Atkinson Samuel F, Lake Matthew C
Advanced Environmental Research Institute, University of North Texas, Denton, TX, United States of America.
Department of Biological Sciences, University of North Texas, Denton, TX, United States of America.
PeerJ. 2020 Feb 4;8:e8174. doi: 10.7717/peerj.8174. eCollection 2020.
Riparian corridors can affect nutrient, organic matter, and sediment transport, all of which shape water quality in streams and connected downstream waters. When functioning riparian corridors remain intact, they provide highly valued water quality ecosystem services. However, in rapidly urbanizing watersheds, riparian corridors are susceptible to development modifications that adversely affect those ecosystem services. Protecting high quality riparian corridors or restoring low quality corridors are widely advocated as watershed level water quality management options for protecting those ecosystem services. The two approaches, protection or restoration, should be viewed as complementary by watershed managers and provide a foundation for targeting highly functioning riparian corridors for protection or for identifying poorly functioning corridors for restoration. Ascertaining which strategy to use is often motivated by a specific ecosystem service, for example water quality, upon which watershed management is focused. We have previously reported on a spatially explicit model that focused on identifying riparian corridors that have specific characteristics that make them well suited for purposes of preservation and protection focused on water quality. Here we hypothesize that focusing on restoration, rather than protection, can be the basis for developing a watershed level strategy for improving water quality in urbanizing watersheds.
The model described here represents a geographic information system (GIS) based approach that utilizes riparian characteristics extracted from 40-meter wide corridors centered on streams and rivers. The model focuses on drinking water reservoir watersheds that can be analyzed at the sub-watershed level. Sub-watershed riparian data (vegetation, soil erodibility and surface slope) are scaled and weighted based on watershed management theories for water quality, and riparian restoration scores are assigned. Those scores are used to rank order riparian zones -the lower the score the higher the priority for riparian restoration.
The model was applied to 90 sub-watersheds in the watershed of an important drinking water reservoir in north central Texas, USA. Results from this study area suggest that corridor scores were found to be most correlated to the amount of: forested vegetation, residential land use, soils in the highest erodibility class, and highest surface slope ( = 0.92, < 0.0001). Scores allow watershed managers to rapidly focus on riparian corridors most in need of restoration. A beneficial feature of the model is that it also allows investigation of multiple scenarios of restoration strategies (e.g., revegetation, soil stabilization, flood plain leveling), giving watershed managers a tool to compare and contrast watershed level management plans.
河岸走廊会影响养分、有机物质和沉积物的输送，所有这些都会影响溪流及下游相连水域的水质。当功能正常的河岸走廊保持完整时，它们能提供极有价值的水质生态系统服务。然而，在快速城市化的流域中，河岸走廊容易受到开发改造的影响，进而对这些生态系统服务产生不利影响。作为流域层面的水质管理选项，广泛提倡保护高质量的河岸走廊或恢复低质量的走廊，以保护这些生态系统服务。流域管理者应将保护和恢复这两种方法视为相辅相成的，并为确定需要保护的功能高度健全的河岸走廊或识别需要恢复的功能欠佳的走廊提供基础。确定使用哪种策略通常是由特定的生态系统服务驱动的，例如流域管理所关注的水质。我们之前报道过一个空间明确模型，该模型专注于识别具有特定特征的河岸走廊，这些特征使其非常适合用于以水质保护为目的的保护工作。在此，我们假设专注于恢复而非保护，可以成为制定流域层面策略以改善城市化流域水质的基础。
此处描述的模型代表了一种基于地理信息系统（GIS）的方法，该方法利用从以溪流和河流为中心的40米宽走廊中提取的河岸特征。该模型专注于可在子流域层面进行分析的饮用水源地流域。根据水质的流域管理理论，对子流域河岸数据（植被、土壤可蚀性和地表坡度）进行缩放和加权，并分配河岸恢复分数。这些分数用于对河岸带进行排序——分数越低，河岸恢复的优先级越高。
该模型应用于美国得克萨斯州中北部一个重要饮用水源地流域的90个子流域。该研究区域的结果表明，走廊分数与以下因素的数量最相关：森林植被、住宅用地、最高可蚀性等级的土壤以及最高地表坡度（r = 0.92，p < 0.0001）。分数使流域管理者能够迅速关注最需要恢复的河岸走廊。该模型的一个有益特性是，它还允许研究多种恢复策略方案（例如，植被恢复、土壤稳定、洪泛平原平整），为流域管理者提供了一个比较和对比流域层面管理计划的工具。
