Red River System Research Articles

Quantifying the relative provenance contributions to submarine channel systems in the Qiongdongnan Basin since the Miocene: Implications for tectonic responses and channel migration

AbstractThe submarine Miocene Central Canyon and Pleistocene channel systems in the Qiongdongnan Basin constitute valuable sedimentary records that provide insight into the depositional processes and sediment routing from the hinterland to the deep sea. However, the primary source of sediment for the Pleistocene channel systems and the variation in relative sediment contributions since the Miocene from potential source terranes remain unknown. We have integrated new and published detrital zircon U–Pb ages and rare earth elements (REEs) from Pleistocene channel sands and late Miocene Central Canyon sands in the Qiongdongnan Basin to analyse the sediment routing system of these channel systems since the Miocene. Qualitative analyses of REEs, comparisons of detrital zircon age spectra, and multidimensional scaling plots suggest that the Red River is a significant source of sediment supply. The quantitative analysis of sediment mixing models indicates that the Pleistocene channel sands were mainly sourced from the Red River (62.8%–85.7%), followed by Central Vietnam rivers (4.8%–27.1%), with a minor amount derived from rivers in Hainan Island, Northern Vietnam and Southern Vietnam. Sand sediments, mainly from the Red River system, were deposited in the Yinggehai Basin, then transported and deposited again in the Qiongdongnan Basin. The relatively stable and major sediment supply from the Red River since the Miocene may have been driven by the uplift of the Tibetan Plateau. This study quantifies the relative provenance contributions to submarine channel systems in the Qiongdongnan Basin since the Miocene. It provides crucial geological implications for tectonic responses to channel migrations and the prediction of gas hydrates in sandy reservoirs.

Anthropogenic impacts on the water chemistry of a transboundary river system in Southeast Asia

The Red River originating from Yunnan province, China is the second largest river in Vietnam in terms of length and discharge. Combination of water chemistry monitoring data of 4 years (2018–2022) from different sub-basins of the Red River (the Da, Lo, Thao, Tra Ly, and Day) with historical datasets indicates a decline in pH from 8.1 in 2000 to 7.7 in 2021, greater CO2 concentrations and a shift from waters naturally dominated by carbonate weathering to waters dominated by evaporite weathering. Such changes were most apparent in the delta area where heavy human activities have increased influxes of most dissolved chemicals, except SiO2. Evaporite weathering is particularly enhanced by mining and deforestation occurring in upstream regions of both China and Vietnam. Pyrite oxidation, alongside silicate weathering, is enhanced along the Red River Fault Zone but reduced in tributaries with a higher proportion of hydropower reservoirs. Longer water residence times in these large reservoirs (total volume > 2.7x1010 m3) located in the Da and Lo sub-basins have also increased primary productivity, leading to higher evasion/uptake of CO2 and SiO2, lower total dissolved solids (TDS), and higher pH. The total physical and chemical denudation rates of upstream mountain tributaries ranged between 0.107 ± 0.108 and 0.139 ± 0.137 mm yr−1, mainly due to reservoir implementation and instream aquatic biogeochemistry changes. Our findings demonstrate that anthropogenic activities are profound factors impacting the water chemistry of the Red River system.

Long-term analysis of sediment load changes in the Red River system (Vietnam) due to dam-reservoirs

The sediment regime of the Red River system, the second largest in Vietnam, has undergone changes since the implementation of dams and reservoirs, with implications for downstream river processes. We analyzed long-term datasets of daily discharge and suspended sediment concentrations collected at key gauging stations downstream of the three main tributaries: HB on the Da River, YB on the Red River (main channel), VQ on the Lo River, and ST, the outlet of the Red River system. The results indicated a sharp reduction in the annual sediment load transported by the Red River system, as observed at the four stations. For example, at the ST station, there was a dramatic decline of 91% in sediment load, dropping from 117.9 × 106 ton/yr in the period 2009–2021 to 10.5 × 106 ton/yr in the period 1958–1987. The Red River system experienced two notable declines in sediment load. The first decline occurred from 1988 to 2008, which can be attributed to the commencement of Hoa Binh dam's operation in 1988. The second decline has taken place since 2009, coinciding with the utilization of new dam-reservoirs. Meanwhile, an abrupt change in water discharge was observed clearly since the end of 2008 at all four stations. However, the reductions in water discharges were found to be less pronounced when compared to the sediment budget. Based on our analysis, we concluded that the impacts of dam-reservoirs have had a more substantial influence on the system compared to variations in climate, such as air temperature and precipitation.

Seasonal variations of sediment load related to all large damming in the Red River system: A 64‐year analysis

AbstractVariations of water discharge and sediment load in the Red River basin have received considerable attention due to its drastic reduction during the past several decades. This paper presents a more specifically investigating of the seasonal variations in water discharge and sediment load from 1958 to 2021, both before and after the impoundment of all large dam‐reservoirs, using daily observations from the Son Tay hydrological gauging station, the outlet of the Red River system and entry to the delta. Sediment loads have decreased progressively since the early 1990s due to sediment yield reduction and dams in the upper basin, with a reduction of about 91% (from 116 × 106 to 11 × 106 t/year) over the 64‐year observation period. Prior to the impoundment of the Hoa Binh dam‐reservoir in 1988, the hydrological processes in the Red River system exhibited seasonal anomalies (clockwise mode on the hysteresis of rating curve), which implies that sediment load is highly proportional to water discharge and precipitation. The hysteresis loops between mean monthly water discharge and suspended sediment concentration after 1988 were altered by tributary dam‐reservoirs and a phenomenon known as ‘temporal monsoon moving’, which shifted the rating curve from clockwise to counterclockwise mode. Our long‐term analysis indicates that approximately 57.5% and 79% of sediments were trapped during the periods 1989–2008 (after Hoa Binh dam‐reservoir impoundment) and 2009–2021 (a series of new dam‐reservoirs went into operation), respectively, primarily during the high‐discharge months (June–October). Additionally, we concluded that the contribution of climate components (e.g., rainfall) to the dramatic decline in sediment load of the Red River system was less than the human impact.

Effectiveness in storing and reducing floods of the red river upstream reservoirs under the incident of Lienmac dyke

The Red river and Thai Binh river’s dyke system includes 56 dikes classified from grade III to special grade with a total length of 2.207,75km which 37.709km of special grade, 553.70km of grade I, 502,43km of grade II and grade III. At the present, on the Red River and Thai Binh River systems, there are 230 existing weak locations, which have not been completely reinforced yet. It might cause unsafety situations of large flood flush and high water levels of rivers for a long time. Therefore, studying the solutions to support the response under unsafety situations of the dike system is a significant meaning topic. The present paper aims to evaluate the effectiveness of solutions using reservoirs at the Red river upstream in order to store and reduce floods in downstream. This also supports the effort to respond the urgent situations upstream such as huge floods, dyke failures in downstream and dyke failure at Lien Mac. In the scope of this paper, one and two-dimensional hydraulic simulation method was utilized, which describes the scenarios to regulate the upstream reservoir of the Red River and hydraulic calculation of the downstream river network. Then, the effectiveness of flood reduction in each scenario can be estimated. Simulation results show that depending on the calculation scenarios, the capacity of reservoirs can be 5.553 million m3 to cut and reduce flood for downstream. The flooded area might be decreased by 47.528 ha in case using a part of the capacity of the construction. The time when the reservoirs completely close the floodgates and do not discharge the flood into downstream is from 27 to 30 hours, this is an important time for the Lien Mac dike to be completely sealed within 24 hours. The time when the reservoirs completely close the floodgates and do not discharge the flood into downstream is from 27 to 30 hours, this is an important time for the Lien Mac dike to be completely closed within 24 hours.

Characterizing sediment load variability in the red river system using empirical orthogonal function analysis: Implications for water resources management in data poor regions

This paper introduces a novel data-based modelling approach, Empirical Orthogonal Function (EOF), to characterize the sediment load variability at the downstream section of the Red River system in Vietnam. We modified the original EOF and performed it on the demeaned datasets of monthly total sediment load. Rating curves between the discharge and sediment load were used to validate the performance of EOF analysis. The results showed significant similarity between simulated and observed patterns. A dramatic decrease in sediment load has been observed via both the EOF and rating curve methods across the observation period (∼1958–2021), with two dramatic decreasing phases identified (1988–2008 and 2009-present). The variation in the sediment load was mainly related to the seasonal and inter-annual hydrological conditions in the basin, as well as the dam-reservoir impact. Before 1988, river discharge and rainfall were well correlated to the first EOF mode, indicating that the natural forces were the main driving factor for the sediment load. However, anthropogenic pressure (dam-reservoir impact) emerged as an important driver to the declining of sediment load since the end of 1988 and became more severe towards the end of 2008. We conclude that the modified EOF method developed in this study successfully demonstrates a simple and efficient means of reconstructing and evaluating the sediment load variability over time in data-poor regions, influenced by complex natural and anthropogenic – drivers. It can, thus, be useful for water resources management in ungauged basins in the region.

First hydrological study on the seasonal occurrence of glyphosate, glufosinate, and their metabolites in the Red River system, North Vietnam

We report the spatial and seasonal distribution of organophosphorus herbicides, namely glyphosate (GLYP), glufosinate (GLUF), and their respective metabolites aminomethyl phosphonic acid (AMPA) and 3-(methylphosphinico)-propionic acid (MPPA), in the Red River system (North Vietnam), a major water body in Southeast Asia. The four compounds were measured at 34 sampling stations located from upstream to the estuary during the dry (March) and wet (July) seasons in 2019. Large seasonal variations in herbicide concentrations were measured for the four analytes from upstream to the estuary, with the highest range of variations observed during the wet season. In the surface waters of the Red River, the maximum concentrations of GLUF (234 ng L–1), GLYP (565 ng L–1) and its metabolite AMPA (1329 ng L–1), occurred in the wet season. These values however, are lower than reported in other rivers worldwide. In contrast, the estimated fluxes of these compounds in the Red River water basin were very high during the wet season, i.e., up to 121, 50.2, 284, and 186 kg d–1 for GLYP, GLUF, AMPA, and MPPA, respectively. During both seasons, we observed correlations between the four compounds and ammonium (NH4+), suggesting that both nitrogen containing fertilizers and herbicides were applied in areas close to the river shore. The concentrations and fluxes of the herbicides GLYP, GLUF, and their metabolites determined in the Red River were compared to those recorded in other world river systems, such as the Garonne River (France), thus highlighting the importance of monitoring these compounds in surface waters.

Application of Machine Learning Algorithms in Studying Water Quality in the Red River System

The Red River system plays an important role in the socio-economic development of the Northern of Vietnam. Therefore, regular monitoring and evaluation of water quality parameters in the Red River system are important in water resources management and protection. However, current monitoring methods are often quite expensive and time-consuming. To predict the downstream water quality, this study uses multiple machine learning algorithms to understand the correlation between environmental parameters measured at upstream and downstream stations of the Red River system. The environmental parameters that are chosen for this study include suspended sediment concentration (SSC), inorganic nitrogen content (total N), phosphorus content (total P), and dissolved silicon (DSi). The results show that machine learning algorithms can estimate the downstream DSi and sediment concentrations based on combining values of three upstream stations with relatively high efficiency (R2 equals 0.75 and 0.66, respectively). Meanwhile, these algorithms have limited performance in estimating total N and P content, due to the influence of many exogenous factors. The study introduces a new direction for applying machine learning algorithms in water quality research in the Red River system with the potential application in other river systems in Vietnam.

Proposing Adjustments to the Dry Season Inter-Reservoir Operation Rules of the Red River System to Improve Water Use Efficiency of the Reservoirs

The Red-Thai Binh River system is an important water resource to the Northern Delta, serving the development of agriculture, people’s livelihood and other economic sectors through its upstream reservoirs and a system of water abstraction works along the rivers. However, due to the impact of climate change and pressure from socio-economic development, the operation of the reservoir system according to Decision No. 740/QD-TTg was issued on June 17, 2019 by the Prime Minister of Government promulgating the Red-Thai Binh River system inter-reservoir operation rules (Operation rules 740) has some shortcomings that need adjustments for higher water use efficiency, meeting downstream water demand and power generation benefits. Through the results of water balance calculation and analysis of economic benefits from water use scenarios, this research proposed adjustment to the inter-reservoir operation during dry season in the Red River system. The result showed that an average water level of 1.0 - 1.7 m should be maintained at Hanoi during the increased release period.

Zircon U–Pb age constraints on the provenance and response to tectonics: Lower Oligocene of the western Qiongdongnan Basin, South China Sea

Provenance changes and tectonic activity during the Early Oligocene in the Qiongdongnan Basin are responses to the evolution of the northwestern South China Sea. However, the provenance of the Lower Oligocene (Yacheng Formation) in the Qiongdongnan Basin is poorly understood owing to a lack of available borehole samples and poorly constrained stratigraphy. Here, combined with published data from wells of different part of the basin, we apply U–Pb dating of detrital zircons on samples nearby the western boundary fault of the basin to analyse the provenance of the Yacheng Formation and its regional tectonic implications. The zircon U–Pb age spectra of the sediments in three different members of Yacheng Formation show different features. A single U–Pb age peak at ca. 235 Ma occurs in the Third Member of the Yacheng Formation, whereas the U–Pb age spectra in the stratigraphically younger Second Yacheng Formation show different zircon U–Pb age spectra features: an age pattern has two major peaks at ca. 248 Ma and 441 Ma and lacks zircons younger than 200 Ma, and another pattern has two major peaks at ca. 95 Ma and 252 Ma. The Early Oligocene provenance evolution of the western Qiongdongnan Basin is reconstructed by comparing the zircon U–Pb age spectra of the sediments in the different samples to potential sources nearby. Abrupt changes in the U–Pb ages throughout the Lower Oligocene in the western Qiongdongnan Basin suggest that sediment supply in the Second Member of Yacheng Formation was dominated by rivers from western Hainan Island and Central Vietnam. By contrast, Hainan Island and local structural highs within the Qiongdongnan Basin were the main sources in the Third and First Members of the Yacheng Formation, respectively. The difference in the U–Pb age spectra between sediments in the Qiongdongnan Basin and the Red River implies that the time at which the Red River system entered the Qiongdongnan Basin was later than the Early Oligocene. Paleorivers sourced from Central Vietnam entered into the western Qiongdongnan Basin and did not reach the central or eastern part of the basin until ca. 31.5–29.9 Ma. An examination of the activity of the Red River Fault showed that the transition of provenance in the study area during the Early Oligocene could be a response to sinistral strike-slip motion along the Red River Fault.

First Hydrological Seasonality Occurrence of Glyphosate, Glufosinate, and Their Metabolites in the Red River System, North Vietnam

First Hydrological Seasonality Occurrence of Glyphosate, Glufosinate, and Their Metabolites in the Red River System, North Vietnam

The double structure of the Estuarine Turbidity Maximum in the Cam-Nam Trieu mesotidal tropical estuary, Vietnam

The characteristic parameters of the Estuarine Turbidity Maxima (ETM), their aggregates and their tidal variations were investigated within the Cam-Nam Trieu mesotidal estuary (Red River and Thai Binh River system, North Vietnam) at spring tides during the early wet season, wet season and dry season. The structure observed repeatedly highlights the separation of two distinct zones of high turbidity around the salt wedge, separated by a zone of lower turbidity. The upstream part developed at very low salinity (from 0.1 psu) on a quasi-homogeneous water column (at Simpson parameter between ~0.65 and 7–10); tidal pumping associated with salinity-induced flocculation are likely responsible for its formation. A second maximum was observed in the lower layer of stratified waters (at Simpson parameters >10), i.e. in the salt wedge, at higher salinities up to ~12–15 psu; in this downstream part, governed by the gravitational circulation, settling is also seasonally enhanced by the presence of transparent exopolymeric particles (TEP) for salinity >10 psu. Turbidity was higher in the upper part of ETM in the dry season and higher in the lower part of ETM in the wet season. Floc size, excess of density and settling velocity were the highest during dry season. Stronger ETMs occur in dry season than in early wet season and wet season, when the tidal-induced ETM is maximum. The locations of both ETM parts changed seasonally, moving upstream in the dry season and downstream in the wet season. Their length depended on the longitudinal salinity gradient and was highest at low tide than at high tide. The intermediate zone of lower turbidity between these two parts was longer in the wet season.

Geochemical record of the sediments in the continental shelf of the northwestern South China Sea: Implications for the provenance and sedimentary evolution

The marine stratigraphic record in the northwestern South China Sea provides an excellent case for understanding the provenance and sedimentary evolution of the marginal sea. However, considerable uncertainty exists in unraveling the geochemical record since the Oligocene due, in part, to a lack of systematic measurements of the sediments. In this study, the major and trace elements of sedimentary rocks from the northern Yinggehai-Song Hong Basin were analyzed to ascertain the provenance and reconstruct the sedimentary evolution in the northwestern South China Sea. The chondrite-normalized rare earth element (REE) patterns show fractionation between light REEs (LREEs) and heavy REEs (HREEs) with significant negative Eu anomalies (Eu/Eu* = 0.59–1.10), combining with discriminant function analysis, implies that the sediments were predominantly eroded from granitic rocks, which are mostly felsic igneous materials. The relatively high index of chemical variability (ICV) values (1.30–3.54) and low chemical index of alteration (CIA) values (36.2–61.5) indicate that these sediments are immature and might have experienced weak to intermediate chemical weathering during transportation and deposition. The geochemical data also show that the Red River catchment was the primary source region for the northern Yinggehai-Song Hong Basin since the late Oligocene. The variations in the element contents and ratios are consistent with the multi-stage tectonic activities of the basin and the provenance shift caused by the recombination of the Red River system in different sedimentary periods.

Application of Water Stable Isotopes for Hydrological Characterization of the Red River (Asia)

Fraction of young water (Fyw) and mean transit time (MTT, τ¯) calculated from water isotope profiles are valuable information for catchment hydrological assessment, especially in anthropogenically impacted region where natural conditions may not be decisive to catchment hydrology. The calculation of Fyw and MTT were performed on three subsets of δ18O_H2O data collected at the Hanoi meteo-hydrological station, Red River, in three periods; 2002–2005, 2015, and 2018–2019. The mean (min and max) values of δ18O_H2O in rainwater over the three periods are, respectively, −5.3‰ (−11.0 and −1.2‰), −5.4‰ (−10.7 and −1.4‰), and −4.5‰ (−13.9 and 1.7‰). The corresponding values in river water are −8.4‰ (−9.8 and −6.9‰), −8.5‰ (−9.1 and −7.7‰), and −8.4‰ (−9.5 and −7.2‰), respectively. The mean of Fyw calculated from the δ18O_H2O data for different periods is 22 ± 9%, 10 ± 5%, and 8 ± 3%. Mean transit time is 4.69 ± 15.57, 1.65 ± 1.53, and 2.06 ± 1.87 years. The calculated Fyw (MTT) is negatively (positively) proportional to change in reservoir volume over the three periods, which is logical, since reservoirs tend to keep more water in the catchment and slower down water flow. The strong variation of Fyw and τ¯, two essential variables characterizing the catchment hydrology, represents an anthropogenic impact in the Red River system.

Comparison of Deep Learning Techniques for River Streamflow Forecasting

Recently, deep learning (DL) models, especially those based on long short-term memory (LSTM), have demonstrated their superior ability in resolving sequential data problems. This study investigated the performance of six models that belong to the supervised learning category to evaluate the performance of DL models in terms of streamflow forecasting. They include a feed-forward neural network (FFNN), a convolutional neural network (CNN), and four LSTM-based models. Two standard models with just one hidden layer—LSTM and gated recurrent unit (GRU)—are used against two more complex models—the stacked LSTM (StackedLSTM) model and the Bidirectional LSTM (BiLSTM) model. The Red River basin—the largest river basin in the north of Vietnam—was adopted as a case study because of its geographic relevance since Hanoi city—the capital of Vietnam—is located downstream of the Red River. Besides, the input data of these models are the observed data at seven hydrological stations on the three main river branches of the Red River system. This study indicates that the four LSTM-based models exhibited considerably better performance and maintained stability than the FFNN and CNN models. However, the complexity of the StackedLSTM and BiLSTM models is not accompanied by performance improvement because the results of the comparison illustrate that their respective performance is not higher than the two standard models—LSTM and GRU. The findings of this study present that LSTM-based models can reach impressive forecasts even in the presence of upstream dams and reservoirs. For the streamflow-forecasting problem, the LSTM and GRU models with a simple architecture (one hidden layer) are sufficient to produce highly reliable forecasts while minimizing the computation time.

Zircon U–Pb age constraints on the provenance of Upper Oligocene to Upper Miocene sandstones in the western Qiongdongnan Basin, South China sea

The provenance of Upper Oligocene to Upper Miocene sandstones in the western Qiongdongnan Basin was studied by zircon U–Pb ages. More than 200 zircon grains were separated from the sandstone of the Upper Oligocene Lingshui, Lower Miocene Sanya, and Upper Miocene Huangliu formations, and spot analysed for U–Pb dating. Most zircon grains from the Upper Oligocene Lingshui and Upper Miocene Huangliu formations had rounded corners, suggesting that the grains were transported a relatively long distance before deposition, while grains from the Lower Miocene Sanya Formation were usually angular in shape, implying a shorter transport distance from their provenance. The Lingshui Formation contained exclusively Cenozoic, Mesozoic, Palaeozoic, and Proterozoic zircon ages, and the age spectrum showed two major peaks at ca. 247 and 441 Ma, along with nine subordinate age peaks at ca. 35, 305, 517, 623, 811, 852, 911, 1158, and 1905 Ma. This indicates that Upper Oligocene sediments in the northwestern area of the Qiongdongnan Basin may have originated from the Red River system, which had four major peaks at 254, 418, 751, and 1848 Ma, and five subordinate peaks at ca. 32, 81, 514, 606, and 967 Ma. Results suggest that sediments from the Red River system entered the Qiongdongnan Basin as early as the Late Oligocene. The zircon age spectrum of the Sanya Formation had two major peaks at 99 and 237 Ma, indicating that Lower Miocene sandstones in the northwestern area of the Qiongdongnan Basin were mainly from Hainan Island, with ages ranging from 110 to 90 to 280–220 Ma. This study infers that the sandstones may be the paleo-Red River capture by the Yangze River, which resulted in a large decrease of sediment supply from the paleo-Red River system, such that the sediments of the paleo-Red River did not develop in the western area of the Qiongdongnan Basin during the Early Miocene. Results indicate that if the Red River capture existed, it would have predated the Early Miocene. The zircon age spectrum from Upper Miocene sediments of the western Qiongdongnan Basin showed five major age peaks at ca. 27, 88, 256, 415, and 785 Ma, indicating that its provenance was the Red River system. The Late Miocene provenance change from Hainan Island to the Red River may have been in response to a major phase of the Tibetan Plateau uplift.

Establishing an empirical equation for the relationship between total suspended solids and total phosphorus concentrations in the downstream Red river water

Recently, the Asian rivers have faced the strong reduction of riverine total suspended solids (TSS) flux due to numerous dam/reservoir impoundment. The Red river system is a typical example of the Southeast Asian rivers that has been strongly impacted by reservoir impoundment in both China and Vietnam, especially in the recent period. It is known that the reduction in total suspended solids may lead to the decrease of some associated elements, including nutrients (N, P, Si) which may affect coastal ecosystems. In this paper, we establish the empirical relationship between total suspended solids and total phosphorus concentrations in water environment of the Red river in its downstream section from Hanoi city to the Ba Lat estuary based on the sampling campaigns conducted in the dry and wet seasons in 2017, 2018 and 2019. The results show a clear relationship with significant coefficient between total suspended solids and total phosphorus in the downstream Red river. It is expressed by a simple equation y = 0.0226x0.3867 where x and y stand for total suspended solids and total phosphorus concentrations (mg/l) respectively with the r2 value of 0.757. This equation enables a reasonable prediction of total phosphorus concentrations of the downstream Red river when the observed data of total suspended solids concentrations are available. Thus, this work opens up the way for further studies on the calculation of the total phosphorus over longer timescales using daily available total suspended solids values.

Tracking the Detrital Zircon Provenance of Early Miocene Sediments in the Continental Shelf of the Northwestern South China Sea

Sediment provenance studies have become a major theme for source-to-sink systems and provide an important tool for assessing paleogeographic reconstruction, characterizing the depositional system, and predicting reservoir quality. The lower Miocene is an important stratigraphic unit for deciphering sediment evolution in the continental shelf of the northwestern South China Sea, but the provenance characteristics of this strata remain unclear. In this study, detrital zircon U-Pb geochronology and Lu-Hf isotopes from the lower Miocene Sanya Formation in the Yinggehai-Song Hong Basin were examined to study the provenance and its variation in the early Miocene. U-Pb dating of detrital zircons yielded ages ranging from Archean to Cenozoic (3313 to 39 Ma) and displayed age distributions with multiple peaks and a wide range of εHf(t) values (from −27.2 to +8.5). Multi-proxy sediment provenance analysis indicates that the Red River system was the major source for the sediments in the northern basin, with additional contribution from central Vietnam, and the Hainan played the most important role in contributing detritus to the eastern margin of the basin in the middle Miocene. This paper highlights the provenance of early Miocene sediments and contributes to paleogeographic reconstruction and reservoir evaluation.

Assessment of impacts of utilization on water resources in the basin of trans-boundary Red river system

The Red river system is the large trans-boundary river system, there has been no united system of hydrology stations as well as integrated plan for the water use and management in the whole basin. The trend of water resources change in the Red river system basin has been assessed on the basic of statistic analyses of data observed during the studies, especially in the time when the exploitation of water resources has been intensified for the multisectoral development. This paper shows some of the results from considerations of the water use in the highlands that is influential in water resources in the Red river system basin and the planned reservoirs which are built in the basin of Red river system. The results include the assessment of the state and trend of water resources in the Red river system basin, the trend of water level lowering in the lowlands and its impacts.

Late Miocene provenance evolution at the head of Central Canyon in the Qiongdongnan Basin, Northern South China Sea

Abstract The head of the Central Canyon system in the Qiongdongnan Basin has been suggested as the key region for understanding the deposition and transportation processes in the northern South China Sea but the sedimentary provenance of this region remains uncertain. In this study, U–Pb geochronology of detrital zircon was used to constrain the source terranes, understand the sedimentary provenance, and reconstruct the provenance evolution in the late Miocene. Measured age populations from the upper Miocene sediments indicate that the sediments in the Central Canyon were mainly derived from the sources of the Red River and central Vietnam, whereas the nearby Hainan Island was not the major source terrane. The southwestern Yangtze Block was likely the primary source for the head of the Central Canyon through the Red River system and played an important role in contributing detritus to the northwestern South China Sea during the late Miocene. The results of this study also showed slight provenance variations in the vertical stratigraphic successions of the upper Miocene, suggesting a relatively stable and continuous detritus supply from the Red River at 10.5–8.2 Ma. In addition, the provenance study is capable to provide important insights in reservoir distribution and quality evaluation in future exploration and production.