Study On Soil An Water Loss Characteristics Of Qi River Basin In Taihang Mountain Based On InVEST Model

Mountain is an important geomorphic unit with abundant biodiversity resources on the earth's land surface,and the mountain is a natural treasure house for storing tourism resources,water resources and mineral resources.It provides a variety of ecosystem services for adjacent areas,such as production,biodiversity,water conservation,soil conservation,and so on.Mountain ecosystem is fragile,and it is the engine and signal amplifier of global change.Under the influence of global change,the soil and water elements and coupling process of the mountain ecosystem will change correspondingly,and have an important influence on the species diversity,types of the mountain vegetation and the service function of the social development.With the rapid development of the economy and society,the vegetation cover area in the ecological system has been reduced,the water conservation ability of the river basin is declining,the river runoff is aggravated,the soil erosion is serious and so on,which has caused serious change in the mountain ecological environment,especially the soil erosion seriously restricts the sustainable development of the mountain area.Mountain system process is very important for ecological evolution and watershed resources and environment.It determines the change of the overall landscape pattern and directly affects the process of water and soil balance.The inherent vulnerability of mountain environment and the instability of ecosystem are very likely to cause soil erosion and ecological degradation.Qihe is a mountainous river,River sourceis short,and the river courseis steeper.The river flow is fast.The Qihe River Basin,located in the south of Taihang Mountain,belongs to the transition zone of mountain and plain,with rich biodiversity and obvious ecological landscape heterogeneity.The basin is located in the Taihang Mountain windward area.It is a rainstorm center in the north of Henan Province,and the flood is very easy to occur.At this time,the river peak is high and the river water is large,which belongs to the serious erosion area.Therefore,under the background of global warming,choosing the typical area of Taihang Mountain(Qihe river basin)as the research area,based on the different land use types,soil types,rainfall data,MODIS-NDVI and DEM data,combined with GIS technology and In VEST model to evaluate the soil erosion characteristics of this area,it can be used for the future of the river water in the Qi River in Taihang Mountain.It provides theoretical basis and decision-making reference for soil loss control,ecological compensation and land use structure adjustment.The conclusions of this study are as follows:(1)The area of cultivated land,grassland and woodland accounts for more than 90% of the total basin area in 2000-2015 years,which is the main land use type in the Qihe River Basin.During the 16 years,the cultivated land area decrease,the grasslandarea,the construction landarea and the water area increased,but the area of woodland changed little.Among the types of land use,the largest soil erosion area is grassland,followed by woodland and cultivated land,and the smallest soil erosion area is unused land.Micro erosion and mild erosion are mainly distributed in woodland,grassland and cultivated land.During the 2000-2015 years,the structure adjustment of land use type and the measures of returning farmland to forest have reduced the annual average soil erosion modulus of the Qihe River Basin.The soil erosion modulus decreased by 79.20% in the 2000-2015 years,and the soil erosion intensity in most areas of the study area shifted from high level to low level.The region of high erosion intensity in Qihe river basin is mainly distributed in Shuzhang Town,Erwu Township and Qiaoshang Township in Huguan County of Shanxi Province,Apricot town in Ping Shun county,Six spring townships in Lingchuan County,In the upper and middle reaches of Sha Yao Township in Huixian of Henan Province,and the middle and lower reaches of Huang Dong Township in Qixian County.(2)Soil erosion has close relationship with the slope,elevation,topography of the terrain factor in Qihe River basin.The soil erosion modulus increases first and then decreases with the elevation of the altitude,The soil erosion modulus at the altitude of 1200 m reaches the maximum,and the largest soil erosion intensity is at 600-1200 m altitude area.The soil erosion modulus increases with the increase of the slope,The slope is greater than 15 degrees,which belongs to moderate or above erosion,and its erosion accounts for 86.98% of total erosion.The modulus of soil erosion increases with the increase of relief.The relief is in the 70-500 m areas,which belongs to moderate or above erosion,and its erosion accounts for 93.86% of total erosion.Soil erosion is serious in the elevation of 600-1200 m,the slope of more than 15 degrees,and the terrain fluctuation of 70-500 m,which is the key area of soil erosion control.(3)The soil erosion modulus of different soil types in the Qihe river basin is in turn from brown soil,tidal soil,yellow soil,cinnamon soil,leached cinnamon soil,calcareous coarse soil,calcareous soil,calcareous red clay,calcareous cinnamon soil,alluvial soil,cinnamon soil,and red clay.The proportion of soil erosion area of different soil types from large to small is as follows: brown soil,Huang Miantu,tidal soil,limy cinnamon soil,leached cinnamon soil,brown soil,calcareous coarse soil,alluvial soil,calcareous soil,cinnamon soil,calcium red clay and red clay.Strong and above erosion intensity mainly occurs in fluvo aquic soil,cinnamon soil,loessial soil and brown soil soil,which is the key point of soil erosion control in Qihe River Basin.(4)The soil retention intensity of Qihe River Basin was significantly reduced in 2000-2015 years,the soil retention intensity was 644.55t/(hm2.a)in 2000,but the soil retention strength decreased to 277.06t/(hm2.a)in 2015.The results of the study on soil retention intensity for various land use types are as follows: The soil retention strength of the woodland is the largest,the grassland is second,and the soil retention intensity of the cultivated land is far less than that of the woodland and grassland;the soil retention strength of the water area is also lower.The total amount of soil conservation in forest land is the highest in the study area,accounting for 45% of the total area,followed by grassland.(5)The soil retention intensity in Qihe river basin is also closely related to terrain factors such as slope,altitude and terrain undulation.The soil retention intensity increased first and then decreased with the increase of altitude.The average retention intensity was the largest in the 1000-1200 m region,and the smallest was less than the 200 m region.In terms of total soil conservation,the total amount of soil conservation in 1200-1400 m elevation area is the largest,followed by 400-600 m area.The soil retention strength increased with the increase of the slope and the relief,and the total soil conservation was mainly in the slope of 15 degree-35 degrees and the relief in 70-500 m,and the soil retention intensity of the region was also large.(6)The soil conservation in Qihe river basin is also closely related to the soil types.The soil conservation strength of the brown soil area and the tidal soil area is the highest,which is 478.27t/(hm2.a)and 331.36t/(hm2.a).The calcareous brown soil area is larger,but the soil retention intensity is small.Therefore,the calcareous brown soil area in the study area is the key area of the next soil and water conservation.