Water resources management under future development and climate change impacts in the Upper Srepok...

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Water resources management under future development and

climate change impacts in the Upper Srepok River Basin Central

Highlands of Vietnam

Tran Van Tya Kengo Sunadab and Yutaka Ichikawab

aCorresponding author College of Technology Cantho University Campus 2 32 Street Ninh Kieu District Cantho City

Vietnam E-mail tvtyctueduvnbInterdisciplinary Graduate School of Medicine and Engineering University of Yamanashi 4-3-11 Takeda Kofu Yamanashi

400-8511 Japan

Abstract

This study aimed to assess the impacts of future development and climate change on the water balance in the

Upper Srepok River Basin in the Central Highlands of Vietnam A hydrological model was calibrated and validated

to model the rainfall-runoff process Estimates of the water demand of different water sectors were based on the func-

tional relationships between water and productive uses The estimates were input into a calibrated basin management

model for simulation The climate projections were downscaled to the studied basin Future land use was predicted

using a geographic information system (GIS)-based logistic regression approach The water balance was examined

under various developed scenarios The results show a relatively high current annual irrigation water deficit at a basin

scale some sub-basins suffer fromwater shortage especially during dry seasons and dry years All water use sectors

will be affected to some extent under the impacts of future development and water supply policies When the new

water policy is introduced the deficits of irrigation and environmental flow are reduced while the power deficit is

increased Considering climate change impact the annual water deficits are reduced However the temporal and

spatial variations of rainfall make future water deficits more severe during the dry seasons and dry years

Keywords Allocation Deficits Hydropower plant Srepok River Supply priority Water balance

1 Introduction

Rapid population growth agricultural expansion and industrial development have led to increased

water demands in turn leading to increased competition and conflicts among water sectors In addition

degraded water quality high temporal and spatial variation of water resources and old and unsustain-

able water management practices have recently hindered accessibility to supplies of fresh water

Water Policy 14 (2012) 725ndash745

doi 102166wp2012095

copy IWA Publishing 2012

(Babel et al 2005) A great deal of attention has been paid by the scientific community to the issue of

water allocation in many regions (Babel et al 2005 Mohammed et al 2007 Liu et al 2010) and a

few recent studies have been carried out on the Mekong River Basin (MRB) (Ringler et al 2004 2006)

But it is rare to find a study that provides an overview of water supply in terms of the supplydemand

balance situation at the local level in the context of climate change and the impact of human activity

and for trans-boundary basins Allocating limited water resources to competing demands has therefore

become an important water-related issue in many countries It also plays a crucial role in improving

water resources management following the principles of integrated water resources management that

have recently been implemented in many countries

The impact of climate change and human development on the future state of global water resources

has been intensively studied (Voumlroumlsmarty et al 2000 Oki amp Kanae 2006) whereas it is rare to find a

study that assesses the magnitude of these impacts on local water resources In the MRB many studies

have investigated the impact of climate change on future water availability (Hoanh et al 2003

Chinvanno 2004 Kiem et al 2008) However they focus only on the large scale with the results indi-

cating broadly similar responses to future climates for example rainfall is projected to increase across

the basin Because climate characteristics the degree of impact and adaptations to it vary across spatial

scales investigating and understanding the extent of the potential impact of climate land usecover and

population changes on local water resources particularly in a developing area such as the MRB is there-

fore needed

Although ecosystems have been found to provide a wide range of valuable services for people

especially in developing and agriculture-based countries ecosystems are frequently ignored in water

allocation decision making (Korsgaard et al 2008) In the MRB for instance under the 1995

Mekong Agreement the riparian countries agreed that any upstream development should ensure protec-

tion of the ecological balance of the river system and established rules for water utilization that prevent

any unacceptable reduction and increase in the dry and wet seasons respectively (MRC 1995) In

addition recognizing the important role of in-stream flow requirements in sustaining the health of eco-

systems a decree on river basin management (Decree No 1202008ND-CP) was issued in December

2008 in Vietnam (GOV 2008) stating that in-stream flow requirements must be incorporated into water

planning and allocation

For better water resources management an insight into the evolution of past water use an understand-

ing of current demand and an awareness of possible future trends are thus very important to

water planners and managers (McCartney amp Arranz 2007) In order to make appropriate decisions

in water management and allocation a comprehensive quantitative assessment of current and future

water supply and demand is needed Therefore this study aims to assess the impacts of current and

future basin development and climate change on water balance For this purpose monthly water avail-

ability and demands were first estimated and then input into a river basin management model (MIKE

Basin) to determine water deficitsurplus at representative nodes The water balance at representative

nodes was then examined under various developed scenarios considering different water supply policies

relative to allocation The Upper Srepok River Basin in the Central Highlands of Vietnam was

selected for this study In this basin high immigration rates from other regions and rapid local

population growth have driven an uncontrolled expansion in the area under cultivation The studied

basin has a moderate hydropower potential compared to other similar basins in the Lower Mekong

Basin (LMB) which may have extensive repercussions for peoplersquos livelihoods and the ecosystem

downstream in Cambodia

T V Ty et al Water Policy 14 (2012) 725ndash745726

2 Study area and data

21 Study area

The Srepok River a tributary of the Mekong River is one of the main rivers in the Central High-

lands of Vietnam and passes through Cambodia before merging into the Mekong The basin area in

Vietnam is 18200 km2 of which 12000 km2 is the Upper Srepok Basin Overall the basin wholly

or partially encompasses three provinces with a total population of 1732 million (2006) The

Upper Srepok Basin representative of the mountainous area in the LMB was selected for this

study The average altitude of the basin ranges from 350 m in the northwest to 1000 m (above

mean sea level) in the southeast The topographical characteristics directly affect the rainfall

distribution with average annual rainfall (1978ndash2007) ranging from 1896 mm at the Duc Xuyen

station to 1576 mm at the Ban Don station downstream More than 70 of the total annual rainfall

occurs during the wet season (June to November) and about 41 is converted into runoff

(Ty et al 2009 2010) In addition high immigration rates from other regions (more than 10)

and rapid local population growth (4ndash5) have driven an uncontrolled expansion in the

area under cultivation (Hook et al 2003) Forest cover in Dak Lak Province one of the three

provinces in the basin declined 25 between 1975 and 2000 (Muumlller 2003) Consequently

the demand for water for agriculture has increased significantly and dominates the total water

demand

Vietnam has a high potential for hydropower development especially in the Northern and Central

Highland regions In 2000 the total electricity production was 8750 MW of which hydropower

accounted for 488 The Central Highland region contributed 259 of the total generated power of

the nation (VNMC 2003) The Upper Srepok Basin has a moderate hydropower potential compared

to other similar basins in the LMB and has so far been undeveloped except for a small-scale hydro-

power plant (HPP) at Dray Linh Old in Vietnam (12 MW) which has not been in operation for the

last few years Currently three power plants are in operation (Buon Koup Buon Tua Srah and

Srepok 3) one plant is under construction and is expected to be completed in 2012 (Srepok 4) and

another plant is at the planning stage (Duc Xuyen) These HPPs are being constructed upstream in Vietnam

and may have extensive repercussions for peoplersquos livelihoods and the ecosystem downstream in

Cambodia (SWECO 2006) The study area HPPs and hydro-meteorological stations are shown in

Figure 1

22 Data

The data required for this study were either collected from local government organizations or

downloaded from the public domain from the Department of Agriculture and Rural Development

(DARD) the Mekong River Commission (MRC) the Hydrometeorological Data Center in

Vietnam (HMDC) the Center for International Earth Science Information Network (CIESIN)

and the Southeast Asia System for Analysis Research and Training Research Center (SEA

START RC) The collected data and their sources are summarized in Table 1 The primary

design data of the five cascade dam projects on the Upper Srepok River Basin are presented in

Table 2 (SWECO 2006)

T V Ty et al Water Policy 14 (2012) 725ndash745 727

Fig 1 Study area hydropower plants and hydrometeorological stations

TVTyet

alWater

Policy

14(2012)725ndash745

728

3 Methodology

The HEC-HMS (Hydrologic Engineering Centerrsquos Hydrologic Modeling System) model was first set

up calibrated and validated to model the rainfall-runoff process in the basin Estimates of the water

demand of different water sectors were based on the functional relationships between water and pro-

ductive uses in irrigated agriculture domestic and industrial use and in-stream flow requirements

The unregulated flow of each sub-basin was then computed The estimates were input into the calibrated

river basin management model (MIKE Basin) to generate flow data The climate projections of the

Global Climate Model (GCM)-ECHAM4 (emission scenarios A2 and B2) were downscaled to the

basin being studied and climate change scenarios were developed Future land use was predicted

using a geographic information system (GIS)-based logistic regression approach and the population

was projected from historical data The water balance was then examined under various scenarios devel-

oped considering different water supply policies in the allocation Due to a lack of necessary data and

the complexity of the river network the economic value of water was not considered in the study

31 Hydrological model

HEC-HMS was developed by the United States Army Corps of Engineers (USACE 2008) to simu-

late the rainfall-runoff processes of dendritic watershed systems The studied basin was delineated into

seven sub-basins based on a digital elevation model and the locations of large-scale reservoirs for power

Table 1 Data and sources

Datatheme Data type Year Data source

Stream flow 2 stations daily basis 1978ndash2007 HMDC

Land usecover Polygon 150000 1993 and

1997

MRC

Digital elevation map 50 m resolution 2000 MRC

Gridded population of the world 25 arc-minute resolution 2008 CIESIN

Gridded rainfall and temperature projection 20 km resolution 1978ndash2007 SEA START RC

2035ndash2064 ECHAM4 (A2 B2)

Rainfall 6 stations daily basis 1978ndash2007 HMDC

Reservoirs hydropower plants Location capacity storage characteristics 2006 DARD SWECO

Table 2 Primary design data of dam projects on the Upper Srepok River Basin

Dam project

Full supply

level (m-MSL)

Minimum

operating level

(m-MSL)

Storage capacity

(106 m3)

Regulation

capacity (106 m3)

Installed

capacity

(MW)

Annual energy

potential

(GWh)

Duc Xuyen (DX) 5600 5510 10880 4315 70 255

Buon Tua Srah (BTS) 4875 4675 7870 4830 86 358

Buon Koup (BK) 4120 4090 632 147 280 1459

Srepok 3 (SP3) 2720 2670 2230 750 220 1002

Srepok 4 (SP4) 2060 2025 270 115 65 299


generation Rainfall data from six stations (Da Lat Duc Xuyen Cau 14 Krong Buk Buon Ma Thuot

and Ban Don) were mapped to each sub-basin using the Thiessen polygon method Stream flow was

simulated on a daily basis and the results were calibrated to observed daily stream flow data for the

period 1978ndash1992 at two stations (Cau 14 and Ban Don) The calibrated parameters were then used

to validate the model for the period 1993ndash2007 The calibration and validation results were evaluated

for goodness of fit using two criteria recommended by Krause et al (2005) and Moriasi et al

(2007) Nash-Sutcliffe Efficiency (NSE) and percent bias (PBIAS) at monthly time scales Calculations

were made using the following formulae

NSE frac14 1

Pnifrac141 Yobs

i Y simi

2

Pnifrac141 Yobs

i Ymeaneth THORN2

(1)

PBIAS frac14

Pnifrac141 Y sim

i Yobsi

100Pn

ifrac141 Yobsieth THORN

(2)

where Yiobs and Yi

sim are the ith observed and simulated flow respectively Ymean is the mean of

observed flow data and n is the total number of observations

32 Water availability estimation

Because observedsimulated flow is in fact post-depletion flow or regulated flow to account for var-

ious withdrawals at demand sites unregulated flow or natural flow was estimated by augmenting

consumptive uses Withdrawals were added and return flows subtracted as expressed below

NF frac14 SFthornWW RF (3)

where NF is unregulated (natural) flow (m3s) SF is simulated flow (m3s) WW is water withdrawals

for different uses (m3s) calculated for each sub-basin (Ty et al 2009) and RF is return flows from

different uses (m3s)

According to Ringler et al (2004) model simulation results for the whole Mekong River Basin indi-

cated that return flow was about 2 of annual runoff and as a share of water withdrawal it was

estimated at 27 for irrigation use and 35 for domestic and industrial uses MRC (2004) estimated

return flows from 0 to 30 for irrigation use in Vietnam Therefore in this study return flows of

27 for irrigation use and 35 for domestic and industrial uses were employed

33 Water demand estimation

Domestic and industrial water demand Since industry has not developed in this area the amount of

water diverted to meet domestic and industrial demand was considered together and estimated as the

product of population and per capita water demand which reflects the different levels of access of

the population to clean water The current unit domestic demand and industrial demand were taken

as 67 Lcapday Future unit domestic demand and industrial demand were taken as 150 Lcapday

for the year 2050 (MRC 2004)


Irrigation water demand Water use in the irrigation sector was estimated based on the irrigated area

and crop water requirements (CWR) Monthly CWR of four crops were estimated using CROPWAT

software (IWRP 2001) Due to a lack of data for the required climatic inputs the FAO Penman-

Monteith equation for estimating potential evapotranspiration (ETo) with limited data was used

based on downscaled maximum and minimum temperature and radiation (Allen et al 1998) Future

irrigation water demand was estimated on a monthly basis for each sub-basin based on projected

land use maps (agricultural area) future CWR calculated from ETo and future effective rainfall

In-stream flow requirements In-stream flow requirements or environmental flows (EF) are the water

regime provided within a river wetland or coastal zone to maintain ecosystems and their benefits

(Dyson et al 2003) EF was estimated by Ty et al (2011) using the widely accepted method known

as the Range of Variability Approach (RVA) (Richter et al 1997 1998)

34 River basin management simulation

The river basin management model MIKE Basin (DHI 2009) was set up using a node-link network

representing the spatial relationships between the physical entities in the river basin sub-basins were

considered as the major modeling units Nodes represent river reaches reservoirs and demand sites

links represent the connections between these entities Inflows to these nodes include runoff from the

upstream sub-basins as well as local drainage runoff

The node-link network of the Upper Srepok River Basin system simulated in MIKE Basin is illustrated

in Figure 2 Water availability generated from seven sub-basins using a hydrological model (HEC-HMS)

was incorporated into the model in the form of specific flow (Ls per km2) There are seven demand sites

for each water use sector including domestic and industry (DampI) and irrigation (IRR) Water uses

demands have been withdrawn from surface sources such as small- and medium-scale reservoirs and

directly from the river Estimates of water withdrawals for specific water users at each sub-basin were

based on assumptions that the withdrawals from different water infrastructures located within a sub-

basin were lumped into a single value The water usesdemands input into the model are the final

values and were adjusted by the return flows Five EF demand sites were set downstream of the five HPPs

The input data for five cascade HPPs along the main-stream Srepok River include the physical charac-

teristics of the reservoir elevation-area-volume relationships rainfall and evaporation installed capacity

designed turbine flow minimum head for power generation etc The elevation-area-volume relationship

of the Srepok 3 reservoir is depicted in Figure 3 Due to a lack of operating rule curves for reservoirs the

power generated by the turbines is calculated by assuming that they run at maximum capacity and being

constrained by defined zones of reservoir characteristics (flood control zone inactive zone etc)

For calibration and validation purposes the priorities were adopted based on the principle of lsquofirst

come first servedrsquo since no specific water supply priority has been established for the water shortage

situation in Vietnam (GOV 2008) The simulation was carried out for a period of 11 years (a period

of 1997ndash2002 for calibration and 2003ndash2007 for validation) on a monthly basis at the two stations

(Cau 14 and Ban Don) This period was selected because it covers all water year types classified by

the Standardized Precipitation Index which was computed for 30 years (1978ndash2007) of observed rainfall

data (McKee et al 1993) The initial water levels in the reservoirs for simulation were assumed to be at

minimum operating levels (Table 2) The outputs from MIKE Basin are the water balances at represen-

tative nodes The calibrated model was then used to evaluate the impacts of potential future


developments climate change and water management policy on water balance under various developed

scenarios

35 Scenario development

Climate change scenario This study utilized the output from a high-resolution Regional Climate

Model (RCM) (20 km grid) developed by the SEA START Regional Center The simulation is based

on a simulation by the PRECIS (Providing Regional Climates for Impact Studies) Regional Climate

Model using the GCM-ECHAM4 dataset as initial data for calculations covering Intergovernmental

Panel on Climate Change (IPCC) emission scenarios A2 and B2 Rainfall output from the RCM

cannot be used directly as input for hydrological simulation due to biases between the simulated vari-

ables for the current (control) climate and observed values The δ change approach was used to correct

Fig 2 Node-link network of the Upper Srepok River Basin


these biases by transferring the signals of climate change derived from a climate model simulation to

observed data (Hay et al 2000) In this study the means were calculated on a monthly basis for

each 30-year period of climate output The 12δ change factors for rainfall were used to perturb the

observed database and were calculated as follows

DP jeth THORN frac14Pscen jeth THORN

Pcontr jeth THORN(4)

PD i jeth THORN frac14 DP jeth THORN Pobs i jeth THORN i frac14 1≏ 31 j frac14 1≏ 12eth THORN (5)

For temperature absolute change was used for the δ change factors as follows

DT jeth THORN frac14 T scen(j) Tcontr(j) (6)

TD i jeth THORN frac14 Tobs(i j)thorn DP jeth THORN (7)

where ΔP and ΔT are the δ change factor of rainfall and temperature respectively Pcontr(j) and Tcontr(j)

are the rainfall and temperature respectively in month j averaged for the 30-year control period (1978ndash

2007) Pscen(j) and T scen(j) are the rainfall and temperature respectively in month j averaged for the 30-

year scenario period (2035ndash2064) centered on 2050 as simulated by the RCM PΔ(i j) and TΔ(i j) are

the rainfall and temperature respectively input into the hydrological model for the A2 and B2 scenario

runs Pobs(i j) and Tobs(i j) are the observed rainfall and temperature representing current climate

respectively and suffixes i and j stand for the ith day and the jth month

For reference evapotranspiration (ETref) the δ change factors were calculated in the same way as for

the rainfall factors ETref was calculated using the FAO Penman-Monteith equation (Allen et al 1998)

from RCM output The described reference evapotranspiration is the potential evapotranspiration for a

hypothetical grass reference crop with an assumed crop height of 012 m a fixed surface resistance of

70 sm and an albedo of 023 (Allen et al 1998) The reference evapotranspiration can be converted to

Fig 3 Reservoir characteristics curves (Srepok 3)


potential evapotranspiration by multiplying it with a surface coefficient (crop coefficient) However in

this study because the relative change in evapotranspiration between the current and future climate was

used it is not necessary to include the crop coefficient

Land use change prediction A simple approach a GIS-based logistic regression which has often been

used as a methodology in land usecover change research was used in this study (Ty et al 2011) After

the calibration and validation the land use change approach was executed for the year 2050 differen-

tiated by various land use demands and their spatial distribution compared to the year 1997 Future

land use demand was estimated assuming that a moderate level of development ie current levels of

agricultural production was maintained Demand was projected using the growth ratio of the historical

trend of land use (1993ndash1997) to the population trend (1990ndash2000) From the generated land use map

the parameters of the runoff process of each sub-basin associated with land usecover were recalculated

and then input into the calibrated hydrological model for future simulations Change in land usecover

directly affects surface runoff by changing the hydrological processes and thus water availability Land

usecover change also affects water demand for instance expansion of agricultural area increases water

withdrawal for irrigation demand

Population projection Many studies have predicted the future population of the MRB (Kristensen

2002 Hoanh et al 2003 Pech amp Sunada 2008) In this study the population in the Upper Srepok

Basin was quantified for the year 2000 using a gridded population of the world obtained from

CIESIN (2008) The estimate of the future population was based on the past population growth rate

(1990ndash2010) taking into account the different growth rates in each population category (rural and

urban) for each sub-basin

36 Water allocation

In Vietnam there are no specific rules for the allocation of water resources among sectors at basin

scale although the legal system has been established ndash the Law on Water Resources ndash LWR (Decree

No 81998QH10) (National Assembly 1998) The LWR only states generally that the regulation

and distribution of water resources is based on the river basin plan In addition the latest sub-law docu-

ment related to water resources management was released in 2008 and stipulated the tasks of a water

allocation plan in a river basin (GOV 2008) However at present many difficulties have been found

in putting such allocation plans into practice because the legislation lacks a general regulation for mana-

ging unfeasible overlapping and unjustified water sector regulations that conflict with other related

regulations (Loan 2010)

As mentioned earlier no specific rules of water supply priority have been established For calibration

and validation purposes (1997ndash2007) priority has thus been adopted based on the principle of lsquofirst

come first servedrsquo ndash also called lsquoriparian water right allocationrsquo ndash among the sub-basins Within a

sub-basin the highest priority is given to the domestic sector followed by industry irrigation hydro-

power and environment For future scenarios priority is given first to the domestic sector other

sectors are allocated based on lsquoprior water right allocationrsquo

By introducing the concept of lsquoprior water right allocationrsquo deficits have been redistributed among water

sectors and between the upstream and downstream sub-basins It was incorporated intoMIKE Basin by set-

ting the appropriate objective function and decision variables for optimization In this study the summation


of monthly relative demand deficits was minimized using an iterative non-linear algorithm in the software

The decision variable is the operational level of the five reservoirs constrained by flood control and top dead

levels The objective function is formulated as (DHI 2009)

OF frac14X

s

jfrac141

nj Yj Gj

pj(8)

Yj frac14X

n

ifrac141

X

m

kfrac141

WDik AWik

WDik

(9)

whereOF is the objective function s is the numberof simulationsYj is one of sMIKEsimulation resultsGj is

a goal value for that result νj is a weight assigned to each term (water sector) pj is power AWi is water allo-

cated for sector i (ifrac14 1simn) in month k andWDik is the water demand of sector i in month k (kfrac14 1simm) The

term ethWDik AWikTHORN=ethWDikTHORN is the relative water demand deficit (WDD) of sector i in month k

37 Simulation scenarios

Four scenarios were developed to examine the impacts of future development and climate change on

water balance at basin and sub-basin scales as presented in Table 3 The baseline scenario represents the

current hydrological data (1997ndash2007) Water demands for different sectors were estimated using exist-

ing data (population in 2000 land usecover in 1997 across the seven sub-basins) HPPs and EF were

not considered in the baseline scenario In order to adopt priorities as near to reality as possible the

lsquoriparian water right allocationrsquo was set for the baseline scenario

4 Results and discussion


Looking at the qualitative performance of flow the shape and character of the simulated flow fits quite

well with observations as can be seen in Figure 4 (which shows monthly flow at Cau 14 station) The

results show fairly good agreement between simulated and observed flow according to the two criteria

(NSE and PBIAS) for both the calibration period (1978ndash1992) and validation period (1993ndash2007)

Table 3 Simulation scenarios

Scenario Climate data POP LUC HPPs EF Priority

Baseline 1997ndash2007 2000 1997 ndash ndash Riparian water right allocation

Scenario 1 1997ndash2007 2050a 2050a HPPs EF Riparian water right allocation

Scenario 2 1997ndash2007 2050a 2050a HPPs EF Prior water right allocation

Scenario 3 ECHAM4 A2 2050a 2050a HPPs EF Prior water right allocation

Scenario 4 ECHAM4 B2 2050a 2050a HPPs EF Prior water right allocation

POP Population LUC Land usecover HPPs Hydropower plants included EF Environmental flow included a Projected


Although the peak flows are under- or over-estimated in the validation period this is not considered to be a

serious problem since the objective of this study is to assess the mean flows and low flows which are well

fitted to observed low flows It is clear that the calibrated HEC-HMS model simulates the runoff with

reasonable quality so it can be used to evaluate the effects of different scenarios on flow in the study area

42 Land usecover prediction and climate change

Land usecover prediction The results from future land usecover change show that the area under

cultivation is expected to increase from 285 in 1997 to 325 in 2050 (Ty et al 2011)

Fig 4 Monthly observed and simulated flow at Cau 14 station


Consequently water demand for irrigation will increase from 4163106 m3 in 1997 to 4726106 m3

in 2050 and will dominate the water use sectors

Climate change Since there is much uncertainty given that adaptive capacity to climate change might

alter emission scenarios it should be noted that the selected scenarios (A2 and B2) for this study are

only two plausible descriptions of how future emissions might develop and are not any more likely

than are any other scenarios (van Roosmalen et al 2007) However these two emission scenarios

are commonly used in climate change impact studies because they allow the investigation of the

entire range of potential system response to climate change As can be seen in Figure 5 the PRECIS

RCM over-estimated the monthly average rainfall of the simulated baseline compared to that of the

observed baseline except for October and November

Details of the monthly δ change factors of rainfall () and flow () at Ban Don station and ETo ()

and maximum temperature (degC) under scenarios A2 and B2 (2035ndash2064) compared to the control period

(1978ndash2007) are shown in Figures 6 and 7 respectively The projected irrigation water demand under

various scenarios is presented in Figure 8

Fig 5 Monthly average rainfall of the observed baseline compared with the simulated baseline in PRECIS

Fig 6 Monthly changes in rainfall () and flow () at Ban Don station in emission scenarios A2 and B2 (2035ndash2064)

compared to control period (1978ndash2007)


The results of downscaled rainfall reveal that future rainfall in the basin being studied would increase

by 67 and 10 in the wet season and decrease by 76 and 112 in the dry season under scenarios A2

and B2 respectively The maximum temperature was projected to increase by 15 and 13 degC in the wet

season and increase by 13 and 12 degC in the dry season under scenarios A2 and B2 respectively Con-

sequently potential evapotranspiration (ETo) will increase by 27 and 22 in the wet season and

increase by 36 and 34 in the dry season under scenarios A2 and B2 respectively Therefore

water demand for the irrigation sector is expected to increase especially in the dry season


The period 1997ndash2007 was selected for simulation using MIKE Basin on a monthly basis to examine

the variations in water balance at representative nodes The results of calibration and validation are pre-

sented in Figure 9 for stream flow at Ban Don station Overall the results show good agreement between

the observed and simulated flow according to two criteria (NSE and PBIAS) This model performance is

adequate for further assessing the impacts of future development and climate change on water balance

Fig 8 Projected irrigation water demand under various scenarios

Fig 7 Monthly changes in ETo () and Tmax (degC) in emission scenarios A2 and B2 (2035ndash2064) compared to control period

(1978ndash2007)


44 Water balance situation under various developed scenarios

Baseline scenario The purpose of the baseline scenario was to examine the current water supply situ-

ation showing demand balance in terms of the water deficit level as a percentage The results show that

the current annual basin irrigation water deficit is 194 (286 in the dry season) The deficits exceed

30 in February March and April Figure 10 shows the annual irrigation deficit at a sub-basin scale

under the four developed scenarios and shows that when the sub-basin scale is considered some

sub-basins experience water scarcity Krong Ana sub-basin for example was found to experience an

annual high water shortage of 295 (437 in the dry season) This can be explained by pointing

out that due to intensive agricultural development in this area during the last two decades agricultural

water demand has increased significantly In addition in the dry years the water deficit in this sub-basin

becomes more severe exceeding 50 in February March and April It should also be noted that

Fig 9 Monthly observed and simulated stream flows at Ban Don station

Fig 10 Sub-basin irrigation deficits () in the dry season under the four scenarios


because the domestic and industrial sectors are given the highest priority among the water sectors for

each sub-basin no water deficits are found in these sectors

Figures 11 and 12 present dry season EF deficit () at five representative locations and the annual

power surplusdeficit () of the five HPPs respectively under the four developed scenarios Figures 13

14 and 15 show monthly reservoir water levels at the Srepok 3 reservoir monthly basin irrigation

deficit () and EF deficit () respectively in the dry years under each of the four developed scenarios

Scenario 1 This scenario was developed to assess the impacts of future development on water balance

and power generation under lsquoriparian water right allocationrsquo The results show an increased basin irriga-

tion deficit of up to 224 on an annual basis and 311 in the dry season Most sub-basins in the studied

area will experience water shortage in the future (Figure 10) with the Krong Ana sub-basin facing the

most severe deficit exceeding 60 in the dry season Furthermore all sub-basins will face water deficits

in the dry years with an annual basin irrigation deficit of 383 the deficit exceeds 50 in March More

details on monthly basin irrigation deficits () are shown in Figure 14 As Figure 11 shows the impacts

of the lsquoriparian right water allocationrsquo on EF along the main stream will increase from upstream to down-

stream the deficit at downstream point (EF5) is expected to exceed 20 In addition the amount of power

generated from the five dams will be lower than their designed power levels except in the case of the

Srepok 4 power plant (Figure 12) This is because the Srepok 4 dam was designed as a re-regulating

Fig 11 Environmental flow (EF) deficits () in the dry season under the four scenarios

Fig 12 Annual power surplusdeficits () of the five HPPs under the four scenarios


Fig 14 Monthly basin irrigation deficits () in a dry year under the four scenarios

Fig 13 Monthly reservoir water levels (Srepok 3) in a dry year under the four scenarios

Fig 15 Monthly basin EF deficits () in a dry year under the four scenarios


reservoir with a smaller designed annual energy potential when compared to the others Consequently its

power production is increased by 247 compared to the calculated annual power potential based on aver-

age historical data (1977ndash2002) (SWECO 2006)

Scenario 2 The purpose of this scenario was to examine the lsquoprior water right allocationrsquo impacts

compared to the lsquoriparian water right allocationrsquo in scenario 1 In general the irrigation and EF water

deficits decrease while power deficits at some HPPs increase as the new priority is introduced This

is because according to the lsquoprior water right allocationrsquo the deficits have been redistributed among

the water sectors and between the upstream and downstream sub-basins by changing the operating

rules of the five HPPs However the effect of the introduced policy on reducing irrigation deficit is

not significant and EFs at five locations still cannot be met in the dry season and in most months in

the dry years (Figure 15) Total power deficit in this scenario is found to be higher than that in scenario

1 (194 and 228 in scenarios 1 and 2 respectively) In scenario 1 the water levels in all reservoirs are

drawn down to the top of the inactive zone (the top dead level) in the dry season and in most months in

the dry years However in scenario 2 the reservoir water levels are slightly increased as can be seen in

Figure 13 which shows the monthly water level at the Srepok 3 reservoir

Scenarios 3 and 4 These scenarios were developed to evaluate the impacts of future basin develop-

ment climate change and water supply policy on water balance power generation and reservoir storage

The results indicate that the increased rainfall from climate change (emission scenarios A2 and B2) at

basin scale will lead to increased stream flow At Ban Don station for example the annual stream flow

averaged over a 30-year period (2035ndash2064) is found to increase 75 and 25 compared to the current

period (1978ndash2007) in scenarios A2 and B2 respectively (Figure 6) However increased temperature in

the future also leads to increased potential evapotranspiration and increased irrigation water demand

Consequently irrigation deficits in both scenarios 3 and 4 are still high with annual irrigation deficits

of 267 and 279 respectively Due to the temporal and spatial variations of rainfall and thus stream

flow water deficits are found to increase in both scenarios 3 and 4 at both the basin and sub-basin

scales compared to those in scenario 2 (Figure 10) The water levels in all reservoirs in these two scen-

arios are also found to increase compared to those in scenario 1 especially in the dry season and the dry

years (Figure 13) When the water supply policy is introduced to water allocation in order to minimize

the total relative water deficit the deficits have been shared among all water sectors and between the

upstream and downstream sub-basins However the effects are very modest

An analysis of the four scenarios indicates that the deficits of irrigation and EF water demand

decrease while the power deficit increases when the lsquoprior water right allocationrsquo is taken into account

Giving priority to only a single sector might lead to a severe water supply situation for the other water

use sectors In this case trade-offs among water use sectors should be considered especially between

off-stream uses and in-stream uses

Due to a lack of data when estimating irrigation water demand it is assumed that all future agricultural

areas will be irrigated However we are aware that in reality especially in developing countries such as

Vietnam all agricultural areas cannot be irrigated sufficiently for crop requirements Moreover because

land usecover changes are expected to be the single biggest driver of greater water demand in the next 50

years our assumption may lead to overestimated water deficits in the future This limitation should be

researched further In addition in order to alleviate water deficits in the future land use development policies

need to be adjusted leading to changes in crop varieties planting dates and crop patterns and thus to


irrigation schedules The results also suggest that better demand management strategies such as water con-

servation should be encouraged as well as the introduction of new and efficient technologies such as drip

irrigation and reuse

5 Conclusions

Based on the results the major findings of this study can be summarized as follows

bull Future rainfall in the studied basin will increase in the wet season and decrease in the dry season

according to the results downscaled from RCM output The maximum temperatures in both the

wet and dry seasons will also increase

bull The current irrigation water deficit at the basin scale is found to be relatively high (194 annually

and 286 in the dry season) When a lower spatial and temporal scale is considered most of the sub-

basins in the study area experience water shortages especially in the dry years

bull All water use sectors would be affected to some extent under the impacts of future development and

water supply policies (scenarios 1 and 2) When the lsquoprior water right allocationrsquo is introduced water

deficits are redistributed among water sectors and sub-basins leading to reduced irrigation and EF

deficits Water levels in all reservoirs will increase especially in the dry season and in dry years

bull When the impact of climate change is taken into account in scenarios 3 and 4 the annual water deficits

will decrease compared to those in scenario 2 due to the increase in future annual rainfall However

the temporal and spatial variations of rainfall and thus of stream flow make future water deficits more

severe in some sub-basins in the dry season and in dry years

The reliability of the results would be improved if the operating rule curves of the five cascade reser-

voirs could be obtained The impacts of climate change strongly depend on the quality of the GCM

output and the downscaling approach Therefore in order to reduce some of the uncertainty more exper-

iments of GCM output should be undertaken in further research In addition to minimize total relative

water deficit the objective function of maximizing net economic value should also be considered in any

future study Similar exercises can be applied to other basins especially the cross-boundary basins

where conflicts over water exploitation often occur

Acknowledgements

The authors express their sincere gratitude for this study to the Global COE (Center of Excellence)

Program of the University of Yamanashi under the financial support of the Ministry of Education Cul-

ture Sport Science and Technology (MEXT) in Japan

References

Allen R G Pereira L S Raes D amp Smith M (1998) Crop Evapotranspiration Guidelines for Computing Crop Water

Requirements Irrigation and Drainage Paper 56 UN-FAO Rome Italy


Babel M S Gupta A D amp Nayaka D K (2005) Model for optimal allocation of water to competing demands Water

Resources Management 19 693ndash712

Chinvanno S (2004) Information for Sustainable Development in Light of Climate Change in Mekong River Basin Southeast

Asia START Regional Center Bangkok Thailand

Center for International Earth Science Information Network (CIESIN) (2008) Gridded population of the world (online)

CIESIN Columbia University Available at httpsedacciesincolumbiaedugpwglobaljsp (assessed October 2010)

Danish Hydraulic Institute (DHI) (2009) MIKE Basin Manual DHI Water Environment Health Hoslashrsholm Denmark

Dyson M Bergkamp G amp Scanlon J (2003) Flow the Essentials of Environmental Flows International Union for

Conservation of Nature (IUCN) Gland (Switzerland) and Cambridge (UK)

Government of Vietnam (GOV) (2008) Decree No 1202008ND-CP of December 01 2008 on River Basin Management

Government of Vietnam Hanoi

Hay L E Wilby R L amp Leavesley G H (2000) A comparison of delta change and downscaled GCM scenarios for three

mountainous basins in the United States Journal of the American Water Resources Association 36(2) 387ndash397

Hoanh C T Guttman H Droogers P amp Aerts J (2003) Water Climate Food and Environment in the Mekong Basin in

Southeast Asia International Water Management Institute (IWMI) Mekong River Commission Secretariat (MRCS) and

Institute of Environmental Studies (IVM) Colombo Sri Lanka

Hook J Novak S amp Johnston R (2003) Social Atlas of the Lower Mekong Basin Mekong River Commission Phnom Penh

IWRP (2001) Water Resources Planning for Dak Lak Province Institute of Water Resources Planning (IWRP) Vietnam In

Vietnamese

Kiem A S Ishidaira H Hapuarachchi H P Zho M C Hirabayashi Y amp Takeuchi K (2008) Future hydroclimatology

of the Mekong River basin simulated using the high resolution Japan Meteorological Agency (JMA) AGCM Hydrological

Processes 22 1382ndash1394

Korsgaard L Jensen R A Joslashnch-Clausen T Rosbjerg D amp Schou J S (2008) A service and value based approach to

estimating environmental flows International Journal of River Basin Management 6(3) 257ndash266

Krause P Boyle D P amp Base F (2005) Comparison of different efficiency criteria for hydrological model assessment

Advances in Geosciences 5 89ndash97

Kristensen J (2002) Food security and development in the Lower Mekong River basin a challenge for the Mekong River

Commission In Defining an Agenda for Poverty Reduction Proceedings of the First Asia and Pacific Forum on Poverty

(Volume 1) Edmonds C amp Medina S (eds) The Asian Development Bank Manila

Liu D Chen X amp Lou Z (2010) A model for the optimal allocation of water resources in a saltwater intrusion area a case

study in Pearl River Delta in China Water Resources Management 24 63ndash81

Loan N T P (2010) Legal framework of the water sector in Vietnam ZEF working paper No 52 Center for Development

Research University of Bonn Bonn

McCartney M P amp Arranz R (2007) Evaluation of historic current and future water demand in the Olifants River

Catchment South Africa Research Report 118 International Water Management Institute (IWMI) Colombo Sri Lanka

McKee T B Doesken N J amp Kleist J (1993) The relationship of drought frequency and duration to time scales In Pro-

ceedings of the 8th Conference on Applied Climatology Anaheim CA American Meteorological Society Boston MA

USA 179ndash184

Mohammed M Mac Kirby M amp Qureshi E (2007) Integrated hydrologic-economic modeling for analyzing water

acquisition strategies in the Murray River Basin Water Resources Management 93(1) 123ndash135

Moriasi D N Arnold J G Van Liew M W Bingner R L Harmel R D amp Veith T L (2007) Model evaluation

guidelines for systematic quantification of accuracy in watershed simulations Trans ASABE 50(3) 885ndash900

Mekong River Commission (MRC) (1995) 1995 Mekong Agreement and Procedural Rules MRC Phnom Penh Cambodia

Mekong River Commission (MRC) (2004) Modeled Observations on Development Scenarios in the Lower Mekong Basin

MRC Phnom Penh Cambodia

Muumlller D (2003) Land-use Change in the Central Highlands of Vietnam Dissertation Georg-August University Gottingen

National Assembly (1998) Law on Water Resources No 81998QH10 National Assembly of the Socialist Republic of

Vietnam Hanoi

Oki T amp Kanae S (2006) Global hydrologic cycle and world water resources Science 313(5790) 1068ndash1072

Pech S amp Sunada K (2008) Population growth and natural resources pressures in the Mekong River basin A Journal of the

Human Environment 37(3) 219ndash224


Richter B D Baumgartner J V Braun D P amp Powell J (1998) A spatial assessment of hydrologic alteration within a river

network Regulated Rivers Research and Management 14 329ndash340

Richter B D Baumgartner J V Wigington R amp Braun D P (1997) How much water does a river need Freshwater

Biology 37 231ndash249

Ringler C Huy N V amp Siwa M (2006) Water allocation policy modeling for the Dong Nai River Basin an in tegrated

perspective Journal of the American Water Resources Association 42(6) 1465ndash1482

Ringler C Joachim V B amp Rosegrant M W (2004) Water policy analysis for the Mekong River BasinWater International

29(1) 30ndash42

SWECO-Groslashner in association with Norwegian Institute for Water Research ENVIORO-DEV amp ENS Consult (SWECO)

(2006) Electricity of Vietnam Environmental Impact Assessment on the Cambodian Side of the Srepok River due to

Hydropower Development in Vietnam Final Report presented at the Stakeholder Meeting on the EIA Report on the

Cambodian Part of the Srepok River due to Hydropower Development in Vietnam Phnom Penh Cambodia

Ty T V Sunada K amp Ichikawa Y (2011) A spatial impact assessment of human-induced intervention on hydrological

regimes a case study in the upper Srepok River basin Central Highlands of Vietnam International Journal of River

Basin Management 9(2) 103ndash116

Ty T V Babel M S Sunada K Oishi S amp Kawasaki A (2009) Utilization of a GIS-based water infrastructure inventory

for water resources assessment at local level a case study in mountainous area of Vietnam Hydrological Research Letters 3

27ndash31

Ty T V Sunada K Ichikawa Y amp Oishi S (2010) Evaluation of the state of water resources using Modified Water Poverty

Index a case study in the Srepok River basin VietnamndashCambodia International Journal of River Basin Management

8(3ndash4) 305ndash317

US Army Corps of Engineers (USACE) (2008) Hydrologic Modeling System ndash HEC-HMS Technical Reference Manual

USACE Washington DC

van Roosmalen L Christensen B S B amp Sonnenborg T O (2007) Regional differences in climate change inpacts on

groundwater and stream discharge in Denmark Vadosezone Journal 6(3) 554ndash571

Vietnam National Mekong Committee (VNMC) (2003) Analysis of Sub-Area 7V ndash Basin Development Plan VNMC Hanoi

Voumlroumlsmarty C J Green P Salisbury J amp Lammers R B (2000) Global water resources vulnerability from climate change

and population growth Science 289(5477) 284ndash288

Received 16 June 2011 accepted in revised form 2 January 2012 Available online 1 March 2012


Water resources management under future development and

climate change impacts in the Upper Srepok River Basin Central

Highlands of Vietnam

Tran Van Tya Kengo Sunadab and Yutaka Ichikawab

aCorresponding author College of Technology Cantho University Campus 2 32 Street Ninh Kieu District Cantho City

Vietnam E-mail tvtyctueduvnbInterdisciplinary Graduate School of Medicine and Engineering University of Yamanashi 4-3-11 Takeda Kofu Yamanashi

400-8511 Japan

Abstract

This study aimed to assess the impacts of future development and climate change on the water balance in the

Upper Srepok River Basin in the Central Highlands of Vietnam A hydrological model was calibrated and validated

to model the rainfall-runoff process Estimates of the water demand of different water sectors were based on the func-

tional relationships between water and productive uses The estimates were input into a calibrated basin management

model for simulation The climate projections were downscaled to the studied basin Future land use was predicted

using a geographic information system (GIS)-based logistic regression approach The water balance was examined

under various developed scenarios The results show a relatively high current annual irrigation water deficit at a basin

scale some sub-basins suffer fromwater shortage especially during dry seasons and dry years All water use sectors

will be affected to some extent under the impacts of future development and water supply policies When the new

water policy is introduced the deficits of irrigation and environmental flow are reduced while the power deficit is

increased Considering climate change impact the annual water deficits are reduced However the temporal and

spatial variations of rainfall make future water deficits more severe during the dry seasons and dry years

Keywords Allocation Deficits Hydropower plant Srepok River Supply priority Water balance

1 Introduction

Rapid population growth agricultural expansion and industrial development have led to increased

water demands in turn leading to increased competition and conflicts among water sectors In addition

degraded water quality high temporal and spatial variation of water resources and old and unsustain-

able water management practices have recently hindered accessibility to supplies of fresh water

Water Policy 14 (2012) 725ndash745

doi 102166wp2012095

copy IWA Publishing 2012



















fore needed




























21 Study area
















demand












Figure 1

22 Data











TVTyet

alWater

Policy

14(2012)725ndash745

728

3 Methodology





















1997

MRC








Dam project

Full supply

level (m-MSL)

Minimum

operating level

(m-MSL)

Storage capacity

(106 m3)

Regulation

capacity (106 m3)

Installed

capacity

(MW)

Annual energy

potential

(GWh)

Duc Xuyen (DX) 5600 5510 10880 4315 70 255

Buon Tua Srah (BTS) 4875 4675 7870 4830 86 358

Buon Koup (BK) 4120 4090 632 147 280 1459

Srepok 3 (SP3) 2720 2670 2230 750 220 1002

Srepok 4 (SP4) 2060 2025 270 115 65 299










NSE frac14 1

Pnifrac141 Yobs

i Y simi

2

Pnifrac141 Yobs

i Ymeaneth THORN2

(1)

PBIAS frac14

Pnifrac141 Y sim

i Yobsi

100Pn


(2)

where Yiobs and Yi



































































scenarios
























































36 Water allocation























OF frac14X

s

jfrac141

nj Yj Gj

pj(8)

Yj frac14X

n

ifrac141

X

m

kfrac141

WDik AWik

WDik

(9)





































































(1978ndash2007)






















































































5 Conclusions























Acknowledgements




References






















Vietnamese



















USA 179ndash184










Vietnam Hanoi












29(1) 30ndash42










27ndash31





USACE Washington DC


























fore needed




























21 Study area
















demand












Figure 1

22 Data











TVTyet

alWater

Policy

14(2012)725ndash745

728

3 Methodology





















1997

MRC








Dam project

Full supply

level (m-MSL)

Minimum

operating level

(m-MSL)

Storage capacity

(106 m3)

Regulation

capacity (106 m3)

Installed

capacity

(MW)

Annual energy

potential

(GWh)

Duc Xuyen (DX) 5600 5510 10880 4315 70 255

Buon Tua Srah (BTS) 4875 4675 7870 4830 86 358

Buon Koup (BK) 4120 4090 632 147 280 1459

Srepok 3 (SP3) 2720 2670 2230 750 220 1002

Srepok 4 (SP4) 2060 2025 270 115 65 299










NSE frac14 1

Pnifrac141 Yobs

i Y simi

2

Pnifrac141 Yobs

i Ymeaneth THORN2

(1)

PBIAS frac14

Pnifrac141 Y sim

i Yobsi

100Pn


(2)

where Yiobs and Yi



































































scenarios
























































36 Water allocation























OF frac14X

s

jfrac141

nj Yj Gj

pj(8)

Yj frac14X

n

ifrac141

X

m

kfrac141

WDik AWik

WDik

(9)





































































(1978ndash2007)






















































































5 Conclusions























Acknowledgements




References






















Vietnamese



















USA 179ndash184










Vietnam Hanoi












29(1) 30ndash42










27ndash31





USACE Washington DC









21 Study area
















demand












Figure 1

22 Data











TVTyet

alWater

Policy

14(2012)725ndash745

728

3 Methodology





















1997

MRC








Dam project

Full supply

level (m-MSL)

Minimum

operating level

(m-MSL)

Storage capacity

(106 m3)

Regulation

capacity (106 m3)

Installed

capacity

(MW)

Annual energy

potential

(GWh)

Duc Xuyen (DX) 5600 5510 10880 4315 70 255

Buon Tua Srah (BTS) 4875 4675 7870 4830 86 358

Buon Koup (BK) 4120 4090 632 147 280 1459

Srepok 3 (SP3) 2720 2670 2230 750 220 1002

Srepok 4 (SP4) 2060 2025 270 115 65 299










NSE frac14 1

Pnifrac141 Yobs

i Y simi

2

Pnifrac141 Yobs

i Ymeaneth THORN2

(1)

PBIAS frac14

Pnifrac141 Y sim

i Yobsi

100Pn


(2)

where Yiobs and Yi



































































scenarios
























































36 Water allocation























OF frac14X

s

jfrac141

nj Yj Gj

pj(8)

Yj frac14X

n

ifrac141

X

m

kfrac141

WDik AWik

WDik

(9)





































































(1978ndash2007)






















































































5 Conclusions























Acknowledgements




References






















Vietnamese



















USA 179ndash184










Vietnam Hanoi












29(1) 30ndash42










27ndash31





USACE Washington DC









TVTyet

alWater

Policy

14(2012)725ndash745

728

3 Methodology





















1997

MRC








Dam project

Full supply

level (m-MSL)

Minimum

operating level

(m-MSL)

Storage capacity

(106 m3)

Regulation

capacity (106 m3)

Installed

capacity

(MW)

Annual energy

potential

(GWh)

Duc Xuyen (DX) 5600 5510 10880 4315 70 255

Buon Tua Srah (BTS) 4875 4675 7870 4830 86 358

Buon Koup (BK) 4120 4090 632 147 280 1459

Srepok 3 (SP3) 2720 2670 2230 750 220 1002

Srepok 4 (SP4) 2060 2025 270 115 65 299










NSE frac14 1

Pnifrac141 Yobs

i Y simi

2

Pnifrac141 Yobs

i Ymeaneth THORN2

(1)

PBIAS frac14

Pnifrac141 Y sim

i Yobsi

100Pn


(2)

where Yiobs and Yi



































































scenarios
























































36 Water allocation























OF frac14X

s

jfrac141

nj Yj Gj

pj(8)

Yj frac14X

n

ifrac141

X

m

kfrac141

WDik AWik

WDik

(9)





































































(1978ndash2007)






















































































5 Conclusions























Acknowledgements




References






















Vietnamese



















USA 179ndash184










Vietnam Hanoi












29(1) 30ndash42










27ndash31





USACE Washington DC








3 Methodology





















1997

MRC








Dam project

Full supply

level (m-MSL)

Minimum

operating level

(m-MSL)

Storage capacity

(106 m3)

Regulation

capacity (106 m3)

Installed

capacity

(MW)

Annual energy

potential

(GWh)

Duc Xuyen (DX) 5600 5510 10880 4315 70 255

Buon Tua Srah (BTS) 4875 4675 7870 4830 86 358

Buon Koup (BK) 4120 4090 632 147 280 1459

Srepok 3 (SP3) 2720 2670 2230 750 220 1002

Srepok 4 (SP4) 2060 2025 270 115 65 299










NSE frac14 1

Pnifrac141 Yobs

i Y simi

2

Pnifrac141 Yobs

i Ymeaneth THORN2

(1)

PBIAS frac14

Pnifrac141 Y sim

i Yobsi

100Pn


(2)

where Yiobs and Yi



































































scenarios
























































36 Water allocation























OF frac14X

s

jfrac141

nj Yj Gj

pj(8)

Yj frac14X

n

ifrac141

X

m

kfrac141

WDik AWik

WDik

(9)





































































(1978ndash2007)






















































































5 Conclusions























Acknowledgements




References






















Vietnamese



















USA 179ndash184










Vietnam Hanoi












29(1) 30ndash42










27ndash31





USACE Washington DC
















NSE frac14 1

Pnifrac141 Yobs

i Y simi

2

Pnifrac141 Yobs

i Ymeaneth THORN2

(1)

PBIAS frac14

Pnifrac141 Y sim

i Yobsi

100Pn


(2)

where Yiobs and Yi



































































scenarios
























































36 Water allocation























OF frac14X

s

jfrac141

nj Yj Gj

pj(8)

Yj frac14X

n

ifrac141

X

m

kfrac141

WDik AWik

WDik

(9)





































































(1978ndash2007)






















































































5 Conclusions























Acknowledgements




References






















Vietnamese



















USA 179ndash184










Vietnam Hanoi












29(1) 30ndash42










27ndash31





USACE Washington DC



















































scenarios
























































36 Water allocation























OF frac14X

s

jfrac141

nj Yj Gj

pj(8)

Yj frac14X

n

ifrac141

X

m

kfrac141

WDik AWik

WDik

(9)





































































(1978ndash2007)






















































































5 Conclusions























Acknowledgements




References






















Vietnamese



















USA 179ndash184










Vietnam Hanoi












29(1) 30ndash42










27ndash31





USACE Washington DC









scenarios
























































36 Water allocation























OF frac14X

s

jfrac141

nj Yj Gj

pj(8)

Yj frac14X

n

ifrac141

X

m

kfrac141

WDik AWik

WDik

(9)





































































(1978ndash2007)






















































































5 Conclusions























Acknowledgements




References






















Vietnamese



















USA 179ndash184










Vietnam Hanoi












29(1) 30ndash42










27ndash31





USACE Washington DC





















































36 Water allocation























OF frac14X

s

jfrac141

nj Yj Gj

pj(8)

Yj frac14X

n

ifrac141

X

m

kfrac141

WDik AWik

WDik

(9)





































































(1978ndash2007)






















































































5 Conclusions























Acknowledgements




References






















Vietnamese



















USA 179ndash184










Vietnam Hanoi












29(1) 30ndash42










27ndash31





USACE Washington DC





























36 Water allocation























OF frac14X

s

jfrac141

nj Yj Gj

pj(8)

Yj frac14X

n

ifrac141

X

m

kfrac141

WDik AWik

WDik

(9)





































































(1978ndash2007)






















































































5 Conclusions























Acknowledgements




References






















Vietnamese



















USA 179ndash184










Vietnam Hanoi












29(1) 30ndash42










27ndash31





USACE Washington DC











OF frac14X

s

jfrac141

nj Yj Gj

pj(8)

Yj frac14X

n

ifrac141

X

m

kfrac141

WDik AWik

WDik

(9)





































































(1978ndash2007)






















































































5 Conclusions























Acknowledgements




References






















Vietnamese



















USA 179ndash184










Vietnam Hanoi












29(1) 30ndash42










27ndash31





USACE Washington DC


















































(1978ndash2007)






















































































5 Conclusions























Acknowledgements




References






















Vietnamese



















USA 179ndash184










Vietnam Hanoi












29(1) 30ndash42










27ndash31





USACE Washington DC









































(1978ndash2007)






















































































5 Conclusions























Acknowledgements




References






















Vietnamese



















USA 179ndash184










Vietnam Hanoi












29(1) 30ndash42










27ndash31





USACE Washington DC























(1978ndash2007)






















































































5 Conclusions























Acknowledgements




References






















Vietnamese



















USA 179ndash184










Vietnam Hanoi












29(1) 30ndash42










27ndash31





USACE Washington DC




























































































5 Conclusions























Acknowledgements




References






















Vietnamese



















USA 179ndash184










Vietnam Hanoi












29(1) 30ndash42










27ndash31





USACE Washington DC














































































5 Conclusions























Acknowledgements




References






















Vietnamese



















USA 179ndash184










Vietnam Hanoi












29(1) 30ndash42










27ndash31





USACE Washington DC


























































5 Conclusions























Acknowledgements




References






















Vietnamese



















USA 179ndash184










Vietnam Hanoi












29(1) 30ndash42










27ndash31





USACE Washington DC






















































5 Conclusions























Acknowledgements




References






















Vietnamese



















USA 179ndash184










Vietnam Hanoi












29(1) 30ndash42










27ndash31





USACE Washington DC











5 Conclusions























Acknowledgements




References






















Vietnamese



















USA 179ndash184










Vietnam Hanoi












29(1) 30ndash42










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USACE Washington DC








Date post:	18-Nov-2023
Category:	Documents
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Water resources management under future development and climate change impacts in the Upper Srepok...

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