scholarly journals THE ANALYSIS OF THE TIME-SERIES VARIATION OF HYDROLOGICAL DATA IN THE MIDDLE, LOWER MEKONG RIVER BASIN

2013 ◽  
Vol 69 (4) ◽  
pp. I_289-I_294
Author(s):  
Kazumitsu MURAOKA ◽  
Koji ASAI
Keyword(s):  
Time Series ◽  
River Basin ◽  
Mekong River ◽  
Mekong River Basin ◽  
Hydrological Data

scholarly journals Upstream GPS Vertical Displacement and its Standardization for Mekong River Basin Surface Runoff Reconstruction and Estimation

2019 ◽  
Vol 12 (1) ◽  
pp. 18
Author(s):  
Hok Sum Fok ◽  
Linghao Zhou ◽  
Yongxin Liu ◽  
Zhongtian Ma ◽  
Yutong Chen
Keyword(s):  
Time Series ◽  
River Water ◽  
River Basin ◽  
Relative Error ◽  
Surface Runoff ◽  
Water Discharge ◽  
Vertical Displacement ◽  
Mekong River ◽  
Mekong River Basin

Surface runoff (R), which is another expression for river water discharge of a river basin, is a critical measurement for regional water cycles. Over the past two decades, river water discharge has been widely investigated, which is based on remotely sensed hydraulic and hydrological variables as well as indices. This study aims to demonstrate the potential of upstream global positioning system (GPS) vertical displacement (VD) and its standardization to statistically derive R time series, which has not been reported in recent literature. The correlation between the in situ R at estuaries and averaged GPS-VD and its standardization in the river basin upstream on a monthly temporal scale of the Mekong River Basin (MRB) is examined. It was found that the reconstructed R time series from the latter agrees with and yields a similar performance to that from the terrestrial water storage based on gravimetric satellite (i.e., Gravity Recovery and Climate Experiment (GRACE)) and traditional remote sensing data. The reconstructed R time series from the standardized GPS-VD was found to have a 2–7% accuracy increase against those without standardization. On the other hand, it is comparable to data that are obtained by the Palmer drought severity index (PDSI). Similar accuracies are exhibited by the estimated R when externally validated through another station location with in situ time series. The comparison of the estimated R at the entrance of river delta against that at the estuaries indicates a 1–3% relative error induced by the residual ocean tidal effect at the estuary. The reconstructed R from the standardized GPS-VD yields the lowest total relative error of less than 9% when accounting for the main upstream area of the MRB. The remaining errors may be the result of the combined effect of the proposed methodology, remaining environmental signals in the data time series, and potential time lag (less than a month) between the upstream MRB and estuary.

scholarly journals Random Forest-Based Reconstruction and Application of the GRACE Terrestrial Water Storage Estimates for the Lancang-Mekong River Basin

2021 ◽  
Vol 13 (23) ◽  
pp. 4831
Author(s):  
Senlin Tang ◽  
Hong Wang ◽  
Yao Feng ◽  
Qinghua Liu ◽  
Tingting Wang ◽  
...  
Keyword(s):  
Time Series ◽  
Random Forest ◽  
Correlation Coefficient ◽  
River Basin ◽  
Water Storage ◽  
Mekong River ◽  
Climatic Research Unit ◽  
Terrestrial Water Storage ◽  
Mekong River Basin ◽  
Terrestrial Water

Terrestrial water storage (TWS) is a critical variable in the global hydrological cycle. The TWS estimates derived from the Gravity Recovery and Climate Experiment (GRACE) allow us to better understand water exchanges between the atmosphere, land surface, sea, and glaciers. However, missing historical (pre-2002) GRACE data limit their further application. In this study, we developed a random forest (RF) model to reconstruct the monthly terrestrial water storage anomaly (TWSA) time series using Global Land Data Assimilation System (GLDAS) and Climatic Research Unit (CRU) data for the Lancang-Mekong River basin. The results show that the RF-built TWSA time series agrees well with the GRACE TWSA time series for 2003–2014, showing that correlation coefficients (R) of 0.97 and 0.90 at the basin and grid scales, respectively, which demonstrates the reliability of the RF model. Furthermore, this method is used to reconstruct the historical TWSA time series for 1980–2002. Moreover, the discharge can be obtained by subtracting the evapotranspiration (ET) and RF-built terrestrial water storage change (TWSC) from the precipitation. The comparison between the discharge calculated from the water balance method and the observed discharge showed significant consistency, with a correlation coefficient of 0.89 for 2003–2014 but a slightly lower correlation coefficient (0.86) for 1980–2002. The methods and findings in this study can provide an effective means of reconstructing the TWSA and discharge time series in basins with sparse hydrological data.

scholarly journals Satellite observations reveal thirteen years of reservoir filling strategies, operating rules, and hydrological alterations in the Upper Mekong River Basin

2021 ◽  
Author(s):  
Dung Trung Vu ◽  
Thanh Duc Dang ◽  
Stefano Galelli ◽  
Faisal Hossain
Keyword(s):  
Time Series ◽  
River Basin ◽  
Satellite Observations ◽  
Mekong River ◽  
Limited Information ◽  
Energy Policies ◽  
Landsat Images ◽  
Mekong River Basin ◽  
Operating Rules ◽  
Satellite Radar

Abstract. The current situation in the Lancang–Mekong River Basin is emblematic of the issues faced by many transboundary basins around the world: riparian countries prioritize national water-energy policies and provide limited information on how major infrastructures are operated. In turn, such infrastructures and their management become a source of controversy. Here, we turn our attention to the Upper Mekong River, or Lancang, where a system of eleven mainstream dams controls about 55 % of the annual flow to Northern Thailand and Laos. Yet, assessing their actual impact is a challenging task because of the chronic lack of data on reservoir storage and dam release decisions. To overcome this challenge, we focus on the ten largest reservoirs and leverage satellite observations to infer 13-year time series of monthly storage variations. Specifically, we use area-storage curves (derived from a Digital Elevation Model) and time series of water surface area, which we estimate from Landsat images through a novel algorithm that removes the effects of clouds and other disturbances. We also use satellite radar altimetry data (Jason) to validate the results obtained from satellite imagery. Our results describe the evolution of the hydropower system and highlight the pivotal role played by Xiaowan and Nuozhadu reservoirs, which make up to ~85 % of the total system's storage in the Lancang River Basin. We show that these two reservoirs were filled in only two years, and that their operations did not change in response to the drought that occurred in the region in 2019–2020. Deciphering these operating strategies could help enrich existing monitoring tools and hydrological models, thereby supporting riparian countries in the design of more cooperative water-energy policies.

Losing faith

2021 ◽  
Author(s):  
Richard Grünwald ◽  
Wenling Wang ◽  
Yan Feng
Keyword(s):  
River Basin ◽  
Speech Acts ◽  
Unintended Consequences ◽  
Mekong River ◽  
Scientific Integrity ◽  
Mekong River Basin ◽  
Political Issues ◽  
Hydrological Data ◽  
Research Standards ◽  
Hydrological Science

<p><span>The presented session examines the politicization of hydrological science and discusses the current implications for misinterpreting the hydrological data that undermine trust in science. As a result of growing medialization of hydrological studies and simplifying the research conclusions for the wide public, it is more difficult for hydrologists to keep scientific integrity and not fall into the realm of subjectivism. By close analysis of two hydrological studies (Pöyry Report and Eyes on Earth Studies), we noticed that (1) research conclusions may be tailored to political demand, (2) intentionally overlook basic theoretical-methodological research standards, and (3) negatively influenced by social media, especially when the research conclusions do not correspond with scientific reviews nor official speech acts from state authorities. On the other hand, we also found several unintended consequences that make politicization science useful and even positive, especially in terms of changing the social perception of water or deepening the water cooperation in hydrological monitoring which still remain sensitive political issues in many corners of the world.<br><br>By drawing on the socio-hydrology and critical hydropolitical theories, this session (i) explores the current challenges for interpreting the hydrological studies, (ii) clarify the techniques how to prevent misinterpretation of the hydrological data, and (iii) demonstrate the politicization of the hydrological science on two micro-case studies within the Mekong River Basin that raise controversies among scientists and potential disputes among states. While the Pöyry Report conclusions served as a political tool to justify the construction of Xayaburi hydropower dam in Laos regardless the opposition of downstream countries, the Eyes on Earth Study was designed to undermine mutual trust among Mekong states and damage the credibility of other hydrological studies that do not share the same opinion on hydrological changes in the Mekong River Basin. The data were retrieved from the Lancang-Mekong Cooperation and Conflict Database (LMCCD) and double-checked with the literature review of the official documents and media sources related to Pöyry Report and Eyes on Earth Study.</span></p>

Intercomparison of ten ISI-MIP models in simulating discharges along the Lancang-Mekong River basin

2021 ◽  
Vol 765 ◽  
pp. 144494
Author(s):  
He Chen ◽  
Junguo Liu ◽  
Ganquan Mao ◽  
Zifeng Wang ◽  
Zhenzhong Zeng ◽  
...  
Keyword(s):  
River Basin ◽  
Mekong River ◽  
Mekong River Basin ◽  
Mip Models

scholarly journals Meteorological and hydrological droughts in Mekong River Basin and surrounding areas under climate change

2021 ◽  
Vol 36 ◽  
pp. 100873
Author(s):  
Yishan Li ◽  
Hui Lu ◽  
Kun Yang ◽  
Wei Wang ◽  
Qiuhong Tang ◽  
...  
Keyword(s):  
Climate Change ◽  
River Basin ◽  
Mekong River ◽  
Mekong River Basin ◽  
Surrounding Areas ◽  
Hydrological Droughts

scholarly journals Attribution of Long-Term Evapotranspiration Trends in the Mekong River Basin with a Remote Sensing-Based Process Model

2021 ◽  
Vol 13 (2) ◽  
pp. 303
Author(s):  
Shi Hu ◽  
Xingguo Mo
Keyword(s):  
Remote Sensing ◽  
Water Resources ◽  
Solar Radiation ◽  
River Basin ◽  
Mekong Delta ◽  
Mekong River ◽  
Catchment Management ◽  
Mekong River Basin ◽  
Area Index ◽  
Available Water

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.

scholarly journals Error Correction of Multi-Source Weighted-Ensemble Precipitation (MSWEP) over the Lancang-Mekong River Basin

2021 ◽  
Vol 13 (2) ◽  
pp. 312
Author(s):  
Xiongpeng Tang ◽  
Jianyun Zhang ◽  
Guoqing Wang ◽  
Gebdang Biangbalbe Ruben ◽  
Zhenxin Bao ◽  
...  
Keyword(s):  
Error Correction ◽  
River Basin ◽  
Regional Scale ◽  
Mekong River ◽  
Precipitation Data ◽  
Climate Data ◽  
Hydrological Simulation ◽  
Mekong River Basin ◽  
Precipitation Estimation ◽  
Simulation Results

The demand for accurate long-term precipitation data is increasing, especially in the Lancang-Mekong River Basin (LMRB), where ground-based data are mostly unavailable and inaccessible in a timely manner. Remote sensing and reanalysis quantitative precipitation products provide unprecedented observations to support water-related research, but these products are inevitably subject to errors. In this study, we propose a novel error correction framework that combines products from various institutions. The NASA Modern-Era Retrospective Analysis for Research and Applications (AgMERRA), the Asian Precipitation Highly-Resolved Observational Data Integration Towards Evaluation of Water Resources (APHRODITE), the Climate Hazards group InfraRed Precipitation with Stations (CHIRPS), the Multi-Source Weighted-Ensemble Precipitation Version 1.0 (MSWEP), and the Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Climate Data Records (PERSIANN) were used. Ground-based precipitation data from 1998 to 2007 were used to select precipitation products for correction, and the remaining 1979–1997 and 2008–2014 observe data were used for validation. The resulting precipitation products MSWEP-QM derived from quantile mapping (QM) and MSWEP-LS derived from linear scaling (LS) are evaluated by statistical indicators and hydrological simulation across the LMRB. Results show that the MSWEP-QM and MSWEP-LS can better capture major annual precipitation centers, have excellent simulation results, and reduce the mean BIAS and mean absolute BIAS at most gauges across the LMRB. The two corrected products presented in this study constitute improved climatological precipitation data sources, both time and space, outperforming the five raw gridded precipitation products. Among the two corrected products, in terms of mean BIAS, MSWEP-LS was slightly better than MSWEP-QM at grid-scale, point scale, and regional scale, and it also had better simulation results at all stations except Strung Treng. During the validation period, the average absolute value BIAS of MSWEP-LS and MSWEP-QM decreased by 3.51% and 3.4%, respectively. Therefore, we recommend that MSWEP-LS be used for water-related scientific research in the LMRB.

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