Stochastic Parsimonious Hydrologic Partitioning Model under East Asia Monsoon Climate and Its Application to Climate Change

A conceptual hydrologic partitioning model suitable for the East Asia monsoon climate region is constructed parsimoniously, and the variability of Horton index, which is the ratio of water vaporization and wetting in the watershed, is investigated. Numerical simulations in the study area show that the inter-annual variability of Horton index is reduced to around 60% of the inter-annual variability of annual precipitation, and there is a strong inverse correlation between Horton index and annual precipitation. Using cumulant expansion theory, the probability distribution function of soil water with various hydro-meteorological variables and watershed characteristics is derived. Using the steady-state soil water probability distribution function, the sensitivity of Horton index to hydro-meteorological variables such as precipitation occurrence probability, average rainfall depth at rainy days, and evapotranspiration rate and hydro-geophysical characteristics such as surface runoff coefficients, threshold soil water value to control vaporization, and exponent value to control groundwater recharge is analyzed. Looking at the future Horton index of the study area using a variety of future climate information ensemble, it is projected that the water stress of vegetation in the watershed is likely to increase due to fluctuations in precipitation patterns and increase in potential evapotranspiration even if annual precipitation increases.

Seismic sedimentological evidence for filling process of western Central Canyon System controlled by the evolution of the Tibetan Plateau and the East Asia monsoon since the Late Miocene, South China Sea

Three-dimensional blended data, comprised of amplitude and coherence cubes, are used to analyze the evolution of the Central Canyon System (CCS) since the Late Miocene within the western Qiongdongnan Basin (QDNB), South China Sea. The evolution of the canyon since the late Miocene includes two phases and five stages, with a dramatic change of deepwater sediment bodies from early, predominantly axial channel-levee deposits (CLDs) to late, primarily side mass-transport deposits (MTD). During the first and second stages (approximately 5.3–3.7 Ma), axial CLDs derived from the western slope of the South China Sea dominated the sediment bodies within the canyon. The last three stages (3.7 Ma to Recent) were dominated by side MTD, which originated from the northern slope of the South China Sea. Since the canyon was completely filled at 2.4 Ma, axial CLDs only reactivated in the lower strata of the most southern region of the study area. The time of formation of the CCS (approximately 11.6–8.2 Ma) is almost synchronous with the rise of the Himalayas and the first enhancement of the East Asia monsoon during the middle and late Miocene. The change of deepwater deposits within the canyon, which has varied from CLDs to MTDs since 3.7 Ma, is in phase with the further rapid uplift of the entire Tibetan Plateau and the second enhancement of the East Asia monsoon during the middle Pliocene. This evidence suggests that the formation and filling of the canyon should be controlled by the evolution of the Tibetan Plateau and the East Asia monsoon. Tectonics and the East Asia monsoon controlled the evolution of the CCS by changing erosion rates from the Tibetan Plateau, South China Block, and Indochina Peninsula, and sedimentary rates within the Yinggehai Basin and QDNB.

The climate reconstruction in Shandong Peninsula, northern China, during the last millennium based on stalagmite laminae together with a comparison to <i>δ</i>¹⁸O

Stalagmite ky1, with a length of 75 mm and the upper part (from top to 42.769 mm depth) consisting of 678 laminae, was collected from Kaiyuan Cave in the coastal area of Shandong Peninsula, northern China, located in a warm temperate zone in the East Asia monsoon area. Based on high-precision dating with the U–230Th technique and continuous counting of laminae, the 1st and 678th laminae have been confirmed to be AD 1894 ± 20 and 1217 ± 20 from top to bottom, respectively. By the measurement of laminae thickness and δ18O ratios, we haved obtained the time series data of thickness of laminae and δ18O ratios from AD 1217 ± 20 to 1894 ± 20, analyzed the climatic–environmental meaning of variations in the thickness of laminae, which have a good correspondence with the cumulative departure curve of the drought–waterlog index in the historical period. The results show that, in the ∼ 678 years from AD 1217 ± 20 to 1894 ± 20, both the thickness of the laminae and the degree of fluctuation in the thickness of the laminae of stalagmite ky1 have obvious stages of variation and are completely synchronized with the contemporaneous intensity of the summer monsoons and precipitation as time changed. There is a negative correlation between the thickness of the laminae and the summer monsoon intensity and precipitation. There is a positive correlation between the degree of fluctuation in the thickness of the laminae and both the intensity of the summer monsoons and the precipitation. Therefore, for the Kaiyuan Cave in the coastal area of both the warm temperate zone and the East Asia monsoon area, the variations in the thickness of the laminae are not only related to the change in the climatic factors themselves but also related to the degree of climatic stability. In the coastal area belonging to the warm temperate zone and the East Asia monsoon area, the climate change between the LIA (Little Ice Age) and the MWP (Medieval Warm Period), in addition to less precipitation and low temperatures (a type of dry and cold climate), also shows an obviously decreasing trend in the degree of climatic stability.

The climate reconstruction in Shandong Peninsula, North China during the last millennia based on stalagmite laminae

Stalagmite ky1 was collected from Kaiyuan Cave in coastal areas of Shandong Peninsula, northern China, located at warm temperate zone and East Asia monsoon area, it was 75 mm in length, and the top 42.77 mm developed 678 laminae. Based on high precision dating with U-230Th technique, by continuous laminae counting, it can be confirmed that the 1st and 678th layer were 1217 and 1892 AD from top to bottom respectively. By the measurement of layer thickness and δ18O values, we got the layer thickness data and δ18O value time series data from 1217 to 1892 AD, analyzed the climatic significance of layer thickness variation on the basis of comparison. The result show that, in the 678 years from 1217 to 1892 AD, both the layer thickness variation of stalagmite ky1 and the variation of layer thickness fluctuation degree have obvious staged characteristic, and completely synchronized with the contemporaneous summer monsoon intensity/precipitation in time. Among, the thickness of layer and summer monsoon intensity/precipitation have negative correlation themselves. On the other hand, the layer thickness and the fluctuation degree of summer monsoon intensity/precipitation have positive correlation themselves. Therefore, Kaiyuan Cave, in the coastal area of warm temperate zone and East Asia monsoon area, the variation of layer thickness are relate to climatic factors variation themselves, and relate to climate stability degree in addition. For to achieve this, in the coastal area of warm temperate zone and East Asia monsoon area, the climate change between LIA and MWP, in addition to presented like less precipitation and low temperature that is to say dry and cold, also showed the climate stability degree obvious decreased.