Observed river discharge changes due to hydropower operations in the Upper Mekong Basin

Räsänen, Timo A.; Someth, Paradis; Lauri, Hannu; Koponen, Jorma; Sarkkula, Juha; Kummu, Matti

doi:10.1016/j.jhydrol.2016.12.023

Cited by 182 publications

(108 citation statements)

References 36 publications

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“…For the first time, an integrated modelling framework was applied to a data-scarce tropical mountainous mesoscale catchment to assess hydrological drought risk by using naturalized and human-impacted reconstructed streamflow and two observed discharge time series. Comparing observed, simulated, reconstructed, and naturalized discharge time series is a widely used method to assess and quantify anthropogenic impacts on streamflow Deitch et al, 2013;López-Moreno et al, 2014;Chang et al, 2015;Räsänen et al, 2017). Our softly linked model set-up shows good results in terms of statistical efficiency performances and provides reliable simulations for both reconstructed and naturalized streamflow.…”

Section: Modelling Discharge Release From Operating Hydropower Reservmentioning

confidence: 84%

Quantifying human impacts on hydrological drought using a combined modelling approach in a tropical river basin in central Vietnam

Firoz¹,

Nauditt²,

Fink

et al. 2018

Hydrol. Earth Syst. Sci.

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Abstract. Hydrological droughts are one of the most damaging disasters in terms of economic loss in central Vietnam and other regions of South-east Asia, severely affecting agricultural production and drinking water supply. Their increasing frequency and severity can be attributed to extended dry spells and increasing water abstractions for e.g. irrigation and hydropower development to meet the demand of dynamic socioeconomic development. Based on hydro-climatic data for the period from 1980 to 2013 and reservoir operation data, the impacts of recent hydropower development and other alterations of the hydrological network on downstream streamflow and drought risk were assessed for a mesoscale basin of steep topography in central Vietnam, the Vu Gia Thu Bon (VGTB) River basin. The Just Another Modelling System (JAMS)/J2000 was calibrated for the VGTB River basin to simulate reservoir inflow and the naturalized discharge time series for the downstream gauging stations. The HEC-ResSim reservoir operation model simulated reservoir outflow from eight major hydropower stations as well as the reconstructed streamflow for the main river branches Vu Gia and Thu Bon. Drought duration, severity, and frequency were analysed for different timescales for the naturalized and reconstructed streamflow by applying the daily varying threshold method.Efficiency statistics for both models show good results. A strong impact of reservoir operation on downstream discharge at the daily, monthly, seasonal, and annual scales was detected for four discharge stations relevant for downstream water allocation. We found a stronger hydrological drought risk for the Vu Gia river supplying water to the city of Da Nang and large irrigation systems especially in the dry season. We conclude that the calibrated model set-up provides a valuable tool to quantify the different origins of drought to support cross-sectorial water management and planning in a suitable way to be transferred to similar river basins.

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Section: Modelling Discharge Release From Operating Hydropower Reservmentioning

confidence: 84%

Quantifying human impacts on hydrological drought using a combined modelling approach in a tropical river basin in central Vietnam

Firoz¹,

Nauditt²,

Fink

et al. 2018

Hydrol. Earth Syst. Sci.

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“…SWAT has been found to simulate the region's hydrology with high accuracy, and is capable of estimating high flow periods within 1% and low flow periods within 3% [123]. The VMOD distributed hydrological model has also been used to: examine the likely effects of climate change and reservoir operation on Mekong streamflow over the next 20-30 years [8], estimate the sediment load at different gauging stations along the mainstem Mekong [42], and examine streamflow changes due to the construction of dams from 1960 to 2004 [124]. The Shuttleworth-Wallace (S-W) model was used by Zhou et al [125] to estimate potential ET (PET) over the Mekong; using the meteorological data from the Climate Research Unit (CRU) TS 2.0 and monthly composite Normalized Difference Vegetation Index (NDVI) from the National Oceanic and Atmospheric Administration (NOAA)-Advanced Very High Resolution Radiometer (AVHRR), they found that the PET averaged over the Mekong ranged from 300 to 2040 mm (average 1354 mm) from 1981 to 2000, with significant seasonal variations that can be linked to changes in leaf area index (LAI).…”

Section: Hydrological Modelingmentioning

confidence: 99%

A Review of the Integrated Effects of Changing Climate, Land Use, and Dams on Mekong River Hydrology

Pokhrel

Burbano

Roush

et al. 2018

Water

186

112

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Abstract:The ongoing and proposed construction of large-scale hydropower dams in the Mekong river basin is a subject of intense debate and growing international concern due to the unprecedented and potentially irreversible impacts these dams are likely to have on the hydrological, agricultural, and ecological systems across the basin. Studies have shown that some of the dams built in the tributaries and the main stem of the upper Mekong have already caused basin-wide impacts by altering the magnitude and seasonality of flows, blocking sediment transport, affecting fisheries and livelihoods of downstream inhabitants, and changing the flood pulse to the Tonle Sap Lake. There are hundreds of additional dams planned for the near future that would result in further changes, potentially causing permanent damage to the highly productive agricultural systems and fisheries, as well as the riverine and floodplain ecosystems. Several studies have examined the potential impacts of existing and planned dams but the integrated effects of the dams when combined with the adverse hydrologic consequences of climate change remain largely unknown. Here, we provide a detailed review of the existing literature on the changes in climate, land use, and dam construction and the resulting impacts on hydrological, agricultural, and ecological systems across the Mekong. The review provides a basis to better understand the effects of climate change and accelerating human water management activities on the coupled hydrological-agricultural-ecological systems, and identifies existing challenges to study the region's Water, Energy, and Food (WEF) nexus with emphasis on the influence of future dams and projected climate change. In the last section, we synthesize the results and highlight the urgent need to develop integrated models to holistically study the coupled natural-human systems across the basin that account for the impacts of climate change and water infrastructure development. This review provides a framework for future research in the Mekong, including studies that integrate hydrological, agricultural, and ecological modeling systems.

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“…However, Li et al [44] found that damming in the upstream area led to a declining trend in the annual streamflow at the upstream Chiang Saen gauging station, whereas no clear effect was observed at the downstream Stung Treng station. Räsänen et al [45] assessed discharge changes using observed discharge data and a distributed hydrological model, and found that the hydropower operations in the Upper Mekong Basin can only partially explain observed river discharge changes in Cambodia (Kratie), suggesting that river discharges are also affected by dam operations in the Lower Mekong Basin.…”

Section: Introductionmentioning

confidence: 99%

Changes in the Lake Area of Tonle Sap: Possible Linkage to Runoff Alterations in the Lancang River?

Luo

et al. 2018

Remote Sensing

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Tonle Sap Lake is the largest freshwater lake in Southeast Asia. Water development infrastructures are increasingly being constructed in the Lancang-Mekong River Basin, which is a major concern considering its potential impact on Tonle Sap Lake. This study aimed to investigate variations in the area of the lake and discuss their possible linkage to runoff alterations in the Lancang River (Upper Mekong) by comparing runoff at the Yunjinghong hydrological station before and after significant changes in runoff trends that occurred in 2008. First, four commonly used water body extraction methods (MNDWI, NDWI, NDVI, and EVI) were compared and MNDWI was found to provide a better and more stable performance. Based on MOD09A1 data, MNDWI was used to extract the water area of the lake from 2000 to 2014, and characteristics of variations in the area before and after 2008 were analyzed. The water area of Tonle Sap Lake displayed an overall decreasing trend, and specifically decreased by 8.3% during the flood season and by 1.5% on average during the dry season after 2008. Seasonal variations in the water area of Tonle Sap Lake were dominantly influenced by runoff from the Mekong River. Compared with the period 2000-2007, runoff at Yunjinghong station were increased during the dry season (20.74%) and decreased during the flood season (34.25%) between 2008 and 2014. Changes in upstream runoff contributed to runoff at the Stung Treng station in the lower Mekong River by 6.17% (dry season) and −2.41% (flood season). Evidently, the operation of dams in the Lancang River does not primarily account for the area decrease of Tonle Sap Lake during the flood season. In contrast, runoff increase during the dry season mitigates the area decrease of Tonle Sap Lake to a certain extent.

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Observed river discharge changes due to hydropower operations in the Upper Mekong Basin

Cited by 182 publications

References 36 publications

Quantifying human impacts on hydrological drought using a combined modelling approach in a tropical river basin in central Vietnam

Quantifying human impacts on hydrological drought using a combined modelling approach in a tropical river basin in central Vietnam

A Review of the Integrated Effects of Changing Climate, Land Use, and Dams on Mekong River Hydrology

Changes in the Lake Area of Tonle Sap: Possible Linkage to Runoff Alterations in the Lancang River?

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