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University of Chinese Academy of Sciences (2016)

Coupling Analysis of Soil Erosion And Topography in The Loess Plateau, China


Titre : Coupling Analysis of Soil Erosion And Topography in The Loess Plateau, China

Auteur : 程楠楠

Grade : Doctoral Dissertation 2016

Université : University of Chinese Academy of Sciences

Soil and water lose is one of the most serious environmental problem, and its influencing factors include natural and anthropogenic aspects. Natural factors include climate, hydrology, topography, etc. ; anthropogenic factors have positive and negative impacts, such as “Grain for Green” and soil and water conservation can prevent soil and water lose. This paper studied climate and hydrology during the last 50 years, and extracted drainage system and topographic characteristics of Loess Plateau. Based on the above datasets, we built Erosive Topography Index(ETI) to analyze the coupling relationships of soil and water lose and topographic characteristics, then investigate impacts of human activities on soil and water lose. The main conclusions were as followed :(1) Topography displays spatial variability in different typical basins, which can cause different soil and water lose. In order to quantitatively analyze topographic characteristics in Loess Plateau, this study built Erosive Topography Index(ETI). There is obvious relationships between ETI and sediment discharge(P<0.05) : sediment discharge increases with the increase of ETI. Topography is an important factor influencing soil and water lose because it can control underlying surface. The slope of regression equation of ETI and sediment discharge of 2000-2011 is larger than that of other sediment discharge, this means that there is other factors that can influence soil an d water lose on the same condition of precipitation, runoff and topography. Sediment discharge decreased significantly since 2000, which means human activities can have obvious impacts on soil and water lose.(2) During 1960-2011, precipitation displays decrease tendency in Loess Plateau, and variable coefficient ranges from 18.13% to 38.66%, which means precipitation presents intermediate variability. Precipitation increased from northwest to southeast, and there is spatial variability in some regions because of topography. During the same period, runoff and sediment discharge have decreased significantly, and the decrease amplitude is 30%-80% and 60%-90%, respectively. Though precipitation and runoff decreased during study period, they appear spatio-temporal variability. The results showed that there is a correlation between precipitation and runoff, runoff and sediment discharge, but precipitation is not the only factor that influence hydrology.(3) During 1981-2009, vegetation coverage of Loess Plateau has been increased obviously, especially since 2000. With increase of vegetation coverage, area and intensity of vegetation cover increased. The vegetation coverage decreased from southeast to northwest and the increase rate became larger since 2000. There is a negative relationship between sediment discharge vegetation coverage : with the increase of vegetation coverage, sediment discharge decreased(R2=0.6). As a result, vegetation is one of the main factors that influence soil and water lose. Except vegetation, check dam is another factor that can influence soil and water lose, and should be studied further.

Mots clés : The Loess Plateau; precipitation; runoff; sediment discharge; Erosion Topography Index(ETI);

Présentation (CNKI)

Page publiée le 31 janvier 2017, mise à jour le 11 septembre 2017