Middle River Basin Research Articles

Assessing chemical composition variations on vintage, vineyard location and grape ripeness: A regional study of red wines produced in the colorado river middle basin, La Pampa (Argentina)

This work aimed to characterize chemical composition of Malbec and Cabernet Franc red wines from two different regions of La Pampa’s province, which stands out as one of the youngest wine-producing regions in Argentina and has remained unexplored until now. These wines were produced from grapes of two consecutive vintages (2021 and 2022), and were harvested at two different ripeness levels. Global phenolic parameters, colour characterization and multi-elemental profile were evaluated. Multivariate statistical approaches were successfully implemented to investigate the vintage and ripeness effects on chemical profile of red wines and characterize them based on regional variations. Our results showed that vintage and ripeness affected both phenolic and multi-elemental profiles, and such chemical variables allowed the wines differentiation according to region. The results of this first study could form the basis for future research into optimizing the region’s winemaking potential.

Investigate the Spatiotemporal Evolution of Drought and Its Interaction with Atmospheric Circulation in the Yellow River Middle Basin

Global warming contributes to an increased frequency and severity of droughts. Drought emerges as a highly prevalent natural calamity, distinguished by its formidable disruptive impact and the capacity to trigger considerable economic setbacks. Understanding the spatiotemporal characteristics of droughts and clarifying the driving role of atmospheric circulation on droughts is vital for agricultural, hydrological, ecological, and socio-economic systems. Leveraging meteorological data from 36 stations in the middle reaches of the Yellow River Basin from 1961 to 2020, we employed the Standardized Precipitation Evapotranspiration Index (SPEI) to calculate drought occurrence. Concurrently, we explored the influence of atmospheric circulation on the SPEI. The findings of our study underscore a concerning trend of worsening drought conditions within the study area. We discovered a significant correlation between the duration and severity of drought (R = 0.83, p < 0.001); longer durations often corresponded to higher levels of severity. Turning our attention to atmospheric dynamics, the Nino Eastern Pacific index (NE) emerged as a critical driver of SPEI dynamics (the contribution of NE to SPEI was 0.22), significantly impacting drought patterns. In conclusion, the study significantly contributes to our comprehension of the evolving drought patterns under the influence of global warming. The findings can provide valuable information for water resource management and drought disaster control.

Evolution of the hydrographic network in the middle Wieprz River Basin (E Poland)

The Wieprz River Valley (Polesie Plain, east Poland) has evolved with regard to its dimensions, position and course since the end of the Neogene, its geological record showing how the Wieprz channel migrated and modified its character. Changes have also been observed in the water balance of the entire middle river basin, related to climate changes in the Pleistocene and Holocene. We provide new maps of the sub-Quaternary surface and trace topographical changes during the Pleistocene. Two separate rivers, the Pre-Bystrzyca and Pre-Wieprz, existed in Preglacial time. During the Narevian Glaciation, a network of subglacial troughs evolved in the area, largely disturbing and overprinting the earlier hydrographic system. Some of the troughs developed in older river valleys. The trough in which the present-day Wieprz gorge near Łęczna is located was most probably formed at that time. During subsequent glaciations and cold periods, sedimentary changes took place in the troughs and valleys – from erosion and removal of the accumulated material to their complete burial by sediments. During the Mazovian Interglacial (MIS 11c), several lakes formed in the study area, recorded by their infills of organic and mineral-organic deposits. During subsequent advances of the Scandinavian ice-sheet, water flow was dammed in towards the north, resulting in the formation of backwaters. Ice-sheet retreat resulted in the flow of proglacial waters towards the south-east, fluvioglacial sediment transport, and then unblocking of flow and subsequent reversal of flow directions to the north and west. During the Odranian Glaciation (MIS 6), catastrophic flow unblocked and shaped the present-day Wieprz gorge.

Checklist of the fish fauna of the Munim River Basin, Maranhão, north-eastern Brazil.

The Maranhão State harbours great fish diversity, but some areas are still undersampled or little known, such as the Munim River Basin in the northeast of the State. This lack of knowledge is critical when considering anthropogenic impacts on riverine systems especially in the face of major habitat destruction. These pressing threats mean that a comprehensive understanding of diversity is critical and fish checklists extremely relevant. Therefore, the present study provides a checklist of the fish species found in the Munim River Basin, Maranhão State, north-eastern Brazil, based on collected specimens. A total of 123 species were recorded for the Munim River Basin, with only two non-native species, Oreochromisniloticus and Colossomamacropomum, showing that the fish assemblage has relatively high ecological integrity. In addition, 29 species could not be identified at the species level, indicating the presence of species that are probably new to science in the Basin. A predominance of species belonging to the fish orders Characiformes and Siluriformes, with Characidae being recovered as the most species-rich family (21 species) agrees with the general pattern for river basins in the Neotropical Region. The total fish diversity was estimated by extensive fieldwork, including several sampling gears, carried out in different seasons (dry and rainy) and exploring different environments with both daily and nocturnal sampling, from the Basin's source to its mouth. A total of 84 sites were sampled between 2010 and 2022, resulting in 12 years of fieldwork. Fish assemblages were distinct in the Estuary and Upper river basin sections and more similar in the Lower and Middle sections indicating environmental filtering processes. Species were weakly nested across basin sections, but unique species were found in each section (per Simpsons Index). High variability of species richness in the Middle river basin section is likely due to microhabitat heterogeneity supporting specialist fish communities.

Analysis of Typical Weather Circulation Patterns of Heavy PM2.5 Pollution and the Transport Pattern in the Yangtze River Middle Basin

The dominant transportation and accumulation patterns of heavy PM2.5 pollution events over the Yangtze River middle basin were identified based on the obliquely rotated T-mode principal component analysis (PCT) method and the daily mean surface pressure. The heavy PM2.5 pollution events over the Yangtze River middle basin during 2015-2019 were divided into four patterns, namely, PCT1:high-pressure bottom transport pattern (number of days:41 d, accounting for 55.4% of the total heavy PM2.5 pollution days), PCT2:low-pressure convergence accumulation pattern (12 d, 16.2%), PCT3:high-pressure static stability accumulation pattern (11 d, 14.9%), and PCT4:high-pressure rear transport pattern (10 d, 13.5%). Regional transport patterns (PCT1 and PCT4) accounted for 69% of the total heavy PM2.5 pollution days and were the major pattern of heavy PM2.5 pollution in the Yangtze River middle basin. PCT1 occurred most frequently among the four patterns, accompanied with strong northerly winds, which could drive the rapid transportation of pollutants from the upstream areas and cause the explosive increase in PM2.5 over the Yangtze River middle basin. The PM2.5 pollution events in the transport corridor, including Xiangyang, Jingmen, and Jingzhou, exhibited a 12-hour lag feature. Most parts of northern China were the source of PM2.5, especially in central and northern Henan and western Shandong. The PCT4 transport pattern was featured by the low-level easterly winds, and the pollution level rose quickly. The PCT2 and PCT3 were characterized by the low ground wind speed, associated with the low-level horizontal convergence and subsidence. Such synoptic conditions were favorable for the accumulation of local PM2.5 pollution, and the pollution rise rate was slower, and the duration was longer than those of other patterns.

Geomorphic assessment of longitudinal profile of the Kanchi river basin, India: Recognition of dynamic equilibrium condition

ABSTRACT The Kanchi, an eastward flowing river, traverses through the Ranchi plateau of the Proterozoic Chhotanagpur granite gneissic complex to meet its trunk stream, the Subarnarekha River. The present study analyzed longitudinal profiles and associated geomorphic indices of the Kanchi River and its tributaries to identify spatial variation in profile form and fluvial response to prevailing controls. This work was carried out using a digital dataset and maps, which were processed in a GIS environment to obtain longitudinal profiles, and different data required in best-fit modelling and geomorphic investigation of longitudinal profiles. The analyses indicate that the rivers are in dynamic equilibrium condition. Spatial distribution of geomorphic indices values reveals that longitudinal profile forms vary from one segment to another along river channels, and these irregularities in the form of prominent and minor knickpoints are highly concentrated in middle river basin areas. The absence of lithological variation and active tectonics, and close association of anomalously steep river segments with structural lineaments and landforms demonstrates structural control on river channel development. PCA denotes strong similarities between geomorphic indices. This understanding of longitudinal variation in river nature may help to formulate strategies for the sustainable development and management of river related resources.

Effects of Dam Construction in the Wang River on Sediment Regimes in the Chao Phraya River Basin

The Wang River is one of the major tributaries of the Chao Phraya River (CPR) system in Thailand as the key riverine sediment source supplying the Chao Phraya Delta that has experienced severe shoreline retreat in the past six decades. Historical and observed river flow and sediment data measured during 1929–2019 were used to assess the variation in total sediment load along the Wang River and evaluate the effects of three major dam constructions on sediment supplied from the Wang River to the CPR. Results indicated that sediment loads increased toward downstream. Variation in long-term total sediment load (TSL) along the river suggested that construction of the Kiew Lom Dam in 1972 did not cause a reduction in sediment yield in the Wang River Basin because it impounded less than 20% of the average annual runoff, while the Mae Chang and Kiew Koh Ma Dams caused downstream sediment reduction. These three dams are located in the upper and middle river basins, and their effects on sediment load in the Wang River are ameliorated by additional sediment supplied from the lower basin. Results confirmed that construction of these three major dams in the Wang River did not greatly impact sediment supply from the Wang River to the CPR system. The dam site and sediment load variation along the river are the primary factors controlling the impact of the dam construction.

Fine-scale genetic structure of the endangered bitterling in the middle river basin of the Kiso River, Japan.

Recently, anthropogenic alterations have had severe and negative impacts on the terrestrial and aquatic species and environments. To conserve species that have a small and limited habitat, it is necessary to focus on fine-scale population structure and its effects on persistence. The deepbodied bitterling Acheilognathus longipinnis is an endangered freshwater fish that occupies ponds scattered in lateral bars in the Kiso River. In this study, we conducted multi-locus microsatellite DNA analysis to evaluate both fine-scale population structure and genetic diversity, in order to conserve A. longipinnis. The smaller number of loci deviating from the Hardy-Weinberg equilibrium in ponds scattered in individual lateral bars compared to the whole river system suggests that A. longipinnis forms a local breeding population in units of ponds. The population was roughly split between the river banks and the local population located in ponds in the mid-channel bar showed intermediate relationships with the river bank populations. Gene flow between local populations was not always homogeneous and was not influenced by geographical distances between local populations or the direction of river flow. The dispersal of A. longipinnis across both river bank sides may be constrained and is probably affected by the ecological characteristics of A. longipinnis and the hydrological regimes. Consequently, A. longipinnis in the Kiso River is maintained as a complex of multiple local populations with appropriate gene flow among them. To conserve A. longipinnis, both the persistence of the unstable ponds and moderate genetic exchanges by individual migration are required.

Population ecology of the spectacled caiman (Caiman crocodilus) in the Apaporis River middle basin

AbstractPopulation ecology studies on spectacled caimans (Caiman crocodilus) in Colombia have been few and far between with many covering short periods and defining population parameters based on relative indices (i.e., individuals/km). This reflects a lack of information on the general effects that environmental variables have on annual cycles of population dynamics, as well as a bias in abundance estimations due to the uncertainty of detection error. Keeping this in mind, we assessed the abundance and demographic structure of the spectacled caiman population inhabiting the Apaporis River middle basin over a year, based on robust hierarchical model that accounts for imperfect detection. We recorded a total of 1156 caiman observations between December 2018 and November 2019, estimating an average predicted value for abundance across all surveys of 29.99 ± 13.17 individuals, slowly increasing as the transect length increases and increasing variation as months passed by. The average detection probability was 0.69 ± 0.25 across all surveys, with no apparent effect as water temperature and relative humidity change across space‐time and slowly decreasing as months go through. The population size estimated based on the top‐performing model was 1763 ± 786 caimans across ~7.1 km2 assessed. We estimate the commonly used relative abundance (encounter rate) index as well as a generalized linear model and discuss how those relate with the values predicted by N‐mixture models. We also discuss the relevance and cautions researchers should have when using N‐mixture models to better understand spectacled caiman ecology.

The application of environmental governance for sustainable watershed-based management

In recent years, it has become popular for some of countries and regions to adapt the system of governance to varied and complex issues concerned with regional development and the environment. Watershed management is possibly the best example of this. It involves flood control, water use management and river environment simultaneously. Therefore, comprehensive watershed-based management should be aimed at balancing those aims. The objectives of this study are to introduce the notion of environmental governance into the planning process, to establish a method for assessing the alternatives and to develop a procedure for determining the most appropriate plan for environmental governance. The planning process here is based on strategic environment assessment (SEA). To verify the hypothetical approach, the middle river basin in the Tokachi River, Japan was selected as a case study. In practice, after workshop discussions, it was found to have the appropriate degree of consensus based on the balance of flood control and environmental protection in the watershed.

Floristic study and conservation value analysis of the Jordán river middle basin forest (Jujuy, Argentina)

The floristic study and the conservation value analysis of forest from the Jordan river middle basin are addressed in this research. This vegetation forms part of the subtropical mountain forests or Yungas, one of the most diverse ecosystems on Earth. Present forest species were surveyed, and the vegetation Interest Conservation index (INCON) was determined based on a series of conservation value criteria (Phytocenotic, Territorial, Mesological, Ethnobotanical, Perceptual and Didactics) recorded in the field. Available data on socio-cultural aspects of the area was also included in the study. All plants were identified up to genera and/or species. INCON was calculated from the sum of scoring assigned to each analyzed criterion. As a result, 42 forest species were identified; for each one, its conservation status was performed, including the altitudinal vegetation belt, biogeographical origin (at least for the genus), and their ethnobotanical value. The INCON obtained (135 points) showed the high natural, ethnocultural, landscape, and educational value of these forest vegetation according to the criteria analyzed. This information provides a useful tool to have a more precise knowledge of the diversity conservation status of Las Yungas. It also serves to recognize the biological and environmental relevance of this area, whose usefulness can be used for conservation purposes or decision making on protection plans.

Heavy air pollution with a unique “non-stagnant” atmospheric boundary layer in the Yangtze River middle basin aggravated by regional transport of PM<sub>2.5</sub> over China

Abstract. The regional transport of air pollutants, controlled by emission sources and meteorological factors, results in a complex source–receptor relationship of air pollution change. Wuhan, a metropolis in the Yangtze River middle basin (YRMB) of central China, experienced heavy air pollution characterized by hourly PM2.5 concentrations reaching 471.1 µg m−3 in January 2016. To investigate the regional transport of PM2.5 over central eastern China (CEC) and the meteorological impact on wintertime air pollution in the YRMB area, observed meteorological and other relevant environmental data from January 2016 were analyzed. Our analysis presented noteworthy cases of heavy PM2.5 pollution in the YRMB area with unique “non-stagnant” meteorological conditions of strong northerly winds, no temperature inversion, and additional unstable structures in the atmospheric boundary layer. This unique set of conditions differed from the stagnant meteorological conditions characterized by near-surface weak winds, air temperature inversion, and stable structure in the boundary layer that are typically observed in heavy air pollution over most regions in China. The regional transport of PM2.5 over CEC aggravated PM2.5 levels, thus creating heavy air pollution in the YRMB area. This demonstrates a source–receptor relationship between the originating air pollution regions in CEC and the receiving YRMB region. Furthermore, a backward trajectory simulation using a Flexible Particle dispersion (FLEXPART) Weather Research and Forecasting (WRF) model to integrate the air pollutant emission inventory over China was used to explore the patterns of regional transport of PM2.5 governed by the strong northerly winds in the cold air activity of the East Asian winter monsoon season. It was estimated that the regional transport of PM2.5 from non-local air pollutant emissions contributes more than 65 % of the PM2.5 concentrations to the heavy air pollution in the YRMB region during the study period, revealing the importance of the regional transport of air pollutants over China as a causative factor of heavy air pollution over the YRMB area.

Quantifying Disaster Casualties Centered on Flooding in the Chikugo River Middle Basin in the Past 400 Years to Determine the Historical Context of the July 2017 Northern Kyushu Torrential Rainfall

In this study, we collated the number of deaths caused by disasters that took place in the Chikugo River middle basin on the island of Kyushu, Japan, from the 1600s to 2017. The compilation of quantitative statistics of floods in Japan began in the modern era, while the statuses of previous disasters are described by vague indices and are thus difficult to quantify. In this study, we geographically restricted our investigation to the Chikugo River middle basin. We quantified the scale of each disaster by using the number of deaths recorded in historical documents. We then compared the disasters that took place in the area since the 1600s to identify the potential disaster risks harbored by our study area. During the period examined, the great famine from 1732 to 1733 was the greatest disaster and caused the most deaths. However, this is the only recorded famine for which fatalities were documented. Meanwhile, floods occurred frequently through this period, 26 of which resulted in fatalities: they had a total death toll of 292. Thus, famines occur infrequently but cause severe damage, whereas floods occur frequently but cause relatively minor damage. During the approximately 400 years examined, there were four floods with death tolls exceeding 30 people. Three of these occurred after 1868, when the modern era of Japan began. Meanwhile, there have been almost no small-scale floods during and after the modern era. By quantitatively assessing the disasters’ scales, we were able to establish that the 2017 northern Kyushu torrential rainfall was the fourth gravest water-related disaster, in terms of its death, toll since the 1600s. If only the north bank of the Chikugo River middle basin is considered, it was the greatest flood disaster to occur in this period.

Spatiotemporal variability and trends in the hydrology of the Xiang River basin, China: extreme precipitation and streamflow

It has been widely recognised that climate changes have significant impacts on hydrological processes and may increase flood risk. In the past 20 years, a frequent occurrence of heavy floods across the Xiang River basin (XRB) was witnessed, a major tributary of the Yangtze River basin (YRB), China. This study quantified impacts of precipitation extremes on streamflow changes across the XRB at annual and seasonal scales using the Mann–Kendall trend test (MK) method and continuous wavelet transform (CWT). Besides, the cross-wavelet transform (XWT) and wavelet coherence (WTC) methods were employed to identify the correlations between extreme precipitation and streamflow. The results indicated no significant trends in annual rainfall and/or streamflow, while the increasing trends in the summer extreme rainfall and streamflow can be observed in the upper and middle XRB. Results by the XWT and WTC indicated highly similar patterns of signal changes at 1–4 and 5–12 years from the 1980s to 2005, between extreme precipitation and streamflow in the upper and middle river basin. Nevertheless, the changes in extreme precipitation in the lower reaches do not always coincide with the extreme streamflow variations. The coherence between extreme precipitation and river flows gradually declines from the upper to the lower basin.

The Chao Phraya River Basin: water quality and anthropogenic influences

Abstract Land use influences and trends in water quality parameters were determined for the Chao Phraya River, Thailand. Dissolved oxygen (DO), biochemical oxygen demand (BOD), and nitrate-nitrogen (NO3-N) showed significant trends (R2 ≥ 0.5) across the year, while total phosphorus (TP) and faecal coliform bacteria (FCB) showed significant trends only in the wet season. DO increased, but BOD, NO3-N, and TP decreased, from the lower section (river kilometres (rkm) 7–58 from the river mouth) through the middle section (rkm 58–143) to the upper section (rkm 143–379) of the river. Lead and mercury showed weak/no trends (R2 < 0.5). Based on the river section, major land use groups were a combination of urban and built-up areas (43%) and aquaculture (21%) in the lower river basin, paddy fields (56%) and urban and built-up areas (21%) in the middle river basin, and paddy fields (44%) and other agricultural areas (34%) in the upper river basin. Most water quality and land use attributes had significantly positive or negative correlations (at P ≤ 0.05) among each other. The river was in crisis because of high FCB concentrations. Serious measures are suggested to manage FCB and relevant human activities in the river basin.

Prácticas de sacrificio en el Cerro de la Mesa (Alcolea de Tajo, Toledo): el depósito ritual de la Casa 1

Deposits with animal bones remains buried under the floor in domestic areas, are well known ritual practices in the Peninsular Iron Age. These practices are traditionally associated either with foundation of new buildings or refurbishment, or linked to propitiation rites and fertility. Although best studied examples are in the east coast of Spain, the phenomenon is also known in other archeological interior sites. This paper presents a ritual deposit, dug in the veton settlement of Cerro de la Mesa, in the Tagus river middle basin, whose formal characteristics relate it to domestic offerings of the Iberian area. This pit, located at the threshold of the Casa 1, contains selected remains of several sheep and a small ceramic bowl placed upside down. The analysis of the skeletal remains, together with the contents of the bowl and the study of the archaeological context, have allowed to relate it with sacrifice and libation practices within the framework of vetonian religiosity. The aim of this paper is to contribute to the formation of a peninsular corpus of ritual domestic deposits contributing to study of the religious practices.

Source and distribution of glycerol dialkyl glycerol tetraethers along lower Yellow River-estuary–coast transect

To assess the source of glycerol dialkyl glycerol tetraethers (GDGTs) and their usefulness as proxies for terrestrial organic matter inputs and temperature in the Yellow River-dominated margin, we measured isoprenoid and branched GDGT concentrations in surface sediments along a lower Yellow River-estuary–coast transect. Branched GDGTs dominated over isoprenoid GDGTs in the riverbed sediments and had similar compositions from river to coast. In contrast, isoprenoid GDGTs displayed an increasing abundance and a decreasing GDGT-0 to crenarchaeol ratio (1.6 to 0.6) toward the sea. Such distribution patterns of GDGTs, combined with the result from a principal component analysis (PCA), confirmed the different origin of branched and isoprenoid GDGTs with branched GDGTs being primarily from soil erosion of the Chinese loess plateau (CLP) whereas, in addition to allochthonous terrestrial inputs, aquatic Thaumarchaeota partially contributes to the isoprenoid GDGT pool in estuarine and coastal areas. The branched GDGT-derived temperature (avg. 11°C) is consistent with the annual mean air temperature (MAT) of the CLP in the middle river basin, a major source region for the Yellow River sediments, whereas the isoprenoid-derived temperature (12.7 to 28.4°C) deviated widely from the annual mean temperature in the study region. Application of a binary mixing model based on δ13C, the branched and isoprenoid tetraether (BIT) index and branched GDGT concentrations showed consistent decreases in the relative amount of terrestrial organic carbon toward the sea, but estimates from the latter two proxies were lower than those from the δ13C.

Vascular Flora of the Tocantins River Middle Basin, Brazil

This study provides a checklist of the phanerogams and pteridophytes of the Tocantins river middle basin, in northern Goiás state and southern Tocantins state, Brazil. Herbarium samples were collected from 2000 to 2009 and this floristic survey recorded 1572 species from 135 families. The most species-rich families were Fabaceae (217), Poaceae (116), Asteraceae (88), Euphorbiaceae (65), Orchidaceae (58) and Malpighiaceae (56). Furthermore, 14 endangered species and 31 rare species were recorded, mainly associated with the campos rupestres in the Veadeiros Plateau region. The flora mainly from the phytophyisiognomies cerrado stricto sensu, campo rupestre (“rocky fields”), mata de galeria (“gallery forest”), mata ciliar (“riverine forest”) and semi-deciduous seasonal forest comprised typical species of the mid-western Cerrado floristic province, such as the most widely known woody plants Anadenanthera colubrina (Vell.) Brenan (popular name angico), Aspidosperma subincanum Mart. ex A. DC. (guatambú), Astronium fraxinifolium Schott ex Spreng. (gonçalo-alves), Callisthene fasciculata Mart. (pau-jacaré), Dipteryx alata Vogel (barú), Guazuma ulmifolia Lam. (mutamba) and Magonia pubescens A. St.-Hil. (tingui). This study is the first to record a wide floristic list of this important region of central Brazil.

Bioarqueología y cronología del sitio Negro Muerto 2 (Noreste de Patagonia)

In this paper we present the first results for the analysis of human remains recovered at the Negro Muerto 2 (NM2) site, located in the south sector of the Negro river's middle basin (Rio Negro Province). During the rescue activities done at the site, four individuals had been recovered: individuals 1 and 2 were part of a double burial (the latter suffered a disarticulation at the level of the skull, which was relocated next to the first one); while individuals 3 and 4 were probably simple burials, although their high degree of disarticulation would not allow us to confirm this. Three radiocarbon dates were obtained for this site between 2,000 and 1,500 years BP. The skull of the individual 2, dated in 1,586 ± 47 years BP, presents a tabular oblique cranial deformation; in this case the date obtained is less than the expected for such morphology.

Nine years of water resources monitoring over the middle reaches of the Yangtze River, with ENVISAT, MODIS, Beijing‐1 time series, Altimetric data and field measurements

AbstractPoyang and Dongting Lakes, major water resources and key elements for natural flood control and reduction within the Yangtze River middle basin, were monitored from 2000 to 2008, with a re‐visiting period of 10 days, using ENVISAT ASAR, and completed by MODIS data, validated by Beijing 1 time series. GPCP and TRMM time series were utilized to derive regional meteorological indicators. At the lake scale as well as their subdivisions ones, results allowed the characterization of lake behaviors. Even if the Dongting and Poyang lakes mechanisms are substantially different, their water surface areas and water level variations exhibit a good similarity, including the same year of major flooding (2002) and the same year of lowest extent of inundation (2001). Both lakes present astonishingly low water levels and low surface areas in summer of 2006, being associated with a very early draw‐off. Few reasons could explained it: (i) a rainfall deficit at the sub‐watershed level; (ii) a hydrological event in the upper stream part, namely a possible closure of the Three Gorges Dam (TGD) gates; or (iii) a global climate change effect at the regional scale. The reasons for the dramatic water dropdown are neither a local rain deficit nor a change in the TGD management. The smallest water extent for wet season observed in 2006, appeared to be linked with a severe drought within the upper stream part of the Yangtze River basin. In addition, an impressive decreasing tendency of water surface and level is observed in the middle reaches of the Yangtze River, linked with relatively constant decreasing precipitations over the last decade. This synergistic utilization of data from earth observation systems and in situ data provide valuable information on water resource management at the scale of the middle Yangtze River watershed.