HYDROGEOLOGY, HYDROGEOCHEMISTRY AND ISOTOPE HYDROLOGY OF BORKENA BASIN

HYDROGEOLOGY, HYDROGEOCHEMISTRY AND HYDROGEOLOGY, HYDROGEOCHEMISTRY AND ISOTOPE HYDROLOGY OF BORKENA BASINISOTOPE HYDROLOGY OF BORKENA BASIN

Sileshi MamoSileshi Mamo

Plot of 2H versus 18O, Borkena final

y = 7.54x + 13.72y = 8x + 10

-30

-20

-10

0

10

20

30

40

-5 -4 -3 -2 -1 0 1 2 3 4

18O (o/oo)

2H (

o/o

o)

cold spring

hot spring

borehole

river

dug well

rfch

rfkch

rfdse

rfwh

rfw

rfk

GMWL

LMWL

Linear(LMWL)Linear(GMWL)

LMWLGMWL

Plot of 18O versus elevation

y = -0.0003x - 0.6642

R2 = 0.0562

-2

-1.8

-1.6

-1.4

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

1000 1200 1400 1600 1800 2000 2200 2400 2600 2800

Elevation (m a.s.l)

18O

(o

/oo

)

570000 580000 590000 600000

1180000

1190000

1200000

1210000

1220000

1230000

1240000

82

83 84

85

87

8990

91

92

94

97

101

104

106

107

108

109

111

112113

114

115

117

119120123

0

0.3

1

2

3

4

5

6

7

8

9

10

0 10000 20000 30000 40000

Tritum m ap of Borkena basin

RECHARGE EVALUATION

1. Water balance method

R= P- AET- SR/O or Surplus- SR/O

2. Cl balance method

R= Clrain*Peff/Clgw, Peff=P-SR/O

3. Hydrograph separation method

Hydrograph separation of Borkena river at the swamp outlet

0

2.5

5

7.5

10

12.5

15

17.5

20

22.5

25

27.5

30

32.5

35

37.5

40

42.5

45

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

Me

an

mo

nth

ly f

low

(m

3/s

)