基于小流域划分的沂源县水土保持规划布局及措施配置

Soil and water conservation planning layout and measures configuration for Yiyuan county based on small watersheds

小流域是水土流失综合防治的基本单元,开展小流域划分并确定其防治方向对县域水土保持规划布局具有重要意义。作者以国家级重点治理区沂源县为对象,通过遥感调查、模型计算、资料收集和统计分析等方法,掌握区域现状和水土保持需求,以小流域为单元,提出县域水土保持布局及措施配置。主要结果如下:1)全县水土流失面积为765. 99 km^2,占46. 83%,以轻度侵蚀为主,主要分布在县域东南部、西南部以及东北部等区域; 2)全县划分小流域68条,平均面积为24. 06 km^2,沟道密度1. 87～2. 99 km/km^2,45%的小流域水土流失严重,水土流失面积比高于50%; 3)根据小流域特征和水土保持需求,全县划分为4个水土保持分区,提出了"三带三片"重点布局; 4)建设生态清洁型小流域21条,以封禁治理为主,占55%;建设生态经济型小流域47条,其中东北部以封禁治理为主(45%),东南部以经济林果为主(60%),西南部以封禁治理(35%)和梯田工程(30%)为主。以小流域为单元,开展县级水土保持布局和措施配置研究,可为县域尺度水土流失防治和水土保持管理提供技术支撑和科学依据。

[Background]Small watershed is the basic unit in the comprehensive control of soil erosion and water loss. It is of great significance to carry out the division of small watersheds and determine the control direction for soil and water conservation layout at county scale. Yiyuan county,located in the national key management area,one of the key counties for the comprehensive control of soil and water conservation at the state and provincial level,was taken as the research object in the paper. [Methods]The basic data were remote sensing ZY-3 with resolution 2. 1 m and 1∶ 50 000 maps of topography,soil,administrative division and forest resources. The characteristics of soil erosion in the Yiyuan county wereobtained by CSLE model,and its main influencing factors vegetation coverage was calculated by NDVI（ normalized difference vegetation index） and field survey. The elevation,topographic fluctuation and slope were extracted and the landform types were classified based on the DEM. The land use was determined by human-computer interaction interpretation and field verification. The division of a small watershed was determined based on the ArcSWAT and 25 m DEM combined with rivers and administration division. The layout of soil conservation and the key area of prevention and control were determined by：1） firstly investigating the needs of soil and water conservation via field investigation,and 2） then by spatial overlay and statistical analysis based on the basic information such as land use,slope,forest and grass vegetation coverage,soil erosion and geomorphology according to the combined method of ＂topdown＂and ＂bottom-up＂and the demand of soil and water conservation while taking a small watershed as an unit. [Results] 1） The total area of soil erosion in the county was 765. 99 km^2,accounting for46. 83%,mainly mild erosion,distributed in the southeast,southwest and northeast of the county. 2）There were 68 small watersheds in the county. The average area of a small watershed was 24. 06 km^2,and channel density was from 1. 87 to 2. 99 km/km^2. Soil erosion area percentage of 45% small watersheds was more than 50%. 3） Four soil and water conservation districts and ＂3 Belts and 3 Areas＂key layouts were taken out according to the needs of soil and water conservation and characteristics of small watersheds. 4） The 21 small watersheds would be developed into ecologic and clean-type small watersheds,with enclosure mainly（ 55%）. The 47 small watersheds would be developed into ecological economy watershed,of which mainly with enclosure（ 45%） in the northeast,with economic fruit forest（ 60%） in the southeast,and with enclosure（ 35%） and bench terrace（ 30%） in the southwest.[Conclusions]Soil and water conservation layout and measures configuration at county level,based on the small watersheds and polygon,may provide technical and scientific support for county soil erosion control and soil and water conservation management.