Linking hydroecologic form and function in estuary-wetland systems

将河口湿地系统的水文生态形式和功能联系起来

• 批准号: 1013843
• 负责人: Steven Gorelick
• 金额: $ 39.87万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-11-15 至 2015-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1013843&HistoricalAwards=false
• 关键词: Linking; hydroecologic; form; function; estuary

Estuarine wetlands are being degraded and lost at a tremendous rate worldwide. Yet there is a lack of science to support consistently successful wetland restorations and consequently many restorations fail for unknown reasons. The premise of this research is that the health of an estuary is intimately linked to its surrounding landscape, particularly shore-fringing wetlands. This research will analyze 96 major salt marshes surrounding San Francisco Bay using a combination of field data, remote sensing-based pattern recognition, and flow and transport simulation. The marshes range in age from 10s to 1000s of years old, thus enabling statistical assessment of whether marsh hydroecologic complexity is related to marsh development and age, and whether the range of marsh forms is consistent with theories of natural marsh development. Analysis is aimed at determining the relative importance of surface water residence time as it relates to sediment accretion potential, groundwater and solute residence time as a measure of chemical sequestration potential, surface water-groundwater exchange linking wetlands to the estuary, and plant-water interactions. We test two main hypotheses: 1) Site-to-site variations in estuarine salt marsh channel and vegetation patterns (form) result in site-to-site identifiable variations in wetland processes (function). 2) The cumulative form of the marsh fringe around an estuary functions analogously to the hyporheic zone of a riparian system, enhancing long fluid and solute residence times in the coupled marsh-estuary hydrologic system. The first hypothesis is tested by analyzing a set of contrasting marsh sites. Preliminary analysis suggests at least five classes of hydroecologic forms present in the San Francisco estuary. Representative sites for analysis will be identified from the sample of 96 salt marshes using object-based remote sensing image analysis and statistical characterization of channel and vegetation patterns. Statistical analysis will test if the complexity of marsh form is correlated with site restoration, age, or other characteristics. The second hypothesis is tested using a large-scale model coupling estuarine circulation with surface and near surface hydrology of the estuarine wetland fringe. Groundwater simulation will represent subsurface water storage and exchange with the estuary, subsurface solute migration and mixing, and evapotranspiration. Estuarine flow simulation will represent shallow water flow behavior in the Bay. The coupled model will quantify cumulative estuary-marsh fluid and solute exchange and residence times. The broader impact of this research is an improved scientific framework linking the desirable form of the wetland, which is typically engineered during restoration by constructing shaped channels and planting vegetation, to its function, which involves surface water-groundwater exchange, plant water use, and spatially variable hydrological processes. In addition, estuarine and wetland science and education will benefit from a new database of salt marsh attributes by providing significant educational potential of further estuary-wide comparative analyses. With the assistance of the Stanford School of Earth Sciences outreach coordinator, this work will improve local education and restoration/management resources for San Francisco regional salt marshes through a map-based exploration tool and a set of brochures on salt-marsh hydroecology.

河口湿地正在以惊人的速度退化和丧失。然而，缺乏科学支持持续成功的湿地净化，因此许多净化因未知原因而失败。这项研究的前提是，河口的健康与其周围的景观密切相关，特别是滨岸湿地。这项研究将分析96个主要的盐沼周围的弗朗西斯科湾结合使用的现场数据，遥感模式识别，流动和运输模拟。沼泽的年龄范围从10岁到1000岁，从而使统计评估是否沼泽水文生态复杂性与沼泽的发展和年龄，以及是否沼泽形式的范围是一致的自然沼泽发展的理论。分析的目的是确定地表水停留时间的相对重要性，因为它涉及到沉积物堆积的潜力，地下水和溶质停留时间作为衡量化学封存潜力，地表水-地下水交换连接湿地河口，植物-水的相互作用。 我们测试两个主要假设：1）河口盐沼通道和植被格局（形式）的站点间差异导致湿地过程（功能）的站点间可识别差异。 2)河口周围沼泽边缘的累积形式类似于河岸系统的潜流区，增强了耦合沼泽河口水文系统中的流体和溶质停留时间。第一个假设是通过分析一组对比沼泽地进行测试。初步分析表明，在旧金山弗朗西斯科河口至少有五类水文生态形式。将利用基于目标的遥感图像分析和对河道和植被模式的统计特征，从96个盐沼样本中确定分析的代表性地点。统计分析将测试沼泽形态的复杂性是否与场地恢复、年龄或其他特征相关。第二个假设是使用一个大尺度模型耦合河口湿地边缘的河口环流与表面和近表面水文测试。地下水模拟将代表地下水储存和交换与河口，地下溶质迁移和混合，和蒸散。河口水流模拟将代表海湾中的浅水水流行为。耦合模型将量化累计河口沼泽流体和溶质交换和停留时间。 这项研究的更广泛的影响是一个改进的科学框架，连接理想的形式的湿地，这是典型的工程在恢复过程中，通过建造成型的渠道和种植植被，其功能，其中涉及地表水-地下水交换，植物用水，和空间可变的水文过程。此外，河口和湿地的科学和教育将受益于一个新的数据库的盐沼属性提供了重要的教育潜力，进一步河口范围内的比较分析。在斯坦福大学地球科学学院外联协调员的协助下，这项工作将通过一个地图勘探工具和一套关于盐沼水文生态学的小册子，改善旧金山弗朗西斯科区域盐沼的地方教育和恢复/管理资源。