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in the lower slope of the study area could be result of the evaporation.
The mean deuterium excess
d
(=
δ
D
8
δ
18
O) is
1
.
88
‰
of precipitation
in the study area. Precipitation affected by evaporation and tends to have
d
values (
d-excess
) lower than 10.
5
−
−
The most depleted value occurred at
10
.
51
‰
for
δ
18
Oand
highest altitude in point P4 which
−
−
82
.
4
‰
for
δ
D,
−
8
.
38
‰
for
δ
18
O
and enriched value at lowest altitude in point P9 which
70
.
3
‰
for
δ
D due to the altitude effect.
The isotopic composition of the groundwater ranged from
−
and
−
8
.
96
‰
to
8
.
46
‰
for
δ
18
Oand
−
61
.
4
‰
for
δ
D in the study area. All ground-
water samples plotted to the right of the global meteoric water line (Fig. 2).
This is also characteristic future of mountain area in the NCP, which is
probably due to isotopic enrichment caused by evaporation that occurred
before and during infiltration in the recharge area, and similar observation
were confirmed by Chen
et al.
1
in Taihang Mountain. In the upper part, the
groundwater sample was enriched at point G5. The groundwater reached
at the middle part of the study area the values was depleted. In this part
groundwater mainly recharged by spring water, point S11, S12, and G3
observed very similar values which
−
72
.
7to
−
8
.
96
‰
for
δ
18
O,
respectively. The more enriched value was found in point G1 (
−
8
.
98,
−
8
.
95, and
−
8
.
46
‰
for
δ
18
O) in the lower part and similar to point R9 and P11. It indicates that
the groundwater may originate from river water and precipitation with a
more enriched low latitude area and should reflect the isotopic composi-
tion of groundwater. The groundwater of the study area was recharged by
the direct diffuse recharge of precipitation, as well as recharge from the
surface water.
The isotopic composition of the surface water (river and spring water)
ranged from
−
64
.
3
‰
for
δ
D
in the Huaisha River Basin. The more depleted isotope values occurred in
the spring water of point S16 (
−
10
.
1
‰
to
−
7
.
67
‰
for
δ
18
Oand
−
74
.
1
‰
to
−
9
.
8
‰
for
δ
18
O) and point S17 (
10
.
1
‰
for
δ
18
O) of upper part, and close to the most depleted precipitation sample
at point P4. Probably it was recharged by the precipitation falling in much
higher altitude.
−
−
3.2.
Interaction between groundwater and surface water
In the upper part of the study area, the stable isotope values of river waters
such as point R8, R19, R20, and R21 were almost same and similar to the
groundwater sample at point G5, which displays enriched value (
8
.
48
‰
for
δ
18
O). When the enriched river water reaches an artificial concrete dam
−
