Global Perspectives on Geography (GPG) Volume Issue 1, February 2013 www.as-se.org/gpg 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 Ho Chi Minh City University of Technology / VNU-HCM, 268 Ly Thuong Kiet St., Dist 10, Ho Chi Minh City, Vietnam 1* bangquoc@yahoo.com, 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 and CH ) 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 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 , 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- www.as-se.org/gpg Global Perspectives on Geography (GPG) Volume Issue 1, February 2013 FIG 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’ - 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 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) www.as-se.org/gpg (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 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 DESCRIBES THE APPLICATION PROCEDURE OF SWAT IN DAKNONG, VIETNAM www.as-se.org/gpg 3) Global Perspectives on Geography (GPG) Volume Issue 1, February 2013 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 and TABLE 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 FIG PREDICTED DAILY STREAMFLOW IN 2030 AT CAU 14 STATION, DAKNONG FIG 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, FIG PREDICTED MONTHLY STREAMFLOW IN PERIODS AT CAU 14 STATION, DAKNONG Global Perspectives on Geography (GPG) Volume Issue 1, February 2013 FIG PREDICTED YEARLY STREAMFLOW IN PERIODS AT CAU 14 STATION, DAKNONG TABLE STREAMFLOW IN 2005-2010, 2015 AND 2020 AT 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 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, www.as-se.org/gpg 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 www.as-se.org/gpg Global Perspectives on Geography (GPG) Volume Issue 1, February 2013 TABLE 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 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 Dak Glun Dak Sor Dak Sor 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 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 Dak Rung Dak N’Teng Nhan Co (ĐR) Dak Mam Dak Buk Sor Dray H'linh Dak Nong Dak Nong DongNai DongNai DongNai Serepok DongNai Serepok DongNai Serepok DongNai DongNai 384 525 576 431 384.5 356.3 746.02 - Dak Nong Dak Nir DongNai DongNai 753 170.5 Dak Muong DongNai 123 Serepok Buon Kuop Serepok Serepok 9592.2 8000 Krông Nô 4267 Buon T Srah Serepok Day H'linh Serepok Serepok 8760 - DongNai DongNai 10400 Dak R’Tih DongNai 2360 DongNai DongNai 10000 DongNai DongNai 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 Global Perspectives on Geography (GPG) Volume Issue 1, February 2013 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., www.as-se.org/gpg 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 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 REFERENCES 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 IMHEN., 2007 Vietnam Institute for Meteorology, Hydrology 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 Thang, N V., 2010 Climate change and its impacts in Vietnam Vietnam Institute forMeteorology, Hydrology and Environment (IMHEN) Van Liew, M W., and Garbrecht, J., 2003 Hydrologic simulation of the Little Washita River experimental watershed using SWAT, Journal of American Water Resources Association, Vol 39, no 2, 413–426 Williams, J R., Jones, C A., and Dyke, P T., 1984 A modeling approach to determining the relationship between erosion and soil productivity, Trans ASAE, Vol 27, no 1, 129-144 Williams, J R., Nicks, A D., and Arnold, J G.,1985 Simulator for water resources in rural basins, J Hydrol Eng., Vol 111, no 6, 970-986 and Environment www.as-se.org/gpg Global Perspectives on Geography (GPG) Volume 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 (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 ... 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. .. 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... 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