盐城典型滨海潮滩湿地地形地貌特征及其对景观分异的影响

发布时间：2019-02-25 14:31

【摘要】：地形是原始湿地保护与管理的基础性数据,并影响着湿地景观的结构和空间格局演变。盐城滨海潮滩湿地作为典型的原始湿地之一,受限于湿地客观条件,过去一直没有完整的高程测量,使得地形研究成为该湿地的“空白区”。地形作为景观结构和空间格局的重要影响因子,不仅为景观格局的形成提供基础,其空间特征也影响着景观的演变过程。另外,潮滩上发育的潮沟系统,不仅形成了复杂的微地貌类型,而且还形成了独特的米草潮沟系统,成为潮滩演变的重要标志。因此,本文以盐城自然保护区核心区为研究区域,采用1996—2012年3期的时间跨度为16年的遥感影像,再结合实测地形数据的基础上,对湿地地形模拟、潮沟微地貌系统及其对米草扩张的影响,以及景观分布与演变对地形因子的响应特征等方面进行了研究。基本结论如下： (1)湿地DEM构建与精度评价。基于Kriging和TIN两种方法对潮滩内DEM进行了构建,结果显示两种方法都能够较好的模拟湿地地形。TIN-DEM精度较高,而Kriging-DEM表面光滑性更好。同时,提取水边线并结合实测高程剖面的方法构建了潮滩外DEM,精度较以往显著提高。 (2)地形特征对湿地景观分异的影响。各景观类型在地形区间上呈梯级分布,米草带主要分布于0.9—1.5m,碱蓬带主要分布于1.5—2.1m,而芦苇带则主要分布于2.1—2.7m。同时,湿地景观空间分布特征与地形关系比较明显。米草空间分布向0.6—1.2m区间演变,显示出强烈的向低海拔区间扩张的趋势；碱蓬分布范围随地形的升高总体上呈下降趋势；芦苇在地形较高区间上的分布指数增长迅速,其优势分布区间向2.1—3.0m扩展。 (3)潮滩淤长与0m等高线变化。1996—2002年0m线所围面积以0.59km2/a的速度在向海方向缓慢淤积,Om线年均向海推进速度只有43m/a,湿地变化处于较缓慢状态,淤积呈自然平衡发展；而2002—2012年的10年间,增长速度达2.89km2/a,0m线年均推进速度也骤升为106m/a,湿地的淤积速度在逐渐加快,稳定性受到较大影响,正呈现着一种非正常的淤积状态。 (4)潮沟系统对米草扩张的影响。在潮流和地形作用的控制下,本区并无大型潮沟分布,潮沟规模从北至南依次增大,发育高程为0—1.8m。米草潮沟系统具有独特特征：潮沟多窄而深、密度大、分级多、侧向迁移小于纵向迁移、宽深比较小；潮沟两侧发育高度不等的不对称性的沿岸堤；盐沼边缘发育有陡坎和冲沟,并贯穿整个米草带。潮沟发育是影响米草向内陆碱蓬区扩张的因素之一,起着非常重要的引领作用,而米草陆向扩张的宽度和幅度取决于所在区域潮沟的发育程度。同时,随米草扩张速度的降低,光滩上潮沟的活动性有所放缓。
[Abstract]:Topography is the basic data for the conservation and management of the original wetland and affects the structure and spatial pattern evolution of the wetland landscape. Yancheng coastal tidal beach wetland, as one of the typical original wetlands, is limited by the objective conditions of the wetland, and there has been no complete elevation survey in the past, which makes the terrain study become the "blank area" of the wetland. As an important influence factor of landscape structure and spatial pattern, terrain not only provides the basis for the formation of landscape pattern, but also affects the evolution of landscape. In addition, the tidal channel system developed on the tidal flat has not only formed complex micro-geomorphologic types, but also formed a unique rice-grass tidal channel system, which has become an important symbol of the tidal flat evolution. Therefore, this paper takes the core area of Yancheng Nature Reserve as the research area, adopts the remote sensing image of the period 1996-2012, which spans 16 years, and then simulates the wetland topography on the basis of the measured terrain data. The micro-geomorphologic system of tidal gully and its influence on the expansion of rice grass, as well as the response characteristics of landscape distribution and evolution to topographic factors were studied. The basic conclusions are as follows: (1) Wetland DEM construction and accuracy evaluation. Two methods, Kriging and TIN, are used to construct DEM in tidal flat. The results show that both methods can simulate wetland topography well. The accuracy of TIN-DEM is higher than that of Kriging-DEM, while the surface smoothness of Kriging-DEM is better. At the same time, the precision of DEM, outside the tidal flat is significantly improved by the method of extracting the water boundary and combining with the measured elevation profile. (2) the influence of topographic characteristics on wetland landscape differentiation. The landscape types were distributed step by step in the terrain interval. The main distribution was 0.9 ~ 1.5 m in the rice grass belt, 1.5 ~ 2.1 m in the Suaeda salsa zone, and 2.1 ~ 2.7 m in the Reed zone. At the same time, the relationship between the spatial distribution of wetland landscape and topography is obvious. The spatial distribution of M. oryzae evolved to 0.6 m 1.2 m, showing a strong trend of expansion to low altitude, while the distribution range of Suaeda salsa decreased with the increase of topography, and the spatial distribution of Suaeda salsa showed a decreasing trend with the increase of topography. The distribution index of Phragmites australis increased rapidly in the higher terrain range, and its dominant distribution range expanded to 2.1 ~ 3.0 m. (3) the change of tidal beach siltation length and 0 m contour line. The area around the 0 m line accumulated slowly in the direction of sea with the speed of 0.59km2/a in 1996-2002, and the average annual propulsion speed of Om line in the sea was only 43 m / a, and the change of wetland was in a relatively slow state. The deposition develops in a natural balance; In the 10 years of 2002 / 2012, the growth rate was 2.89km2 / a, and the average advancing speed of 0m line was also increased to 106m / a. The deposition rate of wetland was accelerating gradually, and the stability was greatly affected, which was presenting an abnormal state of siltation. (2) in the past 10 years, the growth rate was 2.89km2 / a, and the average advancing speed of 0m line was also increased to 106mpa. (4) the effect of tidal channel system on the expansion of rice grass. Under the control of tidal current and topography, there is no large tidal gully distribution in this area. The scale of tidal gully increases from north to south, and the development elevation is 0. 8m. Meicao tidal trench system is characterized by narrow and deep tidal gully, high density, multi-grade, lateral migration less than longitudinal migration, small width and depth, asymmetric coastal dikes with different height on both sides of tidal gullies. The edge of salt marsh has steep ridges and gullies, and runs through the whole rice grass belt. The development of tidal gutter is one of the factors that affect the expansion of rice grass to the inland area of Suaeda salsa, which plays a very important leading role, and the width and amplitude of the land expansion depends on the development degree of the tidal trench in the region where it is located. At the same time, with the decrease of the speed of rice grass expansion, the activity of tidal trench on the light beach slowed down.
【学位授予单位】：南京师范大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P737.1;P901

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