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SURFACE WATER AND OCEAN TOPOGRAPHY (SWOT) MISSION Science Definition Team Workshop Toulouse, 17-20 June 2014. Interest of SWOT from the Perspective of Global Hydrology and the Global Runoff Data Centre (GRDC). Dr. Wolfgang Grabs Chief, International Water Affairs
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SURFACE WATER AND OCEAN TOPOGRAPHY (SWOT) MISSION Science Definition Team Workshop Toulouse, 17-20 June 2014 Interest of SWOT fromthePerspectiveof Global Hydrologyandthe Global Runoff Data Centre (GRDC) Dr. Wolfgang Grabs Chief, International WaterAffairs Federal Institute ofHydrology, Germany (grabs@bafg.de) For GRDC contact: Ulrich Looser, Head, GRDC, (looser@bafg.de)
SWOT HYDROLOGY OBJECTIVES • Provide (geo-referenced) Global Inventory of terrestrial water bodies (rivers, lakes, reservoirs) • Measure global storage change in terrestrial water bodies at sub-monthly, seasonal and annual time scales • Estimate global change in river discharge at sub-monthly, seasonal and annual time scales Source: SWOT SRD, second release These objectives fully meet the interests and expectations of the GRDC Tremendous application opportunities for operational purposes and improved water management at sub-regional, regional and global scales
SWOT – A Case for Global Hydrology • From a global hydrologicalpointofview, thereis at presentnosystemavailablethatprovides global hydrologicaldata on regular time-intervalsworld-widewithknownerror-band-widthandqualitycheckedaccuracy. • Thereis a lack ofcontinuoushydrological observations in manyofthe large riverbasinsoftheworld, compoundedbythe non-accessibilityof observations wheretheyexistfor a numberofreasons • Same istrueforhydrological observations oflakesandreservoirswiththeaddedchallengethatthese observations areundertakenby a multitudeofagenciesandservicesevenwithinonecountry • Continuedandregularhydrological observations are a requirementforhydrologicalmodelling, dynamicwaterresourcesassessmentsandwateraccounting in riverbasins • CAVEAT: Satellite-based observations canbemostvalulablyusedcomplementarytoterrestrial observations but cannotreplacethese.
Key ConclusionsfromtheGRDC Station Map • Especially in AfricaandAsia, most time-series end beforethe end ofthe mid-1980-ies • Withfewexceptions, thelargest transboundary riversoftheworldarepoorlycoveredbyconventionalhydrologicalstationsthatare on recordwithGRDC (therearemorestations, but thesearedifficulttoaccessordataareofpoorqualityor not at all madeavailabletothe larger public)
Interest of GRDC in SWOT Observations • SWOT observations couldgenerateliterallythousandsof geo-referencedvirtualgaugingstationswithsuccessivelygowing time-seriesalongmajorrivers, lakesandreservoirsthatwouldcomplementterrestrial observations andthuslargelyincreasethedensityofgaugingnetworks at regional and global scales; • SWOT observations wouldprovidegauginginformationfromsitesthataredifficulttoaccess such as in braidedstreams, estuariesanddeltas, remote areas; (specialcase: topotentiallyobtaindatafromriverswhereconventionaldataare not availableorshared) • Dischargeestimatesderivedfrom SWOT observations (validated, quality-checked) havethe potential toenlargethe GRDC databaseof global dischargedatasets in time scalesthat in generalare not matchedbyconventionaldatadeliveryto GRDC
Top 10 products required by users, but notavailableoruseable
Challenges in the use of Satellite Products in Hydrology (1) • Hydrological Services are not familiar with satellite-based systems (by far less than Meteorological Services!) • Lack of user guidance in the selection of satellite systems and products • Preference of hydrological services to use nationally-controlled observing systems; sensitivity towards dependency from foreign (satellite) system operators • Perceived (or actual) high costs for using satellite products
Challenges in the use of Satellite Products in Hydrology (2) • Perceived (or actual) high technical skill requirements for the operation of satellite products in an operational manner • Integration difficulties of multiple-observation hydrological networks using satellite systems • Skepticism over the long-term access and use of satellite services needed for operational hydrological observations (short mission lives and doubts of transfer of services to follow-up missions)
From Research toApplications Mainstreaming Satellite Observations for Operational Use Example: Global Implementation ofthe Flash FloodGuidance System (FFGS) (Core service: Satellite-basedprecipitationestimates, based on the NOAA - HYDROESTIMATOR, supplementedby QMORPH-IR, repetitionof observations: every 1 hour/ every 6 hours)
Flash Flood Guidance System Flow Chart Source: HRC 17
The Global Distribution of Flash Flood Guidance Systems FFG ImplementationStatus (2013) Completed In Progress Under Planning Total Total # Countries 30 15 6 51 Total Population Reached645,698,967 184,846,165 65,542,913 896,088,045
RequirementsfortheUseof SWOT Products (1) • Clear definitionofthesystemcapabilitiesandlimitations, errorbandwidthandsystemoperationasfarasnecessaryfortheuseofthealtimetryproducts • Front-end toolsdesignedfortheuseofhydrologicalservicestoaccessandusethedata in the form ofdatumadjustedgaugeheightsandestimateddischarge (ifapplicable) • Development of „Standing Operating Procedures“ fortheuseof SWOT productsincluding a HelpDesk
RequirementsfortheUseof SWOT Products (2) • Development ofhands-on trainingworkshopsor e-learningmaterialsfortheaccesstoanduseof SWOT products • Information on continuityofservicestobeprovided, contingencyplansifservicesareinterruptedandtransferofservicestoanotherplatform after the end ofthe SWOT mission
SWOT System Configuration Source: SWOT Homepage
From Mission Operation toUseof Products • Note: • The majorityof National Hydrological Services in developing countries havelowto medium technicalcapabilitiesoftheirstaff. • Ifproductsdeliveredare not user-friendlyor quasi ready-to-use (withinthelimitsofthesystem), thentheseservices will not beused at all. • Thereneedstobe a strategyforthelong-term availabilityofaltimetryservices, casacadingfromoneplatformtotheother after themissionlife-time of SWOT. Few, ifanyhydrologicalservice will engage in operationallyusingtheproductsifthesystemisdiscontinued after themissionlifetime. • Thought: • Service-deliverycould also beoutsourcedtotheSatelliteApplication Facility of EUMETSAT andwithinthis Facility totheHydrology-SAF (H SAF).
Suitabilityof SWOT for Hydrological Applications in Hydrological Services Reality Check (1) Floods Monitoring oftheonsetanddevelopmentoffloodevents in very large riverbasins; floodplainmappingifsufficientlydetailedDEM´sareavailable, flooddepth/extentmappingtogetherwithothersatelliteproducts (such as MODIS) Insurance In theareaoffloodhazardandriskmapping, othermethodsarebeingsuccessfullyusedand SWOT informationmaybeonlycomplementary
WHYCOS components WMO Global Hydrological Cycle Observing System (WHYCOS) At theobservationalcore: (Near) real-time networksofgaugingstations in transboundary riverbasins; andcapacitybuilding) …couldbeeffectivelysupplementedwith SWOT observations
Suitabilityof SWOT for Hydrological Applications in Hydrological Services Reality Check (2) Lakes & Reservoirs • Highlyusefulasfor a large numberoflakesandreservoirs, observations on changesofwaterlevelsandvolumesareeither not observedor not accessible; • Volume changecalculations on thebasisofbathymetricinformation. • Hazardouslakes: Especiallyobservationofdammedlakesand glacier lakeswithoutburst potential Large Transboundary Rivers Highlyusefulashydrologicalinformationisoften not accessible; SWOT informationprovidestheopportunitytocomplementconventionalgaugingstationsespecially in complexriverenvironments (braidedriversystems, estuaries, deltas); opportunitytogenerate – over time – a seriesofvirtualstationsalongriverswith time-seriesofhydrologicalrecords
Challengesforconventionalgauge observations in complexriversystems Amazon river Source: SWOT webpage