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 C3S_422_Lot1_SMHI – D5.1.1B | Copernicus Climate Change Service 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. C3S_422_Lot1_SMHI – D5.1.1B | Copernicus Climate Change Service 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 C3S_422_Lot1_SMHI – D5.1.1B | Copernicus Climate Change Service 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. C3S_422_Lot1_SMHI – D5.1.1B | 4 Copernicus Climate Change Service 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