Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Sciences Discussions Earth System Hydrology and 1 542 541 99th SSC percentile) coincide frequently (57– ≥ , and D. Scherler 2 , B. Bookhagen 1 This discussion paper is/has been under review for the journal Hydrology and Earth System Sciences (HESS). Please refer to the corresponding final paper in HESS if available. Department of Earth and EnvironmentalDepartment Science, of Potsdam Geography, University, University Potsdam, of Germany California, Santa Barbara, USA ized by high monsoonal rainfall andwe thick find soil an cover. Third, anticlockwise in hysteresisrelated seven loop to of enhanced of eight glacial catchments annual sediment sediment evacuationphasizes flux, during the late which importance summer. appears of Our to unconsolidated analysiscan be em- sediments easily in the be high-elevation mobilized sectorcontributions. that by hydrometeorological events and higher glacial-meltwater 80 %) with heavy rainstormsflux in and the account semi-arid for tosuspended about sediment arid 30 flux % interior from of of the thenual the Tibetan orogen. timescales. suspended Plateau Second, This to sediment the we sediment-fluxin Himalayan observe gradient front the suggests an at increase that western mean of averaged, Himalaya an- modern is erosion most pronounced at frontal regions, which are character- quality and accountHere, for we present extensive a hydropower comprehensive analysissediment reservoir of flux filling the based spatiotemporal on and trends daily inalong turbine data suspended the during abrasion. Sutlej the past Riverlite decade and data (2001–2009) from from depicting four four rainfall of sites Schmidt and its hammer snow rock main strength cover, tributaries. measurements, airof we In temperature, peak infer conjunction climatic suspended earthquake and with sediment records,key geologic satel- concentration and findings: controls (SSC) First, events. peak SSC Our events study ( identifies three The sediment flux through Himalayan riverstant directly for impacts water sustaining quality and agriculturegeneration. is as Despite impor- the well recent asabout increase maintaining in the demand drinking-water triggers for and these and hydropower resources, sources little is of known extreme sediment flux events, which lower water Abstract Hydrol. Earth Syst. Sci. Discuss.,www.hydrol-earth-syst-sci-discuss.net/9/541/2012/ 9, 541–594, 2012 doi:10.5194/hessd-9-541-2012 © Author(s) 2012. CC Attribution 3.0 License. 1 2 Received: 19 December 2011 – Accepted:Correspondence 25 to: December 2011 H. – Wulf Published: ([email protected]) 11 JanuaryPublished 2012 by Copernicus Publications on behalf of the European Geosciences Union. Climatic and geologic controls on suspended sediment flux in theRiver Sutlej Valley, western Himalaya H. Wulf 5 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | erent geologic , Brahmaputra: ff 1 − 10 % to the global ), due to lower rain- ∼ 1 − ect active tectonics (Burbank et 0.03 mm yr ff < , Ganges: 520 Mt yr 1 − 544 543 yr) rates of erosion and models of landscape evolution are typically ) (Burbank et al., 1996; Burg et al., 1998; Finnegan et al., 2008; ects the lifetime of hydropower reservoirs and abrades hydropower 1 3 ff − 10 > ) rank among the highest in the world and contribute 1 − In this study, we analyze daily river discharge and suspended sediment concen- Long-term ( High topographic relief, steep river profiles, and elevated stream power all indicate main stem of therainfall and Sutlej snow and cover from data,rock-strength four as measurements well of to as its investigate airfrequency, the largest high-magnitude temperature climatic tributaries and sediment and earthquake with discharges. geologic records,peak remotely controls Previous events and sensed on research often low- account shows for thatal., a 2001; such large Bookhagen fraction et of al.,2010). 2005; the In Henck sediment a et budget final al., (e.g. step 2010;across Barnard we Kirchner the et compare et the al., Himalaya new 2001; to datatransport. Wulf with identify et published al., spatial sediment flux patterns data and from first-order controls on sediment in the Himalayan region (IPCC, 2007). tration (SSC) data fromsediment the flux Sutlej (i.e. Riverand discharge Valley in climatic multiplied the regions. by western SSC) We Himalaya characteristics to compare in study the di the sediment flux data from four sites along the inferred from sediment accumulationmeasurements rates of in suspended reservoirs sedimenting) (sediment and (Meade, trapping), bedload 1988; or fluxes from innot Wulf reliable rivers et record (sediment al., low-frequency, gaug- high-intensityfraction, 2010). events they and provide rarely Although valuable include fluvial insightsweather the into sediment and bedload the measurements climate behavior of (e.g. do and rivers Wolman rivers and and also their Miller, elucidates coupling 1960). thesediment to impact flux, This of as climate coupling increasing change temperatures between on cause climate surface pronounced erosion environmental and changes fluvial al., 2005; Craddock et al., 2007; Wulf et al., 2010). based on thermochronological (e.g. Reiners(e.g. et Bierman, al., 2005) 1994; and Bookhagen cosmogenicdirect and nuclide data Strecker, measurements 2012; of von Blanckenburg, fluvial 2005). sediment More yields, spanning years to decades, can be amounts of sediments in the orogen’s interior (e.g. Bookhagen, 2010; Bookhagen et the orographic barrier and result in heavy rainfall events, which can mobilize enormous Most authors agree thatrapid rapid fluvial rock incision upliftmalaya and and (e.g. hillslope Galy heavy and mass monsoonal France-Lanord,Particularly 2001; wasting precipitation Hodges the along lead et eastern al., the to and 2004;sion southern western Thiede (1–10 syntaxes et front mm yr al., are of 2004). areasStewart of the et high al., Hi- exhumation 2008; and Zeitlerbetan et ero- Plateau, al., erosion 2001). rates In arefall contrast, significantly on amounts lower the and ( orographically lower shieldedsuggest topographic Ti- that relief during (Lal active monsoon et phases al., strong convective 2003). cells can However, migrate several across studies quantifying the spatiotemporal patternstant, and because variation it of a fluvialturbines sediment (e.g. flux Singh is et impor- al., 2003). high erosion rates throughout the Himalaya (Finlayson et al., 2002; Vance et al., 2003). iment loads of these540 Mt yr rivers (Indus:sediments 250 reaching Mt yr the oceans (Millimannitude and and Syvitski, distribution 1992). of Knowledgeis of crucial orogenic the for erosion mag- understanding rates howSmall these as and landscapes well Anderson, evolve 1995) as (Molnar andal., and the how England, 1996; operating erosion 1990; Clift might processes et a climatic al., changes 2008; Thiede (Raymo et et al., al., 2004, 1988; 2009; Raymo Wobus et and al., Ruddiman, 2005) 1992). and global Furthermore, Pronounced erosion in theand Himalaya delivers the large Ganges-Brahmaputra amountssubmarine river of fans sediment systems, in to which the theBay Arabian build Indus of Sea up (up Bengal to the (up 10 to worlds km 16.5 thickness) two km (Clift thickness) largest et (Curray al., et 2001) al., and 2003), the respectively. The sed- 1 Introduction 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 2 m at the > 4000 m a.s.l.) is < 4000 m asl and has virtually no > above 500 m a.s.l.). Approximately 2 magnitude. 300 m a.s.l. at the southern Himalayan Front 546 545 ff ± 3500 m. The Ganvi catchment is part of this region, < erences in runo ff 400 m and 2100 ± dominated by snow- and glacial-melt from the high, orographically- 0.2 m in the interior parts of the orogen over a horizontal distance of ff < 15 %), mostly in the lower part of the Sutlej Valley. Glacial cover is particularly dense The rocks in the study area can be subdivided into several contrasting units, which Throughout this study we distinguish between the Himalayan Front, the Himalayan 100 km (Wulf et al., 2010). The highly seasonal precipitation results in peak river dis- < malayan Crystalline Sequence (LHCS), whichgneiss consists of with mylonitic minor micaschist, granitic metabasite and quartzite (Vannay and Grasemann, 1998); (d) the are bounded by major north-dippingthe tectonic fault mountain systems that belt runand parallel (e.g. along Gansser, strike Burchfiel 1939; et Hodges,prise al., 2000). (a) the 1992; From Sub-Himalayafrom Fuchs, southwest foreland erosion basin, to 1975; of which northeast the Gansser, contains(LHS), these orogen detrital which 1964; units (Vannay mainly sediments et com- Heim consists derived al.,al., of 2004); massive 2000); (b) quartz-arenites the (c) intruded Lesser by the Himalaya basalts medium- Sequence (Miller to et high-grade metamorphic sequence of the Lesser Hi- that inhibits most monsoonal moisturefore to creates migrate a northward into steep thefrontal orographic orogen parts rainfall and gradient. to there- Rainfall< decreases from charges and sediment flux duringin the summer pronounced season spatial and di orographic processes result 2.2 Climatic and geologic setting Precipitation in the western Himalaya(Bookhagen has and pronounced Burbank, 2010). seasonal and Mostand snowfall spatial increases occurs variations with between elevation December (Singh and and March to Kumar, 1997; mid-September Wulf et the al., Indian 2010).at monsoon From elevations mid-July accounts of for 900 intense(Bookhagen rainfall, and which Burbank, is 2006). focused The Higher Himalaya acts as an orographic barrier ern part of the Spitilow catchment relief belong and to almost the nobetan Himalayan vegetation Plateau Crest due region. region, to High which aridthe elevations, climatic comprises Sutlej conditions catchment the upstream characterize northern of the Namgia Ti- part (the of so-called Zhada the basin). Spiti catchment and high degree of glaciation, and sparse vegetation. The Baspa, Wanger, and the south- Valley (Fig. 1). The HimalayanHimalaya Crest and region leeward comprises areas the that high are characterized mountain by peaks high of relief, the abundant snowfall, a shielded Himalayan Crest is comparable indominated magnitude by to monsoonal the rainfall Himalayan (Bookhagen Front, and which Burbank, is 2010). Crest, and the Tibetantics Plateau (Fig. region 1b). based on Theand topographic Himalayan and Front the marks climatic high the characteris- Himalayan areadense peaks, between vegetation the and at Indo-Gangetic elevations is Plains although characterized somewhat set by back high into the monsoonal orogen due rainfall to and the broad and deeply incised Sutlej lush and dense. Therefore(81.2 %), the next primary to landand trees cover and in lakes the shrubs (1.1 %) Sutlej (7.2( %), (FAO, Valley is 2009). cultivated bare areas ground (6.8 Hence,at %), the developed glaciers Himalayan soils (3.7 Crest, %), where coverresult, snowfall only river is runo a highest (e.g. small Singh fraction and Kumar, 1997). As a two-thirds of this area areNW–SE located in between China the and drain southernrange. the edge Zhada To the basin, of which west,tions the stretches the between Tibetan Indian the Indo-Gangetic part Plateau Plains of (400malayan and m Crest the a.s.l. the (6400 Sutlej – m a.s.l.) Mount above Valley sea coversMore (Fig. Kailash level, a 1). asl) than and wide 80 The % the range catchment-average Hi- of altitudevegetation of the is eleva- cover catchment 4400 (Fig. m area a.s.l. 1a). islocated located at The at the lower monsoon-impacted part southern of front of the the catchment Himalaya, area where ( vegetation is 2.1 Geographic setting The Sutlej River iscatchment the largest area tributary in of the the Himalaya Indus (ca. River 55 and 000 km drains the third largest 2 Geographic, climatic, and geologic setting 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ◦ (1) (2) (3) 0.25 × ) to part ◦ 1 − s 3 ), and suspended 1 15 km) earthquakes − < s 3 (m ), according to: 1 − Q yr 2 − 5 were recorded in the Sutlej Valley ≥ 547 548 ). We convert daily river discharge (m ), to calculate the suspended sediment load, SSL 2 1 − (Larson et al., 1999; Wang et al., 2001) causes con- ), according to: 1 1 − − )) i (m yr R , SSC( ff · ) i ( . Q /A ) ( i ( 30 km) and a temporal resolution of 3 h. This data set combines microwave 1 Q is the catchment area (km = × A i 365 SSL X 1 A = P ), and the suspended sediment yield, SSY (t km i 365 = = man et al., 2007). The recently published APHRODITE rainfall dataset (Yatagai et 1 ff − = 30 km We use the measurements of daily river discharge, In our analysis, river discharge and SSC data represent the daily average of usually The continuous northeastward movement of India with respect to Eurasia at a ∼ SSL (t yr R hourly and hourly basis, respectively. DespiteRiver the at high Wangtoo, sampling we frequency had ofof only the which Sutlej access we to calculated the the daily arithmetic minimum mean and for maximum our SSC analysis. sediment data, concentration, SSC (g l SSY of the annual runo satellite-derived rainfall data product TRMM 3B42. Baspa River and the Sutlej River at Wangtoo measurements are conducted on a 6- where To investigate links betweenfall we extreme use events the of( TRMM suspended product sediment 3B42,and flux which infrared and rain-rate has estimates rain- a fromgeosynchronous spatial sensors onboard satellite, resolution several of low-earth which(Hu orbit 0.25 have and one been rescaledal., 2009) with has been monthly shown todata rain-gauge be density a data is good high rainfall (Andermann indicatorfall et in stations al., the are central 2011). sparse, Himalaya, However, especially where in in the the western upper Himalaya, Sutlej rain- area. Hence, we here rely on the two measurements, one in the early morning and one during late afternoon. In the network of weatherconcentrations stations (SSC). and River measure dischargerating river measurements curves, discharge are which based and are annually oncause suspended recalculated stage-discharge sediment of during low-flow channel conditionsseveral in bed of winter, changes. its be- tributaries isthe Year-round done SSC high at the sampling velocity water and ofment surface mixing turbulence and the and close of that Sutlej to the the thecolumn. River SSC riverbank. streams, samples and are Given we therefore assume representative of a the entire high water degree of sedi- (Hintersberger et al., 2010). 3 Data sets and methods In the Indian part of the Sutlej Valley, several hydropower companies operate a dense al., 2004). present rate of ca.siderable 35 mm seismic yr activityfive in decades, the 20 earthquakes Himalaya(Fig. with 1a). (Bilham magnitude Whereas et largerelated NW–SE al., to shortening the 2001). earthquakes underthrusting atat of the the India Himalayan Himalayan During beneath Crest Front Eurasia, and are the shallow Tibetan past Plateau ( mainly document ongoing E–W extension cies to migmatiticgranitic paragneisses gneisses with often minor intruded byand metabasites, granitic Grasemann, plutons calc-silicate 1998); (Thiede and gneisses, et (e)Himalayan and al., the Sequence weakly 2004, (THS), metamorphosed 2006; sediments which Vannay comprise of consists the the of cover Tethyan sediments metapelites of and the metapsammites former that Indian continental margin (e.g. Vannay et Higher Himalaya Crystalline Sequence (HHCS), which is composed of amphibolite fa- 5 5 10 20 15 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ´ ardossy, as days exceeding 0.8) in river discharge > 2 erent rock types that are r ff on sediment flux we further ff peak SSC days , which encompass a variable length of ¨ oschl, 2006). We reduced data gaps due 550 549 during the 12-year catchment rainfall time se- as rainfall days exceeding the 90th percentile 1 − 10 SHR probably indicate fractured rock and were < peak SSC events rainstorms 2 mm day regimes, whereas the smallest, mostly rain-fed Ganvi tribu- ≥ ff because river discharge is confined to low flow conditions, as 1 − cient of determination among all SSC gauging stations indicates a ffi . Consequently, the summer season accounts for more than 80 % of the faces of road cuts (Katz et al., 2000). We conducted measurements 1 − ff concentration To assess the spatial variability of river discharge and SSC we cross correlate all In all catchments we find a strong positive correlation between daily river discharge In order to obtain information on spatial variations in rock strength, we estimated To study the control of snow and glacial melt water runo We calculated the daily catchment-average TRMM rainfall for each catchment from and daily SSC (Fig. 3), i.e. the higher the river discharge the higher the sediment among all stations in the Himalayansimilar Crest and nivo-glacial Tibetan runo Plateau regions, whichtary indicates at the Himalayan Frontoverall exhibits the lower weakest coe correlation withhigher all other spatial stations. variability The intween SSC small- and and is large-scale most catchments.stations likely along The due the pronounced to Sutlej correlation variablethe River of response data. (bold neighboring times numbers be- in Table 2) underpins our confidence in increased stream power andabove enhanced 0.5 transport g l capacity thatannual elevates river SSC discharge typically budget and more than 98 % of thegauging annual sites SSL (Table budget 2). (Table 1). Here, we find strong correlations ( 4.1 Relationship between river discharge and suspended sediment River discharge and suspended sedimentby concentration a (SSC) pronounced are seasonality botherally (Fig. characterized 2). below 0.5 During g l wintermost (November precipitation to above April) 2000 SSCOctober) m a.s.l. rainfall, is falls snow- gen- in and glacial form melt of increase snow. the river During discharge, summer which (May results to in discarded (e.g. Craddock etmade at al., 20-cm 2007). intervals. At each site, 10 to4 40 measurements Results were Schmidt hammer rebound values characteristic for the entire Sutlej Valley (Fig. 1b). Individual measurements returning spline interpolation on the FSC2009). time series The (Dozier smoothing et al., splinesis 2008; are provided Gafurov weighted in and the based B MODIS onFinally, surface we the reflectance filled sensor product all zenith MOD09GA remaining angle, (DozierCarlson, data et 1980). which gaps al., 2008). by piecewise linear interpolation (Fritsch and the rock compressive strengthat using steep a cli Schmidtin the hammer Spiti, on fresh Sutlej, bedrock and surfaces Baspa catchment, which cover di tem (Hall et al., 1995,snow 2002). Comparison measurements of in MODIS snow the95 products % western with (Klein ground-based and US Barnett, and 2003;to Parajka Austria clouds and have Bl by yielded combiningrected accuracies Terra and for of artifacts Aqua introduced 94– observations by from large the viewing angles same and day other and systematic we errors cor- with the 99th percentile ofpeak the SSC catchment days, SSC we time2–7 refer days series. to in our In data. casein Such of SSC peak several followed SSC successive by eventsthat a are successive characterized gradual peak by decrease. SSC an days abrupt We are increase related refer to to a peak singleuse SSC trigger daily mechanism. events fractional if snow weinstrument cover onboard assume (FSC) the observations Terra and that Aqua are satellites derived of the from NASA the Earth MODIS Observation Sys- 1998 to 2009of and all define precipitation days ries (Fig. 2).treme Rainfall rainfall in events (e.g. the Bookhagen,2009). 90th 2010; percentile Cayan Based et has on al., been the 1999; previously Krishnamurthy same associated et approach, al., with we ex- define 5 5 20 25 15 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ). 1 − yr 2 6.6 (cf. Ta- − = S ect large areas. M ff 30 % to the total ∼ in this arid region results ff 90th percentile) throughout > ). At the Himalayan Front sediment 1 − yr ). On the contrary, the Himalayan Crest is 2 1 − − 552 551 yr 2 − 20 % of the total suspended sediment flux. ∼ , they leave only a low imprint on the overall sediment ff along with moderate SSC, which results in moderately high ff increases by a factor of 20 (Table 1) and therefore, mean are both high resulting in high SSY (ca. 1500 t km ff ff Whereas peak SSC events are generally associated with the most intense rain- The foregone analysis indicated that peak SSC events frequently coincide with rain- The sediment amount transported during peak SSC events varies considerably concentration and runo Himalayan Crest, followed bycontrast an to increase the towards 8-fold theHimalayan decrease Himalayan Crest, in Front mean runo (Fig. annualannual 8a). SSC suspended sediment from In yields the (SSY)spite Tibetan (eq. the Plateau 1) high to continuously SSC the increasein levels a (Fig. at comparably 8a). the low SSY De- Tibetancharacterized (ca. Plateau, by 250 high t low km runo runo levels of mean annual SSY (ca. 1000 t km 4.3 Spatial patterns in suspended sedimentIn yields the following wein investigate the the large-scale Sutlej patterns(SSC) of River decreases mean network. downstream annual along sediment the flux The Sutlej mean River annual from the suspended Tibetan sediment Plateau concentration to the most complete SSC time series,Baspa covering rivers five and to six theSSC years, Sutlej events stem River are from at directly theevents Wanger related Wangtoo, occur and to and almost rainstorms indicate on (Table an that 3).River annual 57–80 at basis % Rainstorm-related Wangtoo, in they of peak the account all SSC semi-arid for orogenic peak interior. At thestorms Sutlej between July and August,the monsoon numerous season rainstorms leave ( no significant imprint on the SSC record (Fig. 7). storms (Fig. 4).rainstorms, delays While of up many to of 1exclusively occur or these 2 in peak days the can largest SSC beof catchments, observed events the we (Fig. discharge suspect occur 6). from that on the Because theywith source these are the delays areas peak related to same SSC to the routing day events gauging typically stations. as last Rainstorms associated for 1–3 days (Wulf et al., 2010). Our longest and suspended sediment flux (Fig. 5). 7 days, which can bewidespread traced simultaneous by occurrence several indicates gauging that stations rainstorms in the can Sutlej a catchment.among Their all catchments rangingthe between largest 5 catchment % area and ofutary 62 the % catchments, Sutlej of River peak the atsuspended SSC Wangtoo, overall sediment which events flux SSL integrates (Table (99th budget. 3). mostorographic percentile) trib- In In barrier all contribute the catchments leeward 90th (northward) SSC of percentile the main accounts for more than 50 % of the total Peak SSC days occur almostcases annually in throughout most the catchments(2001–2009) and Sutlej can we River be find traced network in thata (Fig. many lake peak outburst 4). flood, SSC and days extremewas melt During related appear events. to In the to an contrast, be observation none earthquake,ble of which A1). concurrent period the occurred peak with Between with SSC 2005 rainstorms, days magnitudes and up 2007 to we identify three major rainstorms, lasting together peak of the Indian monsoonsnow and season, glacial when melts. river Therefore, discharge peaksediment is SSC load. days highest are due However, generally some to associateddue peak with additional a to SSC high the days generally also lower occurbudget runo (Fig. in 4). June or September; but 4.2 Peak suspended sediment concentration events sediment along the rivercharacterized as by extraordinary the high river SSCmagnitude discharge values above that increases. the occasionally seasonal range However, averagesediment-rating 1–2 some and curve orders days therefore of (Fig. are exhibit large 3).ceeding residuals the from 99th Such SSC the peak percentile, occur SSC predominantly days, during which July and we August, define i.e. the as days ex- concentration. This correlation suggests increasing mobilization of transiently stored 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 90th > ected by ff 10.3 SHR). Some- 9.3 SHR), similar to ± ± 5 years provides a more erent rock units and there- ≥ ff 6.6 SHR), whereas the granitic ± 7.6 SHR), which slightly exceeds the rock 554 553 ± erences in vegetation cover and rock types also ff erences in erodibility, or gradients in sediment availabil- ff erences in erosion processes are likely between the arid ff erent Sutlej tributaries that are characterized by contrasting ff erences, di ff 8.7 SHR) (Fig. 10). erences between lower SSC in May and June and higher SSC during ± ff erent climatic zones from the Himalayan Front to the Tibetan Plateau. ff erences between rock types. The quartzite in the Lesser Himalayan Sequence contrasts sharply along the Sutlej River. In the following we discuss variations in ff ff erences in rock strength can influence the erodibility of di erences are less pronounced or do not exist. During July and August, when the ff ff across di runo sediment availability and sediment supply basedand on compare their spatial climatic patterns and of geologic controls sediment flux in the Himalaya. 5.1 Monsoonal controls on suspended sediment flux During our observation period (2001–2009) wepercentile) identified monsoonal as rainstorms ( the dominant driving mechanism to deliver sediments to the steams ity. Large downstreamTibetan di Plateau, the snowfallHimalayan dominated Front. Himalayan Catchment-wide Crest, di andsuggest the pronounced rainfall dominated variations insediment that erosion can susceptibility. be mobilized Furthermore, during the extreme supply hydrometeorological events of with high strength measurements ofquence the (47.1 paragneisses in the High Himalayan Crystalline Se- 5 Discussion In our studyTibetan we Plateau observe to anprocess-based overall di the increase Himalayan in Front. suspended sediment This flux spatial from pattern the could reflect either gneisses in the Lesser Himalayan Crystallinetalline Sequence Sequence and indicate the significantly High lower Himalayanthe rock Crys- granitic strengths (40.7 intrusion inwhat surprisingly, the metasedimentary Tethyan Himalayan rockson Sequence of average, (39.4 the a Tethyan Himalayan high Sequence rock yield, strength (51.0 is characterized by the highest rock strength (60.0 is 8.5 SHR. Despite suchple di variability, the average rock strength indicates some princi- infrequent extreme events. 4.5 Rock strength measurements Di fore SSC levels inrock the di units. Ourrange rock between compressive-strength 12 measurements andtype 74 of SHR strength the (Schmidt measurements hammer studied rebound vary rock values). types widely, Within such each that rock the average standard deviation nizable. The simplified meanon an monthly annual hysteresis basis loop strongly influencewhich of by can individual the timing alter years, and the however, magnitude is that of orientation peak a and SSC mean shape events, monthly ofaccurate hysteresis the representation loop mean of based monthly the on hysteresis. time seasonal We series sediment argue flux, because it is less a limb of the hydrograph (May,for June) a compared given discharge. to For the individualsis falling years, limb we loop find (September, in a October) pronounced the anticlockwiseyears, hystere- daily the sediment di flux duringSeptember and 2001, October 2002, are 2006, mostdi and distinctive. 2007. For the During remainingmonsoonal these years rainfall these and seasonal glacialand discharge river peak discharge are in very this pronounced region, and variations no in characteristic daily daily SSC pattern is recog- In most catchmentsmean we monthly find sediment aat flux weakly Wangtoo shown pronounced (Fig. in 9a). anticlockwiseWanger a River hysteresis characteristic (Fig. This loop 9b) example anticlockwise and of hysteresis for indicates loop less the suspended is Sutlej sediment most transport River pronounced on the in rising the 4.4 Seasonal variations of suspended sediment flux 5 5 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | and rainfall (e.g. Meigs ff ect may be related to the vari- ff in glacial and periglacial areas repre- ff 556 555 ) over the past decades (Bhambri and Bolch, 1 − In the western Himalaya, recent increases in surface temperatures caused the re- The frequent occurrence of peak SSC events during rainstorms in July and August During a field visit in September 2009 (cf. Fig. 6a), we witnessed an intense rainstorm et al., 2006).risk Furthermore, imposed the by increase glacial in lakes surface and temperatures caused increased widespread the permafrost flood degradation, which meltwaters most likely account forfrom 23 this April peak to SSC 29 event.accounted August 2008 For for this the 58 suspended % measurement sedimentsuspended of period discharge sediment event the (3–29 load. June) total suspended sediment flux, correspondingtreat to of 3.1 Mt most of glaciers2009). (ca. As 20–50 m a yr result,highly these susceptible glaciers to erosion expose processes unstable driven paraglacial by landscapes, glacial which runo are SSC event, snow coverage wasmoderately less during than the 15 peak % sedimentfore, in discharge it the from Spiti is 14.2 catchment unlikely toamounts and that 8.8 of decreased % snow sediment. (Fig. avalanches 11b). Into or There- contrast, glacial snow elevations, glacial which melt ablation generally derivediment initiated, corresponds floods (e.g. as to Haritashya mobilized the the et evacuation snowline large of al., retreated subglacial 2006). sed- We suggest that sediments mobilized by glacial few peak SSC events,occurred which in cannot June be 2008 related(Table in to A1) the monsoonal or Spiti rainfall. rainstorms tributaryJune Such (Fig. during corresponds an closely the 11a). event to absence an of Instead,ing increase major in mid the air earthquakes and increase temperature. late in Despiteair June heavy SSC temperature rainfall the (Fig. from dur- SSC 11a). early decreased, Thisduring correlation to which this suggests mid again event that was corresponds the inducedglacial-melt suspended to related by sediment decreases source changes flux in for in the temperature, sediment which discharge. suggests During the a initiation snow- of or this peak the frozen and permafrost areas. 5.2 Extreme melt events Besides the apparent relation between rainstorms and peak sediment flux, there are are evacuated. Furthermore, the coeval temperature increase results in a decline in we suspect that these areas may act as source regions from where stored sediments could also indicate thatsents an rainfall-induced important runo sediment source2006; (e.g. Singh Collins et and al., Hasnain, 2003). 1995;discharge This Haritashya argument from et is al., supported the by Gangotri studiesthat of and glacial water sediment Dokriani and flux sediment Glacier, peaksSingh western during et monsoonal Himalaya, al., rainstorms 2003; which (Haritashya Thayyen indicate et etanticlockwise SSC-hysteresis al., al., loop 2007). 2006; in In the addition, glaciatedan we Wanger observe increase catchment, the which in most indicates pronounced SSCseason during the the snowline course is elevated of and the more monsoon glacial season. and periglacial Because ground late is in exposed, the no significant imprint on theations SSC in record sediment (Fig. availability, 7). rainstormfied This intensity, or in e soil other parts moisture of thresholdsand the as Himalaya Starkel, identi- (e.g. 2007). Dahal and Hasegawa, 2008; Gabet, 2004; Soja Crest and Tibetan Plateau region. event in the semi-aridwidespread region rockfalls, leeward debris of flows, theserved and during main mudflows. a orographic prolonged Similar intense barrier, rainfall eventset which phase were at al., triggered the previously 2005). end ob- of The Augustrainstorms correlation 2002 (Bookhagen between frequently peak trigger SSC landslides eventsriver and and discharge. enhance rainstorms suggests fluvial However, that erosion several due rainstorms to throughout increased the monsoon season leave Himalayan Front, which contrast thein more the pronounced orographically rainstorm shielded Himalayan magnitude Crestet variability and al., Tibetan Plateau 2007; regions Wulf (Craddock ments, et which al., indicate 2010). frequent,Himalayan This Front low-magnitude and observation SSC less is pulses frequent supported during but by rainstorms high-magnitude our at SSC SSC pulses the measure- at the Himalayan Previous studies emphasized the high rainstorm magnitudes and frequencies at the 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 2 ff or 1 − day 2 − results in an and a SSC of ff 1 − s 3 (15.7 %) to 395.8 km (SJVNL, 2005) with an 2 1 − in semi-arid areas upstream 1 − on 27 June. The decrease in SSC 1 . Farther downstream the peak SSC − through snow and glacial melt, which 1 is constrained by a maximum SSC of ff − 1 s cient to erode these layered and densely − 3 ffi ) until 30 June 2005. Compared to the total (Kumar et al., 2007). The day preceding the 1 558 557 − 1 s − 3 s 3 with a maximum depth of about 40 m storing about 2 1700 m ∼ ) reduced by 52.3 % from 830.1 km 2 of water in September 2004 (Gupta and Sah, 2007). The dam failure estimated at the confluence with the Sutlej (Gupta and Sah, 2007). The 4- 3 1 ciently erode and transport sediment stored in the riverbed (Baker and Kale, − m on 26 June and a minimum SSC of 32 g l s ffi 6 for the flood day, for which only limited measurements are available (Fig. 6c). 1 3 − 1 10 − × We estimate the suspended sediment load of the flood event (26 June–3 July 2005) soils. Despite the protective vegetation cover, these soils are commonly detached easily mobilized by increasedglacial river and discharge periglacial or processes are rainstorms highlyfractured (Fig. e metasedimentary 12a). rocks We (Heimsath argue andThe that McGlynn, decrease 2008; in Molnar mean etCrest annual al., is 2007). SSC primarily caused from by thedilutes an Tibetan increase the in Plateau suspended runo towards sedimentincrease the in concentration. Himalayan transport capacity, which This alsoSitaula includes increase et a in al., higher 2007). bedload runo fractionHimalayan In (e.g. Front contrast Pratt- is to characterized the by bare lush Himalayan vegetation, Crest which and indicates Tibetan highly Plateau, developed the 5.4 Geologic controls on suspended sedimentThe flux supply of sedimentcontrasts that sharply can along be the mobilized Sutlejfeature during River. large In alluvial extreme the fans events at Tibetan with their Plateau high base, region runo which many provide hillslopes abundant sediments that can be exponential decrease during rainstorms (Fig.tionally 6), high which river might discharge be ( eight caused peak by SSC the events excep- measured atParechu the Flood Sutlej accounted River at for Wangtooduring 51 during % these 2004–2009 peak of the SSC the events.three Due total to times suspended its the sediment prolonged magnitude duration load of (eightration) the transported days) in highest it the was rainfall same almost induced year peakthe (Fig. SSC dominant 6c). event erosional (five Therefore, event day during the du- Parechu our Flood observation can period be (2001–2009). considered as underestimation) is based on an50 average g l daily discharge of 2000The m estimated SSC of151 average g l daily of 50 gduring l the eight-day period after the flooding day was rather linear as compared to the at the Sutlej River at41 % Wangtoo of to be the about 2005 34 suspended Mt, sediment which budget. equates to This 88 t conservative km estimate (likely an flood, TRMM indicates heavyof rainfall of the 10–20 landslide, mm day whichimagery coincides between with 23 pronounced and snowupstream 27 melt area June as (5294 2005. indicated km (7.5 by %). During MODIS the 5-day Therefore,of period, it rainfall snow is and cover likely in rain-on-snowhydrostatic the pressure that event, on which the the caused dam. dam an failure increase was in triggered river by discharge a and combination 64 released a flood2000 wave m of about 20year m averaged discharge in at height thisof with site the is a Sutlej 100 m maximum Riverestimated discharge at peak Wangtoo of discharge was of about 4000 measured m to be 151 g l 5.3 The 26 June 2005, ParechuFloods Flood e 1998; Bookhagen etOn al., 26 2005; June 2005 Coppus aRiver, and flood which Imeson, occurred was in 2002; caused the bylandslide Hartshorn Parechu the occurred River, et failure the in of main al., latewhich tributary a 2002). spring/early covered of landslide an the summer dam area Spiti of that of blocked 2004 1.9 the km and river. formed The an artificial lake, 2007; Lawrence andwestern Slater, Himalaya 2005; experienced Zhao reducedprecipitation et snow-cover falls al., in (Shekhar 2004). form eterosion of al., processes, rain. Likewise, especially 2010) large in Therefore, as the recent areas glacial more climate in and change periglacial the enhances regions. surface in turn decreases the slope stability and enhances erosion processes (Cheng and Wu, 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ) ), is 1 6) 1 − ff − < yr yr S 2 2 − M − ) earthquake S M erent time spans erences in litholo- ff ff 5 years) mean of the SSY in > ) (Tables 4 and A2). 1 due to the high sediment flux of tribu- erences may be explained by variable − erent rock types, we measured the rock ff ff ff yr culties in comparing di 2 ffi − 560 559 ) that is fed by the Batura glacier (6086 t km 1 − yr , creep, bioturbation, and shallow landsliding (Burbank, ff 2 − erences in grain size, and joint spacing gradients within in the Tethyan ff . This pattern is evident in the upstream catchments of the Indus, Chenab, ff Sediment flux measurements in proglacial streams exhibit large variations in their In general, the elevated, arid regions are characterized by low sediment yields, due to Our analysis suggests that low- and intermediate-magnitude earthquakes ( In order to characterize the erodibility of di gions, others in the easternand Karakorum are or comparable central to Himalaya sediment exhibitquently, yields low the from sediment the yields glacial arid sediment Tibetan yieldacteristics Plateau of exerts (Fig. their 13). a downstream Conse- large rivers.the influence This Hunza on is River the exemplified (3373 by sediment t thewhich km flux high contrasts char- sediment the yield relatively of that low is sediment fed by yield the of Siachen the glacier (707 Shyok t km River (924 t km suspended sediment yields (Table 4),gies, which topography, might glacial be2011a,b). related debris Whereas to some di cover, glaciers in the andcharacterized western by Karakorum seasonal and peak western precipitation suspended Himalaya are sediment (Scherler yields et exceeding those al., in monsoonal re- the low runo Sutlej and Marsyandi Rivers (Table A2).of In these a rivers downstream increases direction,taries gradually the with sediment with higher yield runo rainfall-triggered hillslopeing erosion high and snowfall a magnitudes highsequently, and the glacial general density, sporadic, indicat- north-to-south intense increasealso monsoonal in reflected rainfall Himalayan in precipitation events. the and sediment Con- runo flux (Fig. 13). Finally, we attempt tosediment place flux our measurements. resultsof Despite in suspended di the sediment yields contextHimalayan rivers (SSY), of indicates the some Himalaya-wide first-order long-term suspended spatial ( patterns. 5.5 Spatial patterns in modern Himalayan erosion strength indicated by thepressive Schmidt strength hammer measurements measurements. doof Therefore, not rock our provide type rock erodibility. comprehensive com- insights on variation have a low impact1999 on in the Garwal suspended Himalaya, sedimentreactivated and Barnard flux. induced et landslides During reached al.to the the intermediate-magnitude (2001) rivers. 6.4 earthquakes ( Therefore, found mobilize we material, that assumethe which that only is rivers. low- rarely one evacuated by third of all 338 rock types, di Himalayan Sequence (Aydin and Basu, 2005).imentary sequence In our is study characterized area bywhich the a greatly Tethyan high metased- reduces joint density thesive oriented rock strength along cohesive may the result strength foliation, in (e.g. a Selby, high 1980). erodibility, despite This an low overall high cohe- rock compressive characterizes the rivers of the Himalayan Front. compressive strength with aations. Schmidt In hammer comparison andCraddock to et identified al. rock (2007), rock-type strength we specific findmalaya. measurements similar However, vari- in rock from strength the the magnitudes Tethyan Himalayan ina central Sequence Lesser Craddock Himalaya and reduction et High by al. in Hi- (2007)within rock observe the strength, metasedimentary which series. contrasts our These finding di of increased rock strength 2009; Morgan, 2004).ize the In lower-elevation addition, Sutlej River largewider river and fluvial valleys tributaries and terraces lower (Bookhagen river and etwhich gradients allow can alluvial al., larger be 2006), storage fans reworked volumes because during character- forment sediments, higher availability, discharges which (Fig. is 12c). mobilized Because by of pronounced this orographic high rainfall, sedi- increased SSC by rain splash, surface runo 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , increases ff 30 % of the sus- ∼ doi:10.1029/2011gc003513 562 561 99th SSC percentile) account for ≥ 99th percentile) days and assess their impact on the sus- ≥ This research was funded by the German Science Foundation (DFG, Rivers Over Rock: Fluvial Processes inE. Bedrock E., Channels, Geophysics edited Monogrograph by: Series, Tinkler, K. Washington, J. DC, and 153–165, Wohl, 1998. 2011. 1–14, 2005. the Himalayan front, Geochem. Geophy. Geosys., 12, Q07023, upper Indus River basin, northern Pakistan, J. Hydrol., 334, 368–387, 2007. Second, we observe an increase of suspended sediment flux from the Tibetan Third, in all but one catchment we find an anticlockwise hysteresis loop, which indi- First, peak erosional events ( Baker, V. R. and Kale, V. S.: The role of extreme events in shaping bedrock channels, in: In Aydin, A. and Basu, A.: The Schmidt hammer in rock material characterization, Eng. Geol., 81, Andermann, C., Bonnet, S., and Gloaguen, R.: Evaluation of precipitation data sets along Ali, K. F. and De Boer, D. H.: Spatial patterns and variation of suspended sediment yield in the References Research (BMBF, PROGRESS) We thank S.D. Kumar, C. P. Goel, Kumar, V. Negi, S. H. Pathak,discharge Negi, records D. K. for Shukla, Srinivasan, us. who Weenduring provided are support grateful suspended during to sediment fieldwork. Tashi Longpo, concentration Swami and Ray, and river Bishan Lal for their more frequent monsoonal rainstormspeak across SSC events, the which Himalaya, will we decreaseimpacting the expect agriculture, water drinking-water an quality and in increase hydropower the in generation. far downstreamAcknowledgements. reaches, GRK 1364).Measuring The Mission data (TRMM)(NASDA) sponsored used and by in the the NASA.NSF this Japan (EAR B. study National 0819874). B. were Space was D. S. Development supported acquired was Agency with supported as grants by part the from German of NASA Federal (NNX08AG05G) the Ministry and of Tropical Education Rainfall and on permafrost regions andin glacial mobilizing discharge, transiently which stored peaksvalleys material. in at August, Transient the sediments play Himalayan aresediment a Front is stored vital and stored in role in in wide the thechange river steep arid scenarios, river sections Tibetan including of Plateau continuous the region, Himalayan glacial Crest. whereas retreat, In little future permafrost climate degradation, and of the monsoonal season. We suggest that increases in temperature and their impact cates more suspended sediment transport during late summer than during the onset sure on the dam. Plateau to the Himalayan Front.20-fold, From north SCC to decreases south along 8-foldand this from increases profile, runo again the 3-fold arid southwardgradient Tibetan to suggests the plateau humid, that to frontal modern the regions.at erosion Himalayan This frontal in sediment Crest regions, flux the whichdeveloped western soils. are Himalaya is characterized most by pronounced intense monsoonal rainfall and highly in the semi-arid to arid interiorlated of to the extreme orogen. melt Further events trigger andFlood of a in peak large SSC June lake events outburst 2005 are flood.41 re- was % For the of example, dominant the the Parechu erosional seasonalthe event flood suspended (35 document Mt significant sediment SSL) rainfall flux. and and snow accounted melt, The for exacerbating remote-sensing the hydrologic data pres- preceding bine these data with remotelymechanisms sensed for peak rainfall SSC and ( snow-coverpended data sediment to budget. elucidate driving Finally, wein discuss the the context spatiotemporal of sediment climatic flux anddata pattern geologic reveal controls three on key sediment conclusions: availability and supply. Our pended sediment flux.rainstorms, which These trigger peak rockfalls, debris SSC flows, and events other coincide mass movements frequently especially (57–80 %) with In this study, we providepended a sediment comprehensive flux analysis of of theis Sutlej spatiotemporal based River patterns on Valley in in gauge sus- centrations the measurements (SCC) western Himalaya. of of Our eight river analysis catchments discharge in and the suspended Sutlej sediment River con- Valley. 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K.: Suspended Sediment Transport Singh, P. and Kumar, N.: E 5 5 25 20 30 15 25 10 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ) 2 1 − − ) yr 0.98 0.97 0.82 0.78 1 − SSC SSY ff 0.13 0.15 ) (%) (g l − 0.930.98 0.91 0.730.79 0.87 1 − 0.95 0.89 ) NDVI (m yr 1 − 572 571 Tributaries Sutlej River erent gauging sites. Neighboring stations along the Sutlej, which are ff min max (km/ area area TRMM tation summer mean (t km ) (km) (km) 5 km) (%) (%) (m yr 2 Area Elevation Relief Ice Snow Rain Vege- Runo (km Correlation of daily river discharge (top) and daily suspended sediment concentra- Topographic, climatic and hydrological characteristics of the studied watersheds. Lo- cient of Namgia Jangi Karchham Wangtoo ffi Ganvi 1 0.43 0.17 0.32 0.08 0.38 River discharge(coe determination) Ganvi WangerGanvi BaspaWanger SpitiBaspa Sutlej atSpiti SutlejSutlej at (Namgia)Sutlej Sutlej (Jangi) at 1 – – Sutlej at – 0.57 1Suspended – –sediment conc. – – 0.75 – – 0.91 GanviWanger 0.77 – WangerBaspa 0.77 1 0.84 BaspaSpiti – 0.86 SpitiSutlej – – (Namgia) 0.62 SutlejSutlej at (Jangi) 0.91 0.95 – Sutlej 0.85 1 at – 0.60 – 1 Sutlej at – – 0.84 1 0.95 – – 0.81 Sutlej at – – 0.79 – 0.93 0.92 0.95 – 1 0.31 – 1 0.56 Namgia 0.91 – 0.96 0.49 Jangi – – 0.49 Karchham – – 0.92 0.41 1 Wangtoo 1 – 0.59 0.64 0.80 0.37 0.92 1 0.41 0.66 0.51 0.82 Sutlej (Karchham)Sutlej (Wangtoo) – – – – – – –Sutlej (Karchham) –Sutlej (Wangtoo) – – – – – – – – – 1 – – – – – – 1 – – 1 – 1 GanviWangerBaspaSpiti 117 264 1.6at 2.5 Namgia 989at 12 477 Jangi 5.6 5.7 2.5at 30 Karchham 950 2.6 2.58at 2.24 6.4 Wangtoo 46 291 2.6 6.7 44 738 1.9 2.21 48 316 7.2 17.2 2.2 1.68 3.7 1.5 7.2 0.93 54.1 25.8 7.2 24.0 7.2 1.22 54.0 6.7 1.21 0.74 1.12 1.27 1.8 37.4 0.93 0.11 3.6 19.8 0.39 3.6 0.36 25.7 4.1 0.09 0.38 25.6 26.5 0.03 1.67 1.27 0.39 0.39 0.08 1.14 85.4 0.41 78.3 0.07 0.26 0.29 0.07 0.93 89.5 0.07 0.06 0.80 86.9 0.16 1507 614 85.1 1.45 0.13 1717 0.20 85.3 2.59 81.5 2.37 85.9 499 1.85 223 2.20 556 302 615 Catchments Topography Climate Hydrology Table 2. tion (bottom) among di expected to correlate strongly, are marked bold. Table 1. cations of the catchmentsOctober. are The suspended indicated sediment in concentration Fig. (SSC) represents 1. the annual Summer mean. indicates the period from May to Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ] 1 − , accounts only for the 3 − ] [mm yr 1 − yr 2 − ] [t km 1 − t yr 6 Suspended-Sediment Catchment Reference ] [10 1 ff − 574 573 Tributaries Sutlej River , and meltwaters. Peak SSC events combine successive ] [m yr 2 ) (#) (%) (#) (%) (#) (%) (#) (%) (#) (%) 1 − ) (mm day ] [m] [km 1 ◦ Parechu Flood − ][ ◦ [ tude tude vation area period Load Yield denudation length threshold threshold events budget rainstroms Parechu Flood meltwaters trigger (days) (g l record percentile percentile SSC of SSL caused by caused by the caused by unknown Suspended sediment flux in proglacial streams of the Himalaya and Karakorum. The Peak suspended sediment concentration (SSC) event and their relation to rainstorms 90th percentile), the GanviWangerBaspaSpiti 1470 215 1867at Namgiaat Jangi 1.3 5.5at 615 Karchhamat 711 Wangtoo 2.1 18.0 379 19.2 286 2059 8.1 18.5 19.2 11.7 5 1 15.5 14.4 14.0 7.8 7 15.2 15.4 14.5 9.8 2 5.6 3 61.9 4 1 3 4 8 1 100 15.3 80 32.0 1 57 2 8.6 0 0 30.1 17.5 1 50 0 6 67 1 33 – 100 75 – 0 0 0 1 – 1 0 0 – 1 – 0 33 0 13 1 14 – 0 0 0 1 0 50 2 0 0 20 0 0 0 29 0 0 1 1 1 0 0 33 33 13 0 River SSC 99th SSC 90th rainfall Peak Percent Events Event Events Events with Glacier RiverSiachen Lati-Batura NubraRaikot Longi-Gangotri Hunza Ele-Dokriani 35.11 Astore Bhagirathi GlacialLangtang 77.23 30.95 36.49 Bhagirathi Obs.Changme Trisuli 3570 79.04 30.86 35.38 74.89 Tista 78.78 74.59 3830 2530 620.0 28.23 3710 3010 1987–1991 Runo 286.0 389.4 85.69 27.91 2000–2003 1990 1.36 88.70 4324 56.0 9.7 0.99 1986 1.26 4650 1995–1998 127.2 2.69 1985–1986 1.60 1.93 4.5 1.35 707 0.04 – 1.01 3.95 4834 0.08 0.32–0.49 3500–5250 2700 6086 0.27 1.3–2.0 245 1.82 – Gardner 1.02 and Jones 2.30 (2002) Bhutiyani (1999) Haritashya et 0.09 0.003 al. (2006) Singh et Collins al. (1995) (2003) 668 Ohta et al. (1987) 0.25 Puri et al. (1999) > Table 4. catchment denudation rate is basedsuspended on a sediment bulk flux, rock and densityarea. of refers 2.65 to g cm the glacial catchment area, which exceeds the glacial Table 3. ( peak SSC days (99ththe SSC Parechu percentile). Flood. Dashes Note indicate the variable that length no of records the were records. obtained during Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ). Hep.pdf ). Abbreviations of the magnitude new/PFR/HP/Luhri 576 575 http://www.iris.washington.edu www.powermin.nic.in/whats List of earthquakes in the study area. Data provided by the Incorporated Research Continued. Date4 Jun 200227 Nov 200127 14:36:03 Nov 2001 17:56:5727 Nov 2001 08:53:54 30.57 Time 29.5517 Jun 2000 07:31:52 Latitude 29.556 Apr 1999 16:34:13 81.42 Longitude 29.6128 81.75 Mar 1999 Depth28 32.00 19:37:24 81.75 Mar 1999 19:36:09 Magnitude28 10.0 81.75 Mar 1999 19:05:12 42.7 30.48 Type5 30.31 Jan 78.41 1997 19:04:50 33.0 Catalog 20 30.51 Oct 1993 5.4 33.0 79.56 5.015 30.72 08:47:25 Sep 79.36 1993 16:15:59 38.8 5.39 Dec 79.42 1991 15:08:15 29.87 MB 5.619 28.69 Oct 16.5 75.13 MB 1991 36.3 33.33 01:02:4221 5.6 Sep MS ISCCD/ISC 1990 22.9 21:23:15 80.56 ISCCD/ISC 9 Aug MB 82.25 29.51 1987 16:08:19 5.5 33.0 MHDF/NEIC 6.116 30.77 75.74 Jul 1986 MS MHDF/NEIC 29.98 21:15:03 6.46 24.9 Jul 1986 81.61 22:03:07 ISCCD/ISC MB 5.926 Apr MS 78.79 29.47 1986 43.7 –18 79.91 Nov MB 31.05 19:24:23 1984 ISCCD/NDI 5.3 07:35:16 ISCCD/ISC 18 May MB 1984 2.9 22:04:36 83.74 13.2 34.45 ISCCD/ISC 5.014 32.15 Mar 5.1 04:28:52 1984 18.7 78.00 ISCCD/DJA MS 28.6714 Mar 1984 15:32:33 29.52 5.619 80.20 6,4 Feb MB 76.40 ISCCD/ISC 1984 01:32:11 MB 5.127 34.23 83.32 – Feb 1983 4.4 15:46:26 ISCCD/ISC 25 29.18 81.79 ISCCD/ISC Jan MB 1982 MB 20:33:07 33.0 9.023 29.84 Jan 79.63 MB 1982 5.5 17:26:17 ISCCD/ISC 5.123 ISCCD/ISC 32.60 Jan 81.12 1982 17:48:02 – ISCCD/ISC 13 31.58 5.2 Jun 80.54 5.7 1981 22.2 – 17:37:29 MB28 31.56 MS May 78.57 1981 14.8 00:56:5715 31.68 5.4 May 82.25 1981 23:14:05 ISCCD/ISC MS 21.0 MB ISCCD/ISC 5.1 5.6 31.82 82.21 17:22:43 40.0 31.83 5.0 ISCCD/ISC ISCCD/ISC 82.28 MB 33.0 29.46 5.1 78.46 MB MB 30.9 ISCCD/ISC 5.3 78.44 MB 25.0 ISCCD/ISC ISCCD/ISC 5.1 81.93 MB 33.0 ISCCD/ISC 5,3 MB ISCCD/ISC 6.0 MB 33.0 – ISCCD/ISC 5,0 MB ISCCD/ISC MB 5.1 ISCCD/ISC 5.2 MB ISCCD/ISC ISCCD/ISC MB MB ISCCD/ISC ISCCD/ISC Date4 Apr 20116 Jul 201022 11:31:40 Jun 201028 May 19:08:26 2010 29.68 23:14:11 Time18 Mar 07:25:03 2010 29.84 Latitude15 29.87 Mar 2010 07:52:29 80.75 31.14 Longitude20 Nov 2009 20:17:17 Depth29 34.33 80.40 Sep 80.43 2009 07:16:59 Magnitude21 30.53 77.84 Sep 12.5 2009 06:01:13 Type 30.764 Jun 81.76 2009 32.8 09:43:51 16.3 Catalog 30.891 Apr 81.88 2009 18.8 5.4 30.8818 02:54:48 83.45 Feb 2009 37.2 5.28 5.2 02:34:37 83.49 Dec 2008 32.78 10:11:44 17.8 5.0 M25 79.06 Sep 2008 19.0 33.66 08:59:09 5.025 30.67 MB Aug 2008 MB 01:47:12 10.0 81.76 5.025 FINGER/NEIC MB Aug 29.99 2008 14:16:03 52.3 WHDF/NEIC 82.44 5.1 WHDF/NEIC 30.8425 Aug 83.86 MB 2008 13:39:39 WHDF/NEIC 5.0 30.825 May MB 2007 13:22:02 7.2 82.09 WHDF/NEIC 5.0 30.9314 83.59 Dec 10.0 MB 2005 35.0 WHDF/NEIC 08:51:40 31.068 83.56 Apr MB 2005 07:09:52 MHDF/NEIC 7 5.2 15.3 83.46 Apr MB 34.27 2005 10.0 5.0 MHDF/NEIC 30.51 5.126 19:51:42 83.65 Oct 2004 MHDF/NEIC 28 7.6 20:04:40 Jul MB 5.3 2004 82.03 10.0 30.48 02:11:31 5.4 MW11 79.25 Jul MW 2004 25.5 30.52 MHDF/NEIC 22:22:18 31.04 MHDF/NEIC 5.1 MHDF/NEIC MB 83.62 23:08:42 5.1 14.2 MB 30.64 36.9 83.66 6.6 ISCCD/ISC 81.08 30.72 MB ISCCD/ISC 60.0 MB 5.7 83.60 5.4 14.7 ISCCD/ISC MS 83.67 ISCCD/ISC 4.0 5.0 MB ISCCD/ISC 51.0 ML 6.1 ISCCD/ISC 8.1 5.9 ISCCD/ISC MB 5.1 MS QED/NEIC 6.2 MB ISCCD/ISC MB ISCCD/ISC MS QED/NEIC ISCCD/ISC Table A1. Table A1. Institutions for Seismology ( types indicate the momentmagnitude magnitude (MS). (MW), Abbreviations body-wave ofternational magnitude the Seismological (MB), earthquake Centre and cataloguesHypocenter (ISCCD), surface-wave Data indicate Quick File the (MHDF), Epicenter BulletinNational Weekly Determinations Earthquake Hypocenter of Data Information (QED), the Service File Monthly hydropower In- (WHDF), (FINGER), project a and report list historical ( distributed earthquake by data the listed in a Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 578 577 Continued. Continued. Date13 May 19816 Mar 02:07:52 198123 Aug 1980 32.5829 05:58:48 Jul 1980 21:50:01 Time29 Jul 1980 29.80 Latitude 14:58:42 32.9022 82.36 Jun 1980 Longitude 12:23:0828 Dec 29.63 1979 14:38:53 80.66 Depth20 75.80 May 29.34 1979 01:59:18 Magnitude8 30.13 Aug 1978 22:59:12 81.09 – Type 30.8214 23.6 Jun 1978 12.5 81.21 Catalog 29.93 10:12:294 Apr 81.77 1978 16:12:0527 5.0 78.57 Mar 32.27 5.1 1977 5.219 80.27 32.24 – 00:40:29 Feb 1977 3.0 05:36:498 Sep MB 1976 06:15:25 23.0 32.98 83.10 MB –6 32.67 Jul MB 76.61 1976 6.5 5.7 ISCCD/ISC 20:13:0110 31.80 May ISCCD/ISC 1976 – ISCCD/ISC 82.26 5.05 Feb 78.66 5.1 02:55:49 32.03 1976 18:43:53 3.3 MS7 6.7 MB Jan 78.43 1976 32.44 29.3311 5.7 12:04:31 Dec MB ISCCD/ISC 1975 MB 26.0 78.76 ISCCD/ISC 5.110 00:24:53 Dec – 1975 31.24 10:09:50 5.0 40.0 ISCCD/ISC 5 78.35 81.46 ISCCD/ISC Dec MB 1975 03:26:06 32.97 33.00 5.15 Nov MB 1975 77.03 5.5 ISCCD/ISC MB 32.95 07:37:10 5.46 – Sep 1975 24.6 ISCCD/ISC 76.12 00:35:5729 76.17 Jul MB ISCCD/ISC 33.10 1975 – 04:44:3319 MB 76.10 Jul MB 32.07 1975 5.5 5.3 5.1 ISCCD/ISC 02:40:512 40.3 Feb 29.21 1975 42.0 ISCCD/ISC 76.13 ISCCD/ISC 06:10:5419 5.2 Jan 32.57 1975 78.74 5.0 MB19 19:14:10 4.5 MB Jan 31.95 1975 5.3 81.95 08:12:10 5.019 23.8 Jan MB ISCCD/ISC 1975 32.55 78.49 08:01:58 ISCCD/ISC 23 21.1 31.94 Dec MB 5.3 1974 78.59 08:00:18 ISCCD/ISC MB16 32.39 Dec MB 5.3 1973 09:45:42 78.50 ISCCD/ISC 32.30 – 78.52 5.0 ISCCD/ISC 19:09:47 MB ISCCD/ISC 29.32 – 78.50 MB 34.27 21.0 – ISCCD/ISC 78.66 5.1 48.6 MB 81.38 ISCCD/ISC 5.5 1.4 74.05 ISCCD/ISC 5.1 5.1 MB 5.8 45.0 – MB ISCCD/ISC 6.2 40.0 MB MB ISCCD/ISC MB 5.2 5.1 ISCCD/ISC ISCCD/ISC MB 5.1 ISCCD/ISC MB ISCCD/ISC MB MB ISCCD/ISC ISCCD/ISC ISCCD/ISC Date24 Oct 197316 Jan 1973 05:23:516 Sep 1972 21:31:2617 33.15 Aug 1972 Time 02:51:2815 33.29 Mar 1972 18:14:25 Latitude4 Feb 75.92 32.49 1972 06:00:30 Longitude 30.753 May 75.83 1971 Depth12 30.53 14:08:22 Feb 1970 78.51 36.9 00:33:25 Magnitude22 78.42 Jun 1969 30.34 01:51:48 39.2 Type5 Mar 84.43 30.79 1969 01:33:23 Catalog 3 29.24 14.0 5.3 Mar 1969 33.0 84.4713 11:14:58 5.1 30.50 Feb 1969 84.3331 06:20:21 May 81.57 5.0 1968 29.46 MB 06:48:36 – 5.211 18.0 Feb 79.40 1968 03:01:36 MB 30.045 ISCCD/ISC 28.50 Jan 1968 20:38:27 81.02 MB 29.91 ISCCD/ISC 18 – 5.1 Dec MB 5.1 1967 79.84 –20 34.15 06:42:44 Feb 75.70 ISCCD/ISC 1967 10:51:36 ISCCD/ISC –21 22.0 79.92 Dec 1966 5.3 MB 30.41 15:18:39 MB 29.4616 18.0 5,3 Dec 78.70 1966 22:10:59 33.015 33.63 ISCCD/ISC Aug 5.3 ISCCD/ISC 1966 5.0 33.0 20:52:16 79.25 MB 29.655 81.71 Aug 1966 5.1 MB 02:15:28 24.0 29.62 5.129 Jun 75.33 ISCCD/ISC 1966 MB MB 5.0 28.67 01:03:0227 ISCCD/ISC 80.79 Jun 1966 42.0 7.0 00:42:10 MB 5.127 ISCCD/ISC 80.79 Jun ISCCD/ISC – 32.76 1966 20.0 13:55:4927 29.69 78.93 MB Jun ISCCD/ISC 1966 21.0 11:21:42 5.027 5.0 29.62 Jun MB 1966 ISCCD/LAO 79.61 10:59:18 ISCCD/ISC 5.527 29.57 Jun 80.86 1966 10:49:51 – ISCCD/ISC 5.327 5.0 29.71 Jun MB 80.93 MB 1966 10:47:456 29.50 Mar 80.82 MB 1966 10:41:08 21.0 ISCCD/ISC ISCCD/ISC 6 29.55 5,7 – Mar MB 80.89 5.6 1966 ISCCD/ISC 11 02:15:57 29.62 Oct 80.90 1965 26.0 ISCCD/ISC – 02:10:52 5.1 80.99 MB 31.49 5.2 20:15:15 MB 80.83 31.51 72.0 – ISCCD/ISC 5.2 33.80 5.3 ISCCD/ISC MB 80.50 43.0 MB 80.55 33.0 ISCCD/ISC 5.4 6.0 78.20 ISCCD/ISC MB MB 5.3 50.0 ISCCD/ISC 6.0 ISCCD/ISC MB 5.0 MB 33.0 MB 6.0 ISCCD/ISC ISCCD/ISC MB 5.4 ISCCD/ISC 5.2 MB ISCCD/ISC MB ISCCD/ISC – ISCCD/ISC ISCCD/QUE Table A1. Table A1. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 3 − ] 1 − ] [mm yr 1 − yr 2 − ] [t km 1 − t yr 6 Suspended-Sediment Catchment Reference ] [10 1 ff − 580 579 ] [m yr 2 ] [m] [km ◦ ][ ◦ [ tude tude vation area period Load Yield denudation Continued. Compilation of suspended sediment flux data for some Himalayan rivers. We first list Date1 Jun 196531 May 196520 07:52:25 Apr 02:04:43 196518 Mar 1965 28.59 05:15:30 32.65 Time20 Dec 1964 02:41:30 Latitude2 33.86 Dec 1964 03:31:32 83.06 Longitude6 29.55 77.99 Oct 1964 Depth 29.35 08:21:4226 Sep 82.10 1964 Magnitude24 20:19:32 20.0 May 80.26 29.58 1964 28.0 00:46:03 Type17 81.10 Jun 00:00:48 1962 29.40 89.0 Catalog 29.9610 Jul 1947 5.3 67.0 81.10 00:00:00 5.2 30.0410 Jul 1946 80.98 00:00:0022 9.0 33.74 5.8 80.46 Jun 1945 MB 00:00:00 5.021 82.18 MB Nov 32.60 1939 3.0 00:00:0028 Feb 11.0 75.83 32.60 5.3 ISCCD/ISC 1906 MB 00:00:00 50.0 ISCCD/ISC 4 32.50 Apr MB 1905 23.0 00:00:00 75.90 5.2 36.50 ISCCD/ISC 5.3 75.90 88.0 MB ISCCD/ISC 5.9 32.00 00:00:00 76.00 5.1 74.00 MB ISCCD/ISC 32.30 MB 5.5 – 77.00 MB ISCCD/ISC – MB ISCCD/ISC ISCCD/ISC 76.20 – – 6.0 ISCCD/ISC – 6.0 – 25.0 6.5 HEP – 6.9 – 7.0 8.0 – HEP – HEP – HEP – HEP HEP HEP SpitiBaspaWangerGanvi Khab Sangla KafnuSutlejSutlej GanviSutlej KhabSutlej 31.42 31.81 Jangi 31.62 78.26Sutlej 78.64 Karchham 78.02Sutlej 2550 31.56 Wangtoo 2550 2450 77.75Yamuna Suni 31.80 31.50 12 477 1730 Kasol 31.63Bhagirathi 78.64 989 78.19 Tajewala 31.56 2005–2008 310Alaknanda 78.43 2004–2008 Maneri 2550 77.98 1820 1999–1905Ganga Srinagar 0.26 2310 1.14 117 1480 30 30.32 1.72 950 46 31.24 2003 438 31.38 44 Rishikesh 732 2005–2008 77.58 2006–2007 77.12 48 30.74 316 30.23 76.88 2007 0.07 2004–2009 78.54 6.2 0.16 78.77 370 645 1.7 520 30.07 1.27 0.2 1295 0.20 524 78.29 52 983 9572 53 768 0.15 1994–1996 25.8 1983 499 4024 6.9 1717 10 1994–1996 330 237 2004 29.7 2004 614 0.2 – 20 600 0.19 – 0.65 13.5 2004 0.23 556 1.10 223 this study 1.22 1507 1.70 615 0.21 36.9 0.08 43.2 302 1.15 0.57 0.23 18.1 10.2 0.11 3.7 686 816 12.9 1889 0.26 0.31 995 917 0.71 Jain et 628 al. 0.38 (2003) 0.35 Jha et al. (1988) 0.24 Chakrapani et al. (2009) ChandraBhaga GhousalMarusudarMarusudar Tillar TandiMarusudar Sirshi 32.53 KuriyaChenab 76.96Chenab 2850Chenab 32.54 Benzwar 33.57 33.46Chenab Premnagar 76,98 75.79 33.35 75.86 Dhamkund 2490 2846 75.73 2066 Akhnoor 33.36 1978–1995 33.15 1620 1106 75.74 33.24 75.70 1530 2800 – 75.14 1135 3335 1977-95 1968–1987 32.89 886 3960 1968–1995 74.74 600 1968–1989 10 040 15 – 490 1972–1995 – – 18 305 1968–1995 750 – 1.3 1968–1995 – 21 808 – 1971–1995 – 1.0 3.1 0.6 513 3.5 – 16.0 21.1 0.19 35.6 373 939 371 878 Rao 1597 et 22.4 al. (1997) 0.14 1363 0.35 0.14 1900 0.33 0.60 0.51 1029 0.72 0.39 River LocationShyokShigarHunza Lati- YugoGilgit Shigar Longi-Gilgit Dainyor BridgeAstore Ele- 35.93Gorband Gilgit Drainage 74.38Brandu Alam 35.18 Bridge Obs. Doyian 35.33 KaroraSiran 76.10 1370 75.75Siran 35.77 Daggar 2469 2438 13 74.60 157Indus 35.93 Runo Phulra 1966–1998Indus 35.55 33 34.89 74.31 670 1280 ThaplaIndus 74.70 6610 72.77 1973–1998 0.80 34.50 1430 KharmongIndus 1985–1998 26 159 1583 72.46 Kachura 0.33Indus 880 1966–1998 34.31 12 095 0.99 PartabIndus Bridge 34.13 34.93 700 73.08 1963–1998 ShatialIndus 0.78 4040 Bridge 44.4 35.73 72.90 76.22 Barsin 1974–1998 635 35.45 0.74 35.53 31.1 74.62 732 Besham 2542 Qila 1975–1997 75.42 16.8 440 73.56 598 1.01 Darband 1250 1970–1998 3373 54.8 1.04 34.92 2341 1040 67 1057 856 142 825 72.88 2799 35.30 0.30 1970–1998 1983–1998 112 665 150 6.0 924 220 1963–1995 1.27 2542 1960–1973 73.27 34.36 1970–1998 1983–1998 0.63 0.23 1.7 580 2095 0.39 72.84 0.35 0.35 0.2 0.30 780 0.42 0.96 162 393 440 0.3 0.79 498 1969–1998 157 600 Ali and 23.9 De 138.3 1974–1979 166 427 Boer 154 2.4 (2007) 0.47 118.6 0.19 80.1 2.9 1960–1973 250 0.36 0.16 442 0.47 0.09 194.4 2306 355 968 1024 789 140.5 0.17 710 0.87 287.6 0.13 0.37 0.39 0.30 1197 0.27 892 0.45 1731 0.34 0.65 Table A2. tributaries followed by theirwest corresponding to main east. stems in The downstream catchment direction denudation ranging rate from is based on a bulk rock density of 2.65 g cm and accounts only for the suspended sediment flux. Table A1. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ) (Ta- Geologic formations ] 1 − (B) ] [mm yr 1 − yr 2 − http://www.iris.washington.edu ] [t km 1 − t yr 6 Suspended-Sediment Catchment Reference ] [10 1 ff − erence vegetation index (NDVI) (Huete et al., 2002), ff Longitudinal river profile of the Sutlej River and its tributaries 582 581 (C) ] [m yr 2 ] [m] [km ◦ ][ ◦ [ tude tude vation area period Load Yield denudation Map of the study area, showing the normalized di Continued. (A) Dudh KholaKhudi Khola DudhMarsyandi KhudiMarsyandi KotoMarsyandi NarMarsyandi UpperMarsyandi Dharapani 28.52 Lower Dharapani 28.53 28.28Gandak 84.36 Bhulbule 28.51 84.35 84.35Brahmaputra 2000 84.36 28.55 2030 Pasighat 820 Triveni 84.25 1880 28.55 28.28 84.26 491 2640 1946 2001–2004 84.36 2605 2001–2003 152 2650 28.08 2001–2002 2000–2005 0.67 0.56 788 812 95.34 27.43 0.44 3.54 1052 2001–2004 83.90 2001–2003 150 3217 0.76 110 249 2001–2003 0.15 000 0.2 1.3 – 2.2 0.5 37 0.76 845 1980–1989 1.4 0.2 508 1.53 678 3392 848 2.7 0.80 0.19 0.26 1696 1.28 0.32 78.5 170 Gabet et 0.64 al. (2008) 210.0 848 0.06 2074 0.32 843 0.78 0.32 Sinha and Friend (1994) Stewart et al. (2008) River Location Lati- Longi- Ele- Drainage Obs. Runo Fig. 1. ble A1). Lithologies areHimalayan grouped into Crystalline the Sequence Sub-Himalaya (LHCS), SequenceSequence (SHS), Higher (THS). Lesser Major Himalayan Himalayan tectonic Crystalline SequenceBoundary faults (LHS), Sequence along Thrust), Lesser (HHCS), the MCT and Sutlej (Mainareas River Central Tethyan show Himalayan are Thrust), elevation indicated MT draped by (Munsiari over shaded-relief the Thrust), map. following STD abbreviations: (South MBT Tibetan (Main Detachment). Surrounding draped over agauging shaded stations relief where river map, dischargestream and and areas suspended overlain of sediment the concentration by Sutlej was River glaciers, measured. and The lakes, its corresponding tributaries up- and are indicated the in Sutlej red and River yellow, respectively. network. Numbers denote analyzed in this study. Red circles and yellow squares denote gauging station location as indicated in 1A. and fault systems (modifiedtogether after with Thiede locations et of al., Schmidt 2004; hammer Vannay test et sites al., and 2004; earthquake Webb locations et ( al., 2011) within the study area Table A2. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , and bins as (B) 1 , and the − (B) is restricted to (A) , the Wanger River 2 mm in 1 mm day ≥ (A) erent orogenic regions represented by ff , the Baspa tributary during 2007 ) and suspended sediment concentration (SSC) 584 583 Q (A) . Panels on the right show the catchment-respective (C) erent scales of the axes. ff showing suspended sediment concentration (SSC) as a function of daily ). Note the di (C) Q Annual course of river discharge ( Sediment rating curves for the Sutlej River at Wangtoo the Baspa River river discharge ( Fig. 3. taken from the 12-year77 days TRMM form 3B42 mid July time to series. mid September. Note that SSC data in probability density (number of occurrences) of wet rainfall days the Ganvi tributarySutlej during River the at year Namgia 2003 during 2007 Fig. 2. underlain by summer rainstorms (May–October) in di Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 586 585 Percentage of peak SSC events on total suspended sediment flux. Length of the time Time series of peak SSC days/events within the Sutlej catchment. Plausible triggers that Fig. 5. series is given in thethe legend. Sutlej The River legend (SR) shows mainstem tributary stations stations (5–8) (1–4) from in south downstream to direction north (cf. and Fig. 1). Fig. 4. are related to peakpended SSC sediment days/events load and (SSL) catchment-average are percentagesevent indicated on that at led the the bottom. to annual the PF sus- breach (Parechu Flood) of is a a landslide rain-on-snow dam and caused significant flooding downstream. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ected ff and the Sutlej (A) represent the 6-year Peak SSC event caused (D) (B) and Peak SSC event triggered by a (C) 90th rainfall percentile), which are (A) ≥ 588 587 . Arrows indicate rainstorms ( ecting several catchments in the Sutlej Valley during August 2007. ff SSC response of the Sutlej River at Wangtoo to the lake outburst flood (B) (C) 90th percentile) during September 2009. Daily rainfall amounts are derived > Histograms of daily TRMM 3B42 data displaying annual and monsoonal (June- Relation between peak SSC events and rainfall. Larger catchments (e.g. Spiti)SSC show measurements. longer response times. Color coding indicates location of (Parechu Flood during June/July 2005) and a successive rainstorm, which especially a Fig. 7. September) rainfall during the given time period for the Baspa catchment by a synoptic rainstorm a SSC levels in the Baspa River. from TRMM 3B42 averaged over the Sutlej catchment at Wangtoo. Fig. 6. 2-day rainstorm ( catchment at Wangtoo associated with peak SSC daystime (99th series SSC of percentile). rainstorms Panel the and Baspa their catchment impact and on Sutlej peak catchment SSC at days Wangtoo, during respectively. the monsoonal period for Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , and SSY ff covering five and six (B) . The error bars represent the daily standard (D) and the Wanger River 590 589 (A) , suspended sediment concentration (SSC), and sus- ff Conceptual model of the spatial distribution of SSC, runo and the Wanger River (C) (B) ) of the monthly river discharge and SSC mean, respectively. σ Spatial gradients in runo 1 ± Time series of daily river discharge and suspended sediment concentration data sepa- years, respectively. Hysteresis loops oflej the River mean at monthly Wangtoo suspended sedimentdeviation ( flux in the Sut- rated by month of Sutlej River at Wangtoo Fig. 9. Fig. 8. (A) from the Tibetan Plateau to the Himalayan Crest and the Himalayan Front. pended sediment yield (SSY)weighted for by the the Sutlej numberaverage River of downstream and measurement distance tributary years. to catchments.ment the The area Sutlej Correlations correlation location. River are is outlet based to account on for the the catchment- predominant catch- Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 0.68) = 2 r erent rock types in parts of the ff Percentage of snow-covered area and the per- 592 591 (B) erent locations: (1) Karchham, (2) Leo Pargil, (3) Baspa. ff Comparison of SSC in the Spiti River with TRMM 3B42 rainfall averaged over the Boxplots of Schmidt hammer rebound values of di between SSC and temperature variations. centage of glacial snow-free area in the Spiti catchment for the same period. Fig. 11. (A) Spiti catchment and meanmonth daily period air in temperature 2008. data from Yellow Namgia background indicates (cf. Fig. periods 1a) of during positive a correlation two- ( Lesser Himalayan SequenceHimalayan (LHS), Crystalline Lesser Sequence Himalayan (HHCS),of Crystalline and individual Tethyan Schmidt Sequence Himalaya hammer Sequence (LHCS), measurementsrock (THS). are type High indicate given Numbers the in approximate circles. locationin or The lithostratigraphic color color group codes code (cf. Fig. below of 1b). each On the The each numbers yellow HHCS box, refer the75th di central percentiles, red the mark whiskers is extendand the to outliers median, the are the plotted most edges in extreme of separate data the red points box crosses. are not the considered 25th outliers, and Fig. 10. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Incised (B) Fluvial terrace and (A) 2000 m a.s.l.), and at outlet locations of > 594 593 Extensive fluvial terraces along the moderately inclined lower Sutlej River (C) 2500 m a.s.l.), upstream river catchments ( > Compilation of mean annual suspended sediment yield measurements in proglacial Images of varying sediment storage in the Sutlej River Valley. major rivers (100–600 m a.s.l.). Data and respective references are given in Tables 4 and A2. Fig. 13. streams ( alluvial fans alongbedrock the along high-elevated the Spiti steep River,Himalayan Crest. middle a Sutlej major River tributary section to upstream the of Sutlej. Rampur (cf. Fig. 1b) at the section downstream of Rampur at the main Himalayan Front (cf. Bookhagen et al., 2006). Fig. 12.