We examine the extent of land cover change and sedimentation within the Tijuana River Estuary due to the significant development within Mexico that has increased sedimentation that could alter estuary elevation. We examined aerial imagery to determine major changes in estuary land cover over time (1995–2016), examined sedimentation patterns by calculating vegetation roughness of two dominant lower marsh species: Salicornia pacifica and Spartina foliosa and directly measured sediment deposition within plant stands at multiple elevations and determined how vegetation may be interrupting flow and affecting deposition. Upper elevation scrub has increased slightly through time while marsh area has decreased. Plant roughness for S. foliosa was significantly higher and, based on modeling, each species creates different water surface and channel velocity conditions that could alter deposition patterns. Vegetation inventories and sediment size deposition analysis within vegetation patches show that S. foliosa occupies those areas closest to the channel, is most frequently inundated, and has the smallest sediment sizes present. Sediment size increases with distance from the channel and where it becomes more commonly dominated by S. pacifica. These areas, typically 0.5-1 m above channel bottom elevation, experience the highest volume of sediment deposition. Modeling and direct measurements of deposition indicate that water velocity is impacted by plant stands and deposition is occurring in areas close to the channel. Because these deposition patterns may eventually result in changes in estuary elevation, continual monitoring should be carried out to determine how vegetation-induced sediment behavior, combined with anthropogenic land-use change and sea level rise, influence estuary elevation and land cover.

中文翻译：

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河口系统中的景观变化与植被-通道相互作用

由于墨西哥境内的重大发展增加了可能改变河口海拔的沉积，因此我们研究了蒂华纳河河口内土地覆盖变化和沉积的程度。我们检查了航空影像，以确定河口土地覆盖物随时间（1995-2016年）的主要变化，通过计算两种主要的下沼泽沼泽物种（Salicornia pacifica和Spartina foliosa）的植被粗糙度来检查沉积模式，并直接测量了多个海拔植物的沉积物沉积并确定植被可能如何中断流量并影响沉积。随着时间的推移，高海拔灌木丛略有增加，而沼泽地面积却有所减少。叶草的植物粗糙度明显更高，并且根据建模，每个物种都会创建不同的水面和通道速度条件，从而可能改变沉积模式。植被斑块内的植被清单和沉积物大小沉积分析表明，叶叶链球菌占据了最靠近河道的那些区域，被淹没的频率最高，并且沉积物尺寸最小。沉积物的大小会随着与河道的距离增加而增加，在此情况下，沉积物通常会以太平洋链球菌为主。这些区域通常在河道底面高程以上0.5-1 m处，沉积物沉积量最大。沉积物的建模和直接测量表明水速受植物林分的影响，并且沉积物发生在河道附近。由于这些沉积模式最终可能导致河口海拔变化，因此应进行连续监测以确定植被引起的沉积物行为，以及人为的土地利用变化和海平面上升如何影响河口海拔和土地覆盖。