IJERD – International Journal of Environmental and Rural Development (2019) 10-2

Research articleerd

The Stream Flow and Water Level Change on Mekong
Mainstream from the Hydropower Development Projects atNakhon Panom, Thailand
THODSAPOL CHATURABUL*
Faculty of Science and Engineering, Kasetsart University Chalermphrakiat Sakonnakhon
Province Campus, Sakonnakhon, Thailand
Email: thodsapol.ch@ku.th

THANAPORN SUPRIYASILP
Faculty of Engineering, Chiang Mai University, Chiangmai, Thailand

KOBKIAT PONGPUT
Faculty of Engineering, Kasetsart University, Bangkok, Thailand
Received 5 January 2019

Accepted 30 November 2019(*Corresponding Author)

Abstract Mekong, a major trans-boundary river, is one of the main source of hydropower
for many Southeast Asian countries. Sources of the hydropower come from many megadams along the river. However, constructing mega-dams for hydropower causes numbers ofhydrological effect especially with the change of water flow and water level along the river.
Nakhon Panom, a province located by the river bank in Thailand, has been severely
affected by the hydropower dam operation. To solve these dilemmas effectively, a set of
up-to-date data from all perspectives is need for the analysis, however, the data that reports
on a transition of hydrological after dam construction are currently limited. This study aims
to respond the needs of data by investigate the change of water flow and water level before
and after the dam construction using various indicators under the principle of Indicators ofHydrological Alteration (IHA). Hydropower project timeline was created to analyze thedaily discharge and water level from 1964 to 2013. Findings portrayed that the water flow
had been significantly changing and may directly affects people along Mekong River interms of their livelihoods, agriculture and tourism activities (e.g. Songkran Festival). The
results of this study also can be used as a reference data for hydrological analysis in thefuture.
Keywords Mekong mainstream, hydropower, hydrological impact, transboundary impact

INTRODUCTION
Mekong River is a major trans-boundary river in Asia which has a lot of potential for hydropower
development. The river can be divided into two parts: the Upper Mekong from Tibetan Plateau andChina where it is named Lancang Jiang and passing Yunnan province of China and Myanmar, andcontinues the flow through the Lower-Mekong passing Thailand, Laos, Cambodia and Vietnam(Fig. 1a)
The Upper Basin covers 24 percent of the total area and contributes 15 to 20% of the waterthat flows into the Mekong River. Most of the total flow volume is delivered to the Mekong fromtributaries in the Lower Mekong Basin. These tributaries can be separated into two groups:
tributaries on the left bank that drain the high-rainfall areas of Lao PDR to the major wet season
flows, and tributaries on the right bank, mainly the Mun and Chi rivers, that drain low relief regionsof lower rainfall a large part of Northeast Thailand. The major contribution comes from the twomajor ‘left-bank’ (eastern) tributaries between Vientiane–Nakhon Phanom and Pakse-Stung Trengthat together contribute more than 40% of the flow (Table 1 and Fig. 1b). These two groups oftributaries are also marked by different levels of resource development i.e. in Thailand there is littleⒸ ISERD170

IJERD – International Journal of Environmental and Rural Development (2019) 10-2

room for further expansion of irrigation development and in Lao PDR, there is a lot of potential forwater resources development of all kinds (MRC, 2005; 2007; 2018).
Nakorn Panom, one of eight provinces of Thailand, is directly affected from the operation ofhydropower projects in both Mekong mainstream and its branches.
The Upper Basin makes up 31% of the water that flows through Nakhon Panom. While thetributaries during Vientiane – Nakhon Phanom contribute 22% of the flow as shown in Table 1.
Table 1 Proportional contributions to total Mekong River flow
River Reach
China
China – Chiang Saen
Chiang Saen – Luang Prabang
Luang Prabang – Vientiane
Vientiane – Nakhon PhanomNakhon Phanom – Mukdahan
Mukdahan – PaksePakse – KratieTonle SapTotal

Left Bank (%)

Right Bank (%)
161611834223224162955

20Total (%)
1648322410249100

Source: MRC (2018)(a) Overview (Rossi et al., 2009)(b) Major contributions to flow (MRC, 2009; 2018)

Fig. 1 Mekong River and its characteristics
Currently, the mainstream in China is dammed by 6 hydropower projects in planned cascadeof up to eight storage hydropower projects i.e. Xiaowan Dam, Jinghong Dam, Dachaoshan Dam,Manwan Dam, Nuozhadu Dam and Gongguoqiao Dam. While the first dam of 10 proposed run-ofriver hydropower projects in Lower Mekong River i.e. Xayaburi Dam is under construction.
Moreover, most Mekong River tributaries have cascades of dams in place or planned (MRC, 2010).
Mega-dam structure construction usually results in huge hydrological effect regarding thewater flow and water level. This alteration also causes worrisome to people along the river aboutⒸ ISERD

171

IJERD – International Journal of Environmental and Rural Development (2019) 10-2

the direct and indirect impacts to their livelihoods in terms of their small-scaled fisheries, theeconomic system and the ecology system of the river.
From the above-mentioned consequences, the monitoring system of transboundary impacts
should be established to monitor the impact prior to the construction, during the construction
process and after the construction has finished.
OBJECTIVE
The objective of this research is to investigate the result of pre and post constructing the dams
using various indicators under the principle of Indicators of Hydrological Alteration (IHA) inNakhon Panom province, Thailand.
METHODOLOGYThe Indicators of Hydrologic Alteration (IHA) model is used to provide information to understandthe hydrologic impacts of human activities as a result of the dam construction. This model cancalculate 67 statistical parameters that later are subdivided into 2 groups i.e. 33 IHA Parametersand 34 Environmental Flow Component (EFC) parameters. For IHA parameters, it can becalculated using parametric (mean/standard deviation) or non-parametric (percentile) statistics.
(Nature Conservancy, 2009).
Daily time series of discharge and water levels from 1964 to 2013 from provided by Thailand
National Mekong Committee were used to investigate the results of pre and post dam construction
using various indicators from IHA by Nature Conservancy (2009), and indicators from the studiesof Piman (2013) and World Bank (2004).
In this study, the time duration was divided into four phases depending mainly on theoperations of the two dams locating on the Upper part of Mekong River: Dachaoshan Dam (2003);
Manwan Dam (1996) and two dams on the tributaries: Nam Ngum Dam (1972); and TheunHinboun Dam (1998). The water flow status and the water level in the past before dam operation
was likely in its natural condition however, natural flow of the mainstream water was changed
because of the dam construction (2014) as illustrated in Fig. 2.
Daily discharge andwater levels
from 1964 to 2013

Indicators ofHydrologicalAlteration model(IHA)

Input

Model simulation

Four scenarios
Dachaoshan
dam (2003)

Manwan dam(1996)

Nam Ngumdam (1972)

Theun-Hinboun
dam (1998)

Results

Monthly Analysis
Flow and Water
Level Alteration

Annual Analysis

Coefficient ofdispersion change

Flow and Water Level Alteration

Fig. 2 Study diagramⒸ ISERD

172

IJERD – International Journal of Environmental and Rural Development (2019) 10-2

RESULTS AND DISCUSSION
Monthly Flow and Water Level Analysis
The analysis of mean monthly flow and mean monthly water level illustrated that under the dam
construction and operation, most of the dam contribute to increasing the water flow and water levelin every month except Nam Ngum Dam in which the flow and the water level are decreased in
July, August, and December (Figs. 3 and 4). These might cause from the operation of Nam Ngum
dam in Nam Ngum River, Laos PDR which diverse the water to Se Bang Fai River (oppositeNakhon Phanom province). The flow had increased more than 30 percent after the constructions inApril and May. This alteration is different from other areas in Thailand which the flow is usually
increase during dry season and decrease during wet season. The highest flow alteration is 50.35%
in April resulted from the Theun-Hinboun Dam. The highest change of flow variation found inJune with the 150.81% change in coefficient of dispersion (CD) resulted from Nam Ngum Dam(Fig. 3).
In terms of water level, the highest water level alterations is 58.22% in April which resultedfrom Manwan Dam, while Theun-Hinboun Dam contributed 49.71% of the change. The highest
change of water level variation is still found in June with the 135.48% of CD change resulted from
Nam Ngum Dam (Fig. 4). Moreover, it was found that during March to May and July, the monthly
water level was also increased.

(a) Flow alteration(b) Change of coefficient of dispersion
Fig. 3 Monthly flow analysis(a) Water level alteration(b) Change of coefficient of dispersion

Fig. 4 Monthly water level analysisⒸ ISERD

173

IJERD – International Journal of Environmental and Rural Development (2019) 10-2

However the characteristic of the average monthly flow graphs from Nakhon Phanom wasincreased every month and showed the differences when comparing to the stations from theupstream (see Piman, 2013; Lu et al, 2014; Rossi et al, 2009) which average monthly flow
increased in dry-season and decreased in wet-season.
Annual Flow and Water Levels Analysis
The annual flow analysis indicated that the operation of dams had significantly increased meanannual flow in Mekong mainstream except Nam Ngum dam. Theun-Hinboun dam contributes themost effect to the flow. The mean annual discharge before and after dam operation is 6,810 and8,390 m3/s, respectively (Fig. 5). The annual flow after dam operation has 1,580 m3/s increased.
While the annual water level analysis showed that the operation of dams just slightly increases
the water level. The highest increment of water level is 0.04 m resulted from Nam Ngum Dam andDachaochan Dam.

(a) Nam Ngum Dam(b) Manwan Dam(c) Theun-Hinboun Dam(d) Dachaoshan Dam

Fig. 5 Annual flow analysis
CONCLUSION
A construction of the mega-dam structure in hydropower project usually results in hugehydrological effect regarding flow and water level. In Nakhon Phanom, the water level was highly
increased as a result of the water releasing from hydropower projects from Nam Ngum, and TheunHinboun project in Laos.
The monthly flow and water level analysis indicated that most of the dams contribute toincrease the flow and water level every month except Nam Ngum dam that the flow and the waterlevel decreases in July, August, and December. The highest flow alteration is 50.35% found inApril resulted from Theun-Hinboun Dam. The highest change of flow variation found in June wasⒸ ISERD174

IJERD – International Journal of Environmental and Rural Development (2019) 10-2

150.81% change in coefficient of dispersion (CD) resulted from Nam Ngum Dam whereas thehighest water level alteration is 58.22% found in April which resulted from Manwan Dam.
The annual flow and water level analysis indicated that the operation of dams significantly
increased mean annual flow in Mekong mainstream except Nam Ngum Dam. Theun-Hinboun Dam
influenced the water flow the most. The annual flow after dam operation was increased to 1,580
m3/s. While the annual water level analysis showed that the dam operations have slightly effect tothe increasing of water level. The highest increment of water level is 0.04 m. resulted from Nam
Ngum Dam and Dachaochan Dam.
To handle with the occurrences, communities along Mekong River need to adapt themselvesto the changes. Additionally, Thailand should be more actively collaborated with other countries
especially for their assistance to supply the water when needed. Further studies need to beconducted regarding the hydrodynamic model to calculate the length of time from the releasing
points and the preferred destinations.
ACKNOWLEDGEMENTS
This paper was originated from “The Study and Monitoring of Transboundary Environmental
Impact towards the Development of Hydropower Projects in Mekong Mainstream” by Thai
National Mekong Committee (TNMC), Department of Water Resources, Thailand.
The authors would like to thank Faculty of Science and Engineering, Kasetsart University
Chalermphrakiat Sakonnakhon Province Campus, Thailand for the research fund and also thank toMiss Tasaporn Wetcharoen, Miss Mattika Khamchoo and Miss Ornuma Phong Sinsu for theircontributions to this paper.
REFERENCES
Lu, X.X., Li, S., Kummu, M., Padawangi, R. and Wang, J.J. 2014. Observed changes in the water ﬂow atChiang Saen in the lower Mekong: Impacts of Chinese dams? Quaternary International, 336, 145-157.
MRC. 2005. Overview of the Hydrology of the Mekong Basin. Mekong River Commission, Laos PDR.
MRC. 2007. Presentation on flow contribution to the Mekong mainstream (1985-2000-using DSF). The 7th
Meeting of the Technical Working Group, Mekong River Commission, Vientiane, Laos PDR.
MRC. 2009. The flow of the Mekong. MRC Management Information Booklet Series No. 2, Mekong River
Commission, Laos PDR.
MRC. 2010. Initiative on sustainable hydropower (ISH) 2011-2015 Document. Mekong River Commission,Laos PDR.
MRC. 2018. Mekong Basin, hydrology. Mekong River Commission for Sustainable Development, MekongRiver Commission, Laos PDR.
Nature Conservancy. 2009. Indicators of hydrologic alteration. Version 7.1 User’s Manual, NatureConservancy, USA.
Piman, T., Cochrane, T.A., Arias, M.E., Green, A. and Dat, N.D. 2013. Assessment of flow changes fromhydropower development and operations in Sekong, Sesan, and Srepok Rivers of the Mekong Basin.
Journal of Water Resources Planning and Management, 139, 723-732.
Rossi, C.G., Srinivasan, R., Jirayoot, K., Le Duc, T., Souvannabouth, P., Binh, N. and Gassman, P.W. 2009.
Hydrological evaluation of the lower Mekong River Basin with the soil and water assessment tool model.
International Agricultural Engineering, 18 (1-2), 1-13.
World Bank. 2004. Modelled observations on development scenarios in the lower Mekong Basin. Mekong
Regional Water Resources Assistance Strategy, World Bank, 41-54.

Ⓒ ISERD

175