Remote Sensing of the Ecology and Functioning of the Mekong River Basin with Special Reference to the Tonle Sap

Using the Global Land Surface Satellite (GLASS) leaf area index (LAI), the actual evapotranspiration (ETa) and available water resources in the Mekong River Basin were estimated with the Remote Sensing-Based Vegetation Interface Processes Model (VIP-RS). The relative contributions of climate variables and vegetation greening to ETa were estimated with numerical experiments. The results show that the average ETa in the entire basin increased at a rate of 1.16 mm year−2 from 1980 to 2012 (36.7% of the area met the 95% significance level). Vegetation greening contributed 54.1% of the annual ETa trend, slightly higher than that of climate change. The contributions of air temperature, precipitation and the LAI were positive, whereas contributions of solar radiation and vapor pressure were negative. The effects of water supply and energy availability were equivalent on the variation of ETa throughout most of the basin, except the upper reach and downstream Mekong Delta. In the upper reach, climate warming played a critical role in the ETa variability, while the warming effect was offset by reduced solar radiation in the Mekong Delta (an energy-limited region). For the entire basin, the available water resources showed an increasing trend due to intensified precipitation; however, in downstream areas, additional pressure on available water resources is exerted due to cropland expansion with enhanced agricultural water consumption. The results provide scientific basis for practices of integrated catchment management and water resources allocation.

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Water-Energy-Food Nexus in a Transboundary River Basin: The Case of Tonle Sap Lake, Mekong River Basin

Water ◽

10.3390/w7105416 ◽

2015 ◽

Vol 7 (10) ◽

pp. 5416-5436 ◽

Cited By ~ 40

Author(s):

Marko Keskinen ◽

Paradis Someth ◽

Aura Salmivaara ◽

Matti Kummu

Keyword(s):

River Basin ◽

Mekong River ◽

Mekong River Basin ◽

Transboundary River ◽

Transboundary River Basin ◽

Tonle Sap Lake ◽

Tonle Sap

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Tonle Sap Lake: Mekong River Basin (Cambodia)

The Wetland Book ◽

10.1007/978-94-007-4001-3_42 ◽

2018 ◽

pp. 1785-1791

Author(s):

Colin Poole

Keyword(s):

River Basin ◽

Mekong River ◽

Mekong River Basin ◽

Tonle Sap Lake ◽

Tonle Sap

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Deriving the Reservoir Conditions for Better Water Resource Management Using Satellite-Based Earth Observations in the Lower Mekong River Basin

Remote Sensing ◽

10.3390/rs11232872 ◽

2019 ◽

Vol 11 (23) ◽

pp. 2872 ◽

Cited By ~ 5

Author(s):

Syed A. Ali ◽

Venkataramana Sridhar

Keyword(s):

Remote Sensing ◽

River Basin ◽

Water Resource Management ◽

Large Population ◽

Dry Season ◽

Water Diversion ◽

Mekong River ◽

Landsat 8 ◽

Wet Season ◽

Mekong River Basin

The Mekong River basin supported a large population and ecosystem with abundant water and nutrient supply. However, the impoundments in the river can substantially alter the flow downstream and its timing. Using limited observations, this study demonstrated an approach to derive dam characteristics, including storage and flow rate, from remote-sensing-based data. Global Reservoir and Lake Monitor (GRLM), River-Lake Hydrology (RLH), and ICESat-GLAS, which generated altimetry from Jason series and inundation areas from Landsat 8, were used to estimate the reservoir surface area and change in storage over time. The inflow simulated by the variable infiltration capacity (VIC) model from 2008 to 2016 and the reservoir storage change were used in the mass balance equation to calculate outflows for three dams in the basin. Estimated reservoir total storage closely resembled the observed data, with a Nash-Sutcliffe efficiency and coefficient of determination more than 0.90 and 0.95, respectively. An average decrease of 55% in outflows was estimated during the wet season and an increase of up to 94% in the dry season for the Lam Pao. The estimated decrease in outflows during the wet season was 70% and 60% for Sirindhorn and Ubol Ratana, respectively, along with a 36% increase in the dry season for Sirindhorn. Basin-wide demand for evapotranspiration, about 935 mm, implicitly matched with the annual water diversion from 1000 to 2300 million m3. From the storage–discharge rating curves, minimum storage was also evident in the monsoon season (June–July), and it reached the highest in November. This study demonstrated the utility of remote sensing products to assess the impacts of dams on flows in the Mekong River basin.

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An implicit wetting–drying algorithm for the discontinuous Galerkin method: application to the Tonle Sap, Mekong River Basin

Environmental Fluid Mechanics ◽

10.1007/s10652-019-09732-7 ◽

2020 ◽

Vol 20 (4) ◽

pp. 923-951 ◽

Cited By ~ 2

Author(s):

Hoang-Anh Le ◽

Jonathan Lambrechts ◽

Sigrun Ortleb ◽

Nicolas Gratiot ◽

Eric Deleersnijder ◽

...

Keyword(s):

Galerkin Method ◽

Discontinuous Galerkin ◽

River Basin ◽

Discontinuous Galerkin Method ◽

Mekong River ◽

Mekong River Basin ◽

Tonle Sap

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Tonle Sap Lake: Mekong River Basin (Cambodia)

The Wetland Book ◽

10.1007/978-94-007-6173-5_42-2 ◽

2016 ◽

pp. 1-8

Author(s):

Colin Poole

Keyword(s):

River Basin ◽

Mekong River ◽

Mekong River Basin ◽

Tonle Sap Lake ◽

Tonle Sap

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A New Remote Sensing Approach to Enrich Hydropower Dams’ Information and Assess Their Impact Distances: A Case Study in the Mekong River Basin

Remote Sensing ◽

10.3390/rs11243016 ◽

2019 ◽

Vol 11 (24) ◽

pp. 3016

Author(s):

Zihan Lin ◽

Jiaguo Qi

Keyword(s):

Remote Sensing ◽

Land Use ◽

Land Cover ◽

River Basin ◽

Vegetation Index ◽

Normalized Difference Vegetation Index ◽

Mekong River ◽

Mekong River Basin ◽

Hydropower Dam ◽

Hydropower Dams

Hydropower dam information such as construction and completion timings is often incomplete and missing in existing dam databases, and the hydropower dam’s adjacency impact distance, which is important to the surrounding environment, is also lacking for many dams. In this study, we developed a new remote sensing approach to specifically determine the timings and to assess the influencing distance on land use and land cover at the above and below dam areas. We established the new remote sensing method by identifying levels shifts in trajectories of Normalized Difference Vegetation Index (NDVI) indicators and by identifying the change point in entropy coefficient of variation (CV) variations to allow an auto-acquisition of the information above at the water basin level. We used three geospatial datasets including 1) a 30-year Landsat time series, 2) an annual Landsat Normalized Difference Vegetation Index (NDVI) composite, and 3) digital elevation model (DEM) data. We applied the proposed method to the Mekong River Basin (MRB) in Southeast Asia, where hydropower dam constructions have increased significantly since the 1990s. Results suggested that we were able to obtain the desired information for 67 Mekong hydropower dams successfully. Pearson correlation tests were used to validate timing results against official records, and the correlation coefficients were found to be 0.96 and 0.90, respectively, for construction and completion timing determination. We discovered that the buffer radius of a Mekong dam’s adjacency impact on land use and land cover was usually 4.0-km and 2.5-km in the above and below dam area. The data determined from this study may fill important information gaps in existing dam databases, and the approach developed in this case may be generalized to the other watersheds of the world, where hydropower dams exist. However, essential dam information is either incomplete or unavailable.

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