Key findings from Vietnam NCAP Project

Submitted by Sukaina Bharwani | published 25th Mar 2011 | last updated 30th Mar 2011

Past trends and future climate projections

The project started with a number of studies in order to better understand the historic trends in climate conditions in the study area. In addition, downscaled climate scenarios were developed for the decades up to 2100. Some of the key results of these studies are presented below. Please follow the links for results of assessments of the climate change impacts on water resources in the Huong River Basin, or the impact of climate change on different sectors in Thua Thien Hue Province.

Historic climate trends

In order to understand the historic trends of the climate conditions in Thua Thien Hue, the study analyzed the variability, climatologically average, moving average and trend line of some key climate parameters, including rainfall and temperature. The rainfall was analyzed in 4 different periods of the year: January to March; April to May; June to July; and August to December. Temperature data was taken from January, April, July and October, typical months for the hot season, the rainy season and the two interchanges. The data was collected from three meteorological stations in Hue Province: Hue, A Luoi and Nam Dong stations. The temperature of all typical months and the mean annual temperature at A Luoi and Nam Dong stations revealed an obvious increasing trend during the studied period (1974 to 2004). Annual rainfall at A Luoi and Nam Dong stations was very high in absolute value (about 3,500mm on average and up to 6,000mm in the peak years), and have significantly increased in the period 1974 to 2004 approximately 800mm and 600mm respectively.

The largest increase in rainfall occurred during the rainy season (August to December), months that were the major contributors to the total annual rainfall. June to July's rainfall at both stations has a noticeably decreasing trend. This indicates a high risk of prolonged drought during the important growth period of major crops as well as a risk of water shortages affecting power generation, especially at a time that the demand for energy is high during the hottest period of the year (Tran Mai Kien et al. 2006). Figures 4 and 5 depict the trends in annual temperature and rainfall changes in the period 1974 to 2004 for different meteorological stations.

Future climate change in Thua Thien Hue

The development of climate scenario data is based on the 'Guidelines on the Use of Scenario Data for Climate Impact and Adaptation Assessment' published by the IPCC (Carter et al. 1999). Global and regional (southeast Asia) scenarios were downscaled into the project area by using MAGICC/SCENGEN software (Wigley, 1995).

Six different emission scenarios (2 High-, 2 Medium- and 2 Low-emission) for Thua Thien Hue were selected. The results of the downscaling represent the changes of rainfall and temperature in the province over the period 2010 to 2100 in comparison to the 1990 baseline for the different emission scenarios. Figure 6 shows an example of the downscaling results of temperature and rainfall for the Huong River Basin for the B2 scenario.

According to the model outcomes, the annual mean temperature is expected to increase by 2.5 to 2.6°C by the end of the 21st century. The increase is more pronounced in January and February (2.6 to 2.7°C) than in the hotter months of June and July (2.4 to 2.5°C)

In the case of the high emission scenario (A1FI), the temperature would increase the most: by 3.9°C on average, and in the March to May period a change of up to 4.7°C may be experienced. Such a high temperature increase in and may bring very serious consequences for socioeconomic and ecosystem wellbeing, especially for human health, but combined with a projected increase in extreme events (droughts, floods, storms, etc.) it may lead to catastrophe in Thua Thien Hue Province.

When it comes to annual rainfall, the model results show an estimated increase of about 7% on average. While the dry season of February to May is showing a decrease of 10 to 15%, rainfall is expected to increase significantly during the rainy season (September to November) by 10 to 24%. Rainfall in August - the first month of the rainy season - is expected to increase much less (2.5 to 3%).

In the ‘worst case' high emission scenario (A1FI), rainfall in the rainy season would increase by 25% whereas the first dry months (December to February) show a decrease of 23%. The most important aspect revealed is that rainfall in the dry season (December to February and March to May) is likely to decrease, which may cause very severe droughts. If this were to occur, severe drought would be added to the phenomena of flood and typhoon events adversely impacting the socioeconomic wellbeing and ecosystem functioning in Thua Thien Hue Province.

In general, the results show that the very high rainfall patterns which are concentrated during certain wet months would increase the already high flood risk of the study area, with associated adverse consequences, unless comprehensive and systematic adaptation measures are implemented. Conversely, the dry season is projected to be longer and more severe, which would increase the risk of drought. The longer, more severe lack of rainfall during this period may adversely impact the energy generation capacity of a number of hydropower plants (currently under construction or soon to be built) on the Huong and other rivers of Thua Thien Hue Province. The decreased dry season rainfall may also threaten the municipal water supply of Hue City and agricultural irrigation requirements and cause fresh water shortages for downstream users and ecological systems. The salinization of surface water, groundwater and soil in the coastal areas will be likely to have negative impacts on agriculture, aquaculture and eco-tourism, as well as the unique wetland ecosystems of the Tam Giang-Cau Hai lagoons. It is evident that both the flood and the drought risks and impacts from projected future climate change are very high for Thua Thien Hue Province.

The sea level rise scenarios of Thua Thien Hue have been estimated by taking average values from Hon Dau Station, representing the coastal zone of north Vietnam; and Vung Tau Station, representing the coastal zone in the south of Vietnam. The projected sea level rise in Thua Thien Hue would reach approximately 50 to 60cm by 2100, much less than in the northern and southern parts of Vietnam and equally, less than the global projected average. However, uncertainties remain with this relatively modest prognosis, which could be skewed by a number of factors, such as geo-morphological change in the level of the sea floor. Another obstacle to accurate estimation is the discrepancy between the data measurement standards of two periods at the central marine hydromet-stations: before and after the re-unification of South and North Vietnam. Further studies need to be done to obtain more accurate projections of sea level rise in the area (Hoang Duc Cuong et al., 2006).

Working Towards an Adaptation Policy for Thua Thien Hue Province

The Integrated Coastal Zone Management (ICZM) strategy for Thua Thien Hue Province reflects the willingness and commitment of the provincial authorities and people to carefully balance interests with respect to the protection and the use of coastal resources and environment for the sustainable development of the coastal zone (TTHPPC, 2004).

The ICZM strategy document was promulgated at the national level in 2003. The strategy of the ICZM agrees with the strategy of adaptation to climate change in the approach, methods of implementation and objectives of environment protection for sustainable development. As such, the document could serve as an appropriate basis for implementing climate change policies and measures at the provincial level.

Many species would be placed at high risk

At this moment, however, the process of preparing the ICZM strategy has not yet considered the changes in climate as well as their impacts on natural conditions of the study area. Therefore, the NCAP project, in close consultation with relevant provincial stakeholders, took the initiative to integrate some climate change adaptation proposals into important sections of the ICZM strategy. The following proposals have been made for inclusion into the ICZM Strategy:

  • Raising management capacity for the ICZM strategy in areas likely to be most affected by climate change. Raising awareness and knowledge among community members, local government authorities and policy makers on future climate-related disasters and adaptive measures for the ICZM to respond to climate change.
  • Re-development of the coastal zone management framework protocol and action plan in the administrative system of Thua Thien Hue focused towards sustainable development, shared benefits and adaptation to climate change.
  • Re-recognition of the areas, fields and communities most vulnerable to climate change impacts and identification of effective measures to maintain sustainable development in these specific zones.
  • Re-assessment of the carrying capacity of the coastal zone and lagoons and potential adaptive capacity of relevant sectors (agriculture, aquaculture, tourism and industrial development) in the coastal zone.