康保县北部土地沙化特征及其地质影响因素

Characteristics of land desertification and its geological influencing factors in northern Kangbao County

康保县北部是以防风固沙和涵养水源为主的生态脆弱区,肩负着构建京津冀绿色生态屏障的任务,其土地呈现不同程度沙化,且有加速扩展趋势。研究区分布大面积不同粒度含水量低的砂层、冲洪积砂层是沙化的物质基础。土地沙化受气候、土壤类型与母岩来源、地形地貌、地下水位埋深及人类活动等因素影响,浅部地层沉积特征与土地沙化程度具有良好的对应关系,全新世湖沼积、冲洪积及马兰组(Qp 3m)分布区基本为土地轻度沙化区。基岩出露或埋深较浅区和迁安组(Qp 3q)分布区大部分地段为土地中度沙化和重度沙化区。为解决好康保县北部生态环境问题对京津冀生态功能建设和资源环境可持续发展的制约,建议提高植被覆盖率,增强防风固沙生态功能;采用多种形式保护土壤,形成良好土壤结构;调整农牧比例,合理利用水资源。

The northern part of Kangbao County is an ecologically fragile area dominated by windbreak and sand fixation,and water conservation.It shoulders the task of building the green ecological barrier Beijing,Tianjin and Hebei.The land shows different degrees of desertification,and the trend of accelerated expansion.The dry sand layer and alluvial-diluvial sand layer with different grain size distributed in the study area are the basic materials of desertification.Land desertification is affected by climate,soil type,source of parent rock,topography and landform,depth of water table and human activities.The sedimentary characteristics of shallow strata exhibit a good corresponding relationship with the degree of land desertification.The distribution areas for holocene lacustrine,alluvial-diluvial and Malan Formation(Qp 3m)are basically lightly sandy areas.Most of the distribution areas of Qian'an Formation(Qp 3q)are moderately and severely desertified areas.In order to solve the ecological problems in the northern part of the Kangbao County,it is suggested to improve the vegetation coverage rate,strengthen the ecological function of windbreak and sand fixation,adopt various forms to protect soil and promote good soil structure,and adjust the proportion of agriculture and animal husbandry to rational usage of water resources.