| Soil and water resources are not only the basic conditions for human survival and development,but also the necessary basic resources for the sustainable development of economy,society and ecological environment.Soil erosion has great realistic and potential danger.Serious soil erosion destroys water and soil resources,deteriorating ecological environment and aggravating natural disasters,seriously restricting the high-quality development of economy,society and ecology.It is very important to understand and master soil erosion degree and ecological environment variation in a timely,comprehensive and accurate manner for soil erosion prevention and control,soil and water conservation supervision,and scientific evaluation of soil and water conservation ecological construction.In 2018,the Ministry of Water Resources issued the National Plan for Dynamic Monitoring of Soil and Water Loss(2018-2022),realizing the full coverage of the national dynamic monitoring of soil and water loss,providing a scientific basis for macro decision-making of soil and water conservation and ecological environment construction.In Laohekou city,the soil erosion is serious due to the the dense tributary,small basin area,and slow river water velocity.Therefore,deepening the dynamic monitoring of soil erosion in Laohekou city and strengthening the modern countermeasures of soil erosion prevention and control are the key to the local soil erosion prevention and ecological environment improvement,and the key to solve the local soil erosion problem.This study took Laohekou city as the research area,the soil erosion factor and soil erosion amount were calculated by using the CSLE model and GIS spatial analysis,and the soil erosion intensity and area in 2010,2015 and 2020 were obtained according to the soil erosion classification and grading standards.Combined with the land use data of the corresponding period,the relationship between land use and soil erosion was analyzed.Finally,based on the soil erosion data of three periods,the CA-Markov model was applied to simulate and predict the soil erosion intensity in IDRISI in 2025,in order to provide scientific and technological support for the construction of water and soil conservation ecological environment in this area.The main conclusions were as follows:(1)Based on the remote sensing images of Laohekou City in 2010/2015/2020,the human-computer interaction interpretation was used to obtain the land use status in different periods.The results showed that the land use area change in Laohekou City was mainly based on arable land,and the change of vegetation coverage area was mainly high,medium high and medium cover.The cultivated land area of Laohekou City accounts for more than 65%of the land area,and the dynamic index of cultivated land,forest land,grassland,construction land and water in 2010-2020 was 0.95%,0.14%,0.005%,-0.75%and-0.34%respectively,and the change of cultivated land is the largest.Compared with 2010,the area of high-cover vegetation increased by 100.82 km2 in 2020,and the area of medium-high and medium-cover area decreased by 56.47 km2 and 40.16 km2,accounting for 98.7%of the total area of vegetation cover change.(2)The soil erosion modulus was calculated and the intensity classification was carried out by CSLE,and the results showed that the average soil erosion modulus of Laohekou City in 2010,2015 and 2020 were 264.42 t/km2·a,98.64 t/km2·a and 49.78 t/km2·a,respectively.Spatially,with a distribution pattern of high in the northwest,low in the west and low in the south.The soil erosion modulus of grassland and construction land was higher than that of forest land.In 2010,2015 and 2020,the soil erosion area of Laohekou City accounted for 13.46%,3.5%and 1.88%of the total land area,respectively,and soil erosion was mainly mild.In terms of land type,mild erosion was mainly distributed in grassland,construction land and cultivated land,moderate erosion was mainly distributed on grassland and construction land,and strong and extremely strong erosion was distributed on grassland,without severe erosion area.(3)From 2010 to 2020,soil erosion amount and soil erosion intensity in Laohekou City showed a double decreasing trend.Compared with 2010,the average soil erosion modulus in 2015 and 2020 decreased by 62.7%and 81.17%,respectively.Compared with 2010,the area of slight erosion increased by 11.51%,while the area of mild,moderate,intense and extremely intense erosion decreased by 73.52%,77.35%,98.18%and 100%,respectively.In 2020,the area of slight erosion increased by 13.38%,while the area of mild,moderate,intense and extremely intense erosion decreased by 85.74%,88.59%,98.79%and 100%,respectively,and without severe erosion area.Under the guidance of macro policy,land use change,higher vegetation coverage,comprehensive control of soil and water loss and supervision of soil and water conservation were the main reasons for the decline in soil erosion.(4)Soil erosion and soil erosion intensity of different land use types in Laohekou City decreased from 2010 to 2020.Compared with 2 010,the average soil erosion modulus of cultivated land,forest land,grassland and construction land decreased by 62.36%,74.56%,68.42%and 56.03%in 2015,respectively,which decreased by 83.8%,87.03%,82.67%and 69.08%in 2020,respectively.The area of slight erosion of various land use types increased in 2015 and 2020,while the area of slight or above soil erosion decreased,compared with 2010.(5)The CA-Markov model was used to predict the soil erosion in Laohekou city in 2025.The results showed that the area of soil erosion with the intensity higher than mild increased in Laohekou City in 2025.Compared with 2020,the micro-erosion area in Laohekou city decreased by 93.42km2 in 2025,with a decrease of 9.01%.The areas of mild,moderate and intense erosion increased by 92.96km2,0.44km2 and 0.02km2,respectively.Moreover,the change of soil erosion was mainly distributed in cultivated land,forest land and construction land with slope below 25°.Part of forest land transferred to cultivated land,and cultivated land converted to construction land,resulting the decrease of high vegetation coverage was the main reason for the increase of soil loss area. |
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