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Accueil du site → Doctorat → Chine → 2003 → Land Use and Wind Erosion Process in Bashang Area of Hebei Province

Beijing Normal University (2003)

Land Use and Wind Erosion Process in Bashang Area of Hebei Province

Hai Chun Xing

Titre : Land Use and Wind Erosion Process in Bashang Area of Hebei Province

Auteur : Hai Chun Xing

Grade : Doctoral Dissertation 2003

Université : Beijing Normal University

Résumé partiel
Wind erosion is one of nature disasters on globe. This phenomenon is widely distributed in arid and semiarid area. Most of China west region locates in that area, and agriculture product is seriously affected by wind erosion. Bashang of Hebei province locates in front transition from semiarid to semi-humid. Wind erosion studied in this area will helpful to understand develop tendency of soil erosion in east of China. This study based on summarizing previously researchers to the wind erosion. Bashang of Hebei province are investigated and researched in southeast wind erosion area of China, such as Kangbao, Zhangbei and Fengning country. Nature condition and human activity affect wind erosion are synthesis analyzed. The factors caused wind erosion is studied by way of gray time series correlation model. The key of the model is compare of geometric curve figure. The more similar geometric, the more development and changing tendency close to, and correlation of time series is big. Computations are as follows : Step 1 Original data processing Let Xij is every index’s original data, i and j are lower index, i=1,2,…m, j=1,2,…n, Data are handled initial value processing. Original time series data must average value handling. It is easy to compare and analysis. Formula for computing as follows : Where Step 2 Determine parent sequence X0 and subsequence Xi. Step 3 Compute absolute value Δ0i(tj) which is parent sequence minus subsequence at every time’s point, that is, Step 4 Difference value which are maximal Δmax and minimal value Δmin are taken from table. Step 5 Compute correlation coefficient between parent sequence X0 and subsequence Xi at every time’s point, formula for computing as follows : In which, Δmax is |Xi-X0| the biggest value, Δmin is |Xi-X0| the smallest value, Δ0i(tj) is |Xi-X0| value at tj time. Step 6 Computing correlated measure, namely compute correlation coefficient’s average value : Step 7 Arrangement correlation coefficient’s order : Arrangement correlation coefficients as column according the big and small is called correlation order, and then clear to see “primary and secondary”and “advantage and disadvantage”relations between parent sequence and subsequence. The model refers to appendix one. According to the relationship between wind erosion and environment in this region, precipitation and temperature of nature factors are analyzed. Month and year mean precipitation and temperature are chosen as wind erosion effective factors. Human activities factors include population increase rate, per capital income, change of grassland and cultivated land area. All above factors related to wind erosion are analyzed by gray correlation model, and summarized change rule in terrain. Experiment area is chosen according to the rule. Soil erosion process and change of different land use are observed and calculated. Field investigation and experiment design are based on model research, and then do experiment in chosen area. Wind erosion is monitored by development instrument. From above study the summarized conclusion as follows : 1. Bashang of Hebei province is located in semiarid and semi-humid ecology environment north of China. The sand’s soil is easy erosion in this fragility environment because of climate changing irregular and landforms conditions. By way of synthesize analyzing nature factor and human activity and then find soil erosion has followed regular pattern : winter high temperature is the direct reason to cause soil erosion. Soil’s moisture evaporate is actuate when temperature is high. Soil’s low moisture is intensified wind erosion process. Precipitation and human activities changing along with landforms change.

Mots clés : Bashang of Hebei Province Gray Correlation of Time Series Model Soil Wind Erosion Desertification

Présentation (Dissertationtopic)

Page publiée le 5 mai 2013, mise à jour le 21 avril 2018