SOLUTION MANUAL e
IN ENGINEERIN
e
G HYDROLOGY
e
(BYeK.eSUBRAMANYA)
(Chapter 1-5) e
Preparede by:eAbrugena
,eKurieLeigheD.eBaylon,eJe
ffreyeR.
Frane,eJuliuseRobertsoneD.eGarci
a,eRyaneC.
Gupit,eA.J.eBernadetteeB.e
LaeRosa,eJohneKarleL.eN
ate,eKharleVincent
, PROBLEMS
CHAPTERe1
1.1 Twoeandehalfecentimeterseoferaineperedayeovereaneareaeofe200ekm2eiseequivalentetoeaverageerateeofeinp
uteofehowemanyecubicemeterseperesecondeofewateretoethatearea?
1.2 Aecatchmenteareaeofe140ekm2ereceivede120ecmeoferainfalleineaeyear.eAtetheeoutleteofetheecatchmentetheef
loweinetheestreamedrainingetheecatchmentewasefoundetoehaveeaneaverageerateeofe2.0em3/sefore3emonth
s,e3.0em3/sefore6emonthseande5.0em3/sefore3emonths.e(i)eWhateisetheeruneoffecoefficienteofetheecatchme
nt?e(ii)eIfetheeafforestationeofetheecatchmentereducedetheeruneoffecoefficientetoe0.50,ewhateisetheeincre
aseeinetheeabstractionefromeprecipitationedueetoeinfiltration,eevaporationeandetranspiration,eforetheesa
meeannualerainfalleofe120ecm?
1.3 Estimateetheeconstanterateeofewithdrawalefromeae1375ehaereservoireineaemontheofe30edayseduringewhi
chetheereservoireleveledroppedebye0.75emeinespiteeofeaneaverageeinfloweintoetheereservoireofe0.5eMm3/
day.eDuringetheemonthetheeaverageeseepageelossefrometheereservoirewase2.5ecm,etotaleprecipitationeo
netheereservoirewase18.5eameandetheetotaleevaporationewase9.5ecm.
1.4 Aeriverereachehadeaefloodewaveepassingethrougheit.eAteaegiveneinstantetheestorageeofewatereinetheereache
waseestimatedease15.5eha-
m.eWhatewouldebeetheestorageeinetheereacheaftereaneintervaleofe3ehourseifetheeaverageeinfloweandeoutf
loweduringetheetimeeperiodearee14.2em3/seande10.6em3/serespectively?
1.5 Aecatchmentehasefouresub-areas.eTheeannualeprecipitationeandeevaporationefromeeacheofetheesub-
e areaseareegivenebelow.
Assumeethatethereeisenoechangeeinetheegroundewaterestorageeoneaneannualebasiseandecalculateeforetheewh
oleecatchmentetheevalueseofeannualeaveragee(i)eprecipitationeande(ii)eevaporation.eWhateareetheeannualeru
noffecoefficientseforetheesub-areaseandeforetheetotalecatchmentetakeneaseaewhole?
Sub-area Areae(Mm2) AnnualePrecipitation Annual
(mm) Evaporatione(mm)
A 10.7 1030 530
B 3.0 830 438
, C 8.2 900 430
D 17.0 1300 600
1.6 Estimateetheeresidenceetimeeof:
(a) Globaleatmosphericemoisture.
(b) Globalegroundwaterebyeassumingethateonlyetheefreshegroundwatererunseoffetoetheeoceans.
(c) Oceanewater.
CHAPTERe2
2.1 Aecatchmenteareaehasesevenerainegaugeestations.eIneaeyearetheeannualerainfallerecordedebyetheegaugese
areeasefollows:
Station Rainfalle(cm)
P 130.0
Q 142.1
R 118.2
S 108.5
T 165.2
U 102.1
V 146.9
Foreae5%eerroreinetheeestimationeofetheemeanerainfall,ecalculateetheeminimumenumbereofeadditionalestatio
nserequiredetoebeeestablishedeinetheecatchment
2.2 TheenormaleannualeprecipitationeofefiveerainegaugeestationseP,eQ,eR,eSeandeTeareerespectivelye125,e102,e
76,e113eande137ecm.eDuringeaeparticularestormetheeprecipitationerecordedebyestationseP,eQ,eR,eandeSear
ee13.2,e9.2,e6.8eande10.2ecmerespectively.eTheeinstrumenteatestationeTewaseinoperativeeduringethatesto
rm.eEstimateetheerainfalleatestationeTeduringethatestorm.
2.3 Testetheeconsistencyeofethee22eyearseofedataeofetheeannualeprecipitationemeasuredeatestationeA.eRainf
alledataeforetheestationeAeasewelleasetheeaverageeannualerainfallemeasuredeateaegroupeofeeighteneighbor
ingestationselocatedeineaemeteorologicallyehomogeneouseregioneareegivenebelow.
Year StationeA 8station Year StationeA 8station
, (cm) averagee(cm) (cm) averagee(cm)
1946 177 143 1957 158 164
1947 144 132 1958 145 155
1948 178 146 1959 132 143
1949 162 147 1960 95 115
1950 194 161 1961 148 135
1951 168 155 1962 142 163
1952 196 152 1963 140 135
1953 144 117 1964 130 143
1954 160 128 1965 137 130
1955 196 193 1966 130 146
1956 141 156 1967 163 161
(a) Inewhateyeareiseaechangeeineregimeeindicated?
(b) AdjustetheerecordededataeatestationeAeandedetermineetheemeaneannualeprecipitation.
2.4 Foreaedrainageebasineofe600ekm2,eisohyetalsedrawneforeaestormegaveetheefollowingedata:
Isohyetalse(interval) Inter-isohyetalearea
(cm) (km2)
15-12 92
12-9 128
9-6 120
6-3 175
3-1 85
Estimateetheeaverageedeptheofeprecipitationeoveretheecatchment.
2.5 Theree aree 10e raine gaugee stationse availablee toe calculatee thee rainfalle characteristicse ofe ae catchmente
whosee shapee cane bee approximatelye describede bye straighte linese joininge thee followinge coordinates
(distanceseinekilometres):
(30,0),e(80,10),e(110,30),e(140,90),e(130,115),e(40,110),e(15,60).eCoordinateseofetheerainegaugeestationsea
ndetheeannualerainfallerecordedeinethemeinetheeyeare1981eareegivenebelow.
Station Coordinates AnnualeRainfall
(cm)
IN ENGINEERIN
e
G HYDROLOGY
e
(BYeK.eSUBRAMANYA)
(Chapter 1-5) e
Preparede by:eAbrugena
,eKurieLeigheD.eBaylon,eJe
ffreyeR.
Frane,eJuliuseRobertsoneD.eGarci
a,eRyaneC.
Gupit,eA.J.eBernadetteeB.e
LaeRosa,eJohneKarleL.eN
ate,eKharleVincent
, PROBLEMS
CHAPTERe1
1.1 Twoeandehalfecentimeterseoferaineperedayeovereaneareaeofe200ekm2eiseequivalentetoeaverageerateeofeinp
uteofehowemanyecubicemeterseperesecondeofewateretoethatearea?
1.2 Aecatchmenteareaeofe140ekm2ereceivede120ecmeoferainfalleineaeyear.eAtetheeoutleteofetheecatchmentetheef
loweinetheestreamedrainingetheecatchmentewasefoundetoehaveeaneaverageerateeofe2.0em3/sefore3emonth
s,e3.0em3/sefore6emonthseande5.0em3/sefore3emonths.e(i)eWhateisetheeruneoffecoefficienteofetheecatchme
nt?e(ii)eIfetheeafforestationeofetheecatchmentereducedetheeruneoffecoefficientetoe0.50,ewhateisetheeincre
aseeinetheeabstractionefromeprecipitationedueetoeinfiltration,eevaporationeandetranspiration,eforetheesa
meeannualerainfalleofe120ecm?
1.3 Estimateetheeconstanterateeofewithdrawalefromeae1375ehaereservoireineaemontheofe30edayseduringewhi
chetheereservoireleveledroppedebye0.75emeinespiteeofeaneaverageeinfloweintoetheereservoireofe0.5eMm3/
day.eDuringetheemonthetheeaverageeseepageelossefrometheereservoirewase2.5ecm,etotaleprecipitationeo
netheereservoirewase18.5eameandetheetotaleevaporationewase9.5ecm.
1.4 Aeriverereachehadeaefloodewaveepassingethrougheit.eAteaegiveneinstantetheestorageeofewatereinetheereache
waseestimatedease15.5eha-
m.eWhatewouldebeetheestorageeinetheereacheaftereaneintervaleofe3ehourseifetheeaverageeinfloweandeoutf
loweduringetheetimeeperiodearee14.2em3/seande10.6em3/serespectively?
1.5 Aecatchmentehasefouresub-areas.eTheeannualeprecipitationeandeevaporationefromeeacheofetheesub-
e areaseareegivenebelow.
Assumeethatethereeisenoechangeeinetheegroundewaterestorageeoneaneannualebasiseandecalculateeforetheewh
oleecatchmentetheevalueseofeannualeaveragee(i)eprecipitationeande(ii)eevaporation.eWhateareetheeannualeru
noffecoefficientseforetheesub-areaseandeforetheetotalecatchmentetakeneaseaewhole?
Sub-area Areae(Mm2) AnnualePrecipitation Annual
(mm) Evaporatione(mm)
A 10.7 1030 530
B 3.0 830 438
, C 8.2 900 430
D 17.0 1300 600
1.6 Estimateetheeresidenceetimeeof:
(a) Globaleatmosphericemoisture.
(b) Globalegroundwaterebyeassumingethateonlyetheefreshegroundwatererunseoffetoetheeoceans.
(c) Oceanewater.
CHAPTERe2
2.1 Aecatchmenteareaehasesevenerainegaugeestations.eIneaeyearetheeannualerainfallerecordedebyetheegaugese
areeasefollows:
Station Rainfalle(cm)
P 130.0
Q 142.1
R 118.2
S 108.5
T 165.2
U 102.1
V 146.9
Foreae5%eerroreinetheeestimationeofetheemeanerainfall,ecalculateetheeminimumenumbereofeadditionalestatio
nserequiredetoebeeestablishedeinetheecatchment
2.2 TheenormaleannualeprecipitationeofefiveerainegaugeestationseP,eQ,eR,eSeandeTeareerespectivelye125,e102,e
76,e113eande137ecm.eDuringeaeparticularestormetheeprecipitationerecordedebyestationseP,eQ,eR,eandeSear
ee13.2,e9.2,e6.8eande10.2ecmerespectively.eTheeinstrumenteatestationeTewaseinoperativeeduringethatesto
rm.eEstimateetheerainfalleatestationeTeduringethatestorm.
2.3 Testetheeconsistencyeofethee22eyearseofedataeofetheeannualeprecipitationemeasuredeatestationeA.eRainf
alledataeforetheestationeAeasewelleasetheeaverageeannualerainfallemeasuredeateaegroupeofeeighteneighbor
ingestationselocatedeineaemeteorologicallyehomogeneouseregioneareegivenebelow.
Year StationeA 8station Year StationeA 8station
, (cm) averagee(cm) (cm) averagee(cm)
1946 177 143 1957 158 164
1947 144 132 1958 145 155
1948 178 146 1959 132 143
1949 162 147 1960 95 115
1950 194 161 1961 148 135
1951 168 155 1962 142 163
1952 196 152 1963 140 135
1953 144 117 1964 130 143
1954 160 128 1965 137 130
1955 196 193 1966 130 146
1956 141 156 1967 163 161
(a) Inewhateyeareiseaechangeeineregimeeindicated?
(b) AdjustetheerecordededataeatestationeAeandedetermineetheemeaneannualeprecipitation.
2.4 Foreaedrainageebasineofe600ekm2,eisohyetalsedrawneforeaestormegaveetheefollowingedata:
Isohyetalse(interval) Inter-isohyetalearea
(cm) (km2)
15-12 92
12-9 128
9-6 120
6-3 175
3-1 85
Estimateetheeaverageedeptheofeprecipitationeoveretheecatchment.
2.5 Theree aree 10e raine gaugee stationse availablee toe calculatee thee rainfalle characteristicse ofe ae catchmente
whosee shapee cane bee approximatelye describede bye straighte linese joininge thee followinge coordinates
(distanceseinekilometres):
(30,0),e(80,10),e(110,30),e(140,90),e(130,115),e(40,110),e(15,60).eCoordinateseofetheerainegaugeestationsea
ndetheeannualerainfallerecordedeinethemeinetheeyeare1981eareegivenebelow.
Station Coordinates AnnualeRainfall
(cm)
