在长期的风水交互作用下，沙漠与河流相互影响和制约着各自的形成与演化，在不同的时空尺度往往呈现出不同空间组合的地貌格局。河岸沙丘是一种典型的在沙丘与河道尺度上经风水交互作用形成的风沙地貌类型，多发育在干旱和半干旱区河道两侧，叠加在河流地貌之上。本研究在沙丘与河道尺度上，基于风沙地貌数据、流域水系数据和遥感影像等，利用遥感与GIS手段在中国北方十一个一级流域内，提取五级及以上河流两岸的河岸沙丘，绘制各流域河岸沙丘分布图，分析河岸沙丘的总体分布格局，比较各流域内河岸沙丘流动性和复杂性类型的分布差异，探讨沙丘类型随河道距离的变化规律，初步取得以下结果： （1）河岸沙丘的总体分布格局 河岸沙丘的分布格局存在显著的东西差异，在外流区和内流区表现也有所不同。东部流域气候湿润，水分条件优越，河流往往横穿沙地，河岸沙丘多分散在河流的中上游沿岸；西部流域气候干旱，沙漠/沙地广布，河岸沙丘多集中分布于河流深入沙漠的中下游沿岸。在外流区，水系较为发达，河流径流量较大，含沙量较低，河岸沙丘多零星分布在河流中上游沿岸或与支流交汇处；在内流区，河流短小，水道贫乏，河流径流量较小且有季节性变化，含沙量较高，在深入沙漠内部时，河岸沙丘多呈片状分布在河流中下游沿岸。 （2）不同流域的河岸沙丘类型分布差异 河岸沙丘类型在外流区和内流区的分布有显著差异，体现了气候和沙源条件对河岸沙丘发育的影响。外流区多为湿润半湿润气候，降水较为丰富，植被覆盖度高，河道两岸以固定、半固定沙丘为主，流动、半流动沙丘一般较零散地分布在河床、河漫滩处，沙丘类型趋于简单，以简单型沙丘和灌丛沙丘占优势；内流区多为干旱半干旱气候，径流贫乏，沙源充足，河道两岸多分布着成片的流动沙丘，固定、半固定沙丘仅在近河岸处零星分布，沙丘类型丰富且趋于复杂，以复合型沙丘和综合型沙丘占优势。 （3）不同河道距离的河岸沙丘类型分布差异 河岸沙丘类型往往随河道距离发生变化。从沙丘流动性来看，外流区河道两岸流动沙丘随着河道距离的加大，来自河道的沙源量减少，流动沙丘逐渐减少，内流区河道两岸固定、半固定沙丘仅在近河岸少有分布，随着河道距离的增大，距水源越来越远，固定、半固定沙丘明显减少；从沙丘复杂性来看，沙丘类型随河道距离的加大逐渐增多并趋于复杂，复合型沙丘往往出现在距离河道3 km之后，在中西部流域较为明显，简单型沙丘、复合型沙丘随河道距离的加大而递增，灌丛沙丘随河道距离的加大而递减，综合型沙丘的分布在各流域表现不同。研究发现，沙丘类型变化在距河道3~6 km的缓冲带处变化最为显著。

Desert and river interact and restrict the formation and evolution each other by long-term dynamic aeolian-fluvial interaction, and the relationship between desert and river is often manifested as spatial combination. Riparian dunes are a typical landform formed by aeolian-fluvial interaction at the scale of sand dune and river channel, mostly developed on the banks in arid and semi-arid areas and superimposed on river landforms. Based on the data of aeolian landforms, watersheds, water systems, remote sensing images and GIS, this study we extract riparian dunes on the banks of the level five and above rivers in eleven first-level watersheds of northern China, map the distribution pattern of the riparian dunes, analyze the overall distribution pattern of riparian dunes, compare the distribution differences of mobility and complexity types of riparian dunes and explore the relationship between dune types and channel distance. The main conclusions are as follows: (1) The overall distribution pattern of riparian dunes The distribution pattern of riparian dunes varies significantly from east to west, as well as in exorheic and endorheic watersheds.In the eastern watersheds with humid climate and superior water conditions , rivers often directly cross the sand lands, and riparian dunes are mostly scattered along the middle and upper reaches of rivers, while in the western watersheds with arid climate and widespread desert and sand lands, riparian dunes are mostly distributed along the middle and lower reaches of rivers when rivers flow into the interior of the desert. In exorheic watersheds where the water system is more developed and the river has large runoff and low sediment concentration, riparian dunes are mostly scattered in the upper reaches of the river or at the intersection with the tributaries, while in endorheic watersheds where the water system is underdeveloped and the river has small runoff and high sediment concentration, riparian dunes are mostly distributed along the middle and lower reaches of rivers. (2) Distribution differences of riparian dune types in different watershed The distribution of riparian dune types in exorheic and endorheic watersheds is significantly different, which reflects the influence of climate and sand source conditions on the development of riparian dunes. In exorheic watersheds with abundant precipitation and high vegetation coverage, fixed and semi-fixed dunes are dominant on both sides of the river, and mobile and semi-mobile dunes are generally scattered in the riverbeds and floodplains. The riparian dune types in exorheic watersheds tend to be simple, mainly simple dunes and nebkha. In endorheic watersheds with poor runoff and abundant sand sources, mobile dunes are dominant on both sides of the river, and fixed and semi-fixed dunes are scattered only near the river bank. The riparian dune types in endorheic watersheds tend to be complex, mainly compound and complex dunes. (3) Distribution differences of riparian dune types with different channel distances The types of riparian dunes tend to change along with increasing distance from the river bank. For dune types by mobility, the proportion of mobile dunes decreases gradually in exorheic watersheds, while the proportion of fixed and semi-fixed dunes decreases gradually in endorheic watersheds, as their distance from the river increases. For dune types by complexity, the number of dune types increase and the sand dune types tend to complex gradually with increasing distance from the river bank. Compound dunes often appear 3 km from the river bank, especially in the central and western watersheds. The proportion of simple and compound dunes increases, while the proportion of nebkha decreases as their distance from the river increases. The distribution of complex dunes varies in different basins. The study found that the change of sand dune types is significant in the buffer zone between 3 and 6 km from the river channel.