Upper Yangtze River Basin Research Articles

Spatial distribution of leptospirosis incidence in the Upper Yangtze and Pearl River Basin, China: Tools to support intervention and elimination

BackgroundSince 2011 human leptospirosis incidence in China has remained steadily low with persistent pockets of notifications reported in communities within the Upper Yangtze River Basin (UYRB) and Pearl River Basin (PRB). To help guide health authorities within these residual areas to identify communities where interventions should be targeted, this study quantified the local effect of socioeconomic and environmental factors on the spatial distribution of leptospirosis incidence and developed predictive maps of leptospirosis incidence for UYRB and PRB. MethodsData on all human leptospirosis cases reported during 2005–2016 across the UYRB and PRB regions were geolocated at the county-level and included in the analysis. Bayesian conditional autoregressive (CAR) models with zero-inflated Poisson link for leptospirosis incidence were developed after adjustment of environmental and socioeconomic factors such as precipitation, normalized difference vegetation index (NDVI), modified normalized difference water index (MNDWI), land surface temperature (LST), elevation, slope, land cover, crop production, livestock density, gross domestic product and population density. ResultsThe relationship of environmental and socioeconomic variables with human leptospirosis incidence varied between both regions. While across UYRB incidence of human leptospirosis was associated with MNDWI and elevation, in PRB human leptospirosis incidence was significantly associated with NDVI, livestock density and land cover. Precipitation was significantly and positively associated with the spatial variation of incidence of leptospirosis in both regions. After accounting for the effect of environmental and socioeconomic factors, the predicted distribution of residual high-incidence county is potentially more widespread both in the UYRB and PRB compared to the observed distribution. In the UYRB, the highest predicted incidence was found along the border of Chongqing and Guizhou towards Sichuan basin and northwest Yunnan. The highest predicted incidence was also identified in counties in the central and lower reaches of the PRB. ConclusionsThis study demonstrated significant geographical heterogeneity in leptospirosis incidence within UYRB and PRB, providing an evidence base for prioritising targeted interventions in counties identified with the highest predicted incidence. Furthermore, environmental drivers of leptospirosis incidence were highly specific to each of the regions, emphasizing the importance of localized control measures. The findings also suggested the need to expand interventional coverage and to support surveillance and diagnostic capacity on the predicted high-risk areas.

Assessment of water and energy scarcity, security and sustainability into the future for the Three Gorges Reservoir using an ensemble of RCMs

The looming impacts of changing climate and ever increasing water and energy demands make it important to quantify expected water and energy availabilities and develop strategies to mitigate expected shortfalls. Keeping these aspects in mind, in this paper, hydrological modeling is performed on the Upper Yangtze River Basin (UYRB) to simulate the inflows to the Three Gorges Reservoir (TGR) based on the Hydrologic Engineering Center’s Hydrologic Modeling System (HEC-HMS) model and a Multiple-input single-output Linear Systematic Model (MLSM). These models are derived for historical (1960–2005) and future (near: 2021–2050 and far: 2061–2090) time periods using bias corrected climate projections from an ensemble of 6 RCMs available through the COordinated Regional Downscaling EXperiment in East Asia (CORDEX-EA) under Representative Concentration Pathway (RCP) 4.5 and 8.5. Simulating with and without snow, hydrological responses to both the historical and future climates are fed into a daily reservoir simulation model where the operation of the TGR follows the designed operating rule curves which can be regarded as a standard operating policy (SOP). The results indicate marginal reduction in mean annual precipitation, inflow and hydropower generation and mean hydropower generation reliability for the future scenarios under RCP 8.5 with the decreases for far future being more prominent than those for near future. The inflow decreases strongly reduce the hydropower generation of the TGR in November and May and have limited impact on other months because of the regulation ability of the SOP. Hydropower generation responses to extreme variations in annual inflow are projected to aggravate the water and energy security stress of the TGR. The without snow projections alter the inflow patterns as well as the hydropower generation patterns of the TGR with respect to the with snow projections and are likely to have positive impact on the waterimpounding and hydropower generation for both the historical and future time periods.

Chronology and provenance of the Yichang Gravel Layer deposits in the Jianghan Basin, middle Yangtze River Valley, China: Implications for the timing of channelization of the Three Gorges Valley

The Three Gorges Valley, linking the upper and the middle-lower Yangtze River areas is a key area for understanding the geomorphological evolution of the Yangtze River valley, especially the timing of its formation, which remains controversial and occurred following the authors to from the pre-Miocene to Late Pleistocene periods. The 100 m thick Yichang Gravel Layer (YGL), extending over an area >100 km2, is immediately observed downstream of the Three Gorges Valley in the middle Yangtze River Basin also named Jianghan Basin. Studying heavy minerals assemblage and chronology of the YGL deposits can shed lights not only on the geological origin of the sediments and the morphological evolution of the Three Gorges Valley, but also the formation of the Yangtze River Valley. In this study, 18 sediment samples carried out from six representative sections of the unconsolidated YGL and 2 samples from the underlying Neogene and Paleogene bedrocks were analyzed in order to examine their heavy mineral assemblage compositions. These assemblages were compared with modern Yangtze River sediments sampled in Yichang area (n = 5) and present-day sediments from other rivers of the Jianghan Basin (n = 6) to further identify the sediment provenance of the YGL. The statistic results indicate that the heavy minerals identified the YGL dominated by zircon, epidote, titanite, hematite, limonite and ilmenite, are similar to the assemblages observed in the 5 modern Yangtze River sediment samples but differ obviously from both underlying bedrock assemblages, containing kyanite, garnet, rutile and monazite, and other modern river sediments (Jianghan Basin), including hornblende, chlorite, tourmaline, rutile, anatase, spinel and garnet). In addition, 8 sandy samples from the YGL were dated by Electron Spin Resonance (ESR) method using Ti–Li center, showing a deposition age ranging between 1123 ± 139 and 734 ± 183 ka. Based on these observations, we propose that the YGL sediments derived from the upper Yangtze River Basin above the Three Gorges Valley, indicating that the Three Gorges Valley was channelized before 1.12 Ma ago. This result is consistent with previous provenance tracing studies of continuous deposited late Cenozoic sediment from central Jianghan Basin (since 3.0 Ma), which also constrains the incision time of the Three Gorges to ~1.1 Ma.

A 439-year simulated daily discharge dataset (1861–2299) for the upper Yangtze River, China

Abstract. The outputs of four global climate models (GFDL-ESM2M, HadGEM2-ES, IPSL-CM5A-LR and MIROC5), which were statistically downscaled and bias corrected, were used to drive four hydrological models (Hydrologiska Byråns, HBV; Soil and Water Assessment Tool, SWAT; Soil and Water Integrated Model, SWIM; and Variable Infiltration Capacity, VIC) to simulate the daily discharge at the Cuntan hydrological station in the upper Yangtze River from 1861 to 2299. As the performances of hydrological models in various climate conditions could be different, the models were first calibrated in the period from 1979 to 1990. Then, the models were validated in the comparatively wet period, 1967–1978, and in the comparatively dry period, 1991–2002. A multi-objective automatic calibration programme using a univariate search technique was applied to find the optimal parameter set for each of the four hydrological models. The Nash–Sutcliffe efficiency (NSE) of daily discharge and the weighted least-squares function (WLS) of extreme discharge events, represented by high flow (Q10) and low flow (Q90), were included in the objective functions of the parameterization process. In addition, the simulated evapotranspiration results were compared with the GLEAM evapotranspiration data for the upper Yangtze River basin. For evaluating the performances of the hydrological models, the NSE, modified Kling–Gupta efficiency (KGE), ratio of the root-mean-square error to the standard deviation of the measured data (RSR) and Pearson's correlation coefficient (r) were used. The four hydrological models reach satisfactory simulation results in both the calibration and validation periods. In this study, the daily discharge is simulated for the upper Yangtze River under the preindustrial control (piControl) scenario without anthropogenic climate change from 1861 to 2299 and for the historical period 1861–2005 and for 2006 to 2299 under the RCP2.6, RCP4.5, RCP6.0 and RCP8.5 scenarios. The long-term daily discharge dataset can be used in the international context and water management, e.g. in the framework of Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) by providing clues to what extent human-induced climate change could impact streamflow and streamflow trend in the future. The datasets are available at: https://doi.org/10.4121/uuid:8658b22a-8f98-4043-9f8f-d77684d58cbc (Gao et al., 2019).

Coupled Snow and Frozen Ground Physics Improves Cold Region Hydrological Simulations: An Evaluation at the upper Yangtze River Basin (Tibetan Plateau)

AbstractCryosphere plays an important role in cold‐region (e.g., Tibetan Plateau) hydrological processes under climate change, and thus cryosphere physics should be carefully represented in the hydrological modeling. In this study, based on the Water and Energy Budget‐based Distributed Hydrological Model (WEB‐DHM), we have further improved the cold‐region hydrological processes, by incorporating the enthalpy‐based coupled snow and frozen ground physics (hereinafter WEB‐DHM‐SF), and comprehensively evaluated at the upper Yangtze River Basin under widespread snow cover and frozen ground. The model was calibrated and validated at the basin scale using observed discharge at Zhimenda station during 1981–2016 and simulated discharge with high accuracies. The model also successfully reproduced the basin‐wide daytime and nighttime land surface temperature (LST) as well as snow depth in basin‐averaged time series and spatial distributions. At the point scale, the model successfully reproduced soil moisture and temperature profiles at Tuotuohe based on available yearlong observations. Furthermore, experiments were designed to investigate model improvements and indicated that the incorporation of the three‐layer snow scheme with correct consideration of incident solar radiation attenuation among snow layers resulted in lowered snow melting and reduced discharges. Additionally, the incorporation of frozen ground physics with a correct description of soil water phase changes rendered the modeled soil moistures and temperatures more accurate in the cold season. Through rigorous evaluations of model performance, the incorporation of coupled snow and frozen ground physics demonstrates significant promise for improving cryosphere hydrological simulations in river basins on the TP.

Genetic analysis of wild Ancherythroculter nigrocauda in tributaries and the main stream of the upper Yangtze River basin of China

Biodiversity is threatened by several factors that are often associated with overfishing, water pollution and hydroelectric dams, among other environmental impacts. The present study aimed to evaluate the genetic aspects of wild groups of Ancherythroculter nigrocauda using the mitochondrial cytochrome c oxidase subunit I (coI) and cytochrome b (cytb) genes and the d-loop region. We collected 89 representative individuals from three geographically distinct ranges of the Upper Yangtze River, including the Longxi River (LOR), Laixi River (LAR), and Hejiang range of the Yangtze River (HJ). The genetic analysis results showed that the three populations of A. nigrocauda had high levels of haplotype diversity (0.3434–0.951) and low levels of nucleotide diversity (0.00074–0.00412) based on the single gene sequences and the combination of gene sequences. Haplotype genealogy showed that only one haplotype (Hap-2) was shared by these three geographic groups, and 2–3 were shared by two groups; the other haplotypes were group-specific. The genetic distance within and between the populations was low; however, most of the molecular variance came from within the populations. Furthermore, high gene flow (>1.0) was found in HJ vs LOR and HJ vs LAR based on the d-loop region sequence and combination. These results suggested that there was a decrease in the degree of A. nigrocauda genetic diversity in the upper Yangtze River, and the genetic protection of the populations should be highlighted in the future.

Evaluation of GloFAS-Seasonal Forecasts for Cascade Reservoir Impoundment Operation in the Upper Yangtze River

Standard impoundment operation rules (SIOR) are pre-defined guidelines for refilling reservoirs before the end of the wet season. The advancement and availability of the seasonal flow forecasts provide the opportunity for reservoir operators to use flexible and early impoundment operation rules (EIOR). These flexible impoundment rules can significantly improve water conservation, particularly during dry years. In this study, we investigate the potential application of seasonal streamflow forecasts for employing EIOR in the upper Yangtze River basin. We first define thresholds to determine the streamflow condition in September, which is an important period for decision-making in the basin, and then select the most suitable impoundment operation rules accordingly. The thresholds are used in a simulation–optimization model to evaluate different scenarios for EIOR and SIOR by multiple objectives. We measure the skill of the GloFAS-Seasonal forecast, an operational global seasonal river flow forecasting system, to predict streamflow condition according to the selected thresholds. The results show that: (1) the 20th and 30th percentiles of the historical September flow are suitable thresholds for evaluating the possibility of employing EIOR; (2) compared to climatological forecasts, GloFAS-Seasonal forecasts are skillful for predicting the streamflow condition according to the selected 20th and 30th percentile thresholds; and (3) during dry years, EIOR could improve the fullness storage rate by 5.63% and the annual average hydropower generation by 4.02%, without increasing the risk of flooding. GloFAS-Seasonal forecasts and early reservoir impoundment have the potential to enhance hydropower generation and water utilization.

Regional Impacts of Climate and Land Cover on Ecosystem Water Retention Services in the Upper Yangtze River Basin

Water retention is an important factor in ecosystem services, owing to its relationships with climate and land-cover change; however, quantifying the independent and combined impacts of these variables remains a challenge. We use scenario analysis and the InVEST model to assess individual or combined impacts of climate and land cover on water retention in the Upper Yangtze River Basin. Water retention decreased from 1986 to 2015 at a rate of 2.97 mm/10a in response to increasing precipitation (3.94 mm/10a) and potential evapotranspiration (16.47 mm/10a). The rate of water retention change showed regional variability (from 68 to −18 mm/a), with some eastern regions experiencing an increase and most other regions experiencing a decrease. Farmland showed the highest decrease (10,772 km2), with land mainly converted into forest (58.17%) and shrub land (21.13%) from 2000 to 2015. The impact of climate change (−12.02 mm) on water retention generally was greater than the impact of land cover change (−4.14 mm), at the basin scale. Among 22 climate zones, 77.27% primarily were impacted by climate change; 22.73% primarily were impacted by land cover change. Our results demonstrate that both individualistic and integrated approaches toward climate and vegetation management is necessary to mitigate the impacts of climate change on water resources.

Organophosphate flame retardants in heron eggs from upper Yangtze River basin, southwest China

The egg samples of four heron species, including black-crowned night heron (Nycticorax nycticorax), little egret (Egretta garzetta), Chinese pond heron (Ardeola bacchus) and cattle egret (Bubulcus ibis), were collected from the upper Yangtze River (Changjiang) Basin, Southwest China in early summer of 2017. Nine out of ten target organophosphate flame retardants (PFRs) were detected in these heron egg samples. The sum of concentrations of the PFRs quantified (∑PFRs) ranged from 63 to 590 pmol g−1 ww (18–185 ng g−1 ww) with a median value of 139 pmol g−1 ww (48 ng g−1 ww) among all samples. The median ∑PFRs in eggs of night herons (160 pmol g−1 ww) was higher than Chinese pond herons (median 121 pmol g−1 ww) and little egrets (median 109 pmol g−1 ww). In heron eggs, ∑PFRs were mainly contributed by tri-n-butyl phosphate (TNBP), tris (isobutyl) phosphate (TIBP), tris (1-chloro-2-propyl) phosphate (TCIPP) and tri-2-methylphenyl phosphate (TMPP). Alkyl-PFRs accounted for approximately 28%–85% (median 57%) of the nine PFRs quantified while the rest is contributed by aryl-PFRs and chlorinated PFRs. Lower levels of PFRs in little egret eggs were found upstream than downstream of the Yangtze. In addition, the daily intakes of PFRs through ingestion of heron eggs were estimated at lower levels.

Projected Effects of Climate Change on Future Hydrological Regimes in the Upper Yangtze River Basin, China

Climate change directly impacts the hydrological cycle via increasing temperatures and seasonal precipitation shifts, which are variable at local scales. The water resources of the Upper Yangtze River Basin (UYRB) account for almost 40% and 15% of all water resources used in the Yangtze Basin and China, respectively. Future climate change and the possible responses of surface runoff in this region are urgent issues for China’s water security and sustainable socioeconomic development. This study evaluated the potential impacts of future climate change on the hydrological regimes (high flow (Q5), low flow (Q95), and mean annual runoff (MAR)) of the UYRB using global climate models (GCMs) and a variable infiltration capacity (VIC) model. We used the eight bias-corrected GCM outputs from Phase 5 of the Coupled Model Intercomparison Project (CMIP5) to examine the effects of climate change under two future representative concentration pathways (RCP4.5 and RCP8.5). The direct variance method was adopted to analyze the contributions of precipitation and temperature to future Q5, Q95, and MAR. The results showed that the equidistant cumulative distribution function (EDCDF) can considerably reduce biases in the temperature and precipitation fields of CMIP5 models and that the EDCDF captured the extreme values and spatial pattern of the climate fields. Relative to the baseline period (1961–1990), precipitation is projected to slightly increase in the future, while temperature is projected to considerably increase. Furthermore, Q5, Q95, and MAR are projected to decrease. The projected decreases in the median value of Q95 were 21.08% to 24.88% and 16.05% to 26.70% under RCP4.5 and RCP8.5, respectively; these decreases were larger than those of MAR and Q5. Temperature increases accounted for more than 99% of the projected changes, whereas precipitation had limited projected effects on Q95 and MAR. These results indicate the drought risk over the UYRB will increase considerably in the future.

A simple regional snow hydrological process-based snow depth model and its application in the Upper Yangtze River Basin

Abstract Snow depth plays a significant role in the regional water balance, for which snowfall is usually determined by a fixed temperature threshold in regional snow research. This study developed a regional hydrological process-based snow depth model in the Upper Yangtze River Basin by using spatially distributed critical temperature data derived from Moderate Resolution Imaging Spectroradiometer (MODIS) data and station data. Based on meteorological station and remotely sensed data, daily snow hydrological components from 1 August 2003 to 31 July 2015 were simulated. Results show that the simulated snow depth patterns agreed with those of the observed snow depth. The multi-year average of the starting date and ending date of snow duration was 16 October and 6 June, respectively, and that of maximum annual snowfall was approximately 455 mm, of which canopy interception comprised 10%, with a maximum value of 50 mm. The proportion of snow sublimation was less than 20%, which was contributed by interception sublimation (40%), snow surface sublimation (40%) and sublimation underneath the canopy (20%). The maximum annual snow sublimation was 29 mm. Snow melting was the primary snow consumption pathway, and approximately 70% of snowfall melted. This research is significant for the assessment and management of water resources in this region.

Error adjustment of TMPA satellite precipitation estimates and assessment of their hydrological utility in the middle and upper Yangtze River Basin, China

Accurate and continuous precipitation amount and spatiotemporal distribution data are essential for water resource management, flood forecasting, and simulation of hydrological processes. Satellite-based precipitation products (SPPs) with high spatio-temporal resolution have been shown to represent a potential alternative data source for ungauged regions. The objective of this study was to evaluate the performance and the hydrological utility of a SPP (TMPA 3B42V7) driving two different hydrological models (Xinanjiang and Tank models) for runoff monitoring in the Yangtze River Basin in China. The results indicate that the TMPA precipitation data can be applied for runoff simulation compared to the ground-gauged data, and the adjustment of TMPA data can be helpful to improve the accuracy of rainfall data at the point and region scale. Two adjustment equations were proposed in this study (the geographical adjustment model and the additive error adjustment model), and the Bias had significantly improved, which solve the problem of data undervaluation. In addition, the TMPA precipitation data show an acceptable accuracy for driving the Xinanjiang and Tank models for the purpose of runoff monitoring. By utilizing the measured runoff data from the four main stations of the Yangtze River Basin, an excellent performance was shown in Xinanjiang model with the determined coefficient of 0.945–0.966 and 0.900–0.922 for the calibration and validation periods, respectively. This was similar for the Tank model with values of 0.943–0.963 and 0.917–0.920 for the calibration and validation periods, respectively. Based on these results, TMPA data would be helpful not only for understanding the characteristics of precipitation at high spatial and temporal resolution, but also for estimating near-real time runoff patterns.

Optimal Operation of Cascade Reservoirs for Flood Control of Multiple Areas Downstream: A Case Study in the Upper Yangtze River Basin

The purpose of a flood control reservoir operation is to prevent flood damage downstream of the reservoir and the safety of the reservoir itself. When a single reservoir cannot provide enough storage capacity for certain flood control points downstream, cascade reservoirs should be operated together to protect these areas from flooding. In this study, for efficient use of the reservoir storage, an optimal flood control operation model of cascade reservoirs for certain flood control points downstream was proposed. In the proposed model, the upstream reservoirs with the optimal operation strategy were considered to reduce the inflow of the reservoir downstream. For a large river basin, the flood routing and time-lag cannot be neglected. So, dynamic programming (DP) combined with the progressive optimality algorithm (POA) method, DP-POA, was proposed. Thus, the innovation of this study is to propose a two-stage optimal reservoir operation model with a DP-POA algorithm to solve the problem of optimal co-operation of cascade reservoirs for multiple flood control points downstream during the flood season. The upper Yangtze River was selected as a case study. Three reservoirs from upstream to downstream, Xiluodu, Xiangjiaba and the Three Gorges reservoirs (TGR) in the upper Yangtze River, were taken into account. Results demonstrate that the two-stage optimization algorithm has a good performance in solving the cascade reservoirs optimization problem, because the inflow of reservoir downstream and the division volumes were largely reduced. After the optimal operation of Xiluodu and Xiangjiaba reservoirs, the average reduction of flood peak for all these 13 typical flood hydrographs (TFHs) is 13.6%. Meanwhile, the cascade reservoirs can also store much more storm water during a flood event, and the maximum volumes stored in those two reservoirs upstream in this study can reach 25.2 billion m3 during a flood event. Comprising the proposed method with the current operation method, results demonstrate that the flood diversion volumes at the flood control points along the river decrease significantly.

Estimating the sediment trap efficiency and lifespan of cascaded reservoirs in the Upper Yangtze River Basin, China

AbstractThe cascaded reservoirs in the Upper Yangtze River Basin (UYRB) are subject to sediment inflow and deposition, resulting in reduction in their effective capacity. The sediment trap efficiency (TE) of the cascaded reservoirs was estimated using several empirical methods, and the factors affecting the TE also were analysed. A new empirical formula was obtained to calculate the TE of the small reservoirs (storage capacity C < 0.5 km3) in the UYRB. Further, four zones were partitioned to describe the relationship between the sediment trap effect and the service function of the reservoirs. The TEs of Xiluodu, Xiangjiaba and Ertan Reservoirs in the UYRB were investigated and compared between stand‐alone and combined operation modes, indicating the TE will be underestimated without considering the cumulative sediment trap of the cascaded reservoirs. Finally, the lifespan of the Xiluodu Reservoir, considering different water storage schemes and different capacity loss percentages, was estimated using the TE method and exhibited good agreement with the results calculated by the mathematical model. The derived TE calculation method under the combined operation of the cascaded reservoirs can be used to assess the sediment trap from the complex hydroelectric project system in the UYRB.

Length-weight relationships of five fish species from the Daninghe River, China

Length-weight relationships were described for five fish species belonging to three families and four genera from the Daninghe River, one of primary tributaries of the upper Yangtze River, China. A total of 1894 specimens were collected from 2014 to 2016 by using electro-fishing equipment. Length–weight relationships for five species were recorded previously in FishBase and new maximum total lengths for five species were also presented in this paper. The results will be useful for fishery research, management and conservation in the upper Yangtze River Basin.

Swimming Performance of Rock Carp Procypris rabaudi and Prenant's Schizothoracin Schizothorax prenanti Acclimated to Total Dissolved Gas Supersaturated Water

AbstractTotal dissolved gas (TDG) supersaturation is becoming an increasingly serious problem in the upper Yangtze River basin and has been identified as a potentially negative environmental effect of hydropower development and operations. Juvenile Rock Carp Procypris rabaudi and Prenant's Schizothoracin Schizothorax prenanti dwell in the upper reaches of the Yangtze River and were selected as experimental fish to evaluate the impact of TDG supersaturation on swimming performance. The results showed that the swimming speeds of Rock Carp and Prenant's Schizothoracin differed significantly under different exposure times to TDG‐supersaturated water (129–131%). Exposure of fish to supersaturated TDG for 2 and 4 h with no recovery resulted in significantly lower critical swimming (Ucrit) and burst swimming (Uburst) speeds compared with those of fish not exposed to supersaturated TDG. The Ucrit and Uburst values for Rock Carp not exposed to supersaturated TDG were 1.4–1.6 times higher than those of fish exposed to supersaturated TDG for 2 h and 1.9–2.0 times higher than those of fish exposed for 4 h. Similarly, the Ucrit and Uburst values for Prenant's Schizothoracin not exposed to supersaturated TDG were 1.4–1.8 times higher than those of fish exposed to supersaturated TDG for 2 h and 2.5–3.1 times higher than those of fish exposed for 4 h. Fish that were exposed to supersaturated TDG for 2 and 4 h and then allowed to recover for 2 d swam better than fish exposed to supersaturated TDG for the same amount of time without recovery. Although a 2‐d recovery improved swimming performance over that of fish not allowed to recover, only the Rock Carp (and not the Prenant's Schizothoracin) returned to the swimming speeds observed in the control fish not exposed to supersaturated TDG. The results of our research can be applied to the operation of hydropower stations and can contribute fundamental data for establishing water‐related environmental standards in China.Received December 4, 2016; accepted July 1, 2017 Published online October 11, 2017

Length-weight relationships for two loach species,Sinibotia superciliaris(Günther, 1892) andSinibotia reevesae(Chang, 1944) collected from the Tuojiang River, China

Length–weight relationships were determined for two loach species, Sinibotia superciliaris (Günther, 1892) and Sinibotia reevesae (Chang, 1944). Samples were collected with gill nets (30 × 15 m, mesh-size 1.5 cm) and fish cages (mesh-size 0.5 cm) as well as by electroshock (CWB-2000 P, 12 V, 250 HZ) between May 2013 and June 2015 from the Tuojiang River in southwest China. It is believed that the size range covered is close to a commonly known size range of each species. The length–weight relationship values of b were determined as 3.105 for S. superciliaris and 3.381 for S. reevesae. The data will be helpful in further research regarding these species in the upper Yangtze River Basin.

Assessing changes of river discharge under global warming of 1.5 °C and 2 °C in the upper reaches of the Yangtze River Basin: Approach by using multiple- GCMs and hydrological models

Assessment of climate change impacts on regional hydrological processes is vital for effective water resource management and planning. The 2015 Paris Agreement includes a two-headed temperature goal: “holding the increase in the global average temperature to well below 2 °C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5 °C”. The current study assesses the potential effect of global warming of 1.5 °C and 2 °C on river discharge, and their differences in the Upper Yangtze River Basin (UYRB) based on three hydrological models (HBV, SWAT and VIC) driven by bias-corrected climate projections from five General Circulation models (GCMs), namely GFDL, HAD, IPSL, MIROC and NOR as abbreviated, and two Representative Concentration Pathways (RCP2.6 and RCP4.5). Results indicate that all discharges (except autumn) especially winter have slight decreasing tendency (−0.3%, −2.3%, −0.8%, −6.4%, −1.2%, −0.3% respectively for annual, spring, summer, winter, 90% percentile and 10% percentile discharges) under RCP2.6 during 2020–2039 (+1.5 °C global warming) comparing to the reference period of 1986–2005. However, all discharges (except autumn and winter) especially summer have an increasing tendency (1.1%, 1.1%, 3.7%, 0.9%, 2.1% respectively for annual, spring, summer, 90% percentile and 10% percentile discharges) under RCP4.5 during 2040–2059 (+2 °C global warming). Moreover, the occurrence frequency and strength of droughts in dry season under global warming of 1.5 °C will increase, while floods in wet season under global warming of 2 °C tend to increase in UYRB. Additionally, the difference of river discharge between global warming of 2 °C and 1.5 °C is positive for almost all the time scales (1.4%, 3.5%, 4.5%, 2.1%, 2.4% respectively for annual, spring, summer, 90% percentile and 10% percentile discharges), which suggests that the increment of 0.5 °C could lead to more flood events in the UYRB.

Evaluating the streamflow simulation capability of PERSIANN-CDR daily rainfall products in two river basins on the Tibetan Plateau

Abstract. On the Tibetan Plateau, the limited ground-based rainfall information owing to a harsh environment has brought great challenges to hydrological studies. Satellite-based rainfall products, which allow for a better coverage than both radar network and rain gauges on the Tibetan Plateau, can be suitable alternatives for studies on investigating the hydrological processes and climate change. In this study, a newly developed daily satellite-based precipitation product, termed Precipitation Estimation from Remotely Sensed Information Using Artificial Neural Networks – Climate Data Record (PERSIANN-CDR), is used as input for a hydrologic model to simulate streamflow in the upper Yellow and Yangtze River basins on the Tibetan Plateau. The results show that the simulated streamflows using PERSIANN-CDR precipitation and the Global Land Data Assimilation System (GLDAS) precipitation are closer to observation than that using limited gauge-based precipitation interpolation in the upper Yangtze River basin. The simulated streamflow using gauge-based precipitation are higher than the streamflow observation during the wet season. In the upper Yellow River basin, gauge-based precipitation, GLDAS precipitation, and PERSIANN-CDR precipitation have similar good performance in simulating streamflow. The evaluation of streamflow simulation capability in this study partly indicates that the PERSIANN-CDR rainfall product has good potential to be a reliable dataset and an alternative information source of a limited gauge network for conducting long-term hydrological and climate studies on the Tibetan Plateau.

Impacts of climate change on streamflow in the upper Yangtze River basin

The impacts of climate change on streamflow in the upper Yangtze River basin were studied using four hydrological models driven by bias-corrected climate projections from five General Circulation Models under four Representative Concentration Pathways. The basin hydrological responses to climate forcing in future mid-century (2036–2065) and end-century (2070–2099) periods were assessed via comparison of simulation results in these periods to those in the reference period (1981–2010). An analysis of variance (ANOVA) approach was used to quantify the uncertainty sources associated with the climate inputs and hydrological model structures. Overall, the annual average discharge, seasonal high flow, and daily peak discharge were projected to increase in most cases in the twenty-first century but with considerable variability between models under the conditions of increasing temperature and a small to moderate increase in precipitation. Uncertainties in the projections increase over the time and are associated with hydrological model structures, but climate inputs represent the largest source of uncertainty in the upper Yangtze projections. This study assessed streamflow projections without considering water management practices within the basin.