摘要
[Objective] Saline-alkali wasteland is a kind of land use type that formed by soil salinization and secondary salinization. To study the causes of spatial distri- bution of saline-alkali wasteland could be used as reference for the amelioration and is significant for developing the reserved land with great potential. [Method] The re- search set a total of 1 729 sampling points in the study area of 34 433 hm2. Spa- tial analyses were used to find out the causes of saline-alkali wasteland in Datong basin from four factors： topography, geology, hydrology and soil. DEM and land use data were used to calculate distribution index of topography, and distribution of the total salinity （TS） and pH was analyzed by means of IDW interpolation. [Result] The results showed that saline-alkali wasteland was distributed on flat and low-lying ter- rains with poor drainage, which led to salt accumulation. 87% of saline-alkali wasteland was distributed on Quaternary Holocene alluvium whose performance of soil hydraulic conductivity was poor. TS value distribution was that in midstream re- gion was the highest, less in upstream region and the least in downstream region along the rivers, and TS value decreased when distance between saline-alkali wasteland and rivers increased. The major soil types in Datong basin were fluvo- aquic soil and saline soil. Both of the two soil types were of high TS value and pH value, and heavily salinized and strongly alkalized. [Conclusion] High groundwater table and the existence of two salt accumulation centers are the two causes of saline-alkali wasteland in Datong basin. The key to ameliorate saline-alkali waste- land is to descend the groundwater table and lessen salt accumulation.
[目的]盐碱荒地是由于土壤盐渍化和次生盐渍化而形成的未开发利用的土地,掌握其空间分异特征并探究其成因,对于开发盐碱荒地的潜力和增加土地后备资源有着重要意义。[方法]该研究对大同盆地的3.44万hm2盐碱荒地进行了土壤采样调查,布设调查样点1 729个,采用空间分析方法 ,利用DEM、土地类型图等计算地形位分布指数、全盐量反距离权重插值、河流纵比降等,从地形、地质、水文、土壤几个方面分析大同盆地盐碱荒地的成因。[结果]1研究区盐碱荒地的地形位分布指数与其它土地利用类型差异明显,主要分布在地形低洼、地势起伏度小的区域。2由于大同盆地形成向中心倾斜的平原,并在洪积扇前形成凹地,导致积水不易排出。3河流纵向上全盐量的分布呈现出中游最高,面积最大,上游次之,下游最低;河流横向上全盐量分布总体为越靠近河流,全盐量越高,距离河流越远,全盐量越低。4大同盆地盐碱荒地土壤以潮土和盐土为主,这两种土壤类型均为重度盐化和碱化。[结论]从盐碱荒地的分布得出大同盆地有两大积盐中心,分别位于桑干河流域的山阴、应县一带,以及洋河流域的阳高、天镇一带。从其成因和分布提出治理盐碱荒地的关键是降低地下水位,有针对性的进行盐碱荒地改良的水利规划,为大同盆地盐碱荒地的治理提供理论依据。
