Impacts of Climate Change on Catchment Flows and Assessing Its Impacts on Hydropower in Vietnam’s Ce

Global Perspectives on Geography (GPG) Volume 1 Issue 1, February 2013

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Impacts of Climate Change on Catchment Flows and Assessing Its Impacts on Hydropower in Vietnam’s Central Highland Region Ho Quoc Bang1*, Nguyen Hong Quan1, Vo Le Phu2 *Institute for Environment and Resources (IER), VNU-HCM, Vietnam, 142 To Hien Thanh st., Dist.10, HoChiMinh, Vietnam 1

Ho Chi Minh City University of Technology / VNU-HCM, 268 Ly Thuong Kiet St., Dist. 10, Ho Chi Minh City, Vietnam 2

1*

bangquoc@yahoo.com, 1 hongquanmt@yahoo.com; 2phulevo@gmail.com

Abstract According to the Fourth Assessment Report – AR4 in 2007 of the Intergovernmental Panel on Climate Change (IPCC), climate change is a complex problem and becoming the leading challenge for humankind in the 21st century. Therefore, assessing climate change impacts on the social, economic activities and proposed solutions to respond to climate change is urgent and necessary. This study applied the GIS (Geographic Information System) technique and SWAT model (Soil and Water Assessment Tool) to simulate water flows due to the impact of climate change. The models were applied for several catchments in and around Dak Nong province. The results of catchment flows can be useful information for many purposes, such as: flood forecasting, predicting sediment loads and impact assessment of climate change on water resource and hydropower. In this study, the issues of hydropower safety and electricity generation capacity in Dak Nong up the year of 2020 are focused. The results of SWAT model show some certain changes in catchment flows due to climate change, for example, the maximum streamflow in the upper part of Serepok River in 2020 is higher than that in the period of 2005 to 2010 about 16.8%. The results also showed that the hydropower dams’ safety in Dak Nong province is secured given the climate change scenarios. In addition, given the changes in catchment flows due to climate change ， the hydroelectric ouput of Dak Nong in 2020 are only 7,063 million kWh/year, which is less than about 12% in comparison to the expected production.

Keywords Climate Change; Swat Model; GIS; Hydropower; Vietnam

Introduction According to the IPCC’s Fourth Assessment Report (AR4), climate change is a complex problem and becoming the leading challenge for humankind in the 21st century (IPCC, 2007). Many studies showed that climate change is mainly caused by the emission of greenhouse gases (mainly CO 2 and CH 4 ). Especially since 1950, the rapid growth of urbanization and industrialization had led to an acceleration of human consumption and an increase in emissions. One of the biggest industries greenhouse gas emissions is electricity production which occupies about 50% of global CO 2 emissions (Lansiti, 1989). Because electrical industry emits a large amount of greenhouse gases, therefore the energy sector has to cut greenhouse gas emissions for mitigation of climate change. Many solutions have been given to the energy sector, such as: using other fuels producing less CO 2 , using modern energy efficient alternatives or increasing use of renewable energy sources. Among the alternative power production in thermal power, hydropower is an attractive option because hydropower is a form of renewable energy, less greenhouse gas emissions and hydropower infrastructures have a long lifetime. Therefore, in recently years, although the construction of large-scale hydropower dams have made locals emigrate and caused ecological impacts on the basin, governments in most countries have still continued to construct more hydropower plants because of its important role played in the econo-

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Global Perspectives on Geography (GPG) Volume 1 Issue 1, February 2013

FIG. 1 LOCATION OF DAKNONG PROVINCE IN VIETNAM (LEFT) AND ITS TOPOGRAPHY (RIGHT)

mic development, especially in developing countries and less developing countries.

12o50’ northern latitude and 107o13’ - 108o10’ eastern longitude.

It is estimated that there will have 69 hydropower projects in Dak Nong province, Viet Nam by 2015.

According to the Dak Nong industry and trade department, 37 hydroelectric projects (including 25 small-scale and 12 large-scale hydropower facilities) have been investing and operating in 2010 with a total capacity of 1905.96 MW. However, the massive hydroelectric development in recent years can be affected by climate change in the future. The change of water flow is likely one of the potential impacts in the age of human-induced climate change. Hence, for ease on the impact of climate change on hydropower systems in Dak Nong, this paper presents an application of GIS (Geographic Information System) and SWAT (Soil and Water Assessment Tool) model to simulate water flows, then results of the model are used for assessing climate change impacts on hydropower in Dak Nong province.

The province’s climate condition is influenced by the climate of eastern and western of Truong Son moutain

Study location, data and methods Study Location Dak Nong is located in the southern part of Vietnam’s Central Highland region (FIG. 1). Dak Nong borders with Dak Lak in the north, Lam Dong in the southeast, Binh Phuoc and Cambodia in the west. Its elevation is about 500m above sea level. The terrain is lower in the west. Dak Nong coordinates at 11o45’ -

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range. It is characterized by less directly affected by storm, high temperatures and solar radiations. The ave-

rage annual temperature is about 21 - 24oC. Total yearly hours reach 2,200 - 2,400 hours/year. Total amount of radiation is 233 240 Kcalo/cm2. Annual evaporation, relative humidity and rainfall are abour 1,000 - 1,400 mm, 81 - 85% and 1,600 - 2,500 mm respectively (Nguyen and Ho., 2011).

Dak Nong has two main river basins, including Serepok and DongNai rivers. Almost area of the province is in the Serepok river basin and the remain-ing part is the DongNai river basin. The Serepok river has two major tributaries which are KrongNo and KrongAna rivers. The total area of KrongNo river basin is 4,620 km2 and the main stream is 56 km in length. KrongAna river has a total river basin is 3,200 km2, and the legnth of the main river section is 215 km. The DongNai river basin covers an area of approxi mately 2,526 km2 (Ngu-yen and Ho., 2011). The stream nerwork in the provin-ce is quite complex, thick and many small tributaries. These are favorable conditions to exploit water resour-ces for agricultural

Global Perspectives on Geography (GPG) Volume 1 Issue 1, February 2013

practices, hydropower pro-duction and domestic uses.

Data Collection Collected data in the catchments are meteorological and hydrological data in many stations in and around Dak Nong (including Cau14 station, GiangSon station, DakMil station, DucXuyen station and Dak Nong station). The collected data are (1) daily evaporation; (2) hourly rainfall; (3) wind direction and speed; (4) hourly temperature; (5) hourly humidity and (6) hourly streamflow.

Land use map is provided by the Dak Nong Department of Natural Resources and Environment, while the topographic map is collected at the Vietnam National Information and Communication Technology Department at 1:25.0000 Scale, which can be used later for generating a Digital Elevation Model (DEM). Climate change variations are up the year of 2030, including temperature, rainfall, and evaporation from the Vietnam Institute for Meteorology, Hydrology and Environment (IMHEN, 2007).

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(EPIC) (Williams et al., 1984). Many docu-mented applications of SWAT model for assessing water resources have are Van Liew and Garbrecht (Van et al., 2003) using the SWAT model to predict streamflow under varying climatic con-ditions for three nested watersheds in Little Washita River Experimental Watershed in Okla-homa. Chu and Shirmohammadi (2004) (Chu et al, 2004) applying SWAT model for the calculation of surface flow for a small watershed in Maryland. Spruill and others (Spruill et al., 2000) using SWAT model to determine daily streamflow for a small karst-influenced watershed in central Kentucky during the period of 2 years, etc.

2)

SWAT’s application in Dak Nong province

Methods 1)

SWAT model

The SWAT model was developed in the early 1990’s by the U.S. Department of Agriculture, Agricultural Research Service (USDA–ARS) (Arnold et al., 1998).

The model was developed to assess and predict the impact of land management affect on water, sludge, and the amount of chemicals used in agricultural practices on a large and complex basin with unstable factors of soil, landuse and management conditions in a long time. The model includes a set of regression calculations to describe the relationship between the input and output parameters. The SWAT model integrates many different models of ARS, which are developed from model for Simulator for Water Resources in Rural basins (SWRRB) (Williams et al., 1985; Arnold et al., 1990). Specific models that contributed significantly to the development of SWAT model were: (i) Chemicals, Runoff, and Erosion from Agricultural Management Systems (CREAMS ) (Knisel, 1980); (ii) Groundwater Loading Effects on Agricultural Management Systems (GLEAMS ) (Leonard et al., 1987); (iii) and Erosion-Productivity Impact Calcu-lator

FIG. 2 DESCRIBES THE APPLICATION PROCEDURE OF SWAT IN DAKNONG, VIETNAM

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3)

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Model calibration and validation

The SWAT model was calibrated by using SWATCUP software. Several statistical approaches can be used to check SWAT model performance such as: coefficient of determination (R2), Nash-Suttcliffe Simulation Efficiency (NSE) (Nash and Suttcliffe, 1970), mean absolute error (MAE), Root Mean Square Error (RMSE), and Theil’s inequality coefficient (U). + Nash-Suttcliffe Simulation Efficiency (NSE).

0.89, 0.84 for Dak Nong station, DucXuyen station and Cau14 station, respectively. These NSE values are almost higher than 0.7, therefore the model and the parameters can be used to simulate catchment flows in the province under climate change scenarios.

Results and discussions Results of streamflow The continous of monthly streamflow at the Cau 14 station and some statistical numbers of streamflow of four catchments in Dak Nong province are shown in FIG. 4 and TABLE 1.

Where: P is simulation values ; O is measurement values and N is the number of monitors. + SWAT-CUP is a computer program for calibration of SWAT models. The program links GLUE, ParaSol, SUFI2, MCMC, and PSO procedures to SWAT. It enables sensitivity analysis, calibration, validation, and uncertainty analysis of a SWAT model. The program structure approach is as shown in the FIG. 3.

FIG. 4 PREDICTED DAILY STREAMFLOW IN 2030 AT CAU 14 STATION, DAKNONG

FIG. 3 SWAT-CUP APPROACH

In this paper, the Nash-Suttcliffe simulation efficiency was used. The statistic results of the average NSE between simulations and measurements for model calibration and validation are 0.86,

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FIG. 5 PREDICTED MONTHLY STREAMFLOW IN 4 PERIODS AT CAU 14 STATION, DAKNONG

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FIG. 6 PREDICTED YEARLY STREAMFLOW IN 4 PERIODS AT CAU 14 STATION, DAKNONG TABLE 1 STREAMFLOW IN 2005-2010, 2015 AND 2020 AT 4 CATCHMENTS (M3/S) Serepok

Krong No

DongNai’s main stream

Dak Nong station

Maximum

2210

1290

2600

147

Average

272

87.4

1110

18.2

Minimum

16.4

0.9

215

1.3

Maximum

1789.7

1263.5

1647.7

93.2

Average

220.3

85.6

703.4

11.5

Minimum

13.3

0.9

136.3

0.8

2120.8

1507.2

2050.7

115.9

Average

261

102.2

875.5

14.4

Minimum

15.7

1.1

169.6

1

Streamflow 2005-2010

2015

2020 Maximum

Assessing Climate Change Impacts on Hydropower 1)

Climate change impacts on hydropower safety

Climate change likely leads to increased intensity of floods and the flood peak. In some extreme cases,

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the hydropower plant has to discharge to ensure the safety of hydropower dams in the flood season.

Streamflows and flash flood levels are the parameters used to assess the impact of climate change on the safety of hydropowers (Thang et al., 2010).

Thus, the changes of streamflows due to climate change from SWAT model simulations and the design flash flood flows of each hydropower (TABLE 2) are used to assess the impact climate change on the hydropower safety. The results show that the design flash flood flows of 37 hydropowers in Dak Nong are higher than the maximum level of streamflows in Dak Nong’s catchments, although the maximum level of streamflows in some river of Dak Nong’s catchements in 2020 are higher that in the period of 2005 to 2010. Such as the maximum level of streamflows in Krong No river is 1507.2 m3/s in 2020, while the maximum level of streamflows in the period of 2005 to 2010 is only 1290.0 m3/s (TABLE 1). Therefore, the hydropower dams’ safety in the province is secured given the climate change scenarios.

2)

Climate change assessment impacts on electricity generation capacity

Climate change refers to any significant change in climate factors, including precipiration, temperature, storm patterns and intensity, etc. The decrease of precipitation or increase of temperature will likely result in drought events. Drought and reducing streamflow lead to the reduction of hydropower supply (Cherry et al., 2010). Therefore, the change of streamflows from SWAT model simulations due to climate change and the expected streamflows for generating maximum electicity are used to assess the impact of climate change on electricity generation capacity in Dak Nong pro-vince (TABLE 2). The results showed that the hydroelectric output in 2010 is about 5,450 million kWh/year. It is expected that the hydropowers are not affected by reduced streamflow due to climate change, and in 2020 the hydroelectric output will reach to 8,072 million kWh/year. However, the hydroelectric ouput of Dak Nong in 2020 is only 7,063 million kWh/year. However, production tends to decrease as it is less than about 12% in comparison with the proposed production due to the impact of human-induced climate change.

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Global Perspectives on Geography (GPG) Volume 1 Issue 1, February 2013

TABLE 2 TECHNICAL SPECIFICATIONS OF HYDROPOWERS IN DAKNONG Hydropower name

River Basin

Q design flash flood flow (m3/s)

Material of dams

Q generated max electricity(m3/s)

Annual electricity generated (106 kWh)

Dak Buk Sor 1 Dak Sin Dak Kar

DongNai DongNai DongNai

746.02 552 683

7.82 12.31 5.72

11.76 105.18 30.52

Dak R’Keh Dak A.Kong Dak Ru Quảng Tin

DongNai DongNai DongNai DongNai

331.5 242.8 758 460

6.85 4.3 10.3 6.7

11.09 7.46 29.8 20.3

Dak Glun 2 Dak Glun 3 Dak Sor 1 Dak Sor 2

DongNai DongNai Serepok Serepok

394.03 458.6 645 590.7

5.8 8.75 5.9 9.74

13.73 25.63 18.326 22.64

Dak Sor 4

Serepok

721

Soil dam Soil dam Soil dam Beton dam Soil dam Soil dam Soil dam Beton dam Soil dam Soil dam Soil dam Beton dam

17.62

27.6

7.53 14.9 13.2 8.36 11.57 5.45 7.82 -

42.33 26.321 31.8 52.8 5.995 19.05 11.76 64.09 8.01 7.21

19.37 8.71

58.688 25.51

2.04

9.55

507.42 316

336.36 1458

204.9

358.6

412.8 -

1060.2 118.4

215

607.1

50/67

636.8

221

1109.5

298 -

604.43 929.16 37

-

132.5

Da Klong Dak Rung 1 Dak Rung Dak N’Teng Nhan Co (ĐR) Dak Mam 2 Dak Buk Sor 1 Dray H'linh 2 Dak Nong Dak Nong 1

DongNai DongNai DongNai Serepok DongNai Serepok DongNai Serepok DongNai DongNai

384 525 576 431 384.5 356.3 746.02 -

Dak Nong 2 Dak Nir

DongNai 1 DongNai 1

753 170.5

Dak Muong

DongNai

123

Serepok 4 Buon Kuop

Serepok Serepok

9592.2 8000

Krông Nô

4267

Buon T. Srah

6

Serepok 3 Day H'linh 1

Serepok Serepok

8760 -

DongNai 3

DongNai

10400

Dak R’Tih

DongNai

2360

DongNai 4

DongNai

10000

DongNai 5 DongNai 6 Chu P.Prong

DongNai DongNai Serepok

8320 -

Hoa Phu

Serepok

-

Beton dam Soil dam Soil dam Soil dam Soil dam Soil dam Soil dam Beton dam Soil dam Beton dam Beton dam Soil dam Beton dam Beton dam Beton dam Beton dam Beton dam Beton dam Note: “-“: Non-value

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Conclusion The results of SWAT model show some certain changes of catchment flows due to climate change, for example, the maximum streamflow in the upper part of the Serepok river in 2020 is higher than that in the period of 2005 to 2010 about 16.8%. It also shows that the hydropower dams’ safety in Dak Nong province is secured given the climate change scenarios. In addition, given the changes of catchment flows, in 2020 the hydroelectric output will reach 7,063 million kWh/year(less than about 12% in comparison with the expected production).

IPCC.,

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2007.

Climate

Contribution

Change

2007:

Synthesis

Report.

of Working Group II to the Fourth

Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge.

Knisel, W. G., 1980. CREAMS: A field scale model for chemicals,

runoff,

and

erosion

from

agricultural

management systems, U.S. Dept Agric. Conserv. Res. Report No. 2 Lansiti, E., and Niehaus, F., 1989. Impact of energy production on atmospheric concentration of greenhouse gases Energy systems must be restructured to reduce emissions of

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Arnold, J. G., Williams, J. R., Nicks, A. D., and Sammons, N .B., 1990. SWRRB: A basin scale simulation model for soil and water resources management, Texas A&M Univ. Press, College Station, TX. Arnold, J. G., Srinivasan, R., Muttiah R. S., and Williams, J. R., 1998. Large area hydrologic modeling and assesement. Part 1: model development. Vol 34, J. Americam Water Resources Associaton, 73-89 Cherry, J. E., 2010. Impacts of Climate Change and Variability on Hydropower in Southeast Alaska, Planning for a Robust Energy Future International Arctic Research Center and Institute of Northern Engineering at the University of Alaska Fairbanks. 2010.

Chu, T. W., and Shirmohammadi, A., 2004. Evaluation of the SWAT model’s hydrology component in the Piedmont physiographic region of Maryland, Transaction of the American Society of Agricultural Engineering (ASAE), Vol 47, no. 4, 1057–1073.

Di Luzio, M., Arnold, J.G., and Srinivasan, R., 2004. Integration of SSURGO maps and soil parameters within a geographic information system and nonpoint source pollution model system, Journal of Soil and Water Conservations, Vol 59, 123–133.

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carbon dioxide, IAEA Bulletin, Feb. 1989 Leonard, R. A., W. G. Knisel, and D. A. Still. 1987. GLEAMS: Groundwater loading effects on agricultural management systems. Trans. ASAE, Vol 30, no 5, 1403-1428.

Nguyen, N. V., and Ho, Q. B., 2011. Climate change adaptation plan for Dak Nong province, Vietnam. Dak Nong Deparment of Natural Resources and Environment and IER. Technical report 12/2011 Spruill, C. A., Workman, S. R., and Taraba, J. L., 2000. Simulation of daily and monthly stream discharge from small watersheds using the SWAT model, Trans.ASAE, Vol 43, no. 6, 1431–1439.

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Global Perspectives on Geography (GPG) Volume 1 Issue 1, February 2013

Bang Q. Ho was born in Vietnam, on 17/12/1979. He got Docteur ès Sciences (Ph.D.) degree on Environmental Science (Emission inventories and air quality modelling) at the Swiss Federal Institute of Technology in Lausanne (EPFL), Switzerland in 2010. He is doing research on Climate Change, Energy and Air quality fields.

He got Master degree on Environmental Science at the Swiss Federal Institute of Technology in Lausanne (EPFL), Switzerland in 2005. From 1997 to 2001: he did Bachelor of Analytical Chemistry at the University Sciences Natural / Vietnam National University in Ho Chi Minh City. From 2001 to 2011 he has worked for several Labs in IER (System laboratories lab, Air quality lab), EPFL (LPAS, LASIG) and also in French National Center for Scientific Research - France on Emission inventory, Modelling of Meteorology and Air pollution, monitoring of air quality and water quality, Climate change. In 2011 he worked at Duke University, USA as visiting scholars on Energy and Environment. He is doing as a National Consultant and Regional consultant on Air emission inventories for ASEAN Ports funded by German Technical Cooperation (GIZ).

Dr. Ho is currently a Director of Air Pollution and Climate Change Department/Institute of Environment & Resources

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(IER)/Vietnam National University, HoChiMinh City (VNU/HCM). He teaches many courses on “Sustainable Energy Use”, “Climate Change”, “Control of air pollution and noise” and “environmental modelling” for master and engineer levels.

Hong Q. Nguyen was born in Vietnam, on 22/12/1979. He got Docteur ès Sciences (Ph.D.) degree on Environmental Science Braunschweig Uni-versity of Technology.

He is doing resear-ch on Climate Change, water management fields.

Dr. Quan is currently a vice director of natural resources management depart-ment / /Institute of Environment & Resources (IER)/Vietnam National University, HoChiMinh City (VNU/HCM).

Le P. Vo was born in Vietnam, on 9/6/1971. He got Docteur ès Sciences (Ph.D.) degree on Environmental Science Adelaide, Sou-th Australia, Australia. He is doing resear-ch on Climate Change, water management fields.

Dr. Vo is currently a Vice Dean of Environment Faculty, of University of technique / Vietnam National University, HoChiMinh.