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Hydrology & Climate HW 6: Hydraulic Conductivity & Water Balance Estimation, Assignments of Environmental Science

Three problems from an environmental science and engineering course focused on hydrology and climate. The first problem involves determining the hydraulic conductivity of an unconfined aquifer using the hvorslev (1951) solution method. The second problem requires estimating the lake evaporation for a given water balance and evaluating the uncertainty of the estimate. The third problem compares open-water evaporation rates using different approaches. Students are expected to use the provided data and equations to solve these problems.

Typology: Assignments

Pre 2010

Uploaded on 08/18/2009

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๎˜ƒ
EnvE/ESS๎˜ƒ110,๎˜ƒHydrology๎˜ƒand๎˜ƒClimate๎˜ƒ
1
HOMEWORK๎˜ƒ6๎˜ƒ
Due๎˜ƒDate:๎˜ƒ๎˜ƒ12/10/2008๎˜ƒ(solutions๎˜ƒwill๎˜ƒbe๎˜ƒmade๎˜ƒavailable๎˜ƒafter๎˜ƒthe๎˜ƒdue๎˜ƒdate.)๎˜ƒ
Textbook:๎˜ƒ๎˜ƒPhysical๎˜ƒHydrology,๎˜ƒ2nd๎˜ƒedition,๎˜ƒDingman.๎˜ƒ
๎˜ƒ
Problem๎˜ƒ1:๎˜ƒ
Use๎˜ƒthe๎˜ƒHvorslev๎˜ƒ(1951)๎˜ƒsolution๎˜ƒmethod๎˜ƒto๎˜ƒdetermine๎˜ƒthe๎˜ƒhydraulic๎˜ƒconductivity,๎˜ƒK,๎˜ƒfor๎˜ƒa๎˜ƒslug๎˜ƒtest๎˜ƒ
conducted๎˜ƒin๎˜ƒa๎˜ƒpartially๎˜ƒpenetrating๎˜ƒwell๎˜ƒin๎˜ƒan๎˜ƒunconfined๎˜ƒaquifer.๎˜ƒ๎˜ƒThe๎˜ƒinitial๎˜ƒdisplacement๎˜ƒin๎˜ƒthe๎˜ƒwell๎˜ƒwas๎˜ƒ
0.671m.๎˜ƒ๎˜ƒOther๎˜ƒparameters๎˜ƒassociated๎˜ƒwith๎˜ƒthe๎˜ƒtest๎˜ƒinclude๎˜ƒthe๎˜ƒwell๎˜ƒradius๎˜ƒ0.125
c
rm
=
,๎˜ƒradius๎˜ƒof๎˜ƒthe๎˜ƒ
piezometer๎˜ƒintake๎˜ƒ0.064
R
m=,๎˜ƒand๎˜ƒlength๎˜ƒof๎˜ƒthe๎˜ƒpiezometer๎˜ƒintake๎˜ƒ1.52Lm
=
.๎˜ƒ๎˜ƒData๎˜ƒcollected๎˜ƒduring๎˜ƒthe๎˜ƒ
slug๎˜ƒtest๎˜ƒincludes๎˜ƒthe๎˜ƒdisplacement๎˜ƒin๎˜ƒh๎˜ƒfrom๎˜ƒthe๎˜ƒoriginal๎˜ƒhead๎˜ƒlevel๎˜ƒat๎˜ƒ0 or tt
<
=โˆž๎˜ƒover๎˜ƒtime.๎˜ƒ
๎˜ƒ
๎˜ƒ
Logarithmic๎˜ƒpaper๎˜ƒis๎˜ƒprovided๎˜ƒon๎˜ƒthe๎˜ƒfollowing๎˜ƒpage.๎˜ƒ๎˜ƒNote๎˜ƒthat๎˜ƒthe๎˜ƒrecommended๎˜ƒnormalized๎˜ƒhead๎˜ƒrange๎˜ƒfor๎˜ƒ
straight๎˜ƒline๎˜ƒmatch๎˜ƒis๎˜ƒ0.15๎˜ƒto๎˜ƒ0.25๎˜ƒfor๎˜ƒthe๎˜ƒHvorslev๎˜ƒ(1951)๎˜ƒsolution๎˜ƒmethod.๎˜ƒ
pf3
pf4

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HOMEWORK 6

Due Date: 12/10/2008 (solutions will be made available after the due date.)

Textbook: Physical Hydrology, 2

nd edition, Dingman.

Problem 1 :

Use the Hvorslev (1951) solution method to determine the hydraulic conductivity, K , for a slug test

conducted in a partially penetrating well in an unconfined aquifer. The initial displacement in the well was

0.671 m. Other parameters associated with the test include the well radius rc = 0.125 m , radius of the

piezometer intake R = 0.064 m , and length of the piezometer intake L = 1.52 m. Data collected during the

slug test includes the displacement in h from the original head level at t < 0 or t = โˆž over time.

Logarithmic paper is provided on the following page. Note that the recommended normalized head range for

straight line match is 0.15 to 0.25 for the Hvorslev (1951) solution method.

Problem 4 (Dingman 7 โ€11) :

Silt loam soil has the following properties: ฯ†^ =^ 0.485,

4 1 K (^) s 7.20 10 cm s

โˆ’ โˆ’

= ร— , | ฯˆ ae | = 78.6 cm , and b = 5.30.

Estimate the field capacity, ฮธ fc and the permanent wilting point, ฮธ pwp , using the following equations,

1

b ae fc

1

b ae pwp

where ฯ† is the porosity, ฯˆ (^) ae is the airโ€entry tension in cm , and b is the exponent describing the moistureโ€

characteristic curve. Construct a graph (similar to the one shown below) for this soil, with actual values of the

relative water content, ฮธ (^) rel , on the abscissa, where ฮธ rel has the form

pwp rel fc pwp

and evapotransporation, ET , is equal to the potential evapotransporation, PET , ( ET = PET )when

ฮธ rel > 0.3.