Informatics Publishing Limited

Yi He ¹, Xingmin Mu ¹, Peng Gao ², Guangju Zhao ², Fei Wang ², Wenyi Sun ², Pengfei Li ³, Jinxi Song ³

Affiliations
1 College of Water Resources and Architectural Engineering, Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, Shaanxi, CN
2 Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, Shaanxi, CN
3 Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling 712100, Shaanxi, CN

Abstract

Longitudinal analyses of hydro-meteorological variables are extremely important for climate studies and water resources planning. Precipitation across the most severely eroded areas of Huangfuchuan Watershed in the Loess Plateau, China was analysed using data from 10 rainfall stations during the period 1954-2010. The ensemble empirical mode decomposition (EEMD), Hurst exponent, and Mann-Kendall methods were utilized to detect periodicities, discontinuities as well as long-term persistence of precipitation. The results show abrupt changes (i.e. discontinuities) in spring during the period 1963-1969 and in 1975, the summer period of 1962 and 1986-1994, the autumn of 1978, and the winter of 1964. These abrupt changes were determined to be statistically significant at the P = 0.05 level. There were inter-annual periods of quasi-3- and quasi-6-year for annual and the four seasons, and decadal periods of quasi-10-, quasi-15-, quasi-25- and quasi-50-year for different seasons. However, periodical features in inter-annual periods were not statistically noticeable. Moreover, Hurst exponent analysis indicated that the current trends of precipitation over the four seasons would continue in the future. The results also indicate that the EEMD method is able to effectively reveal deviations in longterm precipitation series at various timescales and could be utilized for complex analysis of nonstationary and nonlinear signal change. These findings could provide important information for ecological restoration and farming operations across the study region.

Keywords

Ensemble Empirical Mode Decomposition, Periodicities and Discontinuities, Precipitation Variability, Watershed.

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Fuquan Tang ¹, Jiaxin Lu ¹, Pengfei Li ¹

Affiliations
1 College of Geomatics, Xi'an University of Science and Technology, Xi'an, 710054, CN

Abstract

Land subsidence in the loess-covered mountainous area is a complex process that contemporary models could not accurately simulate. We assumed that flatground mining subsidence was the result of joint action of bedrock mining subsidence under equivalent load of the loess layer and the spread of bedrock surface subsidence to land surface via thick loess layers. Quantitative relationships between equivalent load of the loess layer and equivalent exploitation width, depth, and bedrock subsidence were examined. A double-medium model of flat-ground mining subsidence based on stochastic medium theory was developed to simulate the interactions between loess layers and bedrock. Another model was established to describe the slip deformation associated with loess in hill side mining. The two models were integrated to account for mining subsidence on flat ground and hillside. The integrated model was demonstrated to be robust in land subsidence deformation prediction for loess-covered mountainous area based on field measurements from a mining area in western China.

Keywords

Deformation Prediction, Loess Layer, Mining Area of Western China, Mining Subsidence, Hillside Slip.

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