Hydrologic Overview & Hydrologic Overview & QuantitiesQuantities

It is important to understand the big It is important to understand the big picture when attempting to forecast. picture when attempting to forecast.

This includes the interactive This includes the interactive components and hydrologic quantities.components and hydrologic quantities.

Hydrologic CycleHydrologic Cycle

The complexity of what we are trying to The complexity of what we are trying to accomplishaccomplish……..

Infiltration

Evaporation & Condensation

The Water Budget

Photosynthesis & Respiration

Antecedent Moisture

Conditions

Transpiration & Interception

Variable Source Area

Time of Concentration The “sphere” concept was borrowed

from Dr. Peter Black:Watershed Hydrology – 2nd Edition, Peter Black, 1996, Ann Arbor Press (ISBN# 1-5704 027-1)

Models try to mimic this!Models try to mimic this!

Basin Process Representation

Infiltration

Excess Precip.

Interception

StorageTime Series

Time Series

From A Basin ViewFrom A Basin View

Excess Precip. Model

Excess Precip.

Basin “Routing”

Unit Hydrograph

Stream “Routing”

Runoff Hydrograph

The Runoff PictureThe Runoff Picture

•• Hydrology is long term and short termHydrology is long term and short term……..•• In this course we will mainly focus on the In this course we will mainly focus on the

shortshort term:term:•• Floods & flood flows.Floods & flood flows.•• Generating runoff/high flows.Generating runoff/high flows.•• Predicting/forecasting flows.Predicting/forecasting flows.•• Space/time scales.Space/time scales.

Recipe(s) for a Flood/High FlowsRecipe(s) for a Flood/High Flows

•• What causes a flood / high flow?What causes a flood / high flow?•• What are the conditions?What are the conditions?•• What are the types of flooding situations?What are the types of flooding situations?•• Your area or other areasYour area or other areas……....

What Are the Defining What Are the Defining Characteristics of a Flood?Characteristics of a Flood?•• Timing Timing –– rise time, recession, duration.rise time, recession, duration.•• Flows Flows –– peak flows, magnitude peak flows, magnitude

(statistical).(statistical).•• Precipitation Precipitation –– intensity, duration, intensity, duration,

frequencyfrequency……..

What Controls the Timing, Flow, What Controls the Timing, Flow, and Precipitation?and Precipitation?•• The hydrology The hydrology –– short term and long term.short term and long term.•• The meteorology The meteorology –– short term short term

(weather/storm type) and long term (weather/storm type) and long term (climate).(climate).

Short TermShort TermWeather (storm type) & Weather (storm type) & ““current hydrologic current hydrologic conditionsconditions””

Watershed CharacteristicsWatershed Characteristics

•• AreaArea•• SlopeSlope•• Land UseLand Use•• SoilsSoils•• GeologyGeology•• ClimateClimate•• GeomorphologyGeomorphology

Some of the Some of the ““RightRight””CombinationsCombinations……..•• Precipitation Precipitation ––vs.vs.-- infiltrationinfiltration

–– Precipitation intensity > infiltration ratePrecipitation intensity > infiltration rate–– Precipitation total > infiltration capacityPrecipitation total > infiltration capacity–– ““StorageStorage”” in the system is fullin the system is full–– Human induced high water or flowsHuman induced high water or flows–– Natural alterations to the watershedNatural alterations to the watershed

Our Focus Our Focus -- ForecastingForecasting

•• Must be both short & long term..Must be both short & long term..•• The combination(s) of precipitation and The combination(s) of precipitation and

hydrologic conditions that lead create a hydrologic conditions that lead create a potential flooding situationpotential flooding situation……

•• ““basin hydrologybasin hydrology”” –– basin hydrology looks basin hydrology looks at the hydrologic budget in both the short at the hydrologic budget in both the short and long term.and long term.

WaterWater, , basicbasic elementelement

WaterWater resourcesresources

How much water is there?How much water is there?

Distribution of Earth's Waters and Residence TimesDistribution of Earth's Waters and Residence Times........Location of

Storage Percent of

Fresh Residence

Time (years)

Total water on earth

Oceans Total Fresh

Water 100.0 6977

Ice and Glaciers

75.4 5210

Groundwater Deep

14.0 973

Groundwater Shallow

11.0 764

Lakes 0.3 21 Biosphere 0.24 17.1

Soil Moisture 0.06 4.17 Atmosphere 0.035 2.43

Rivers 0.003 2.1

WaterWater ResourcesResources

•• Mean Mean annualannual precipitationprecipitation

726 726 mmmm//yearyearAsiaAsia

670 670 mmmm//yearyearNorthAmericaNorthAmerica

1648 1648 mmmm//yearyearSouthAmericSouthAmericaa

686 686 mmmm//yearyearAfricaAfrica

734 734 mmmm//yearyearEuropeEurope

HydrologicalHydrological processesprocesses

•• CloudsClouds andand atmosfericatmosfericmovementmovement

•• PrecipitationPrecipitation•• LossesLosses

–– InterceptionInterception–– EvapotranspirationEvapotranspiration–– InfiltrationInfiltration–– DepressionDepression storagestorage

•• RainfallRainfall –– runoffrunoff•• FloodFlood RoutingRouting

Units & Properties of WaterUnits & Properties of Water

Property Symbol Value Comments Density

(mass/volume) ~1.94 slugs/ft3

~ 1.0 g/cm3 Slug = lb*s2/ft

Specific Weight (weight/volume)

62.4 Lbs/ft3

9.81 kN/m3 g

Specific Volume Specific Gravity s.g. 1.0 for water

@ 0o C s.g.fluid = gfluid/gwater

WaterWater (gas)(gas)

WaterWater ((solidsolid))

WaterWater ((liquidliquid))

No No waterwater -- desertdesert

CloudsClouds andand atmosfericatmosfericmovementmovement

Global Global cyclecycle

SunSun: : energyenergysourcesource

Solar Solar RadiationRadiation

Sun: distance 150 millions of Km Energy received: 1000 W/m2

Solar Solar RadiationRadiation

•• DifferencesDifferences accordingaccording toto thethe latitudelatitude

Solar Solar RadiationRadiation

•• DiferencesDiferences betweenbetween JuneJune andand SeptemberSeptember

EffectiveEffective RadiationRadiation

•• DifferenceDifference betweenbetween receivedreceived andand back back radiationradiation

RRnn = = RRii (1(1--) ) –– RRee

•• RiRi, solar , solar radiationradiation•• , albedo, albedo•• RRe,e,, back , back radiationradiation

CloudsClouds•• EvaporationEvaporation fromfrom seas, seas, lakeslakes andand riversrivers

CloudsClouds

CloudsClouds

CloudsClouds

CloudsClouds

MeteorologicalMeteorological phenomenaphenomena

twisterstwisters

HurricanesHurricanes

CloudCloud structurestructure

•• WaterWater dropsdrops fromfrom 0.01 0.01 toto 0.03 mm0.03 mm•• WeightWeight fromfrom 0,5 0,5 toto 1 1 grgr/m/m33

•• GrowingGrowing processesprocesses up up toto 10.000 10.000 toto100.000 times 100.000 times initialinitial valuesvalues

•• WaterWater in in cloudsclouds can can explainexplain 10 10 toto 12 12 mmmm

AtmosphericAtmospheric circulationcirculation•• Tropical Tropical cellscells

Tropical Tropical cellscells

WaterWater dropletsdroplets

••CondensationCondensation••CoalescenceCoalescence

CondensationCondensation

CoalescenceCoalescence

DropletDroplet aggregationaggregation

•• RaindropsRaindrops up up toto 3 3 toto 4 4 mmmm

•• Terminal Terminal velocityvelocity9 a 12 m/s9 a 12 m/s

WaterWater precipitationprecipitation

•• WaterWater, , snowsnow, , hailhail

TypesTypes ofof rainfallrainfall

•• CiclonicalCiclonical / Frontal / Frontal rainrain

•• OrographicOrographic

•• ConvectiveConvective cellscells

Frontal Frontal rainrain•• Cold Cold andand hot hot airair massesmasses movingmoving alongalong thethe

planeteplanete

Frontal Frontal behaviorbehavior•• Hot Hot andand cold cold airair massmass frictionfriction

Frontal Frontal behaviorbehavior

•• Hot Hot andand cold cold interfaceinterface

Frontal Frontal precipitationsprecipitations

•• AssociatedAssociated toto largelarge areasareas ((tenstens ororhundredshundreds ofof miles miles ofof KmKm22))

•• LongLong durationsdurations ((daysdays) ) andand highhigh total total rainfallsrainfalls butbut withwith lowlow rainfallrainfall intensitiesintensities

OrographicOrographic rainfallsrainfalls

OrographicOrographic PrecipitationsPrecipitations

•• TypicalTypical MediterraneanMediterranean patternpattern•• DuringDuring thethe fallfallHot Hot airair comingcoming fromfrom thethe MagrebMagreb, , MountainsMountains closeclose toto seasideseaside

HeavyHeavy rainfallsrainfalls

ConvectiveConvective cellscells

•• AfectingAfecting toto smallsmall areasareas•• ConvectiveConvective cellscells appearingappearing andand

disappearingdisappearing duringduring thethe rainrain periodperiod•• Can produce Can produce veryvery intense intense rainfallsrainfalls

ConvectiveConvective cellscells

•• SchemeScheme

RainfallRainfall measurementsmeasurements

•• PrecipitationPrecipitation: mm l/m: mm l/m22

•• IntensityIntensity mmmm/h/h•• Temporal Temporal registerregister: : pluviographpluviograph oror

hyetographhyetograph

GreatestGreatest precipitationprecipitation datadata

•• Data Data onon differentdifferent observatoriesobservatories

ReuniReunióón, n, FebruaryFebruary 196419641350 mm1350 mm12 h 12 h

ReuniReunióón, n, MarchMarch 195219521870 mm1870 mmDayDay

HoltHolt, Missouri, , Missouri, JuneJune 19471947300 mm300 mm42 minutes42 minutes

CherrapunjiCherrapunji, , JulyJuly 186118619300 mm9300 mmMonthMonth

CherrapunjiCherrapunji, 1860, 1860--010126470 mm26470 mmYearYear

HawaiiHawaii, , MountMount WaialealeWaialeale11680 mm11680 mmAnnualAnnual precipitationprecipitation

47.0425DP

RainfallRainfall envelopeenvelope

•• MathematicalMathematical relationshiprelationship

•• P, mmP, mm D, D, hourshours

IntensityIntensity

•• IntensityIntensity, ratio , ratio betweenbetween precipitationprecipitationandand timetime

•• HyetographHyetograph

RainfallRainfall measurementsmeasurements

•• PluviometerPluviometer / / pluviographpluviograph

Total Total rainfallrainfall

PluviometerPluviometer ofof intensityintensity

•• TippingTipping bucketbucket gaugegauge

RainfallRainfall monitoringmonitoring

•• SatellitesSatellites, , qualitativequalitative observationobservation

RainfallRainfall radarradar

MeasurementMeasurement networksnetworks

•• INM, INM, rainfallrainfall data in 24 hdata in 24 h•• SMC, SMC, shortershorter time seriestime series•• RainfallRainfall radarsradars

RainfallRainfall data data analysisanalysis

•• HypothesisHypothesis: : toto studystudy thethe historicalhistoricalrainfallrainfall data data toto predictpredict futurefuture rainfallrainfall

•• WeWe assumeassume thethe futurefuture rainfallrainfall willwill be be thethe samesame as as thethe previousprevious oneone

•• ClimaticClimatic changechange effecteffect: : toto studystudy•• ApplicationApplication in in hydrologicalhydrological studiesstudies

Data Data analysisanalysis

•• Time series Time series analysisanalysis•• QualitativeQualitative analysisanalysis

–– FillingFilling gapsgaps–– ConsistencyConsistency testtest ((doublesdoubles massmass))

•• StatisticalStatistical analysisanalysis

StatisticalStatistical analysisanalysis II

•• AnnualAnnual rainfallrainfall seriesseries•• ExtremalExtremal distributionsdistributions

–– GumbelGumbel–– Log Pearson IIILog Pearson III–– SQRT SQRT –– ETET

•• AssociatedAssociated valuesvalues toto returnreturn periodperiod ofof N N yearsyears

•• PartialPartial durationduration series, (series, (peakpeak overoverthresholdthreshold) )

•• AppropriatedAppropriated toto returnreturn periodsperiods belowbelow 10 10 yearsyears

StatisticalStatistical analysisanalysis IIII

RainfallRainfall data data sourcessources

•• AEMET AEMET -- SMC, time series, in SMC, time series, in SpainSpain andandCataloniaCatalonia

•• PreviousPrevious workwork: Lluvias m: Lluvias mááximas en la ximas en la EspaEspañña Peninsular, DGC 2001a Peninsular, DGC 2001