Study On Distribution Pattern And Driving Factors Of Water/Wind Erosion In Yellow River Alluvial Area Of Huaihe River Basin

This research has chosen Yellow River Alluvial Area of Huaihe River Basin as the studyarea. Multi-resources satellite imageries, such as ALOS、TM、MODIS、AMSR-E、IRS,were used in the research as mainly data sources. Theory of soil and water conservation, aswell as geographic information theory were applied as guidance. Erodible soil distributionregion, model parameter factors, wind/water erosion pattern, complex erosion division bywind and water, wind/water erosion causes and driving factors were analyzed and evaluatedusing methods of remote sensing and field investigation and verification. Main results are asfollows:1. Demarcation of erodible soil features in Yellow River Alluvial AreaDefing the features of erodible soil according to aeolian sands erodibility, soil type, soiltexture, soil bond force. As follows: Aeolian sands of granulometric composition between0.075to0.40; erodibility is easily erodible; soil types are meadow aeolian soil, loamywarping alluvial soil, sandy flove aquic, loamy alluvial soil, chloridate damp soil, sandyalluvial soil genus; soil texture is loose sand, tighten sandy, sandy loam, light loam or sandysoil, loamy sand; Soil bond force is weak.2. Model parameter factors（1）Wind erosionWind erosion involves Wind factors, surface moisture factor, surface roughness factor,and vegetation factor. Compute wind erosion modulus at last.Wind factors. Mainly consist of leaving speed of sand and cumulated time over leavingspeed.According to field investigation and homogeneous region research results, ascertainleaving speed of loose sand and tighten sandy5.5m/s, sandy loam and light loam6.8m/s.Cumulated time of western region, such as Zhengzhou, Kaifeng, Lankao and Yongcheng islong, while the central region, such as Shanxian, Jinxiang is limited.Surface moisture factor. Surface moisture distribution is of obvious regional difference,presenting a declining trend from east to west. Areas along the Nansihu lake are of highermoisture, while Zhongmu, Xinzheng, Kaifeng are low. Surface roughness factor. West of the area are lower, compared with Suixian, Ningling,Caoxian, Yuncheng, where are the Peak center. Roughness becomes higher with the growthof wheat, during which, the vegetation coverage becomes higher too.Vegetation coverage factor. From the spatial distribution, vegetation coverage ofsouthern areas, such as Yongcheng, Xiayi, Suiyang, Zhecheng is higher, while Liangshan,Juancheng, Yuncheng, Jinxiang are lower. From the temporal distribution, vegetationcoverage is very low in winter and spring. Vegetation coverage becomes higher with thedevelopment of wheat, meanwhile, the variation bewteen south and north becomes narrower.Wind erosion modulus. Maximum2513t/km~2a, minmum201t/km~2a, average673t/km~2a. The distribution of wind erosion is comparatively centralized, mainly in areas wheremicrotopography is obvious, such as Xinzheng, Zhongmu, Zhengzhou, Kkaifeng, Kaifengmunicipal districts, and areas south of Yellow River bank, such as Lankao, Dongming,Juancheng, Yuncheng.（2）Water erosionWater erosion involves rainfall erosion force factor, soil erodiblity factor, terrain factor,biological-control factor, engineering-control factor, and agricultral-control factor. Computewater erosion modulus at last.Rainfall erosion force factor. Rainfall erosion force is between2250MJ mm/hm~2h aand5680MJ mm/hm~2h a, Presenting the increasing trend from northwest to southeast alongthe south bank.of Yellow River The peak centre is in Yongcheng city, Henan province.Thesoil eroblity is between0.222and0.465. Salinization fluvo-aquino soil holds the firstplace(0.465), meadow cinnamon soil seconds(0.225), meadow solonchak subclass last. Theterrain of the study area is flat, with minor slope. Maximum slope is31°, which appears intorso mountain of Jiaxiang. Maximum water erosion modulus is494t/km~2a, minimum0. Thehigher water erosion modulus mainly take place in low mountain and monadnock of Jiaxiangand Liangshan.3.Construct wind erosion classification system of Yellow River Alluvial AreaAccoding to field investigation and samles, Combined with the characteristics of winderosion occurrence and development, topography features, remoute sensing features anddistribution status of Yellow River Aluvial Area, the author constructed wind erosionclassification system of Yellow River Alluvial Area in Huaihe River Basin through theanalysis of mutual relations between different factors and wind erosion,as well as based oncharacteristic factors feedback method, quantitative features classification method, andNatural Breaks method. Dominant principle, comprehensive principle, practical principle, as well as scientific and objective principle were also applied in the construction system. At last,the author established the interpretation keys.4. Identify wind/water erosion pattern in Yellow River Alluvial Area（1）Wind erosionTotal wind erosion area sums8742.95km~2, takes up24.89%of the total land area.Among all the erosion area, light erosion6341.86km~2, takes up72.54%of wind erosion area;middle degree erosion1548.84km~2,17.72%of wind erosion area; intensive erosion852.24km~2,9.75%of wind erosion area. The data indicates the wind erosion area is large, and theerosion intensity are mainly light erosion and middle degree erosion, partially intensiveerosion.Wind erosion unevenly-distributes, mainly in Jialuhe river system, such as Xinzheng,Zhengzhou, Zhongmou, along Yellow River, Kaifeng, Lankao, Dongming, Yuncheng, as wellas the former Yellow River alley area, such as Caoxian, Shanxiany.The occurance and development of wind erosion in the study area is related to theunderlying surface conditions and the corresponding climate. The underlying surface (soil,vegetation, landform etc.) provides matrix of wind erosion, while climatic conditions (windspeed, wind, etc.) are dynamic factors of wind erosion. Meadow sandy soil wind erosionintensity is high, while the corrosion stability of fluvo-aquic soil and cinnamon soil becomesstronger, wind erosion intensity becomes weaker under human cultivation. In the same time,the process was going with the increasing of organic matter and improvement of soil physicalproperties.（2）water erosionTotal water erosion area sums2.01km~2, just took up0.01%of the total land area, andall of the erosion are light erosion, which indicates the intensity of the study area is weak.Water erosion centralized distributes, mainly in microgeomorphology area, such as Jiaxiang,Liangshan, Xinzheng, Zhongmu, Weishi and Yongcheng.5.Divide complex erosion division by wind and water in Yellow River Alluvial AreaThe author discussed the doubts of existence of complex erosion division by wind andwater in Yellow River Alluvial Area based on wind erosion and water erosion contour maps.At the same time, according to the erosive force combination, topography and surfacematerial combination, the author divide the Yellow River Alluvial Area into threeregions:①wind erosion zone;②w ater erosion zone;③wind/water composit erosion zone,which were based on wind/water erosion counter maps. Among the divisions: wind erosion zone mainly distributes in Xinzheng-Zhongmu-Kaifeng area, where the microgeomorphology is obvious relatively. The wind/watercomposite erosion zone mainly distributes in Kaifeng-Dongming-Juancheng-Yuncheng stripeand Caoxian-Shanxian stripe, which besides the south coast of Yellow River and the formerYellow River vally.The water erosion zone mainly distributes in West of Nansihu Lake-Eastof Henan inclined plain.6. Identify causes and driving factors of wind/water erosion in Yellow River AlluvialAreaThe climate factors are the main background for wind/water erosion. Large amount ofsediment carried by Yellow River diversion, flood and irrigation; erodible soil and seasonalsuccession of vegetation provide the basic condition for wind erosion. At the same time, withthe increasing of population and demands of resources, the development of economic forest,traditional try farming as well as human cultivation further the wind/water erosion. In aconclusion, the occurance and development of wind/water erosion is a historical process withthe mutual interaction of natural factors and artificial factors.