contributing significantly to global biodiversity.Water Filtration:Wetlands act as natural water filters by trapping and removing pollutants, sediments, and excess nutrients from water sources.This filtration function helps maintain water quality and prevents contaminants from reaching downstream ecosystems.Flood Control:Wetlands act as natural buffers against floods by absorbing and storing excess water during heavy rainfall or storm events.The vegetation in wetlands helps to reduce the speed of floodwaters and minimize the risk of downstream flooding.Carbon Sequestration:Wetlands are essential for carbon sequestration, storing large amounts of carbon in the form of organic matter.The preservation and restoration of wetlands contribute to mitigating climate change by preventing the release of stored carbon into the atmosphere.Recreation and Tourism:Wetlands provide opportunities for recreational activities such as bird-watching, hiking, fishing, and photography.They attract tourists and nature enthusiasts, promoting eco-tourism and creating economic opportunities for local communities.Groundwater Recharge:Wetlands play a critical role in recharging groundwater by allowing water to infiltrate into the soil.This helps maintain water levels in aquifers and ensures a sustainable supply of freshwater for surrounding ecosystems and human use.Erosion Control:The dense vegetation in wetlands stabilizes soil and reduces erosion by binding the soil particles together.This prevents sedimentation in water bodies and maintains the integrity of adjacent landscapes.Nutrient Cycling:Wetlands are involved in nutrient cycling, where they absorb, store, and release nutrients such as nitrogen and phosphorus.This cycling process supports the growth of aquatic and terrestrial vegetation.Cultural and Traditional Importance:Many communities rely on wetlands for cultural and traditional practices, including the harvesting of wetland resources for food, medicine, and construction materials.Understanding and appreciating the multifaceted functions of wetlands are crucial for their conservation and sustainable management, ensuring the continued provision of these valuable ecosystem services.。

地下水脆弱性评价方法060316

地下水脆弱性评价方法的探讨及实例研究范琦王贵玲蔺文静陈浩中国地质科学院水文地质环境地质研究所，河北石家庄，050061摘要：地下水脆弱性研究是合理开发利用和保护地下水的基础，是预防地下水污染的一种有效途径。

近年来它已成为国际水文地质研究的热点问题。

本文在阐述地下水脆弱性概念及分类的基础上，指出了目前应用最为广泛的DRASTIC法的不足之处。

根据实际情况，选择了地下水埋深等4个参数作为评价因子；并以河北省中部平原区的栾城为例，应用该体系，结合GIS技术对该地区进行了脆弱性评价及分区。

关键词：地下水脆弱性DRASTIC法权重Evaluation Method of Ground Water Vulnerability and Its ApplicationFan Qi Wang Guiling Lin Wenjing Chen HaoInstitute of Hydrogeology and Environmental Geology, CAGS, shijiazhuang 050061Abstrac t：Evaluation of ground water vulnerability is an effective way to study and pre-vent ground water from pollution. The paper firstly discusses the meaning,effective factors and evalution method of ground water vulnerability;secondly puts forward the shortcom-ings in the past researches and improvement suggestions;and finally ,taking Shijiazhuang，Hengshui and Cangzhou districts in middle of Hebei Plain as an example,attempts an actu-al appication of the method.Key word s：Ground water vulnerability, Evaluation method,水是生命之源，是人类赖以生存之本，是生态环境控制因素之一。

groundwater

groundwaterGroundwater: An Invaluable Resource for Sustainable DevelopmentIntroduction:Groundwater, also known as subsurface water, is one of the Earth's most precious and valuable resources. It plays a crucial role in supporting human activities, agricultural production, and ecological systems. This document aims to provide a comprehensive overview of groundwater, exploring its characteristics, importance, challenges, and sustainable management approaches.1. Understanding Groundwater:Groundwater refers to water that exists beneath the Earth's surface in soil pores and rock formations. It primarily originates from precipitation, infiltrating the soil and percolating downwards, eventually filling the interconnected spaces within rocks and sediments. Due to its hidden nature, groundwater is often unseen and unappreciated, but its significance cannot be overstated.2. Importance of Groundwater:2.1. Drinking Water Supply:Groundwater serves as a reliable source for drinking water supply in many regions worldwide. Its natural filtration process through the soil and rock layers often ensures its purity, making it suitable for consumption.2.2. Agricultural Use:Agriculture heavily relies on groundwater for irrigation purposes. In areas where surface water is limited or unreliable, groundwater becomes a lifeline for crop growth and food production.2.3. Industrial and Municipal Water Supply:Groundwater also plays a vital role in industrial processes, serving as a source for manufacturing and cooling purposes. Many municipalities depend on groundwater reserves to meet the water demands of their residents.2.4. Ecological Support:Groundwater not only sustains human activities but also maintains aquatic ecosystems, wetlands, and springs. It serves as a vital source of water for rivers, lakes, and other surface water bodies, ensuring their ecological health and functionality.3. Challenges and Threats:Despite its importance, groundwater resources face numerous challenges and threats that require attention and proactive management measures:3.1. Over-extraction:Excessive pumping and extraction of groundwater beyond natural recharge rates can lead to an imbalance between supply and demand. Over-extraction can result in sinking water tables, land subsidence, and the depletion of aquifers, threatening long-term water availability.3.2. Contamination:Groundwater contamination is a significant concern due to the potential introduction of pollutants and contaminants. Industrial activities, improper waste disposal, and agriculturalpractices can introduce harmful substances into groundwater, rendering it unsuitable for various uses.3.3. Climate Change:Climate change alters the hydrological cycle, impacting groundwater availability and quality. Changing precipitation patterns and increased evaporation rates can reduce recharge rates, exacerbating water scarcity issues in already water-stressed regions.4. Sustainable Groundwater Management:To ensure the long-term sustainability of groundwater resources, effective management practices must be implemented:4.1. Conservation and Efficiency:Promoting water conservation practices and efficient water use in agriculture, industry, and households can alleviate the strain on groundwater resources. Implementing technologies like drip irrigation and promoting responsible water usage can contribute to sustainable groundwater management.4.2. Monitoring and Assessment:Developing robust monitoring systems to track groundwater levels and quality is crucial. Regular assessments can identify potential issues early on, enabling prompt management interventions and preventing irreversible damage.4.3. Enhanced Recharge Techniques:Strengthening natural groundwater recharge mechanisms and implementing artificial recharge techniques can boost groundwater levels. Collecting rainwater, reusing treated wastewater, and improving infiltration areas are effective strategies for enhancing recharge rates.4.4. Integrated Water Resource Management:Coordinating and integrating surface water and groundwater management is essential for sustainable water resource planning. Adopting a holistic approach that considers the interconnectedness of water sources can prevent conflicts and ensure effective water allocation.Conclusion:Groundwater plays a fundamental role in supporting human well-being, maintaining ecosystems, and driving economicdevelopment. However, its sustainable management is crucial to overcome the existing challenges related to depletion and contamination. By implementing conservation measures, monitoring systems, and integrated management approaches, societies can secure this invaluable resource for future generations, ensuring a sustainable and water-secure future.。

水利典型案例材料范文

水利典型案例材料范文英文回答：Case Study of Water Resources Management: Sustainable Water Use in an Arid Environment.Water scarcity is a critical issue in arid environments, where limited rainfall and dwindling groundwater resources pose challenges to sustainable water management. This case study presents a comprehensive approach to water conservation and sustainable use implemented in an arid region, demonstrating how innovative solutions can mitigate water shortages and ensure long-term water security.Background:The case study region, located in a semi-arid zone, faced severe water scarcity due to insufficient rainfalland overexploitation of groundwater. The increasing population and agricultural activities put further pressureon the already scarce water resources.Approach:To address water scarcity, the region embarked on a multi-pronged strategy that included:Water conservation: Implementing efficient irrigation systems, such as drip irrigation and sprinkler systems, to reduce water consumption in agriculture.Groundwater recharge: Establishing artificial recharge systems to replenish groundwater aquifers and enhance water storage capacity.Water reuse: Utilizing wastewater treatment plants to recycle and reuse wastewater for non-potable purposes, such as irrigation and industrial use.Public awareness campaigns: Educating the local population about water conservation practices and the importance of responsible water use.Implementation:The water conservation strategies were implemented through a combination of government policies, incentives, and community involvement. Farmers were encouraged to adopt modern irrigation technologies, and financial assistance was provided for the installation of efficient irrigation systems.Artificial recharge systems were developed in areas with suitable geological conditions. These systems involved capturing excess rainwater during the rainy season and directing it into underground aquifers for long-term storage.Wastewater treatment plants were upgraded to higher standards to ensure the safe reuse of wastewater. Treated wastewater was used for irrigation in parks, golf courses, and industrial settings.Public awareness campaigns were launched to educate thelocal population about the importance of water conservation and responsible water use. These campaigns promoted simple water-saving tips, such as taking shorter showers andfixing leaky faucets.Results:The implementation of these water management strategies led to significant improvements in water sustainability in the region. Agricultural water consumption was reduced by over 30%, and groundwater levels stabilized or even increased in some areas. The reuse of wastewater reduced the pressure on freshwater resources and provided an alternative source of water for non-potable uses.The public awareness campaigns raised awareness about water conservation and influenced behavior change. Thelocal population understood the importance of water conservation and adopted responsible water use practices.Conclusion:This case study demonstrates the effectiveness of a comprehensive approach to water resources management in an arid environment. By implementing innovative water conservation, groundwater recharge, water reuse, and public awareness strategies, the region was able to mitigate water scarcity and ensure long-term water security.This model can be replicated in other arid or semi-arid regions facing water challenges, providing a sustainable solution to water management and ensuring a secure water future for generations to come.中文回答：水利典型案例材料范文。

珍视地下水作文英语

珍视地下水作文英语英文：I value groundwater because it is a vital natural resource that is essential for our daily lives. Groundwater is the water found beneath the Earth's surface in soil pore spaces and in the fractures of rock formations. It is one of the most important sources of water for drinking, irrigation, and industrial use. In fact, about 30% of the world's fresh water supply comes from groundwater.Groundwater is also crucial for maintaining ecosystems and supporting biodiversity. Many plants and animals rely on groundwater for their survival, and it plays a key role in sustaining wetlands, rivers, and lakes. Without groundwater, these ecosystems would suffer and many species would be at risk of extinction.In addition, groundwater helps to recharge surface water bodies during dry periods and droughts. It acts as anatural buffer, ensuring that water is available even when rainfall is scarce. This is particularly important in regions with unpredictable weather patterns or limited access to surface water sources.Personally, I have a deep appreciation for groundwater because it has a direct impact on my life. I live in an area where groundwater is the primary source of drinking water, and I rely on it for my daily needs. I also enjoy outdoor activities such as hiking and camping, and I understand the importance of preserving groundwater for the natural environments I love to explore.I remember a time when a local community came together to protect a nearby groundwater source from pollution. There was a proposed industrial development that threatened to contaminate the groundwater with harmful chemicals. Residents organized protests, lobbied local officials, and raised awareness about the importance of safeguarding this precious resource. Their efforts paid off, and the development was halted, ensuring that the groundwater remained safe for future generations.In conclusion, groundwater is a precious resource that we must cherish and protect. It sustains our communities, ecosystems, and natural environments, and its value cannot be overstated. By understanding its importance and taking action to preserve it, we can ensure that groundwater continues to benefit us and future generations.中文：我珍视地下水，因为它是一种至关重要的自然资源，对我们的日常生活至关重要。

地下水渗流偏微分方程

地下水渗流偏微分方程英文回答：Groundwater flow is a complex process that can be described by partial differential equations (PDEs). These PDEs are used to model the movement of water through porous media underground. One commonly used PDE for groundwater flow is the groundwater flow equation, also known asDarcy's law.Darcy's law states that the rate of groundwater flow is proportional to the hydraulic gradient, which is the change in hydraulic head per unit distance. Mathematically, it can be written as:Q = -K A (dh/dl)。

where Q is the discharge rate of groundwater flow, K is the hydraulic conductivity of the porous medium, A is the cross-sectional area through which the groundwater flows,dh/dl is the change in hydraulic head per unit distance.This equation can be used to solve for the groundwater flow in a given system. For example, let's consider a scenario where we have a groundwater well that is pumping water out of an aquifer. The hydraulic conductivity of the aquifer is 10 m/day, and the cross-sectional area of the well is 1 m^2. If the hydraulic head at the well is 10 m higher than the hydraulic head at a distance of 100 m away, we can use Darcy's law to calculate the discharge rate of groundwater flow:Q = -10 1 (10/100) = -1 m^3/day.This means that the well is pumping out 1 cubic meter of groundwater per day.Another commonly used PDE for groundwater flow is the groundwater flow equation in transient conditions, which takes into account the change in hydraulic head over time. This equation can be written as:∂h/∂t = S ∇^2h + Q.where ∂h/∂t is the rate of change of hydraulic head with respect to time, S is the specific storage of the aquifer, ∇^2h is the Laplacian operator of the hydraulic head, and Q is the source/sink term.This equation is used to model the transient behaviorof groundwater flow, such as the response of an aquifer to pumping or recharge events. By solving this equation, wecan predict how the hydraulic head will change over time in a given system.For example, let's consider a scenario where we have a recharge event in an aquifer. The specific storage of the aquifer is 0.001 m^(-1), and the recharge rate is 0.1 m/day. If we want to determine how the hydraulic head will change over time, we can solve the groundwater flow equation in transient conditions:∂h/∂t = 0.001 ∇^2h + 0.1。

【doc】地下水水质参数在抽水过程中的不稳定性及其？…

地下水水质参数在抽水过程中的不稳定性及其？…地球科学——中国地质大学第25卷值稳定性等原因这种逼近还与观测数据的取样密度存在一定的内在联系对于同样一个随机过程,采样密度变了,基函数(即"协方差函数")中的参数亦应相应调整,否则将导致数值不稳定性出现(如矩阵求逆失败).基于本文的研究可得如下结论:(J)协方差参数在一定程度上与采样数据的密度(或间隔)有一定联系(2)以一维Gauss函数为例,设z.Aa-为数据间隔,则其最优参数应取d=08Z.Ax,17,.4a-],更具体的值应视实际情况或结合协方差拟合再行确定(3)对于Gauss函数,d<0.5的参数应该避免使用,否则将在逼近函数中出现许多不应有的极大值或极小值.(4)其他协方差函数参数的代数确定可依本文准则1或准则2类似确定,但应注意这些准则的前提是随机场高度连续或噪声部分已被事先确定,否则不宜盲目使用从这一点来说,这也是本文准则的一个缺陷.参考文献:[1](,nieNatjforspatialdata[MNewY ork:J0hnWiley&S0m,1991[2:WackemagelHMultivariategoc~slatlsticsM:Hdddberg:Spnngcr-V erlag,1995:3]MenzJ,,~1wendungderGeostatistikzurGebirgs-undLage~sta'ttengeometrlsierung【MJTUBergakademie,Freiberg:Forschungbericht,1996:4]MartheonGSpLinesandKriging:theirformalequivalenceindowntoearthstati~tic-s[AIn:MerrlamD,edSolutionsl~xMngforgmkxgic~Lpatterrks[C].Symcum UnlvGeolcgyContribution.1981.8:77～97[5]rnpanngsplinesandKd~ng[J]Computer&Gea~ienem,1984.10(2):327--328[6]UnserM,,addroubiAPolynomialsplineandwave]ors:a signalprocessingperspective[A].in:ChuiCK,edWavelel:atutorialintheory,andapplications:C]Boston:AcadenfiePr髑.1992q】～123ANAL YI1CALINTERPRETA TIoNT0KRIGINGESTIMATIoNAND ALGEBRAICDETERMINATIoN0lFC0V ARIANCEFUNCTIoN'SPARAMETERBianShaofengJoachimMe11z2(1.TheSurwe~qngandGeophysicalInstituteofChineseAcademyofSciences,Wuhan,4300 77,China;2BergakademieFrei~erg,09599Freiberg,Germany)Abstract:TheanalyticalinterpretationtoKrigingestimationandthealgebraicdetemlination ofaoovariancefunction'sparameterarepresented.Thispaperfirstintroducestheoo nceptoffunc tionapproximationusingarotatingsurfaceasabasicfunction.Thenitisdemonstratedthattheuniv er~lKriging maybeexpressedasthetraditionalweightedleastsquarefittingandaSthefunctionapproxima tionwitharotatingsurfaceasabasicfunctionItisalsoden]onstratedthattheparameterofacovariancefu nction(i.e.arotatingsurface)canbedeterminedbythemathematicalanalysisonacertaincondition(i.eahi ghlycontinuouslumpgold—freeeffectinarandomfield)Finally,thispaperpresentstwoprinciplesforthe determinationofaeovariancefunction'sparameterwiththeGauasianfunctionasanexample: oneis formulatedthroughanalysisofthelinearcombinationsoftheshiftedGauasianfunctions,and theotheris derivedfromtheequivalencebetweenB—splinesandGauasianfunctions. Keywords:Krlgingestimation;eovafiancefunction;geo-statisfics第25卷第2期2O00年3月地球科学——中国地质大学EarthSeioncc--Joum-a[ofChinaUniversityof~enee.qV o】25Na2Mar20I_0.t{,地下水水质参数在抽水过程中的不稳定性及其水化学模拟一以大庆市齐家水源地为例./贾国东张建立秦延君.刘金和钟佐巢——————一——————一(1中国科学院广州地球化学研究所,广州510640;2中国地质走学环境科学系,北京1000833走庆石油管理局供水公司.走皮163454)摘要:大庆市齐家水源地井口现场和实验室测定的地下水水质参数与其真实情况存在差异运用水文地球化学手段模拟了地下水从含水层被抽出至地表的过程中由于所承受压力降低不可避免地导致0,H2S等气体的逸出,从而影响pH,Eh的测定结.最后指出丁地下水霎戮水扛过经关键词差登;毫垦叁垫查些互中图分类号:P332文献标识码:A文章编号:1000—2383(2000)02—0201—04作者简介:贾国东,男,1969年生,1997年毕业于中国地质大学(北京),获博士学位.现主要从事水文地球化学研究.环境样品的采集是一项极其重要的工作.一个缺乏可靠性或没有代表性的样品没有任何分析价值.地下水环境,尤其是承压地下水环境,与地表水环境有着截然的不同,诸如没有光照,温度较低但温差变化小,处于多孔介质中,承受一定压力(承压水),缺氧甚至无氧等.地下水被采集的过程就是从这种相对封闭的环境进入地表开放环境的过程,也是地下水的水文地球化学平衡被破坏而不得不重新调整以适应新环境的过程.这种特点就使得地下水的采样工作相对要复杂得多.比如,采样前要对井筒进行抽水清洗,其抽水量与抽水速度的确定,所采水样的位置,样品处理(过滤,酸化等)过程中如何隔绝空气,某些水质参数必须在现场测试等.即使这些都给予了足够重视并进行了严格操作,笔者认为地下水水化学平衡的破坏仍难以避免,因而取得真正具有代表性的水样仍然十分困难.下面以大庆市齐家水源地为例作一详细论述.1齐家水源地泰康组含水层简介齐家水源地位于大庆油田西部地区,主要承担收藕日期19990526大庆市龙南区和让湖路区约30万人口的生活饮用水及其他用水任务.该水源地于1991年竣工投产,以开采第四系和第三系地下水为主,有水源生产井48口,设计综合供水能力l0×10m3/d.本文以第三系泰康组地下水为研究对象.该含水层岩性主要为灰白色含砾中,粗砂和砂砾,物质组成以石英为主,另有长石,燧石等矿物及花岗岩,石英岩,火山岩岩屑.含水层顶底板为灰黑色湖相淤泥质亚粘土层,隔水性好.地下水位埋深在21ITI左右,井深200多m,单井涌水量3000--8000m3/d.表1为该层地下水水化学平均成分,其中HC03和Na为水中主要的阴,阳离子,水的硬度和矿化度较高,且水中铁,锰含量超标2泰康组含水层评价本地区的水文地质工作始于20世纪60年代,为满足大庆油田的需要而展开的地下水资源调查与开发.近40年来,积累了大量水化学资料,然而,这些水化学资料基本无现场测试,样品的采集,储存等都无严格的操作规范,因而其某些水质参数的分析结果极有可能背离自然真值通过对水源地现场的实地尸^地球科学——中国地质大学第25卷表1齐家水源地泰康组含水层水化学成分平均值TabLe1Meanvaluesofgroundwaterchemic'elcxxnFositionsofiawatersopply(mg?L 表2地下水中某些矿物的饱和指数Table2Saturationindices0f∞emineralsinthegroundwater考察及对水化学数据的分析更加肯定了这一点.(1)已有水化学资料中,齐家水源地泰康组含水层地下水pH值介于74--7.8之间(室内测试).笔者在水源地现场井口取水测试,其初始pH值介于7.1～72之间,且随测试时间的延长有向高值漂移的趋势(2)井口出水中可观察到连续不断的气泡逸出,还可闻到明显的H2s气味一般情况下,coe和H2S是地下水中控制pU和E值的两个重要气体成分,取样时需倍加小一CJ,(3)溶解氧(DO)的测定需要使水样保持在与大气隔绝的环境中进行.虽然进行了现场0(DO)值测定,但却是在暴露于大气的情况下,p(DO)值介于0.5～4.0mg/L之间,可信度差.(4)泰康组含水层以富铁为一大特征.现有资料中铁的分析结果显示0(Fe3)>P(Fe2一),且常出现o(Fd)=0的现象.一般地,除非水中存在足够的有机质络合作用或者水体呈强酸性,Fe3才能在水中富集.富铁水一般应为以亚铁为主要存在状态的还原条件下的水.可见,铁的上述分析结果可能与样品的采集,保存不佳及分析不及时有关(5)以pH= 7.5,Eh=+100mV(现场实测)为条件,利用表1的平均水化学组成计算有关矿物的饱和指数见表2. 按以上数据,水中cE,M,Fe的碳酸盐和(0lH)处于过饱和态.由于泰康组地下水埋藏条件好,在水平方向和垂直方向上的水交替是很缓慢的,地下水与含水层物质问有着充分的接触,因而其所呈现的pH,Eh等主要的水化学参数在含水层中应该具有比较好的稳定性.水中ca2,M,FJ,Fle3应与相应的固相处于平衡状态故上述计算得出的过饱和数据表明所测pH,Eh可能与实测情况不符.FeS的高度不饱和则是由于上述Eh值过高, 还原态S不能在水中存在的缘故,这又与水中存在前述的s气味相矛盾,以上分析表明,泰康组地下水的实际pn,Eh,p(DO)等环境参数与地表测试结果所反映的情况相差很大.由于采样手段的落后.气体(c,H2S等)的逸出氧气的渗人难以避免,从而使pH,,p(DO)和p(Fe3一)\p(F)的分析结果都有偏高的可能.为揭示地下水所处的真实水文地球化学环境,对上述参数有必要进行尽可能的修正3抽水过程中地下水水质参数变化的水化学模拟地下水从含水层抽出至地表的过程是一个从具有较高压力,对大气封闭的还原环境进人地表常压的氧化环境的过程在抽水前后,地下水静,动水位之羞可视为井底压力的相对变化1]J.齐家水源地泰康组抽水时,其静,动水位之差平均为5.46m,即井底过滤器附近的压力比井漏斗区外的地层水压力低约053×10Pa.在水从井底抽运至地表的过程中,所受压力则更是大幅度急剧降低(从约2O×10Pa 降为1×105Pa).这就使水中溶解的cOe,UzS等气体从漏斗区边缘开始不断逸出.Clark曾报道某些深井中在过滤器部位及其上方出现气体从水中分离的现象因而在井口取样,即使进行及时而严格的现场测试,也难以保证Eh,pit测试结果的足够准确.上述导致Eh,pH测试结果失真的原因,提示我们可以运用水化学模拟手段反演抽水过程中Eh,pH的变化情况,进而恢复地下水的真实环境思路是:向失真的水样中逐渐"加入"C和s气体,直至模拟出接近真实的地下水环境那么,真实的地下水环境应如何确定?现场调查取样分析表明,在井底沉砂管内有大量化学沉淀物,主要物相为硫化铁(Fes),菱铁矿(FeCfh)和方解石(C~Cfh)据此.可以把过滤器附近的地下水界定为与上述物相处于相对过饱和状态,而含水层中地下水则与上述物相不饱和或至多接近饱和(含水层中未发现上述矿物).本文运用了PHREEQC水文地球化学模拟软件_3对表1中的水化学成分以pH=75,Eh=100mV为初始条件进行了模拟第2期贾崮东等:地下水水质参数在抽水过程中的不稳定性丑其水化学模拟——大庆市齐家水源地为例203表3抽水过程中地下水pH,E变化的水化学模拟结果Fable3HydmehemicalcaoddingresultsofgroundwaterpHEhva]uesduringpumping*摩尔浓度,单位10mol,L模拟表明,只有o32的逸出可导致CaCO3,Fe('O3的饱和沉淀,但FeS的高度不饱和状态却变化甚微;只有s的逸出可导致FeS饱和沉淀,但对CaO3~,FeCOs的饱和指数影响甚微.可见,只有cch逸出或只有s逸出都不符合实际情况.将toe和s同时加入水中来模拟二者同时逸出的情况.为此,需选择好CO2和H2s加入的比例,以便能使CaCO3,FeCO~,FeS能在一定的pH,Eh范围同时处于从不饱和向饱和转变的状态(只有这样才符合上述3种物相在沉砂管共同存在的实际情况),经多次调整,得到较为理想的结果,见表3.由表3可以看出,井底过滤器处地下水的环境条件大约为:6.9<pH<7.2,一185mV<Eh<一167mV,此时c~coa,FeO3a和FeS同时趋于饱和和过饱和,有从水中沉淀析出的趋势而含水层中地下水可能处于pH<6.7,Eh≈140～一150mV条件下,此时,CaC03不饱和,FeCO3和FeS不饱和或接近饱和.于是地下水从含水层进入过滤器附近后随着CO2,IJ2S的逸出将会产生上述3种矿物的饱和沉淀.地下水从井底到地表的过程中,CaC03, FeO3a一直是过饱和,FeS则由于s的逸出又变得不饱和,而在地表则将会出现Fe(0lH)3沉淀图1为齐家水源地泰康组含水层铁的Eh—pH稳定场图,该图据EFe,HCA和sOj的活度值绘pH图l泰康组地下水中铁的EhpH稳定场FL臣lEhpHgraphofironinTaikanggroundwaterp(Fe065mg/L,P(H(x)i)=511)mg/L()=213mg/L其中(()卜1)1为非晶志制.代表含水层(pH=6.5,Eh=140mV),过滤器(pH=7.05,Eh=一175mV)和地表实测(pH=7.5,Eh=+100mV)环境的点分别投于其上可以看出,地下水从含水层进^沉砂管后FeCOs,FeS发生共沉淀的趋势很明显,而在地表将检测到高含量的三价铁(图中以Fe代替FeS,因FeS相对于FeS)是亚稳态的).4讨论对于地下水的采样测试,大家已经公认,水质的某些参数必须在水样从井口运走之前进行测定,但并非所有水质参数必须都应或者可以实现在现场的快速测试.对此,StuartGarnerl4提出了地下水基本水质参数(pr[marygroundwaterqualityparameters)的概念,规定基本水质参数是可以通过便携式电子仪器实现低成本,高精度野外测试的那些参数,并指出温度,电导率,pU,Eh,IX)等必须包括在内.由本文研究可知,地下水在从含水层抽出至地表的过程中其基本水质参数是不稳定的,对地下水的井口取样地面现场测试,仍然不能保证基本水质参数的准确性.因此,水下定深取样,定位测试技术应该成为地下水取样测试技术的发展方向L4J.204地球科学——中国地质大学第25卷参考文献:[1.陈国富,陈虹雁,王学工等井筒内水头高度与井底压力对比实验[J:工程勘察.1997.(4):32～35[2ClarkFEThecorrosivewe¨watersofEgypt'sWGC,i~rn d~ertlAJIn:GeologicalSurvevProfes~ionPaperl757一o.CJWashin4~ton:USGovPrint(f.1979.1--50[3dLPUser's出[(]PHREEQC—acorflputer programforspeciation,reaction-path,adveefive, [rarLsport,andinverse,geochemicalcalculations[AIn: USGeologicalSurvey,edsWaterResource*Investigatio~t Report954227[CLakewood,Colorado:[s.n],l995.1～15l[4St.ar*GarnerPEMakingthemostoffieldmeasurable groundwaterqua]ityparameters_lIJ.GroundWaterM~nitoringReview,1988.Summer:60--66[5JDanielR,MordechedMAnintumultileve}saroglerfor preventivemonitoringandsludyofhydrochemicalprofiles inaquifers[J]GroundWaterMonitoringReview,1987.ll:69～74【6]KatherlneWD,DonaldLMFieldmethodsformeasurementofgmulldv,-Rte//"edoxehmJi,.:dIzeaametem【JJo.Waterblallto6.ngReview,1990,Fl:81～90 INSTABILITYOFGRoUNDWATERQUALITYPARAMETERS DURINGPUMPINGANDIIHYDR0CHEMICALSIMULATIoN:EXAMPLEFR0MQIJIAWATERSUPPL YBASE JiaGuodongZhangJimlliQinYanjunLiuJinhe3ZhongZuoshen2(1.GuangzhouInstituteC~chenlistry,ChineseAcademy,~iences,Guangzf~ou510640,Chi na;2DepartmentofEnvironmentalSciences,ChinaUniwersit3,Geosciences,B由ing100083.China3.WaterSupplyCompa,~yofDaqingAdministratio*tBureau,Daqing163454,China) Abstract:Thegroundwaterqualityparametersdeterminedbothatthewellheadandinthelabo ratoryofQijiawatersupplybase,Daqingcity,differfromwhathappensintherealsituation.Hydrogeoc hemical methodisusedtosimulatethechangesofpHandEhvaluesduetotheinevitabledegassingofC OaandHaSresultingfromthepr~sumdropintheCourseofthegroundwaterpumpingfromthewater—bearingbedtotheearthsurface.Thetrendsinthegmundwatersamplingarepr0p0sednthefinalpartofthepaper. Keywords:groundwater;.sampling;waterqualityparameter;hydrogeochernicalsimulatio n.《地球科学——中国地质大学》2000年第25卷第3期要目预告构造坡折带:断陷盆地层序分析和油气预测的重要概念……?一盆地三维构造一地层格架的矢量剪切原理及方法…………?内蒙古临汉一集宁深断裂中段早期韧性剪切带及其构造演化内蒙古固阳地区新太古代侵^岩的岩石特征及时代………..大别木子店石榴辉石岩的麻粒岩相退变质作用……………? 内蒙古固阳一带渣尔泰山群摺皱构造研究…………………" 凡口超大型铅锌矿床成矿流体的性状………………………. 内蒙古色尔腾山的推覆构造…………………………………? 林畅松田宜平李龙张维杰张泽明高德臻陈学明陈志勇。

[英语作文]How water cycle水循环是怎样的

[英语作文]How water cycle水循环是怎样的Title: The Intricate Dance of the Water CycleThe water cycle, also known as the hydrologic cycle, is nature's way of recycling water through a continuous process that involves the Earth's surface, atmosphere, and bodies of water. It ensures that our planet's water supply remains in balance, despite the fact that the amount of water on Earth remains relatively constant.The water cycle begins with evaporation, where sunlight warms water in oceans, lakes, and rivers, causing it to change into water vapor and rise into the air. This warming effect is aided by factors such as wind and temperature differences between the water and the surrounding environment.As the water vapor rises, it cools and condenses into tiny droplets, forming clouds. When these droplets become heavy enough, they fall back to Earth in the form of precipitation, such as rain, snow, sleet, or hail. This process is known as precipitation.Once on the ground, the water can take several paths. Some of it will evaporate back into the atmosphere, some will be absorbed byplants through their roots and released into the air through a process called transpiration, and the rest will flow over land and into bodies of water like streams, rivers, and eventually back to the oceans.Groundwater recharge is another significant part of the cycle. Some of the water infiltrates the ground and becomes part of the underground reservoirs, which can later discharge into surface waters or even become part of the water supply for humans.The water cycle is influenced by various factors, including climate, topography, and human activities such as deforestation and urbanization. Climate change can alter the cycle by changing patterns of precipitation and evaporation. Human-made structures like dams and levees can also disrupt natural water flows.In conclusion, the water cycle is a complex system that involves the exchange of water between the Earth's surface, the atmosphere, and living organisms. It is a delicate balance essential for life on Earth, providing fresh water for drinking, irrigation, and industry, while also shaping our landscapes and ecosystems. Understanding and protecting this vital cycle is crucial for the sustainability of our environment and the well-being of all living beings.。

水文地质学术语

第七章术语解释水文地质学 hydrogeology研究地下水的形成和分布、物理及化学性质、运动规律、开发利用和保护的科学。

地表水 surface water地球表面的各种形式天然水的总称。

地下水 groundwater埋藏于地表以下的各种形式的重力水。

承压含水层 confined aquifer具有承压水的含水层，其上界和下界是不透水层或弱透水层。

含水岩组 water-bearing formation指含水特征相近的一套岩层所构成的统一的含水岩体。

承压水 confined water充满于上下两个相对隔水层间的具有承压性质的地下水。

承压含水层厚度thickness of confined aquifer承压含水层相对隔水顶底板之间的垂直距离。

地下水补给条件condition of groundwater recharge指地下水的补给来源、补给方式、补给区面积及边界、补给量等。

地下径流 underground runoff由补给区向排泄区运动的地下水流。

地下水排泄 groundwater discharge地下水从含水层中以不同方式排泄于地表，或另一个含水层中的过程。

水文地质单元 hydrogeologic unit具有统一补给边界和补给、径流、排泄条件的地下水系统。

地下水赋存条件 groundwater occurrence地下水埋藏和分布、含水介质和含水构造等条件的总称。

地下水系统 groundwater system具有水量、水质输入、运营和输出的地下水基本单元及其组合。

降落漏斗cone of depression由抽水（排水）而形成的漏斗状的水头（水位）下降区。

地下水开采动态groundwater regime under exploitation主要由人工开采引起地下水的水位、水量、水温及化学成分等要素随时间的变化。

可分为潜水开采动态和承压水开采动态。

地下水监测网groundwater monitoring network为掌握地下水（水位、水质、流量等）的动态，对空间散布的点及其对每个点以一定时间进行观测，由此组成的网络称为地下水监测网。

水的循环英语作文

Water is an essential component of the Earths ecosystem,and it plays a vital role in the water cycle,which is a continuous process that involves the movement of water between the Earths surface,atmosphere,and underground.Heres a detailed English composition about the water cycle:Title:The Water Cycle A Journey of TransformationIntroduction:The water cycle,also known as the hydrologic cycle,is a fascinating process that sustains life on our planet.It is a complex system of evaporation,condensation,precipitation,and collection that ensures the continuous availability of water.Evaporation:The journey of water begins with evaporation.When the suns rays heat the surface of the Earth,water from oceans,lakes,and rivers turns into water vapor and rises into the atmosphere.This process is also seen in smaller bodies of water like puddles and even from the soil and plant surfaces through transpiration.Condensation:As the water vapor rises,it cools and condenses to form tiny droplets,which gather together to create clouds.This phase change from gas to liquid is known as condensation. The clouds are a result of the cooling of the air as it reaches higher altitudes where the atmospheric pressure is lower.Precipitation:When the cloud droplets grow large enough,they fall back to the Earths surface as precipitation.This can take the form of rain,snow,sleet,or hail,depending on the temperature and atmospheric conditions.Precipitation is a crucial part of the water cycle, as it replenishes the water sources on the Earths surface.Collection and Runoff:After precipitation,the water either infiltrates the ground,becoming part of the groundwater system,or it flows over the surface as runoff.Runoff collects in rivers, streams,and eventually returns to the oceans,continuing the cycle.Infiltration and Groundwater Recharge:Water that infiltrates the soil replenishes aquifers,which are underground layers of waterbearing permeable rock or unconsolidated materials.This process is known as groundwater recharge and is essential for maintaining the water table and providing water to wells and springs.Conclusion:The water cycle is a continuous and vital process that ensures the availability of fresh water for all forms of life.It is a delicate balance that is influenced by various factors such as climate,geography,and human activities.Understanding and protecting this cycle is crucial for the sustainability of our planets water resources.Reflection:As we learn about the water cycle,it is important to consider our role in its preservation. Simple actions like conserving water,protecting natural habitats,and reducing pollution can have a significant impact on maintaining the health of our water cycle and,by extension,our planet.。