| Hilly Region of Central Sichuan Basin(HRCSB)is the most serious area of soil erosion in Sichuan Province,which seriously restricts the ecology,economic and social sustainable development of the local and even the whole province.It is extremely important to find out its temporal-spatial feature and driving factors for prevention and cure work.Based on the RUSLE model,the temporal-spaital features over the 16 years of soil erosion modulus,intensity and amount in HRCSB were analyzed then.Proceed from the aspects of potential erosion,retention capacity and EINDEX,the driving factors and drvie-response mechanism of spatial distribution pattern and dynamics of soil erosion were analyzed too.The main conclusions are as follows:1.The multi-year average modulus of the whole stuy area is about 15.126t·hm-2·a-1,and the erosion amount is about 96 million tons per year.The erosion intensity structures in the past years are all micro > light > moderate > strong > None> extremely strong> intense,under the average state,the proportion is nearly: 51.35%,26.10%,8.64%,4.91%,4.38%,3.70%,0.92%.During the 16 years,all indicators showed an overall downward trend.Erosion improved during 2000 to 2005,but deteriorated in the period of 2005 to 2010,From 2010 to 2015,it has improved greatly again.The soil and water conservation work has achieved the greatest results over the years.2.During the 16 years,the spatial pattern of soil erosion in HRCSB is roughly that the northern deep hill,the middle part of Xin Chang low mountain area and the southwest were severely eroded,and other areas are relatively good.The erosion problems are serious in the counties of Yingshan,Langzhong,Yilong,Yanting,Shehong,Santai,Peng’an,Pengxi,Jialing,Xichong,Nanbu,Pingshan,Muchuan,Weiyuan,etc.but the erosion situation in Shizhong of Neijiang,Longchang,Wusheng,Guang’an,Jianyang,Shawan,Gongjing,Yanjiang,Fushun,Yuechi,Jingyan,Zizhong,Quxian,Gaoping,Jianwei and Shunqing are relatively good.Yilong,Langzhong,Santai,Yanting,Yingshan and Nanbu have the larger amount of erosion,which are more than 5 million tons per year.The lower amount of erosion are in Ziliujing,Shizhong of Neijiang,Qingshen,Gongjing,etc.,which are generally less than 300,000 tons per year.3.In the past 16 years,the erosion intensity of Da’an,Zhongjiang,Daying,Anyue,Fushun,Ziliujing,Jintange,etc.is continuously increased,while the erosion-sensitive counties such as Yingshan,Yilong,Gaoping,Peng’an and Yuechi is continuously improved.After 16 years,the total erosion amount of the whole area has dropped by about 8 million tons.The erosion amount of erosion-sensitive areas such as Yilong,Yingshan,Peng’an and Gaoping has continued to decline.It can be seen that the control is effective,but due to the large base amout,the tratment still needs to be strengthened;For the area of Fushun,Longchang,Yantan,Da’an,Anyue,Zhongjiang,Jin tang and Lezhi where the erosion amount are continuously to rise,great attention to control its continued deterioration should be paid.As for other fluctuating counties,prevention work should also be strengthened.4.The spatial pattern of soil erosion in HRCSB is mainly determined by slop and soil and water conservation measure factor.The slopes in the north,southwest and central areas are large,at the same time,the large-area distribution of sparse woodland with low inhibition ability has little change during the 16 years,so the spatial pattern is maintained.In addition,the medium-and low-coverage grassland with poor inhibition capacity is basically distributed in the deep hills in the north for each period,so the northern deep hills have become the most severely eroded areas for the whole period.LUCC is the main driving factor for the dynamic change of soil erosion.The inhibitory effect from the dynamic transfer of land use types over the past 16 years is highly consistent with the dynamics of soil erosion.In the past 16 years,the waters,forest land,construction land,other woodland and high coverage grassland area with high capacity have been increasing,which has contributed greatly to the improvement of soil erosion.Among them,construction land and other forest land have the largest contribution rate.To a certain extent,it can be considered as the driving result of urbanization development and ecological civilization construction.5.Zoning for prevention and control of soil erosion based on the regional spatial and temporal differentiation of soil erosion is necessary to define the keys of soil and water conservation work in different region.And then,reasonable planning and adjustment of regional land use structure combined with "Land Use/Cover-Erosion" drive-response mechanism,at the same time,reasonable layout of specific engineering measures,biological measures and farming measures combines the driving-response mechanism of "slope-erosion". |
