First Insights on Lake General Carrera/Buenos Aires/Chelenko Water Balance

Adv. Geosci., 22, 173–179, 2009 www.adv-geosci.net/22/173/2009/ Advances in © Author(s) 2009. This work is distributed under Geosciences the Creative Commons Attribution 3.0 License.

First insights on Lake General Carrera/Buenos Aires/Chelenko water balance

G. Zambrano1, R. Abarca del Rio1, J.-F. Cretaux2, and B. Reid3 1Departamento de Geof´ısica (DGEO), Universidad de Concepcion,´ Concepcion,´ Chile 2LEGOS (UMR5566), Observatoire Midi-pyren´ ees,´ Toulouse, France 3Centro de Investigacion´ en Ecosistemas de la Patagonia (CIEP), Universidad Austral de Chile, Bilbao 449, Coyhaique, Chile Received: 19 May 2009 – Revised: 1 July 2009 – Accepted: 8 July 2009 – Published: 17 December 2009

Abstract. Lago General Carrera (Chile) also called Lago strongly influenced by perhaps the largest system of temper- Buenos Aires (Argentina) or originally Chelenko by the ate glaciers and ice fields in the world (North Patagonian Ice- native habitants of the region is located in Patagonia on field, Warren et al., 1993), and whose influence will possibly the Chilean-Argentinean border. It is the largest lake in diminish with global climate change. Chile with a surface area of 1850 km2. The lake is of Region Aysen is divided into four climatic zones (IGM glacial/tectonic origin and surrounded by the Andes moun- (1998)) (see Fig. 1): (a) a cold wet temperate, (b) a trans- tain range. The lake drains primarily to the Pacific Ocean Andean merging into steppe, (c) a sub-zero high-altitude to the west, through the Baker River (one of Chile’s largest climate, and finally (d) a cold steppe climate. The re- rivers), and intermittently eastward to the Atlantic Ocean. gion presents a highly dynamic geography that underscores We report ongoing results from an investigation of the sea- the interaction between the topography due to high alti- sonal hydrological cycle of the lake basin. The contribu- tudes who act as a barrier to wind and precipitation (Walsh, tion by river input through snowmelt from the Andes is of 1994), ocean influence and atmospheric circulation (Town- primary importance, though the lack of water input by un- ley, 2007). The atmospheric circulation is dominated by gaged rivers is also critical. We present the main variables in- westerly winds, low pressure, frontal systems (Seluchi et al., volved in the water balance of Lake General Carrera/Buenos 2000) and the South Pacific subtropical anticyclone (Rodwell Aires/Chelenko, such as influent and effluent river flows, pre- and Hoskins, 2001). cipitation, and evaporation, all this based mostly in in-situ An example of the complexity of the regional climate is information. high longitudinal precipitation gradient around the lake, approximately 1350 mm/yr, with 1470 mm/yr in the coast and 120 mm/yr in the east zone (Townley, 2007). The tempera- 1 Introduction ture is dominated by the oceanic influence on the coast, the microclimate in the interior under the influence of lakes, low Lake General Carrera/Buenos Aires/Chelenko (LGC/BA/C) temperatures in high altitude areas and a large temperature is the largest lake in Chile and the second largest lake in variation in the steppe zone (Jobbagy´ et al., 1995; Paruelo et South America, and based on a recent global review of lake al., 1969). On account of these variations in temperature and characteristics (Kalff (2001)) it is possibly the 13th largest precipitation, snow cover has a seasonal pattern, with move- and 7th deepest in the world. There are few scientific inves- ments influenced by temperature variations (73% of the vari- tigations on the biology, hydrology, and physical limnology ance explained) and precipitation in the area (Lopez´ et al., of this large and potentially very significant lake. Basic hy- 2008). drologic data exist in raw form from a network of sensors The purpose of this paper is to develop a synthesis of the maintained by the Directorate General Water (DGA in Span- existing hydrologic data, interpret the sources of variability ish acronym). Meanwhile the lake and its catchments are still over seasonal time scales, conduct a basic hydrologic mass balance, and propose recommendations that address the uncertainty and data gaps. Because of its limitations, this re- Correspondence to: G. Zambrano search intends to give a first insight on the lake level vari- ([email protected]) ability, and is a first step towards a better understanding of the

Published by Copernicus Publications on behalf of the European Geosciences Union. 1742 G. Zambrano, R. Abarca, J-F. Cretaux, G. Zambrano B. Reid: et First al.: Insights First insights on LGC/BA/C on LGC/BA/C and Water water Balance balance

Fig.Fig. 1. 1.StudyStudy site, site, showing showing the the location location of of the the in in situ situ monitoring monitoring stations and the main climatic climatic zones. zones. wholestatistical basin methods hydrological used for balance analysis and are probable explained influences in section by 2.2the lake Method level variability (r2=0.89 and r2=0.96 respectively 2 and results are presented in section 3. Finally Section 4 local and remote climate variability. with Chile Chico and Puerto Guadal lake level). provides discussion and conclusions. The paper is presented as follows. Description of data and statistical methods used for analysis are explained in Sect. 2 To2.2 complete Method a lake water balance computation, we need vol- and results are presented in Sect. 3. Finally Sect. 4 provides umes of water inputs and outputs from precipitation and discussion2 Data and and Methodologyconclusions. evaporation.To complete aWe lake therefore water balance employed computation, the Thiessen we polygons need vol- methodumes of (Hartkamp water inputs et al. and (2001)), outputs which from allows precipitation computing and theevaporation. precipitation We and therefore evaporation employed water the volumes Thiessen average polygons in 2.1 Data Set 2 Data and methodology themethod basin (Hartkamp through the et following al., 2001), expression: which allows computing the precipitation (and evaporation) water volumes average in the The in situ daily and monthly data set (see Table 1) (pre- 2.1 Data Set basin through the following expression: cipitation, temperature, evaporation, river flows, lake level) P around the lake, were provided by the DGA (Directorate PN P A The in situ daily and monthly data set (see Table 1) (pre- i==11 PiiAii ´ Pm = PN cipitation,General Water) temperature, of Aysen evaporation, region. From river this flows, data set, lake in which level) PN A i==11 Aii aroundsome time the series lake, goeswere back provided to 1985, by we the choose DGA the (Directorate period in which most of the time series were complete, i.e., the 2000- General Water) of Aysen´ region. From this data set, in which where Pi is the precipitation of station i, Ai is the area of 2006 time span. The time series were then processed through some time series goes back to 1985, we choose the period in influence of the station i, N is the number of stations and Pm interpolation in order to complete small gaps in the daily where P is the precipitation of station i, A is the area of which most of the time series were complete, i.e., the 2000– is the averagei rainfall in the basin. Errorsi due to this esti- time series, before constructing monthly means, and then a influence of the rain gauge station i, N is the number of sta- 2006 time span. The time series were then processed through mation (usually due to over or under estimation of areas of monthly mean climatology for he period (2000-2006). tions and P is the average rainfall in the basin. Errors due interpolation in order to complete small gaps in the daily influence) arem considered within the margin of error of com- We note here that although Lake level in Puerto Guadal only to this estimation (usually due to over or under estimation of time series, before constructing monthly means, and then a puting the water balance. The balance is estimated in units covers years 2003-to-2006, its variability is exactly the same areas of influence) are considered within the margin of error monthly mean climatology for he period (2000–2006). of volume, so each of the variables involved in estimating as registered in Chile Chico (r2 = 0.95). Both were also of computing the water balance. The balance is estimated in We note here that although Lake level in Puerto Guadal the balance should be converted to units of volume. This is corroborated with lake level by satellite altimetry (Cretaux´ unitscomputed of volume, monthly so each over ofthe the climatology variables involved data. Of in course, estimat- the onlyet al. covers (2006)) years data 2003-to-2006, (r2 = 0.81 and its variabilityr2 = 0.77 isrespectively exactly the ing the balance should be converted to units of volume. This same as registered in Chile Chico (r2=0.95). Both were also closer to the in situ station, the greater the accuracy of the with Chile Chico and Puerto Guadal). It is also the case for isdetermined computed amounts monthlyof over precipitation the climatology and evaporation data. Of course, water corroboratedthe flows of riverwith Baker,lake level being by thesatellite sole river altimetry output (Cr itetaux´ follows et the closer to the in situ station, the greater the accuracy of 2= 2= inputs and outputs, respectively. al.exactly, 2006) the data lake (r level0.81 variability and r 0 (.r772 respectively= 0.89 and r with2 = Chile 0.96 the determined amounts of precipitation and evaporation wa- Chicorespectively and Puerto with ChileGuadal). Chico It andis also Puerto the Guadal case for lake the level). flows ter inputs and outputs, respectively. of river Baker, being the sole river output it follows exactly

Adv. Geosci., 22, 173–179, 2009 www.adv-geosci.net/22/173/2009/ G. Zambrano et al.: First insights on LGC/BA/C water balance 175

G. Zambrano, R. Abarca, J-F. Cretaux, B. Reid: First Insights on LGC/BA/C and Water Balance 3 Table 1. Meteorological and river discharge monitoring stations. D and M refers to daily and monthly mean values, respectively, and dates refer to the range of data availability. All river discharge stations are inputs to the system, except for River Baker which is the sole output Table 1. Meteorological and river discharge monitoring stations. D and M refers to daily and monthly mean values respectively, and dates refer to the rangeStations of data availability. Location All riverWeather discharge stations River discharge are inputs (daily to the mean) system, [m except3/s] Lake for Rio Level Baker (daily which mean) is the [m] sole output ◦ 0 Bah´ıa Murta 46 27 S 1993–2007 1985–2006 3 Stations Location72◦400 W D Pre Weather [mm] M River River Murta discharge (daily mean) [m /s] – Lake Level (daily mean) [m] o 0 Bah´ıa Murta 46 27 S Temp1993 [−◦C]2007 M (50 km length) 1985 − 2006 o 0 72 40 W DEvap Pre [mm][mm] M River Murta - o Chile Chico 46◦320 S 1993–2004Temp [ C] M( 1995–200450 km length) 2000–2006 71◦440 W DEvap Pre [mm][mm] River Jeinimeni (40 km length) Chile Chico 46o320 S M1993 Temp− [2004◦C] 1995–2006 1995 − 2004 2000 − 2006 71o440 WM D Evap Pre [ mm]mm] RiverRiver El Ba Jeinimenino˜ (18 km (40 length)km length) Puerto Ibańez˜ 46◦180 S 1993–2007M Temp [oC] 1985–2006 1995 − 2006 71◦560 W DM Pre Evap [mm]mm] RiverRiver Ibańez˜ El (88 Bano˜ km (18 length)km length) – ◦ Puerto Ibańez˜ 46o180 S M1993 Temp− [2007C] 1985 − 2006 71o560 WM D Evap Pre [ [mm]mm] River Ibańez˜ (88 km length) - ◦ 0 Perito Moreno 46 31 S 1971–2008M Temp [oC] ◦ 0 71 00 W MM Pre Evap [mm][mm] – – o 0 Puerto Guadal 46o 500 S 1993–2007 2003–2006 Perito Moreno 46◦310 S 1971 − 2008 7172o00430 W M M Pre Pre [mm][mm] – -- Lago Bertrand 47◦040 S 2003–2006 Puerto Guadal 46o500 S 1993 − 2007 2003 − 2006 72◦470 W – River Baker (370 km length) – 72o430 W M Pre [mm] - Lago Bertrand 47o040 S 2003 − 2006 72o470 W - River Baker (370 km length) - Table 2. Accumulated water per year Table 3. Historic water balance for basin river Baker (1951 to 1980: Water Balance, DGA-1987) Table 2. AccumulatedVariable water per Accumulated year [km3] Table 3. Historic water balance (1951 to 1980: Water Balance, Variables Value [mm/year] Precipitation 3.10 (1478 [mm/yr]) DGA-1987) 3 EvaporationVariable 0.66 Accumulated (534.7 [mm/yr])[km ] Precipitation 1759 PrecipitationRivers inflow 3.10 9.64 (1478 [mm/yr]) Total RunoffVariables Value [mm/year 1336 ] EvaporationRivers outflow 0.66 18.99 (534.7 [mm/yr]) EvaporationPrecipitation (lakes, open water) 1759 85.9 Rivers inflow 9.64 EvapotranpirationTotal Runoff 1336 336 Rivers outflow 18.99 Evaporation (lakes, open water) 85.9 Evapotranpiration 336 3 Results

3.1observed Seasonal in some cycles of the five in situ stations (Figure 2) along the lake. Their diversity illustrates the extreme complexity Precipitation:of microclimates an annual surrounding cycle the of lake, precipitation, as presented whose in the maximaintroduction. coincided For with example, the austral measurements winter season of Bah (June–´ıa Murta September)precipitation is observed presents the in some greatest of theannual five accumulation, in situ stations with (Fig.maxima2) along in June the and lake. October, Their correspondingdiversity illustrates with the winter ex- and tremespring complexity precipitations of microclimates and a well pronouncedsurrounding the minimum lake, as dur- presenteding February in the (summer). introduction. Although For example, the other measurements stations such ofas Bah Chile´ıa Murta Chico, precipitation Puerto Ib presentsańez˜ and the Perito greatest Moreno annual present accumulation,lesser annual with accumulated maxima in June precipitations and October, (by correspond- half), it shows ingimportant with winter variance and spring from April precipitations to October and (mid a well autumn pro- to Fig. 2. Monthly mean precipitation (accumulated mm/month) nouncedmid spring) minimum and during less precipitation February (summer). during summer. Although Finallythe Fig. 2. Monthly mean precipitation (accumulated mm/month) for the different in-situ meteorological stations and the averaged otherPuerto stations Guadal such presents as Chile its Chico, peak rainfall Puerto Ibduringańez˜ and autumn Per- and for the different in-situ meteorological stations and the averaged monthly mean precipitation over the lake. itoearly Moreno spring, present and lesser is lower annual in winter accumulated and summer. precipitations However monthly mean precipitation over the lake. (byits half), contribution it shows is important the less important. variance from As aApril result, to Octo- the accu- bermulated (mid autumn monthly to mean mid spring) rainfall and over less the precipitationlake (Figure 2), dur- com- ing summer. Finally Puerto Guadal presents its peak rainfall 3 Results puted following the method described in section 2, reaches its duringhighest autumn values and during early mid spring, autumn and isto lower winter in (April winter to and June). 3.1 Seasonal cycles It shows also some variability during spring, and precipita- www.adv-geosci.net/22/173/2009/tion during summer (Figure Adv. 2). Geosci., 22, 173–179, 2009 Precipitation: An annual cycle of precipitation, whose max- Temperature: The air surface temperature measurement over ima coincided with the austral winter season (Jun-Sept) is the 3 stations (Table 1) presents a similar pattern: a marked 4 G. Zambrano, R. Abarca, J-F. Cretaux, B. Reid: First Insights on LGC/BA/C and Water Balance 4176 G. G. Zambrano, Zambrano, R. R. Abarca, Abarca, J-F. J-F. Cretaux, Cretaux, G. Zambrano B. B. Reid: Reid: et First Firstal.: FirstInsights Insights insights on on LGC/BA/C LGC/BA/Con LGC/BA/C and and Water water Water balanceBalance Balance

Fig. 4. In situ Lake Level associated variability. The upper panel Fig. 3. Monthly mean air temperature for the different in-situ mete- Fig.Fig. 4. 4.InIn situ situ Lake Lake Level Level associated associated variability. variability. The The upper upper panel panel Fig. 3. Monthly mean mean air air temperature temperature for for the the different different in-situ in-situ mete- mete- Fig.shows 4. In monthly situ Lake mean Level lake level. associated The lower variability. panel the The monthly upper mean panel orological stations. showsshows monthly monthly mean mean lake lake level. level. The The lower lower panel panel the the monthly monthly mean mean Fig. 3.orologicalMonthly mean stations. air temperature for the different in-situ mete- lake level variation. showslakelake monthly level level variation. variation. mean lake level. The lower panel the monthly mean orological stations. lake level variation. summer. However its contribution is the less important. As a annual cycle peaking peaking in in summer summer and and minimum minimum in in winter winter result, the accumulated monthly mean rainfall over the lake annual(Figure cycle 3). peaking Indeed in the summer distribution and of minimum temperature in highlights winter (Figure(Fig. 2), 3). computed Indeed the following distribution the method of temperature described inhighlights Sect. 2, (Figurealso 3). the Indeed complexity the distribution of of microclimates microclimates of temperature in in the the zones; zones; highlights high high tem- tem- reaches its highest values during mid autumno to winter (April also theperatures complexity in Chile of microclimates Chico, Chico, reaching reaching in30 the30 o zones;CC inin summer summer high tem- and and a a to June). It shows also some variabilityo during spring, and winter minima at Perito Moreno (−o10 oC). peratureswinterprecipitation in Chileminima Chico, during at Perito summer. reaching Moreno30 (−10C inC summer). and a winterEvaporation: minima at Perito The The measured measured Moreno ( evaporation− evaporation10 oC). over over the the 3 3 stations stations (TableTemperature: 1) along the the lake air coasts surface differs temperature substantially measurement in am- Evaporation:(Tableover the 1) The along3 stations measured the lake(Table evaporation coasts1) presents differs over a substantially similar the 3 stations pattern: in am- a plitude, showing a a 314314 mmmm summersummer (January) (January) evaporation evaporation (Tableinmarked 1) Chile along Chicoannual the lake and cyclecoasts minimum peaking differs evaporationin summer substantially and in Bah minimum in´ıa am- Murta in in Chile Chico and minimum evaporation in Bah´ıa Murta plitude,ofwinter showing1 mm (Fig.in a winter3314). Indeedmm (June). thesummer Evaporationdistribution (January) of tracks temperature evaporation with air high- sur- of 1 mm in winter (June). Evaporation tracks with air sur- in Chilefacelights Chico temperature also and the complexity minimum (figure not of evaporation microclimates shown), i.e., in a in Bah marked the´ıa zones; Murta annual high face temperature (figure not shown), i.e.,◦ a marked annual of 1 mmcycletemperaturesin that winter peaks in (June). in Chile summer Chico, Evaporation and reaching minima tracks 30 in winter.C with in summer air The sur- com- and cyclea winter that minima peaks in at summer Perito Moreno and minima (−10◦ inC). winter. The com- face temperatureputed global (figure lake evaporation not shown), using i.e., the a same marked method annual as for Fig. 5. Monthly mean river discharges and and total total fluvial fluvial inputs inputs into into puted global lake evaporation using the same method as for Fig. 5. Monthly mean river discharges and total fluvial inputs into cycle thatcomputingEvaporation: peaks inglobal summer the precipitation measured and minima evaporation input in over winter. the over lake Thethe (Thiessen 3 com- stations Lake General Carrera/Buenos Aires/Chelenko. computing global precipitation input over the lake (Thiessen Lake General Carrera/Buenos Aires/Chelenko. putedmethod, global(Table lake1 see) along evaporation section the lake 2), givesusing coasts an the differs annual same substantially method accumulation as in for am- of Fig. 5. Monthly mean river discharges and total fluvial inputs into method, see section 2), gives an annual accumulation of computingaboutplitude, global534 showing.7 mm/yr precipitation a( 3140.66 mmkm input summer3). over The historical the (January) lake (Thiessen (1951-1980) evaporation Lake General Carrera/Buenos Aires/Chelenko. about 534.7 mm/yr (0.66 km3). The historical (1951-1980) method,annualin see Chile accumulated section Chico 2), and evapotranspiration gives minimum an annual evaporation over accumulation the in Bah entire´ıaBaker Murta of sideter measurements of the Lake (i.e., (correlation from 71 ino43 Sect.0 W 2.1). to 72 Theo470 lakeW, corre- level annual accumulated evapotranspiration over the entire Baker showsside of a maximum the Lake (i.e., during from summer71o43 and0 W minimum to 72o47 in0 W, winter, corre- about 534Basinof. 17 mm asmm/yr reported in winter(0. by66 (June). (Loboskm3). Evaporation et The al. historical (1987a)) tracks (1951-1980) is 336 withmm/yr air sur-, spondingly to 970 square kilometers), we assumed over a Basinface temperature as reported by (figure (Lobos not et shown), al. (1987a)) i.e., ais marked336 mm/yr annual, respectivelyspondingly 2.2 to and970 1.2square m, i.e., kilometers), an annual range we assumed of about 1 over m, a annualwhile accumulated the reported evapotranspiration historical evaporation over the for entire open Baker water is sidemeter of thea constant Lake (i.e., surface from over71 depth,o430 i.e.W to the72 surfaceo470 W, covered corre- whilecycle the that reported peaks in summerhistorical and evaporation minima infor winter. open The water com- is correspondingmeter a constant with surface a maximum over depth, volume i.e. change the surface through covered the Basinabout as reported85.9 mm/yr by (Lobos(Table et al. 3). This (1987a)) gives is insight336 mm/yr on the fact, spondinglyat the superficies to 970 issquare equivalent3 kilometers), to the one weat a assumed1 meters depth. over a thataboutputed the85 global measurement.9 mm/yr lake evaporation(Table stations 3). along using This gives the samelake insight are method measuring on the as factfor yearRivers:at the of superficies about Variations 1.85 kmis in equivalent the. Indeed flow of volume to the the rivers one variation at are a shown1 dependsmeters in depth.Fig- on while the reported historical evaporation for open water is meterbathymetry. a constant However, surface since over depth, the only i.e. reported the surface bathymetry covered evapotranspirationthatcomputing the measurement global precipitationrather stations than open along input water overthe lake the evaporation. lake are measuring (Thiessen Re- ureRivers: 5. Iba´ Variationsnez˜ and Murta in the rivers, flow of that the originates rivers are inshown the highs in Fig- about 85.9 mm/yr (Table 3). This gives insight on the fact at( theMurdie superficies et al., 1999 is equivalent) covers toonly the the one Chilean at a 1 meters side of depth. the gardlessevapotranspirationmethod, of see the Sect. method 2), rather gives of than estimation, an annual open water accumulationthe annual evaporation. water of about vol- Re- ofure the 5. Andes Ibańez˜ in Huemulesand Murta (45 rivers,o560 thatS, 72 originateso520 W) and in Erasmothe highs that the measurement stations3 along the lake are measuring Rivers:Lake (i.e., Variations from 71 in◦43 the0 W flow to 72ofo ◦ the470 0 riversW, correspondinglyo are0 shown in Fig-to umegardless534.7 loss mm/yr of by the evaporation (0.66 method km ). of is The estimation, not historical meaningful the (1951–1980) annual when compared water annual vol- (46ofo the080 AndesS, 73o in03 HuemulesW) snowdrifts (45 56 respectivelyS, 72 52 andW) and then Erasmo flow evapotranspiration rather than open water evaporation. Re- ure970 5.o square Iba´0nez˜ kilometers), ando Murta we rivers, assumed that over originates a meter in a constant the highs withumeaccumulated theloss outflowing by evaporation evapotranspiration water isby not the meaningful Baker over the river entire (seewhen Baker table compared 2Basin and eastward(46 08 throughS, 73 03 theW) mountains snowdrifts down respectively to the lake and in a then course flow surface over depth, i.e. the surfaceo 0 coveredo at0 the superficies gardlessfigurewithas of reported the the 7) outflowing method by Lobos of water estimation, et by al. the(1987a Baker the) annual is river 336 (see mm/yr,water table vol- while 2 and ofof theeastward about Andes88 through inand Huemules50 thekm mountainsapproximately (45 56 downS, 72 (Figure to52 theW) lake 6). and in The Erasmoa course two iso equivalent0 o to the one at a 1 m depth. ume lossLakefigurethe by reported level: 7) evaporation All historical these is water not evaporation inputs meaningful and for outputs openwhen give water compared rise is to about the (46othersof08 aboutS, rivers7388 (Jenimeni03andW)50 snowdriftskm andapproximately El Ba respectivelyno)˜ originates (Figure and respectively 6). then The flow two 85.9 mm/yr (Table 3). This gives insight on the fact that the with thelakeLake outflowing level level: variability, All water these bywater or the change inputs Baker in and river lake outputs (seestorage table give (Figure rise 2 and to 4). the eastwardoverothersRivers: the throughrivers south variations (Jenimeni eastern the mountains in side the and offlow El the downBa of lake.no)˜ the to originates rivers Rio the lakeJenimeni are respectively shownin a course origin measurement stations along the lake are measuring evapo- Fig. 5. figureThelake 7) lake level level variability, shows strong or change correlation in lake across storage both (Figure sides of 4). ofinates aboutover the in88 a southand mountainous50 easternkm approximatelyside lakeof with the the lake. same (Figure Rio name Jenimeni 6). (El The Jeini- orig- two transpiration rather than open water evaporation. Regardless Lake level:theThe lake lake All (correlation level these shows water in stronginputs section correlationand 2.1), outputs and across agrees give rise both with to sides the the al- of othersmeniinatesIba´ riversnez is˜ in located and a (Jenimeni mountainous Murta at 46o rivers,51 and0 lakeS- El that72 Ba witho00 originatesno)˜ ’W), the originates same while in name the Rio respectively highs El (El Ba Jeini- ofno˜ of the method of estimation, the annual water volume loss o 0 ◦ 0 o ◦ 0 lake leveltimeterthe lake variability, measurements (correlation or change in (correlation section in lake 2.1), in storage and section agrees 2.1). (Figure with The the4). lake al- overoriginatesthemeni the Andes is south located around in eastern Huemules at4646o37 side51S- (4572 ofS-o5603 the72’W.S,00 lake. 72’W), Both52 Rio whileriversW) Jenimeni and flow Rio Erasmo El north- orig-Bano˜ by evaporation is not meaningful when compared with the ◦ 0 ◦ o o The lakeleveltimeter level shows measurements shows a maximum strong (correlation correlation during summer in across section and both 2.1). minimum sides The of lake in inatesward(46originates08 in through aS, mountainous 73 around the03 W) mountains46 snowdrifts37 lakeS-72 down with03 respectively’W. theto the Bothsame lake rivers nameand in a then flowcourse (El flow Jeini-north- of outflowing water by the Baker river (see Table 2 and Fig. 7). the lakewinter,level (correlation shows respectively a maximum in section 2.2 and during 2.1),1.2 m and summer, i.e., agrees an and annual with minimum the range al- of in meniabouteastwardward is40 locatedthroughand through18 at thekm the46 mountainsoapproximately. mountains510 S- 72 downo down00’W), to to the the while lake lake inRio in a a course Elcourse Bano˜ of Lake level: all these water inputs and outputs give rise to of about 88 and 50 km approximately (Fig. 6). The two oth- timeteraboutwinter, measurements1 respectivelym, corresponding (correlation 2.2 and with1. in2 am section maximum, i.e., an 2.1). volumeannual The range changelake of originatesBothabout Ib40a´ aroundnez˜ and and1846km Murtao37approximately.S- river72o03 flows’W. shows Both rivers an annual flow cycle north- the lake level variability, or change in lake storage (Fig. 4). ers rivers (Jenimeni and El Bano)˜ originates respectively over level showsthroughabout 1 a them maximum, year corresponding of about during1.85 with summerkm a3 maximum. Indeed and volume minimum volume variation change in wardwithBoth through maxima Ibańez˜ the during and mountains Murta summer river down (January) flows to the shows and lake minima an in annual a course during cycle of The lake level shows strong correlation3 across both sides of the south eastern side of the lake. River Jenimeni originates winter,dependsthrough respectively the on year bathymetry. 2.2 of aboutand 1.1 However,2.85mkm, i.e.,. since Indeed an annual the volume only range reported variation of aboutwinterwith40 maxima (July).and 18 Thiskmduringapproximately. annual summer cycle (January) is less prominent and minima in duringriver dependsthe lake on(correlation bathymetry. in Sect. However, 2.1), and since agrees the with only the reported altime- inwinter a mountainous (July). This lake annual with the cycle same is name less prominent (El Jeinimeni in river is about bathymetry1 m, corresponding (Murdie et with al. (1999)) a maximum covers volume only the change Chilean BothMurta. Ibańez˜ Both and present Murta additional river flows peaks shows in March an andannual August. cycle bathymetry (Murdie et al. (1999)) covers only the Chilean Murta. Both present additional peaks in March and August. through the year of about 1.85 km3. Indeed volume variation with maxima during summer (January) and minima during dependsAdv. on Geosci., bathymetry. 22, 173– However,179, 2009 since the only reported winter (July). This annual www.adv-geosci.net/22/173/2009/ cycle is less prominent in river bathymetry (Murdie et al. (1999)) covers only the Chilean Murta. Both present additional peaks in March and August. G. Zambrano, R. Abarca, J-F. Cretaux, B. Reid: First Insights on LGC/BA/C and Water Balance 5

G.G. Zambrano, Zambrano R. et R. al.:Abarca, Abarca, First J-F. insights J-F. Cretaux, Cretaux, on LGC/BA/C B. B. Reid: Reid: First First water Insights Insights balance on onLGC/BA/C LGC/BA/C and and Water Water Balance Balance 5 177 5

Fig.Fig. 6. 6.MainMain rivers rivers within within the the basin basin of of Lake Lake General General Car- Car- rera/BuenosFig. 6. Aires/Chelenko.Main rivers within the basin of Lake General Car- rera/BuenosFig.rera/Buenos 6. Main Aires/Chelenko. Aires/Chelenko. rivers within the basin of Lake General Car- rera/Buenos Aires/Chelenko. Fig. 7. Mean monthly water balance. (A) Inflows from rivers (- Fig. 7. Mean monthly water balance. (A) Inflows from rivers (- ◦ 0 ◦ 0 Fig. 7. Mean monthly water balance. (A) Inflows from rivers (-×- TheThelocated highest highest at peak 46 peak51 in inS–72 January January00 isW), is due due while to to summer River El snow snow Bano˜ melt- melt- origi- ×-)×Fig. and-) and precipitation7. precipitationMean monthly (-∗-), (- outputs∗ water-), outputsbalance. from evaporationfrom (A) evaporation Inflows (-M-)from and (-M Rio-) rivers and Rio(- ◦ ◦ 0 ) and precipitation (-∗-), outputs from evaporation (- -) and River ingingThenates over over highest the around the Andes, Andes, peak 46 37 and in and S-72 January agrees agrees03 W. iswith with due Both results results to rivers summer by by flow L Lopezópez´ snow northward et etmelt- al. al. BakerBaker×-)(— and()—. precipitation(B)). (B) Total Total inflows (- inflows∗-), (-¤ outputs-) (- and¤-) outflows from and outflows evaporation (-◦-). (-◦M (--).M-) and Rio Baker (—). (B) Total inflows (- -) and outflows (-◦-). (2008)(2008)ingthroughwhom over whom the the investigated mountains Andes, investigated and down the agrees the snowmelt snowmelt to the with lake results seasonal in a bycourse cycle, Lcycle,opez´ of par- about par-et al. Baker (—). (B) Total inflows (-¤-) and outflows (-◦-). ticularlyticularly(2008)40 and over whom 18 over km the the investigatedapproximately. Northern Northern Icefield. the Icefield. snowmelt Note Note seasonal that the the cycle,air air tem- tem- par- peratureperatureticularlyBoth also Ibalso over peaksańez˜ peaks the and in Northern in early Murta early autumn autumn river Icefield. flows (March) (March) Noteshows and that an early early annual the spring air spring cycle tem- (September(Septemberperaturewith maxima also and andpeaks October) during October) in summerearly (see (see autumn Figure Figure (January) (March) 3), 3), that and also andalso minima earlycoincides coincides duringspring withwith(Septemberwinter the the river (July). riverflow and flow This October) rates, rates, annual and and (see cycle can can Figure also alsois less 3), be thatprominent associated also coincides in with with river snowsnowwithMurta. melting.the melting. Both river In present In addition,flow addition, rates, additional satellite satellite and can peaks precipitation precipitation also in Marchbe associated fields fields and August. (res- (res- with olutionolutionsnowThe 25highest melting. 25 km, km, peak Kubota InKubota inaddition, January et et al. al. satellite is (2007)) (2007)) due to precipitation summer over the the snow mountains mountains fields melting (res- where the rivers originate shows peaks in March and August whereolutionover the the rivers 25 Andes, km, originate andKubota agrees shows et withal. peaks results (2007)) in by March overLopez´ the and et mountains al. August(2008) (not shown). Therefore, rainfall also plays a role, though it is (notwherewhom shown). the investigated Therefore, rivers originate the rainfall snowmelt shows also peaks seasonal plays in a March role,cycle, though andparticularly August it is not(not the shown). most important Therefore, contribution. rainfall also plays a role, though it is not theover most the Northern important Icefield. contribution. Note that the air temperature also Jeinimeninotpeaks the in most early and important Elautumn Bano˜ (March)contribution. rivers peak and earlybetween spring October (September and Jeinimeni and El Bano˜ rivers peak between October and NovemberJeinimeniand October) and (see are El almost BaFig.no˜ 3), riversuniform that also peak over coincides between the rest ofwith October the the year. river and November and are almost uniform over the rest of the year. AlthoughNovemberflow rates, the and pluvial canare almost alsoregime be uniformcould associated be theover with source the snow rest of main of melting. the vari- year. In Although the pluvial regime could be the source of main variability,Althoughaddition, the satellite the timing pluvial of precipitation the regime water could flow fields bein (resolutionspring the source suggests of 25 main km, thatKub- vari- it ability,couldability,ota etthe al.also the timing, 2007 be timing fed) of over partly theof the water bymountains water spring flow flow in nival where in spring spring regimes the suggests suggestsrivers following originate that that it it winter accumulation. Fig. 8. Total water balance. Difference between total inflow and couldcouldshows also also peaks be befed in fed partly March partly by and by spring August spring nival (notnival regimes shown). regimes following Therefore, following Finally, being the only outflow from the lake, Rio Baker ex- totalFig. outflow 8. Total(−¤− water), lake balance. volume variation Difference(−◦− between) and DV/DT total inflow− and winterwinterrainfall accumulation. accumulation. also plays a role, though it is not the most important Fig.Fig. 8. 8. TotalTotal water water balance. Difference Difference between between total total inflow inflow and and its from Lago Bertrand (fed directly by Lago General Car- (INtotal− OUT outflow) = ∆?(--), (— lake). volume variation (-◦-) and DV/DT-(IN- Finally,Finally,contribution. being being the the only only outflow outflow from from the the lake, lake, Rio Rio Baker Baker ex- ex- totaltotal outflow outflow((−−¤¤−), lake volume volume variation variation((−◦−−◦−))andandDV/DTDV/DT−− rera/Buenos Aires/Chelenko) presenting its annual peak in OUT)=1? (—). its from Lago Bertrand (fed directly by Lago General Car- ((ININ−−OUTOUT)) = = ∆? (—).. lateitsJeinimeni from summer Lago early and Bertrand autumnEl Bano˜ (fed (January rivers directly peak to March) by between Lago and General October minimum Car- and rera/Buenosrera/BuenosNovember Aires/Chelenko) and Aires/Chelenko) are almost uniform presenting presenting over its the its annual rest annual of peak the peak year. in in in September (early spring), similar to the annual cycle of the error. latelateAlthough summer summer early the early pluvial autumn autumn regime (January (January could to be to March) the March) source and and of minimum main minimum vari- QSS are outputs of surface water, groundwater is G (incom- General Carrera lake level (see Figure 4 and below). The accumulated annual water volume input by rainfall di- in Septemberinability, September the (early timing (early spring), of spring), the water similar similar flow to to thein the spring annual annual suggests cycle cycle of thatof the the it ing and outgoing) and is the error. We will assume first, rectlyerror.error. into the lake is about 3.1 km3 (1478 mm/yr, see sec- to compute a first guess of the water balance, a small error, General3.2Generalcould CarreraWater also Carrera be Balance lake fed lake level partly level (see by (see Figurespring Figure nival4 and4 and regimes below). below). following tionTheThe 2 andaccumulated accumulated Table 2), annualwhile that water attributed volume volume to input input river by flows by rainfall rainfall is di- di- i.e. negligible when compared to the33 magnitude of other vari- winter accumulation. aboutrectlyrectly9.64 into intokm the the3. lake lake Therefore is about the33 contribution..11kmkm ((14781478 bymm/yrmm/yr rainfall, di- see, see sec- sec- 3.2The3.2 Water water Water Balance balance Balance is given by the expression (Custodio and Finally, being the only outflow from the lake, River rectlytiontionables. into 2 2 andHowever, and the Table lakeTable is it 2), isone clear while third for that that us of(see attributed attributed river the inflows discussion to to river river (Table section)flows flows is is Llamas (1983)): Baker exits from Lago Bertrand (fed directly by acronyms 2),aboutaboutthat i.e., there not99..6464 negligible. iskmkm a significant33.. Therefore Instead amount evaporation the the of contribution contribution unmonitored when compared by by catchments, rainfall rainfall di- di- TheThe water water balance balance is given is given by by the the expression expression (Custodio (Custodio and and LGC/BA/C)DV presenting its annual peak in late summer early to riverrectlyandthe baker into larger outflows the the lake area (Table is one of 2), the third is ungaged negligible that of basins, river (given inflows the that larger al- (Table the Llamas= P (1983)):+ QSE − (E + QSS) ± G ± ² rectly into the lake is one third that of river inflows (Table LlamasautumnDT (1983)):| (January{z } to| March){z } and minimum|{z} in|{z} September ready2),error. evapotranspiration i.e., not negligible. is negligible), Instead evaporation and therefore when outgo- compared Groundwater error 2), i.e., not negligible. Instead evaporation when compared DV(earlyDV spring),IN similar toOUT the annual cycle of the General Car- ingto waterThe river is accumulated baker mostly outflows driven annual by (Table flow water in 2), Rio volume is negligible Baker. input This (given by israinfall sum- that di- al- = P + Q − (E + Q ) ± G ± ² to river baker outflows (Table 2), is3 negligible (given that al- rera= P lake+| levelQSE{z (seeSE−}(E Fig.+ 4QandSSSS) below).± G|{z} ± |{z}² rectly into the lake is about 3.1 km (1478 mm/yr, see Sect. 2 DTWhereDT | DV/DT{z } is| the| volume{z{z } variation} |{z} of the lake,|{z}P is pre- marizedreadyreadyin evapotranspiration evapotranspiration Figure 7, where the is is average negligible), negligible), evaporation and and therefore therefore over the outgo- outgo- IN OUT Groundwater error cipitation,INQSE are inputsOUT of surfaceGroundwater water, E is evaporation,error lakeingand does water Table not is change2 mostly), while the driven pattern that byattributed of flow the outgoing in Rio to river Baker. water, flows This while is is about sum- 3.2 Water balance ing water3 is mostly driven by flow in Rio Baker. This is sum- QWhereSS areDV/DT outputs ofissurface the volume water, variation groundwater of the is lake,G (incom-P is pre- themarized9.64 averaged km in. precipitation Therefore Figure 7, thewhere does contribution changethe average that by of evaporation rainfall the incoming directly over into the WhereingDV/DT and outgoing)is the and volume² is the variation error. We of the will lake, assumeP is first, pre- watermarizedthe fluxes. lake in is Figure one third 7, thatwhere of the river average inflows evaporation (Table 2), i.e., over not the cipitation, QSE are inputs of surface water, E is evaporation, lake does not change the pattern of the outgoing water, while cipitation,The waterQ balanceare inputs is given of surface by the water, expressionE is (evaporation,Custodio and lake does not change the pattern of the outgoing3 water, while toQ computeare outputsSE a first of guess surface of the water, water groundwater balance, a small is G (incom- error, Thethenegligible. comparison averaged Insteadof precipitation the evaporation outgoing does water when change (18 compared.99 thatkm of) thewithto river incoming re- baker Q LlamasareSS outputs, 1983): of surface water, groundwater is G (incom- the averaged precipitation does change that of the incoming SSi.e.ing negligible and outgoing) when andcompared² is the to the error. magnitude We will of assume other vari- first, gardswateroutflows to the fluxes. total (Table (rivers2), is+ negligibleprecipitation (given into lake) that already incoming evapo- ing and outgoing) and ² is the error. We will assume first, water fluxes. 3 ables.toDV compute However, a first it is guess clear of for the us (seewater the balance, discussion a small section) error, waterThetranspiration (10 comparison.74 km is) shows negligible), of the that outgoing43 and% of thereforewater the total (18 incoming. outgoing99 km3) wa- water with re- is to computethat there= P a is+ first aQ significantSE guess−(E of+ amountQ theSS) water± of unmonitored balance,G ± a catchments, small error, terThe is unaccounted comparison for. ofthe The outgoing seasonal cycle water of (18 the.99 differencekm3) with re- i.e.DT negligible when compared to the|{z} magnitude|{z} of other vari- gardsmostly to driven the total by flow(rivers in+ Riverprecipitation Baker. This into is lake)summarized incoming in | {z } | {z } error i.e.and negligible the larger whenIN the compared area ofOUT the to ungaged theGroundwater magnitude basins, the of largerother vari- the betweengardsFig. 7 tolake, where the volume total the3(riversvariability average+ evaporationprecipitation (DV/DT ) over and into all the water lake) lake into does incoming not ables. However, it is clear for us (see the discussion section) water (10.74 km3 ) shows that 43% of the total incoming wa- ables.thatWhere However, thereDV/DT is a significantitis is the clear volume for amount us variation (see of unmonitored the ofdiscussion the lake, catchments, section)P is pre- waterterchange is ( unaccounted10 the.74 patternkm ) of showsfor. the The outgoing that seasonal43% water, of cycle the while total of the theincoming difference averaged wa- precipitation does change that of the incoming water fluxes. thatandcipitation, there the is larger a significantQSE theare area inputs amount of theof surfaceungaged of unmonitored water, basins,E is catchments,the evaporation, larger the terbetween is unaccounted lake volume for. variability The seasonal (DV/DT cycle) and of all the water difference into and the larger the area of the ungaged basins, the larger the between lake volume variability (DV/DT ) and all water into www.adv-geosci.net/22/173/2009/ Adv. Geosci., 22, 173–179, 2009 178 G. Zambrano et al.: First insights on LGC/BA/C water balance

The comparison of the outgoing water (18.99 km3) with As a constraint on the water balance, we can calculate po- regards to the total (rivers + precipitation into lake) incom- tential inputs based solely on precipitation. The entire Baker ing water (10.74 km3) shows that 43% of the total incoming basin covers 26 726 square kilometres (page 22, Lobos et al., water is unaccounted for. The seasonal cycle of the differ- 1987a) and about half may be associated to Lake Carrera ence between lake volume variability (DV/DT) and all wa- basin (approximately 13000 squared kilometres). As an av- ter into the lake (Fig. 4), shows that the missing water does erage estimate, we used the historically derived precipitation present a cycle with a maximum in January through March (Table 3, Lobos et al., 1987a) from the whole Baker basin, and minima in August (Fig. 8). i.e., 1750 mm/yr. By subtracting the average historically derived evapotranspiration 336 mm/yr, we obtain the incoming runoff into the lake (assuming all water is transported instan- 4 Discussion and conclusions taneously) which is 1423 mm/yr. When computed over the Carrera Basin, it gives a volume of about 18.49 km3, which We investigated the seasonal water balance of the west-east is indeed comparable to the outflowing water reported for oriented 200 km long Lake Carrera/Buenos Aires/Chelenko. River Baker (18.99 km3). Note that by their computed runoff In situ, historical, and satellite data allowed us to character- (which takes into account also lake evaporation; Table 3) it ize the main contributors to the lake and understand the lake results in an amount of water of 17.40 km3. Of course both level variability. Precipitation, through melting snow and precipitation and evapotranspiration varies along the basin, rainfall into the basin, associated with four climatic zones and most probably underestimated in the case of precipita- with large differences in the precipitation patterns and which tion, especially given that precipitation over the North Ice- are crossed by the lake (Fig. 1) has a major impact in the wa- field could exceed 6000 mm/yr. The same may be true for ter balance of the lake. The summer nival flow river regimes, evapotranspiration. However, this gives us insights on the arising from the western side Andean region, play a prepon- fact that there’s an amount of water incoming into the basin derant role into the river inflow into the lake, accompanied that is effectively unaccounted by the actual river inflows by a winter-spring probably pluvial-nival regime associated (close to half) into the lake. with the southern region of the lake. This gives insights into Indeed this is only a first approximation of the total water the seasonal cycle of the lake level variability. balance. A correct analysis will first require de visu all the It is interesting to note that the seasonal cycle of the miss- possible rivers and streams coming into the lake, and then at- ing water presents a maxima in summer that agrees with sum- tempt to gauge them or estimate their contribution. Ground- mer melted water, for example an influx regime similar to water may be a major contribution of mass flux of water to River Ibańez.˜ However, we note that the missing water also some lakes, for example shallow isolated lakes in glacial out- has a seasonal pattern with water inflows during winter and wash plains (Magnusen et al., 2006). A rough estimate based spring seasons, which indicates that some water must also on regional scale geologic mapping indicates that unconsoli- arise with a seasonal flow regime similar River Jenimeni or dated deposits, mostly fluvial, represent somewhere between River El Bano,˜ which follow a southern lake nival-pluvial 5 and 10 per cent of the lake shore interface. There are regime. also considerable areas of volcanic rocks, including basalts, As a result the missing water must arise from the en- which are generally highly transmissive (Fetter, 2001). Anal- tire lake basin from both nival and pluvial regimes. This ysis over the broader lake reveals that although the regional is in fact not surprising: a geographic investigation using rock geology, as reported by plate 5 of Chilean Hydrogeo- a high-resolution regional map (Lobos et al., 1987a) shows logical Map (Lobos et al., 1987b) (excluding the along river that there are many rivers incoming into the lake, known path, considered as highly permeable) favours surface flows, or unknown (at least to our knowledge), which are still un- groundwater flow present a great potential. Thus groundwa- gaged. For example, over the west and directly related with ter inputs may therefore be significant in this lake. However a glacier connected with North Icefield is river Soler which given the extreme depth and volume of the lake, lack of di- is a tributary to the lake Bertrand in the south western side rect estimates of groundwater inputs, the perils of estimating of Lake LGC/BA/C at 46◦580 S–72◦520 W. Between Puerto groundwater as the residual in mass-balance estimates (Win- Ibańez˜ and Bah´ıa Murta, there’s also an ungaged river, the ter, 1981) and the large uncertainty in ungauged river inputs, river Avellanos (46◦300 S, 72◦100 W). Over the southern side, we conservatively propose that groundwater inputs are prob- close to Chile Chico, there’s at least three ungaged rivers that ably less than 10% of the overall water budget. input into the lake at 46◦330 S–72◦140 W, 46◦430 S-72◦310 W Finally, in parallel, a computer hydrological model of the and 46◦460 S–72◦360 W. Clearly, there is a lot of surface wa- basin could be another useful approach. For example, anal- ter incoming into the lake. Other inputs are also possible, ysis such as the one reported by Pellicciotti et al. (2008) such as groundwater, which is currently unreported. allowed them to estimate the amount of snow melted water over the highs of the Juncal Norte Glacier (32◦980 S, 70◦110 W) located in the upper Aconcagua River Basin, in the semi-arid Andes of central Chile. This same approach

Adv. Geosci., 22, 173–179, 2009 www.adv-geosci.net/22/173/2009/ G. Zambrano et al.: First insights on LGC/BA/C water balance 179 could give us an estimate of the amount of snow melted wa- Kalff, J.: Limnology, Prentice Hall, Upper Saddle River, New Jer- ter compared to rainfall. sey, USA, 2001. Although incomplete, due to the substantial lack of infor- Kubota, T., Shige, S., Hashizume, H., Aonashi, K., Takahashi, N., mation on incoming water, the investigation of Lake Car- Seto, S., Hirose, M., Takayabu, Y. N., Nakagawa, K., Iwanami, rera/Buenos Aires/Chelenko water budget resulted in impor- K., Ushio, T., Kachi, M., and Okamoto, K.: Global Precipita- tant information on the source of its variability. Given the tion Map using Satelliteborne Microwave Radiometers by the GSMaP Project: Production and Validation, IEEE T. Geosci. Re- large volume of water in its hydrological basin, the depen- mote, 45(7), 2259–2275, 2007. dence of the River Baker basin on its variability, and finally Lobos, E., Garc´ıa, E., and Pena,˜ H.: Balance H´ıdrico de Chile, Di- its dependence on the summer snow melting over the Andes, reccion´ general de Aguas, Ministerio de obras Publicas,´ Gob- the lake appears to be an important proxy for understanding ierno de Chile, 58 pp., 1987a. the local hydroclimate variability as well as for monitoring Lobos, E., Garc´ıa, E., and Pena,˜ H.: Mapa Hidrogeologico´ de Chile, future impact of climate changes over the whole basin. No Direccion´ general de Aguas, Ministerio de obras Publicas,´ Gob- doubt reconstruction of past lake level variability could also ierno de Chile, 8 pp., 1987b. be useful for understanding the influence of remote climates Lopez,´ P., Sirguey, P., Arnaud, Y., Pouyaud, B., and Chevallier, P.: on the Andean snow accumulation and hydrologic cycle and Snow cover monitoring in the Northern Patagonia Icefield using help us in determining the impact of future climates in the MODIS satellite images (2000–2006), Global Planet. Change, whole Baker hydrological basin. 61, 103–116. 2008. Magnusen, J. J., Kratz, T. K., and Benson, B. J. (Eds.): Long-term Acknowledgements. We are highly indebted to Directorate General Dynamics of Lakes in the Landscape, Oxford University Press, Water (DGA, Chile) of Coyhaique in the Aysen Region for the USA, 464 pp., 2006. in situ data and support. Particularly to Mr. Juan Salas and Murdie, R. E., Pugh, D. T., and Styles, P.: A lightweight, portable, Mr. Francisco Guzman´ whom both sent us the required information digital probe for measuring the thermal gradient in shallow water and delivered us important insights on the lake basin variability. sediments, with examples from Patagonia, Geo-Mar. Lett., 18, Mrs. G. M. Zambrano is funded by national CONICYT 21080378 315–320, 1999. grant (CONICYT Ph.D doctorate scolarship 21080378). This work Paruelo, J., Beltran,´ A., Jobbagy,´ E., Sala, O., and Golluscio, R.: was part of the ECOS C04U02 (Chile (DGEO)-France (LEGOS)) The climate of Patagonia: general patterns and controls on biotic project Continental hydrology from a combination of altimetry, processes, Ecologa Austral, 8, 85–101. 1969. gravimetry and in-situ data. Application to the Andean Region. Pellicciotti, F., Helbing, J., Rivera, A., Favier, V., Corripio, J., Araos, J., Sicart, J.-E., and Carenzo, M.: A study of energy bal- Edited by: R. Garraud ance and melt regime on Juncal Norte Glaciar, semi-arid Andes Reviewed by: one anonymous referee of central Chile using melt models of different complexity, Hy- drol. Process., 22, 3980–3997, 2008. Rodwell, M. J. and Hoskins, B. J.: Subtropical Anticyclones and References Summer Monsoons, J. Climate, 14, 3192–3211. 2001. Seluchi, M. and Marengo, J.: Tropical-Midlatitude Exchange of Air Custodio, E., and Llamas, M.: Hidrogeolog´ıa Subterranea.´ Tomo I. Masses During Summer and Winter in South America: Climatic Ediciones Omega, S. A. 2350 pp., 1983. Aspects and Examples of Intense Events, Int. J. Climatol., 20, Cretaux´ J.-F. and Birkett, C.: Lake studies from satel- 1167–1190, 2000. lite altimetry, C. R. Geoscience, 338, 1098–1112, Townley, B.: L´ınea de Base del Medio F´ısico del Proyecto doi:10.1016/J.crte.2006.08.002, 2006. Hidroelectrico´ Aysen.´ Cap´ıtulo 2: Clima y Meteorolog´ıa, 75 pp., Fetter, C. W.: Applied Hydrogeology 4th ed., Prentice, 598 pp., 2007. 2001. Walsh, K.: On the Influence of the Andes on the General Circulation Hartkamp, A. D., De Beurs, K., Stein, A., and White J. W.: Interpo- of the Southern Hemisphere, J. Climate, 7, 1019–1025, 1994. lation Techniques for Climate Variable, NRG-GIS Series 99-01, Warren, C. R. and Sugden, D. E.: The Patagonian Icefields: A Mexico, D. F., CIMMYT 1999. Glaciological Review, Arctic and Alpine Research, 25(4), 316– IGM – Instituto Geografico´ Militar: Atlas geografico´ de Chile: para 331, 1993. la educacion.´ 1998. Winter, T. C.: Uncertainties in Estimating the Water Balance of Jobbagy´ E., Paruelo, J. and Leon,´ L.: Estimacion´ del regimen´ de Lakes, Water Resour. Bull., 17(1), 82–115, February 1981. precipitacion´ a partir de la distancia de la cordillera en el noroeste de la Patagonia, Ecolog´ıa Austral, 5, 47–53, 1995.

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