‘Wicked problem’ in managing water balance in the Vu Gia – Thu Bon river basin

Early November 2017, storm no. 12 (Typhoon Damrey) with level 12 winds, level 15 gusts and heavy rain made a landfall on the central coast of Vietnam. Fearing that the increasing water levels would risk reservoir safety, many hydropower reservoirs opened their floodgates and released huge amounts of water for several days continuously, causing extensive flooding downstream.

At the time, Da Nang City was at the height of preparation to host the Asian and the Pacific Economic Corporation (APEC) Summit from November 6-11, 2017, and Hoi An City of Quang Nam Province was also selected as the venue for the visit of the spouses of APEC leaders, Ministers and other representative agencies on November 7, 2017. Though escaping the brunt of the devastating typhoon, both municipalities still suffered tremendous damages[1]. Floodwater released from the reservoirs of Sông Tranh 2, Đăk Mi 4, Sông Bung 4 hydropower plants[2] caused the Thu Bon and Vu Gia rivers to swell, raising floods in many low-lying areas of Da Nang and Quang Nam, with Hoa Vang district of Da Nang city and Dai Loc and Dien Ban districts of Quang Nam province being the hardest hit.

As reported by local people in Hoa Khuong commune, Hoa Vang district, the flood caused by Typhoon Damrey in 2017 was an extreme event, with some flood posts in the commune recording flood levels higher than those in the historical flood in 1999, partly due to changes in the local landscape as a result of construction and renovation of belt roads and national highways in the area (such as ĐT406, ĐT08, and National Highway 14B).

Occurring right before the APEC week, the severe impacts of storms and flooding on all aspects of the socio-economic life in Quang Nam and Da Nang was put in the spotlight. However, not only in 2017 with typhoon Damrey but year after year, flooding and also droughts are becoming more and more severe, affecting the lives, livelihoods, safety and health of local people. Moreover, during the recent years, flooding and droughts in this region have become less and less mere ‘natural’ events, but more and more driven by the impacts of human activities, particularly the construction and management of the cascade of hydropower dams, water resource management infrastructure, and other infrastructure in the Vu Gia – Thu Bon river basin. An inter-provincial river system, originating from the mountainous areas of Quang Nam and reaching the sea via estuaries in both Quang Nam and Da Nang, the management of water balance in this river basin in the context of the existing infrastructure system from upstream to downstream areas poses a tricky multi-variable problem for both municipalities, especially when rains and storms are becoming more unpredictable because of climate change.

The fifth Shared – Learning – Dialogue event of the Inter-provincial Coordination Board of Quang Nam and Da Nang for integrated management of the Vu Gia – Thu Bon River basin—organized on May 25, 2018 and presided by Mr. Ho Ky Minh, the Vice Chair Da Nang People’s Committee—focused on regulating the flow division rate from the mother river Vu Gia to the Quang Hue Branch (which flows into the Thu Bon River). According to Mr. Hoang Thanh Hoa (Deputy Director of Da Nang Department of Agriculture and Rural Development), the historical flood in 1999 had cut off the flow into the Quang Hue river (by forming a new Quang Hue shortcut channel bringing water from Vu Gia River straight into Thu Bồn River, causing increased flooding and erosion downstream of this river, and gradually draining up the original Quang Hue River in the dry season, considerably reducing the amount of water in the Vu Gia). In addition, since 2010 when Đăk My 4 hydropower plant was constructed upstream, nearly half of the Vu Gia River flow has been diverted into Thu Bon River for electricity production, causing serious water shortages and salinization downstream of the Vu Gia (areas including Dai Loc and Dien Ban districts of Quang Nam Province, and especially Da Nang City).

IMG_9821

Dr. Tran Van Giai Phong, expert from the Institute for Social and Environmental Transition (ISET) speaking at the workshop. This is the fifth in a series of workshops of the inter-provincial Coordination Board of Quang Nam and Da Nang, under the framework of a project on Integrated Management of the Vu Gia – Thu Bon River Basin, implemented by ISET and supported by the Global Resilience Partnership (GRP). Photo: Thanh Ngo, ISET 2018.

Dai Hong commune, Dai Loc district of Quang Nam Province, and Hoa Khuong commune, Hoa Vang district of Da Nang City are areas directly affected by water shortages in the dry season due to hydropower and water management activities upstream. Remarkably, an impact assessment by CARE International in Vietnam[3] noted that, in the dry season of 2016, the distance between the bank of the Vu Gia River and the water edge at the time of their survey in Dai Hong commune was recorded at 200 m, and the river depth was 1.85 m lower than before hydropower development took place.

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Measuring retreat of the water edge and change of water level at pier 14, Dai Hong commune, Dai Loc district, Quang Nam. Photo: CVN 2017

The release of water from hydropower reservoirs in the rainy season also caused river bank erosion, rising floods, and sand deposition in agricultural fields, causing huge losses of land, properties, and agriculture production in both Dai Hong and Hoa Khuong. People in La Chau commune, Hoa Khuong commune shared that the 2017 flood affected 90% of the commune’s area, and though not causing any lose of life, and happening after local farmers had finished harvesting their rice, the flood still resulted in great loses among local households as it entered their houses and damaged the newly harvested rice, killed the livestock, and completely spoilt the mushroom they were growing.

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Local people from Hoa Khuong commune, Da Nang City sharing about the impacts of natural disasters and hydropower plant operation on local life and livelihoods. Photo: Thanh Ngo, ISET 2018.

To address the issue of water division described above, from 2002, the Ministry of Agriculture and Rural Development started to construct/plan the construction of infrastructure such as soft embankments, diverson dams, check dams, etc., and filling of the newly formed Quang Hue channel, in order to bring the division rate to Quang Hue river bank to the level before 1999 (i.e. reducing it to about 20%). However, the construction of some structures was challenged by flooding. Many SLD5 participants also questioned the effectiveness, feasibility of these structures, and any ramifications they might have on the hydrological and environmental regime in the area and the region.

Representing Quang Nam Province, Mrs. Le Thi Tuyet Hanh, the Deputy Director of Quang Nam Department of Natural resources and Environment, emphasized that comprehensive assessments, covering various dimensions, and using sufficiently long data series of the entire river basin are needed to draw detailed picture of the current hydrological and flow conditions, to understand expected impacts of proposed measures, and to come up with measures that balance the benefits for both municipalities.

‘Balanced measures’ that can tackle the existing water management problem are what people in both municipalities would like to see, as these measures will have direct implications on their lives and livelihoods. To adequately address this problem requires comprehensive, multi-dimensional information, including both scientific data and calculations and practical information from affected communities, as well as a transparent information sharing mechanism, and good will of stakeholders in Quang Nam and Da Nang in their collaboration.

Tho Nguyen, ISET-Vietnam

[1] By November 16, 2017, a total of 36 people had been killed and 1 person was missing in Quang Nam because of Typhoon Damrey. Source: https://news.zing.vn/quang-nam-thiet-hai-1500-ty-do-mua-lu-va-sat-lo-post796570.html

[2] According to the Steering Committee for Disaster Prevention and Control, Search and Rescue of Quang Nam province, floodwater release from the reservoirs was at the highest rate at 21:00 of November 4, 2017. Specifically, Sông Bung 4 reservoir water was released into the Vu Gia river at 4,270 m3/s (the rate was only 1,658 m3/s at 12:00 of the same day), Sông Tranh 2 reservoir water was released into the Thu Bồn river at 2,198 m3/s (the rate was only 305 m3/s at 12:00 of the same day), and Đăk Mi 4 reservoir at 3.349 m3/s (1.416 m3/s). Source: http://plo.vn/thoi-su/hoi-an-va-vung-trung-da-nang-ngap-chim-trong-lu-737631.html

[3] Report on Assessment of Vulnerability to floods and droughts of communities in the Vu Gia – Thu Bon river basin in Quang Nam and Da Nang, CARE International in Vietnam, December 2017.

 

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