1
Conditions of the surface water and ground water resources in the
rural area of the Mekong Delta, Vietnam – exemplary investigations
at the study sites An Binh and Hoa An
Thomas Nuber
1
, Harro Stolpe
1
, Le Anh Tuan
2
,

Vu Van Nam
2

1
Environmental Engineering and Ecology, Ruhr-University Bochum, Germany, Univer-
sitätsstr. 150, 44780 Bochum, Germany
2
College of Technology, University of Can Tho, Can Tho City, Vietnam

1. Introduction
As a consequence of a fast-growing economy the Mekong Delta region is facing severe envi-
ronmental problems related to industrial and agricultural activities. These environmental
problems include soil reclamation (L
E QUANG MINH ET AL., 1997), deforestation (MILLER ET
AL
., 1999) and water quality problems due to pollution of the water resources by pesticides,
herbicides and fertilizers (L
E QUY AN, 2000). Besides those anthropogenic impacts on the

cases the waste water is treated with small biogas plants before discharged into the canals.
Usually the domestic waste water and waste water from the animal husbandries are dis-
charged into the rivers, canals or ponds (see figure 2).
Besides the general similarities of the two study sites there are also major differences. In
addition to socio-economic differences (e.g. higher living standard in An Binh (see W
IENEKE,
2005)) one of the most important differences are the soil-conditions. Here, the study site An
Binh is characterized by alluvial clay soils, whereas the study site Hoa An is burdened by
acid sulphate soils. This leads to different cropping systems and also to an acidification of the
surface water bodies in Hoa An.

2.2. Hydrological conditions
The entire Mekong Delta is characterized by a large network of rivers and canals of
10.000 km in length. Those canals are mainly used for irrigation and for transportation of
goods and people. The canal system is connected to the open sea.
In An Binh the canals are influenced by the tidal regime of the South Chinese Sea. Here, the
tidal amplitude is approx. 1.5 m. The study site Hoa An is located in an area where an inter-
action of the tidal regimes of the South Chinese Sea and of the Gulf of Thailand eliminate
each other. Here, the tidal amplitude is less than 10 cm. Because of its lower elevation se-
vere flooding occurs in Hoa An by the end of the rainy season for approx. two or three
months.

2.3. Hydrogeological conditions
A detailed description of the hydrogeological conditions of the Mekong Delta can be found in
H
UNG ET AL. (2000). According to HUNG ET AL. (2000) there are five major geological units in
the Mekong Delta: Holocene, upper-middle Pleistocene, lower Pleistocene, Pliocene and
upper Miocene (see table 1), whereas the ground water use from the upper-middle Pleisto-
cene aquifer is prevailing.
According to geological profiles of the study site An Binh and Hoa An (see figure 3) the thick-

4. Results and Discussion
4.1. Ground Water
For Can Tho City and Hau Giang province the spatial distribution of the different ground wa-
ter types (see table 3) is illustrated in figure 4.
The study site An Binh is located in an area where the ground water quality is characterized
by a moderate hardness, a moderate chloride content (around the taste limit of 200 mg/l) and
a ferrous iron concentration around 2 mg/l. According to the classification method described
in chapter 3, it can be rated as ground water type II.
Unlike in An Binh, the ground water quality in the area of Hoa An is characterized by a high
chloride concentration, a high hardness and a high ferrous iron concentration. According to

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The classification method described in chapter 3 it can be rated as ground water type III.
Those observations can be confirmed by the water analyses taken at the study sites An Binh
and Hoa An during the survey (see table 4).
In figure 5 the ion-composition of the ground water samples taken at both study sites are
illustrated in a Piper-diagram. According to the classification method by F
URTAK & LANGGUTH
(1967) the ground water in An Binh can be rated as a alkaline-earth water with higher alka-
line content with a predominantly hydrogen carbonatic content whereas in Hoa An there is
alkaline ground water with a predominantly chloridic content.

4.2. Surface Water
As already described in chapter 2.2 the quality of the surface water is generally influenced by
the discharge of domestic and industrial waste water, agricultural entries and a high amount
of suspended solids as well as fuel residues. In comparison to the ground water situation
there are local differences regarding the water quality within Can Tho city and Hau Giang
province. But additionally and probably more important there are seasonal differences as
well.
The surface water at the study sites An Binh and Hoa An are influenced by leachate water

expensive for an implementation on a regional scale. In spite of the moderate surface water
quality the use of surface water should be considered. Here, the combination of technologi-
cally simple but effective methods is possible. One possible treatment scheme could be a
flocculation with a rapid filter to eliminate the high amount of suspended solids in combina-
tion with a slow sand filter for the decay of organic matter and disinfection.
At both study sites and also for the entire Mekong Delta the use of alternative water re-
sources (e.g. rain water) should be considered. In this context artificial ground water re-
charge or the pure storage of rain water in aquifers over the dry season could be a supple-
mentary water resource. Especially in areas where the situation of the water resources is
very strained those methods could be applied.
But the water resources management and the water supply in the Mekong Delta will remain a
challenge in the future. Because of the high population- and economical growth rates it can
be expected that the water demand will increase rapidly. Additionally, the impact of waste
water on the surface waters will increase.

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6. Literature
Benstöm, F.; Nuber, T.; Stolpe, H.,2005: Determination of Hydraulic Conductivity with Slug
and Bail Tests in Small Diameter Wells in the South of Vietnam, in Department of Geol-
ogy and Minerals of Vietnam (eds ): Journal of Geology, Series B, No. 25, Hanoi, pp.
58-63.
Do Tien Hung; Nguyen Hong Bang; Pham Van Giang, 2000: Availability and Quality of
Groundwater Resources, Ministry of Industry, Department of Geology and Minerals Divi-
sion of Hydrogeology and Engineering Geology for the South of Vietnam (DHES), Ho
Chi Minh City
Furtak, H; Langguth, H.R., 1967: Zur hydrochemischen Kennzeichnung von Grundwässern
und Grundwassertypen mittels Kennzahlen, Mem. IAH-Congress, Hannover
DVWK, 1992: Entnahme und Untersuchungsumfang von Grundwasserproben – DVWK-
Merkblatt 128, Parey-Verlag, Hamburg
Lam Minh Triet and Nguyen Thanh Hung, 2001: Problems of Drinking Water Supply and En-

Piper, A.M., 1944:A graphic procedure in the geochemical interpretation of water analyses –
Trans. Am. Geophys. Union, 25; Washington D.C.,pp 914-928
SIWRMP, 1995: Major Issues in Water Resources Development in the Mekong Delta, Report
of the Sub-Institute of Water Resources Management and Planning, Ho Chi Minh City
Wieneke, F., 2005: Acceptance Anaylsis of New technologies for Sustainable Water Man-
agement and Sanitation – A Case Study of Operating Farm Households in the Mekong,
Delta, Vietnam, Disseration, Faculty of Agr., University of Bonn, Bonn Germany
World Bank, DANIDA and MONRE, 2003: Vietnam Environment Monitor 2003 – Water, Ha-
noi

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figure 1: provinces, provincial capitals and location of the study sites within the Mekong Delta

9figure 2: setting of rural areas in the rural area of the Mekong Delta (modified after LE ANH
TUAN, 2003)

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figure 3: geological logs in An Binh (left) and Hoa An (right)

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figure 4: ground water types of Can Tho City and Hau Giang province

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(m)
stratigraphy
1
st
aquifer
/aquiclude
QIV U,T,S 55 – 80 Holocene
2
nd
aquifer QII-III fS-mS, G 15 – 40
upper-middle
Pleistocene
aquiclude - U,T 10 – 20 -
3
rd
aquifer QI gS, mS, fS 10 – 60
lower
Pleistocene
aquiclude - U, T 10 – 20 -
4
th
aquifer NII S, G 25 – 120 Pliocene
aquiclude - U, T 50 – 120 -
5
th
aquifer NI S, G 0 – 100 Miocene

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table 2: Methods
Parameters Method

600 180 1 200 16
table 4: results of the ground water samples (selected parameters)
Parameter Unit An Binh Hoa An
Limits according to
TCVN 5944-1995
pH - 6,5 – 7 6,5 – 6,6 6,5 – 8,5
EC µS/cm 1.000 – 1.300 3.800 – 4.100 no limit specified
chloride mg/l 150 – 250 880 – 1.200 600
hardness mg/l 80 – 130 560 – 630 180
ferrous iron mg/l 1,6 – 2,5 6,2 – 7,1 1

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table 5: results of the surface water samples (selected parameters)
Parameter Unit An Binh Hoa An
Limits according to
TCVN 5942-1995
pH - 6,6 – 6,8 6,0 – 6,6 6 – 8,5
EC [µS/cm] 148 – 220 179 – 250 no limit specified
BOD mg/l 1,5 – 2 1,5 – 2 < 4
COD mg/l 8 –15 52 – 82 < 10
NH4-N mg/l 0,01 -0,08 0,05 – 0,1 0,05
PO4 mg/l < 0,5 < 0,5 no limit specified
E.coli
MPN/100ml
2 ⋅ 10
3
– 7 ⋅ 10