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Pearl River Basin (pearl + river_basin)
Selected AbstractsGenetic analysis of ratmouth barbell (Ptychidio jordani Myers) from different geographic sub-populations in the Pearl River Basin using microsatellite markersJOURNAL OF APPLIED ICHTHYOLOGY, Issue 2 2009X.-P. Zhu Summary Thirteen polymorphic microsatellite markers were used to study the genetic variation of Ptychidio jordani sampled from the three sites of Liuzhou, Guiping and Yunan in the Pearl River Basin with the help of local fishers. Allele numbers ranged from 2 to 19 and fragment sizes ranged from 108 to 288. Average polymorphism information content (PIC), average observed heterozygosity (Ho) and average expected heterozygosity (He) were 0.439917, 0.4147 and 0.4986, respectively, which indicate a comparatively high level of genetic diversity. The coefficient of genetic differentiation (Gst) between the two sub-populations ranged from 0.0074 to 0.0156, which shows little differentiation between sub-populations. amova analysis also offered evidence of weak differentiation with 0.53% variation between sub-populations, 99.47% variation within sub-populations and the Fst = 0.00531. The morphological variation among geographic sub-populations might result from different habitats. The correlation between genotype and morphological characters was analyzed and a significant correlation found between the genotype of microsatellite locus Hlj038 and the ratio of body depth and body length. The results suggest a possible linkage between this locus and these morphological characters. [source] Trends and abrupt changes of precipitation maxima in the Pearl River basin, ChinaATMOSPHERIC SCIENCE LETTERS, Issue 2 2009Q. Zhang Abstract We applied the Mann-Kendall (MK) test and Bayesian model to systematically explore trends and abrupt changes of the precipitation series in the Pearl River basin. The results showed that no significant trends were detected for annual precipitation and summer or winter precipitation totals. Significant negative trends were identified for the number of rainy days across the Pearl River basin; significant positive trends were observed regarding precipitation intensity (PI). In particular, the precipitation totals and frequencies of extremely high precipitation events are subject to significant positive trends. In addition, the number of extremely low precipitation events was also increasing significantly. Factors affecting the changes in precipitation patterns are the weakening Asian monsoon and consequently increasing moisture transport to Southern China and the Pearl River basin. In summary, the main findings of this study are: (1) increased precipitation variability and high-intensity rainfall was observed though rainy days and low-intensity rainfall have decreased, and (2) the amount of rainfall has changed little but its variability has increased over the time interval divided by change points. These finds indicate potentially increased risk for both agriculture and in locations subject to flooding, both urban and rural, across the Pearl River basin. Copyright © 2009 Royal Meteorological Society [source] Effects of Land-Use and Land-Cover Change on Evapotranspiration and Water Yield in China During 1900-2000,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 5 2008Mingliang Liu Abstract:, China has experienced a rapid land-use/cover change (LUCC) during the 20th Century, and this process is expected to continue in the future. How LUCC has affected water resources across China, however, remains uncertain due to the complexity of LUCC-water interactions. In this study, we used an integrated Dynamic Land Ecosystem Model (DLEM) in conjunction with spatial data of LUCC to estimate the LUCC effects on the magnitude, spatial and temporal variations of evapotranspiration (ET), runoff, and water yield across China. Through comparisons of DLEM results with other model simulations, field observations, and river discharge data, we found that DLEM model can adequately catch the spatial and seasonal patterns of hydrological processes. Our simulation results demonstrate that LUCC led to substantial changes in ET, runoff, and water yield in most of the China's river basins during the 20th Century. The temporal and spatial patterns varied significantly across China. The largest change occurred during the second half century when almost all of the river basins had a decreasing trend in ET and an increasing trend in water yield and runoff, in contrast to the inclinations of ET and declinations of water yield in major river basins, such as Pearl river basin, Yangtze river basin, and Yellow river basin during the first half century. The increased water yield and runoff indicated alleviated water deficiency in China in the late 20th Century, but the increased peak flow might make the runoff difficult to be held by reservoirs. The continuously increasing ET and decreasing water yield in Continental river basin, Southwest river basin, and Songhua and Liaohe river basin implied regional water deficiency. Our study in China indicates that deforestation averagely increased ET by 138 mm/year but decreased water yield by the same amount and that reforestation averagely decreased ET by 422 mm/year since most of deforested land was converted to paddy land or irrigated cropland. In China, cropland-related land transformation is the dominant anthropogenic force affecting water resources during the 20th Century. On national average, cropland expansion was estimated to increase ET by 182 mm/year while cropland abandonment decreased ET by 379 mm/year. Our simulation results indicate that urban sprawl generally decreased ET and increased water yield. Cropland managements (fertilization and irrigation) significantly increased ET by 98 mm/year. To better understand LUCC effects on China's water resources, it is needed to take into account the interactions of LUCC with other environmental changes such as climate and atmospheric composition. [source] | ||||||||||