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Li, J.; Song, Y.; Mao, C., and Li, T., 2018. Assessing the distribution characteristics of surface water geochemistry and pollution of heavy metals within soil in the Changjiang River Delta, China. In: Wang, D. and Guido-Aldana, P.A. (eds.), Select Proceedings from the 3rd International Conference on Water Resource and Environment (WRE2017). Journal of Coastal Research, Special Issue No. 84, pp. 109–113. Coconut Creek (Florida), ISSN 0749-0208. This study aimed to understand the spatial distribution and geochemical characteristics of heavy metals in soil in Changjiang River Delta, and also the impact of surface water geochemistry on the mobility of heavy metals in soil. The levels of Ca2+ and Na+ in surface water reached 80% of total cation level, ranging 33.00–97.50 mg/L and 9.00–334.90 mg/L, respectively. HCO3− was more than 50% of total anion concentration, making the type of surface water as Ca-HCO3 or Ca-Na-HCO3. The concentration of cations and anions followed the order: coastal > middle > inland. The soils were strongly polluted with Cd in this study. More than 50% of Cd concentration exceeded the standard. Spatial changes in As, Cd, and Pb levels followed the order: middle > coastal > inland, same as that for soil pH. Speciation results of heavy metals showed that more than 50% of Cd was exchangeable. Principal component analysis results showed that the change in exchangeable fraction of As, Hg, and Pb followed the same order: middle > coastal > inland. Exchangeable Cd followed a trend different from that of Cr. Three areas were characterized by the mobility of As, Hg, and Pb. Scores of samples from different areas implied the influence of surface water on the mobility of heavy metals in soil. Geochemical variation in surface water indicated the mobility of heavy metals through correlation and spatial analysis of geochemistry of surface water and speciation of heavy metals in soil. [ABSTRACT FROM AUTHOR]

Regional characteristics of extreme precipitation indices (EPI) of precipitation magnitude, intensity and persistence were analyzed based on a daily rainfall dataset of 135 stations during the period of 1961-2010 in the Yangtze River basin, China. The spatial distribution of temporal trends of the selected indices was regionally mapped and investigated by using non-parametric test method. Future projections of EPI changes derived from the output of general circulation model (HadCM3) under the SRES A2 and B2 emission scenarios were downscaled and analyzed. The results show that: (a) there is not a general significant increasing or decreasing trend in EPI for the Yangtze River basin based on historical recorded data; (b) the automated statistical downscaling method-based precipitation captures some spatial distribution of the EPI and the bias correction can improve the simulation results; (c) a mixed pattern of positive and negative changes is observed in most of the nine indices under both scenarios in the first half of twenty-first century, and they increase continuously in the second half of twenty-first century; and (d) the concurrent increase in the heavy rain and drought indices indicates the possibility of the sudden change from drought to water logging in the lower region of Yangtze River basin. [ABSTRACT FROM AUTHOR]

The coincidence of flood flows of the mainstream and its tributaries may determine flood peaks. This study analyzed the risk of flooding as a result of such flood coincidences by considering flood magnitudes and time (dates) of occurrence. The Pearson Type III (P3) and log-Pearson Type III (LP3) distributions were selected as the marginal distribution of flood magnitude for annual maximum flood series; the mixed von Mises distribution was selected as the marginal distribution of flood occurrence dates. Two four-dimensional (4D) copula functions were developed for the joint distribution of flood magnitudes and occurrence dates. The upper Yangtze River in China and the Colorado River in the United States were selected to evaluate the method of computing risk. The coincidence probabilities of flood magnitudes and dates were calculated, and the conditional probabilities for the Three Gorges Reservoir (TGR) were analyzed. Results show that the von Mises distribution can fit the observed flood dates data well. The X-Gumbel copula was selected for risk analysis. On the basis of the proposed model, the coincidence and conditional probabilities for any return period were obtained. [ABSTRACT FROM AUTHOR]

Abstract: Due to the frequent water exchange and turbulence between Poyang Lake and Yangtze River, the measured runoff hydrograph at the Hukou outlet control station is unable to be directly used in hydrological model calibration. As a result, the rainfall runoff relationship and water budget analysis in Poyang Lake regions is an unsolved problem so far. In this study, the basin area analogue and water budget methods was used to modified runoff hydrograph at the Hukou, and multiple-input single-output system model was used to derive intervening basin runoff. The Variable Infiltration Capacity (VIC) distributed hydrological model based on different types of remote sensing data was used to simulate daily runoff in the ungauged Poyang Lake Intervening Basin (PLIB). The comparison of estimated and simulated daily runoff hydrographs shows that the VIC model is performed relatively well. It is proved that with the help of remote sensed data, important hydrological characteristics of the PLIB can be reproduced and predicted. [Copyright &y& Elsevier]