D422Lot1.SMHI.5.1.1B: Detailed workflows of each case ... · HYPE model setup: By using all...
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Copernicus Climate Change Service
D422Lot1.SMHI.5.1.1B:
Detailed workflows of each case-study
on how to use the CDS for CII
production and climate adaptation
Full Technical Report:
Climate Change Impacts to Water
Safety in the Greater Mekong region
Bui Du Duong, PhD
National Center for Water Resources Planning and Investigation (NAWAPI),
Ministry of Natural Resources and Environment (MONRE) of Vietnam
REF.: C3S_422_Lot1_SMHI D5.1.1B
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Summary
Srepok is a transboundary river basin and it is a major tributary in the Greater
Mekong River basin. The region is extremely vulnerable to adverse effects of
changing climate that result in droughts. Furthermore, considering the poor living
condition of local communities and the difficulties in reaching common
agreements in water management among national and international
stakeholders, assessing climate change impacts on the region through a drought
model is necessary for a better management of the river’s water.
Interactions with stakeholders through a survey show that many have a similar
perspective with the same views and requirements on water resources and
climate change information. They also reflect the proportion of users who are
working in water resources related fields. Most of them show concerns about
raising awareness or getting informed on climate indicators, especially with water
pollution, seawater intrusion, drought, etc.
The impacts of droughts in local, national and regional scale are severe and poor
local management can increase the outcomes, especially considering the future
scenario in a climate change prospective. The effect of using the climate service
covers an important role in technology and global open data in order to reduce
burden on local related infrastructures (e.g. reservoirs, gauged stations) while
facilitating access to information. Meanwhile, it allows decision makers to
understand and predict the likelihood of hazards, vulnerability of the system and
adopt the required measures.
Increasing access to open data sources including daily precipitation,
evapotranspiration, temperature, topography Digital elevation model (DEM), C3S
future scenarios, and multi-basin modelling tools helps the study bring useful
Essential Climate Variables (ECVs) and Climate Impact Indicators (CIIs) towards
drought risk reduction in the Greater Mekong region. The study results also show
that there are increasing demands on water resource and climate change
information from not only academic researchers and governmental decision
makers, but also from private interests. This study, together with the NAWAPI
interactive web-site, can help bridge the gap between institutes who provide
climate impact data on one side, and water managers and policy makers on the
other side, as well as providing users such as citizens, university students and
entrepreneurs a space to discover information for their purposes.
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Contents
1- Case study description ........................................................................................................ 4
1.1 Issue to be addressed ......................................................................................................... 4
1.2 Decision support to client .................................................................................................. 4
1.3 Temporal and spatial scale ............................................................................................... 4
1.4 Knowledge brokering ........................................................................................................... 4
2- Potential adaptation measures ........................................................................................ 5
2.1 Lessons learnt ........................................................................................................................ 5
2.2 Importance and relevance of adaptation .................................................................... 5
2.3 Pros and cons or cost-benefit analysis of climate adaptation ............................. 5
2.4 Policy aspects ......................................................................................................................... 5
3- Contact ...................................................................................................................................... 6
3.1 Purveyors ................................................................................................................................. 6
3.2 Clients/users ........................................................................................................................... 6
4- Data production and results ............................................................................................. 6
4.1 Step 1: Data collection and model setup .................................................................... 7
4.2 Step 2: Model calibration and validation ..................................................................... 9
4.3 Step 3: Model simulation and analysis ....................................................................... 10
4.4 Step 4: Climate Impact Indicators related to drought risks .............................. 11
5- Conclusion of full technical report ................................................................................ 21
References ......................................................................................................................................... 23
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1- Case study description
1.1 Issue to be addressed
Disaster events pose increasing threats to sustainable development in the
Greater Mekong region, including Srepok river basin. Nevertheless, lack of
consistent and coherent data does not allow policy makers to set adaptation plan
to climate change. Therefore, we aim to provide projected climate and
hydrological data and information, focusing on drought risks in a showcased
Srepok river basin to ensure its sustainable development and disaster resilience.
1.2 Decision support to client
The analysis is expected to provide information on how the frequency of
droughts has happened and increase/decrease in the future. The clients are local
functional departments, especially Mekong River Commission (MRC) and
Vietnamese Disaster Management Center (DMC), who are decision-makers. They
could base their decisions on these results to apply appropriate measures and
prepare adaptation, and mitigation plans in the near future. Accordingly, it is
expected that MRC and DMC could avoid huge economic losses and minimize
impacts on local people.
1.3 Temporal and spatial scale
The Srepok River basin with 86 sub-basins is explored. To facilitate both near
future and far future assessments, we provide the indicators for different time
ranges: reference period (1980-2015) and the expected future changes including
early century (2016-2040), mid-century (2041-2070) and end-century (2071-
2099).
1.4 Knowledge brokering
NAWAPI, as a governmental agency, has close operational relation with all local
functional departments, especially with MRC and Vietnamese Disaster
Management Center (DMC). NAWAPI and MRC have a long history of
collaboration in the management of the Greater Mekong River basin, where
NAWAPI operates in the national boundaries, while MRC is in charge of the entire
basin from an international prospective.
NAWAPI often collaborates with DMC providing forecasting information.
Furthermore, MONRE (Ministry of Natural Resources and Environment) delegates
both NAWAPI and the DMC in order to handle several national issues, supporting
their cooperation.
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2- Potential adaptation measures
2.1 Lessons learnt
The cooperation among the major institutions involved in the region has proven
itself a key tool in the management of water allocation and river basin
sustainable development. On one hand, a rapid information sharing between
NAWAPI and DMC plays an essential role in case of droughts, reducing the
dramatic outcomes of disaster events. On the other hand, a constant
communication between NAWAPI and MRC allows improving the cooperation
between Vietnam and Cambodia. Therefore, collecting data should be a priority
in the institution’s agenda in order to make more informed decisions.
2.2 Importance and relevance of adaptation
The impacts of droughts in local, national and regional scale are severe and a
bad management of the site increase the outcomes, especially considering the
future scenario in a climate change prospective. The effect of using the climate
service covers an important role in technology and global open data in order to
reduce burden on local infrastructures (reservoirs, gauged stations) while
facilitate access to information. Meanwhile, it allows decision makers to
understand and predict the likelihood of hazards, vulnerability of the system and
adopt the required measures.
2.3 Pros and cons or cost-benefit analysis of climate adaptation
Cost benefit analysis of climate adaptation is not available yet, but from previous
experiences, costs would be numerous if the adaptation measures are not
placed. Indeed, a weak preparation in prevention and protection from droughts
due to climate change would result in significant damages to infrastructure,
environment and human lives. A better understanding of these phenomena
ensures a more efficient management and a reduction in costs and risks.
2.4 Policy aspects
The Law on Water Resources is available at
http://www.wepa-db.net/policies/law/vietnam/lwr.htm.
The Law on natural disaster prevention and control is available at
https://www.preventionweb.net/english/policies/v.php?id=42335&cid=190.
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3- Contact
3.1 Purveyors
Duong Du BUI, PhD, Director of Water Resources Monitoring Department,
National Center for Water Resources Planning and Investigation (NAWAPI),
Ministry of Natural Resources and Environment (MONRE) of Vietnam.
3.2 Clients/users
Mekong River Commission, National Disaster Management Authority, Center for
Water Res Forecasting and Warning and Local functional departments (natural
environment; agriculture and rural development)
4- Data production and results
Bias adjusted Essential Climate Variables (air temperature and precipitation on
daily time scale) for the historical period were used. This was combined with
monthly change factors from GCMs for future periods and for both RCPs 4.5 and
8.5 developed within the C3S_422_Lot1_SMHI contract, available in the CDS.
Data available from national databases (topography, soil type, river discharge,
evapotranspiration, population density, water demand, infrastructures and
management rule, drought and flood indicators) were collected. Calibration,
validation and accuracy assessment of the hydrological model were performed,
using the data from national databases. Hydrological simulations were performed
using as forcing the bias adjusted ECV to calculate CII for future periods. The
following analysis was performed: comparisons of ECVs and model output
(surface runoff and outflow; soil moisture deficit and potential
evapotranspiration) for historical period. Then CIIs related to drought risk were
calculated and drought risk was assessed based on the result analysis for
historical and future periods. Finally the results were communicated to
representatives of the national hydrology departments of member countries of
the Mekong River basin, especially Vietnam, Lao, and Cambodia.
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4.1 Step 1: Data collection and model setup
Data collection: To setup the hydrological model for modeling, a diversity of
data was collected Here we used the HYPE hydrological model. Data collection
included:
- Hydro-meteorological data: Precipitation, air temperature and river
discharge.
- Geographical data: Digital Elevation model, sub-basin area, soil type, land
use, hydrographical network
- Lake information: Depths, regulation rules, rating curve, water level
HYPE model setup: By using all collected data, the HYPE model was set up step
by step.
- Geographical and hydraulic network:
A 30×30 m DEM (Figure 1) which derived from open data of the U.S. Geological
Survey (USGS) was used. The HYPE model was set up for the whole of Srepok
(∼18,500 km2), including parts of Gia Lai, Dak Lak, Dak Nong and Lam Dong
with water discharging to Cambodia, with a total number of 86 sub-basins. Sub-
basin areas ranged between <30 km2 and >400 km2 (the latter including the
large lakes) with an average of 218 km2. (median = 170 km2).
The hydraulic network in the basin is dense (Figure 1) and there are lakes as
results of hydropower production, storing water. Lake depths were taken from
the No. 1201/QĐ - TTg dated 23 May 2014 on the issuance of operational
procedures associated reservoirs of Srepok river basin QĐ-Nr.12 (2014). Since
depth information is only available for few lakes, regression equations were
constructed and used for 5 lakes when estimating lake depth, with surface area
as the most important variable.
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Figure 1: DEM and drainage networks of the Srepok basin
- Land Use/Land Cover (LULC) and Soils
Srepok is mainly covered by forests (Figure 2), although there is a mountain
range in the southwest with plateaus. Forestry land is concentrated in the
southern part of Srepok, where most of the inhabitants live and the climate is
milder. This area has a population of 3 million inhabitants. Due to the region’s
forest, lakes are steady and the dominant soil type is basalt. The annual average
temperature is 23°C, with little variation between seasons, latitudes and
altitudes.
Figure 2: Summary of dominant LULC of Srepok
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- The Hydro-metrological data
The hydrological information of daily river discharge (Q) was obtained and
inputted to the HYPE from four on-site stream stations among five stations
located in the basin (Table 4). The location of the used station is marked (red
triangles) in the figure 1. The collection data time is from 2000 – 2009. Daily
rainfall data were recorded by 13 terrestrial rain gauges (Blue circles - figure 1) ,
and the daily maximum, minimum and averaged temperature of 9 Global
Forecast System (GFD) stations (blue square – figure 1) stations are used for the
inputs with the same period of 10 years.
The annual average temperature of the region is 23oC, with only slight variations
between seasons, latitudes and altitudes. The annual mean precipitation varies
from 1600 to 2700 mm. The dynamic forcing was obtained from daily
precipitation and temperature data sets for each sub-basin.
4.2 Step 2: Model calibration and validation
By using the collected data to fill up all HYPE model’s input requirement, the
calibration and validation were implemented in two periods: 2000-2005 and
2006-2009. Based on the comparison between simulated and observation value,
the HYPE parameters which are best fit with this Srepok area can be found. In
this process, we used the 13 ground rain gauges for calibration the discharge at
four stations of Giang Son, Cau 14, Ban Don and Duc Xuyen for the 2000-2005
periods.
In order to evaluate the calibration and to fix the calibrated values, we’ve
estimated the goodness of fit between simulated and observed Q based on the
values of RMSE, NSE, R2 and KGE. From Figure 3, it can be seen that Duc Xuyen
station was the weakest point of the model where all the coefficients showed the
low accuracy such as NSE, R2 and KGE under 0.5. In contrast, Ban Don and
Giang Son presented the most reliable parts of the model with highest values of
NSE, R2 and KGE. Although the accuracy assessment showed the model accuracy
was not homogeneous entire the watershed, the overall errors demonstrated the
model performance was acceptable.
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Figure 3. Daily and monthly HYPE discharge compared to in-situ measured data
in the model validation for the 2006-2009 periods at Giang Son, Cau 14, Ban
Don and Duc Xuyen stations
4.3 Step 3: Model simulation and analysis
The GCM data we have used in this study are provided within the
C3S_422_Lot1_SMHI contract and available in the Climate Data Store. The
calculations are based on daily time series of four Essential Climate Variables
(ECVs), namely mean, minimum and maximum near-surface air temperature,
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and precipitation. The ECVs are provided as downscaled and bias adjusted GCM
data using HydroGFD2.0 (Hydrological Global Forcing Data) as reference data.
HydroGFD is a merged data set of historical precipitation and temperature from
meteorological reanalysis and global observations (Berg et al., 2018). The spatial
resolution of the ECVs is 0.5 degree (about 50 km) on a regular global grid.
We defined a reference period and future periods for anomaly analysis for river
discharge as an implication for droughts or floods under climate change. To
estimate future climate conditions, we used the corresponding monthly change
values of the ECVs to modify the daily HydroGFD dataset used as input to HYPE.
Change values obtained for specific future time periods were thus used to create
representative datasets for HYPE modelling of these representative future
periods.
Emission Scenario
Scenarios for the evolution of greenhouse gas emissions are provided by
Representative Concentration Pathways (RCPs). The climate-modelling
community has developed four RCPs. In this study, we used two scenarios: low-
emission scenario RCP4.5 and high-emission scenario RCP8.5 to characterize
future climate change conditions. Ensemble monthly change factors from global
downscaled climate projections of precipitation, average, minimum and
maximum temperature from 18 GCM models ('ACCESS1-0', ‘ACCESS1-3’, ‘IPSL-
CM5B-LR’, HadGEM2-ES’, ‘HadGEM2-CC’, ‘BCC-CSM1.1(m)’, ‘EC-EARTH’ 'bcc-
csm1-1', 'BNU-ESM', 'CNRM-CM5', 'GFDL-CM3', 'GFDL-ESM2G', 'GFDL-ESM2M',
'inm-cm4', 'IPSL-CM5A-LR', 'IPSL-CM5A-MR', 'MPI-ESM-LR', 'MPI-ESM-MR',
'NorESM1-M') for different future periods.
Historical and future time periods
Any climate scenario must adopt a reference baseline period from which to
calculate changes in climate. The reference period usually represents present-
day climate. The projections are calculated relative to the baseline. In this study
three future periods have been chosen, in order to visualize the evolution of the
changes in the water availability over several decades. The following reference
period (baseline) and future periods were considered:
Reference period (historical): 1981-2015
Future periods: Upcoming: 2016-2040; Mid Century:2041-2070; Late Century:
2071-2099
4.4 Step 4: Climate Impact Indicators related to drought risks
The term "drought" has different meanings depending on how a water deficiency
affects them. Droughts have been classified into different types such as
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meteorological drought (lack of precipitation) and agricultural drought (lack of
soil moisture), but this also depends on how land use is classified. In another
aspect, urban areas need streamflow or groundwater for domestic water supply
plants, which can cause a deficit in soil moisture, leading to drought. Drought
impact can therefore be a function of drought risks and land use.
For the analyses done here, we define drought as a function of streamflow deficit
and adopt a threshold for streamflow deficit that we use as a general indicator
for drought. For the results presented below, drought is defined as those
occurrences where the mean streamflow deficit exceeds -50 m3s-1.
a. Historical simulations
This step provides an assessment over precipitation, soil moisture, streamflow
and groundwater anomalies over the baseline period of 1981-2015. This helps
decision makers to adopt the required measures in order to reduce the drought
risk in the area (Du et al., 2018).
Figure 4 illustrates the variation of the HydroGFD precipitation over the Srepok
river basin from 2001 to 2015. Values for the dry season months (December –
April) are shown in red. In the dry season of 2001, although the precipitation is
bigger than in 2004, the deficit in soil moisture, streamflow and groundwater is
less for almost all sub-basins (Figures 4 and 5). This can be explained by the
small rain for previous wet season. In 2010, it witnesses a small amount of
precipitation deficit, whereas soil moisture and streamflow saw an increase for a
few basins and less deficit in others
Figure 4: Change of the precipitation and soil moisture during dry season of Srepok river basin
from 2001 to 2010. The rectangles highlight three periods that were analysed in more detail.
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Figure 5 Change of the streamflow and groundwater during dry season of Srepok river basin from
2001 to 2010. The rectangles highlight three periods that were analysed in more detail.
Details from the three specific years of 2001, 2010 and 2004 are presented in
more detail in figures 6 – 11 to show how drought characteristics can be
analysed. The drought impact maps in figures 7, 9 and 11 show varying levels of
drought during the historic period. Drought is defined here as those occurrences
where the mean streamflow deficit is -50 m3s-1 or more. According to this
definition, there was no drought 2001, there was drought in parts of the Srepok
basin during 2010 and drought covered most of the basin during 2004.
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Figure 6: Maps of Precipitation Deficit and Soil Moisture Deficit in Srepok River Basin in 2001
Figure 7: Maps of Streamflow Deficit and Drought Impact in Srepok River Basin in 2001
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Figure 8: Maps of Streamflow Deficit and Soil Moisture Deficit in Srepok River Basin in 2010
Figure 9: Maps of Streamflow Deficit and Drought Impact in Srepok River Basin in 2010
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Figure 10: Maps of Streamflow Deficit and Soil Moisture Deficit in Srepok River Basin in 2004
Figure 11: Maps of Streamflow Deficit and Drought Impact in Srepok River Basin in 2004.
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b. Future simulations under climate change
This section presents projected hydrological anomalies as they were derived from
the hydrological model. As mentioned in section 4.3, we used the ensemble
mean of monthly change values from the 18 GCM climate projections in
combination with the HydroGFD time series as forcing. Precipitation and mean
temperature for two emission scenarios RCP 4.5 and RCP 8.5 were used. The
anomalies are calculated as relative change (in percent) with respect to the
baseline period for three future periods: early-century 2016-2040, mid-century
2041-2070 and late-century 2071-2099.
Drought impact is a function of drought risks and land use. Since land use is unknown in future, we only show streamflow anomalies. We assume that
negative anomalies are an indication of future drought risk and positive values indicate increasing flood risk in the respective future periods.
For the early-century (2016-2040), drought is generally shown to be more frequent as most of the Srepok basin shows negative streamflow anomalies
(Figure 12). The eastern areas in particular indicate trends toward more extreme drought with more pronounced negative anomalies.
Figure 12: Streamflow anomalies compared to historical reference period in RCP 4.5 scenario: (a)
Early-Century: 2016-2040; (b) Mid-Century period: 2041-2070; (c) Late-Century: 2071-2099.
For the mid-century period of 2041-2070 compared to the historical reference
period in the RCP 4.5 scenario, drought also tends to be more frequent than in
past. However, the severity is lower than shown for the early century and the
southwest area shows little change.
The late-century period of 2071-2099 shows more severe drought risk conditions
than either of the two earlier periods. As with the early century results, the
eastern areas indicate trends toward more extreme drought..
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Regarding streamflow anomalies for the RCP 8.5 scenario, the early-century
period shows the greatest drought risk, also more pronounced in eastern areas
of the basin, but the most severe is in the north (figure 13).
Figure 13: Streamflow anomalies compared to historical reference period in RCP 8.5 scenario. (d).
Early-Century: 2016-2040; (e) Mid-Century period: 2041-2070; (f) Late-Century: 2071-2099.
In the mid-century period the climate tends to be relatively normal compared
with past conditions. Some drought is indicated in the northern area whereas the
southwestern area indicates the potential for more flooding.
For the late-century period, conditions appear quite similar to the mid-century
period, with the exception that the southwestern areas show even more
tendency for wetter conditions.
Comparing the RCP 4.5 scenario to RCP 8.5, the climate change impacts on
streamflow appear more severe for RCP 4.5. In particular, RCP 4.5 indicates a
greater occurrence of increased drought risk. This was not expected and
warrants additional analysis. The fact that ensemble mean changes from the 18
GCMs were used may be a contributing factor. It would be worthwhile to
investigate in more detail the range of differences in monthly change factors
between the different GCM projection results. The results shown here may simply
be an indication that the precipitation changes from the GCM projections react
quite differently to increasing temperatures for this region.
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4.5. Step 5: Stakeholder communication and dissemination
The Stakeholder communication and dissemination took place through various
capacity building workshop and meetings organized throughout the project
(Figures 14 and 15). It saw the participation of the representatives of the
national hydrology departments of member countries of the Mekong River basin,
especially Vietnam, Lao, and Cambodia. The main objective of these workshops
was to share and get feedback from clients on the new hydrological products of
water information developed as part of the project implementation. Aspects
discussed during this workshop include:
Presentation of the project objectives and identification of sectoral
information needs by clients.
Exchanges of the case study results of hydrological modeling and climate
change impacts assessment with regional peers and clients;
Presentation of the interactive atlas and story map.
Figure 14: Capacity building workshop at NAWAPI on HYPE modeling
Figure 15: Presentation session of the
interactive atlas and client consultation on sectoral information needs
A part of case study is designed to collect information related to the demand of
information on climate change and water resources and other related indicators
in Vietnam which will be supported for policy decision of government as well as
for specific purposes from individuals to private sectors such as researchers,
entrepreneurs, etc. (Figure 16). Respondents focus on data in each level are
distinguished and among these national scale data is the most concern (Figure
17). As recommended information that could provide, reports are the main
materials that respondents want to have, followed by mapping, models (Figure
18).
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Figure 16: Purpose of using climate and hydrological data
Figure 17: Demographic information of respondents
Figure 18: Survey results on users request on water resources and climate
change information in Viet Nam
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Respondents represent the similar perspective group who has the same views
and demand on water resource and climate change information. They also reflect
the proportion of users who are work in and our water resources related fields.
Most of them concern about raising awareness or get informed the Climate
indicators, especially with water pollution, seawater intrusion, drought, etc. The
study results also indicate that not only academic researchers, governmental
decision makers have strong demand on water resource and climate change
information but also private requirements are very huge (Figure 18).
With the views of contributing to proof-of-concept and identifying target users
accompanied with specific demand for a Vietnam service website, the study helps
bring climate data useful in water-management decisions. It is a NAWAPI
interactive web-site (Figure 19) aims to bridge the gap between institutes who
provide climate-impact data on one side, and water managers and policy makers
on the other side as well as providing normal users as citizens, university
students, entrepreneurs a space to discover information for their private
purposes.
Figure 19: Development of WebGIS portal for sharing data and information from
the case study
5- Conclusion of full technical report The goal of this case study is using a global climate service to support drought
risk assessment in Srepok catchment, a part of Mekong basin. After calibration
and validation of HYPE model for periods 2000-2005 and 2006-2009, essential
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climate variables (in this case air temperature and precipitation) for historical
and future periods, available in the C3S Climate Data Store were collected, and
used as input to the impact models for simulating historical drought risk through
a number of deficit maps (precipitation, soil moisture, groundwater, streamflow).
The assessment of future drought was also made using ensemble global daily
downscaled climate projections for two emission scenarios RCP 4.5 and RCP 8.5
for three upcoming periods: (a) 2016-2040; (b) mid-century period: 2041-2070;
(c) end-century: 2071-2099.
This suggests that the C3S climate service is potentially applicable for general
local decision support related to drought assessment. The case study also
demonstrates that global data provided by C3S can be a cost-effective methods
supporting quick decision making in basin scale, particularly in un- or poorly
gauged basin. Open access to global climate data and model projections through
the CDS is helpful to improve resilience and adaptation to climate change.
This study support formulation of local policies that manage drought and allocate
water fairly among water user groups and local residents. These decisions have
large impacts on the local life and business activities. The methods and added
values of C3S for the Srepok River basin can be useful for similar studies in other
regions, including the Greater Mekong.
The cooperation among the major institutions involved in the region has proven
itself a key tool in the management of water allocation and river basin
sustainable development. A rapid information sharing between local, national
(NAWAPI, DMC) and regional (MRC) plays an essential role in case of droughts,
reducing the dramatic outcomes of disaster events. Therefore, producing data
and making them accessible should be a priority in order to make more informed
decisions.
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