Ramos-Scharrón Carlos E, Macdonald Lee H
Department of Geosciences, Colorado State University, Fort Collins, CO 80523-1482, USA.
J Environ Manage. 2007 Jul;84(2):157-72. doi: 10.1016/j.jenvman.2006.05.019. Epub 2006 Oct 6.
Accelerated erosion and increased sediment yields resulting from changes in land use are a critical environmental problem. Resource managers and decision makers need spatially explicit tools to help them predict the changes in sediment production and delivery due to unpaved roads and other types of land disturbance. This is a particularly important issue in much of the Caribbean because of the rapid pace of development and potential damage to nearshore coral reef communities. The specific objectives of this study were to: (1) develop a GIS-based sediment budget model; (2) use the model to evaluate the effects of unpaved roads on sediment delivery rates in three watersheds on St. John in the US Virgin Islands; and (3) compare the predicted sediment yields to pre-existing data. The St. John Erosion Model (STJ-EROS) is an ArcInfo-based program that uses empirical sediment production functions and delivery ratios to quantify watershed-scale sediment yields. The program consists of six input routines and five routines to calculate sediment production and delivery. The input routines have interfaces that allow the user to adjust the key variables that control sediment production and delivery. The other five routines use pre-set erosion rate constants, user-defined variables, and values from nine data layers to calculate watershed-scale sediment yields from unpaved road travelways, road cutslopes, streambanks, treethrow, and undisturbed hillslopes. STJ-EROS was applied to three basins on St. John with varying levels of development. Predicted sediment yields under natural conditions ranged from 2 to 7Mgkm(-2)yr(-1), while yield rates for current conditions ranged from 8 to 46Mgkm(-2)yr(-1). Unpaved roads are estimated to be increasing sediment delivery rates by 3-6 times for Lameshur Bay, 5-9 times for Fish Bay, and 4-8 times for Cinnamon Bay. Predicted basin-scale sediment yields for both undisturbed and current conditions are within the range of measured sediment yields and bay sedimentation rates. The structure and user interfaces in STJ-EROS mean that the model can be readily adapted to other areas and used to assess the impact of unpaved roads and other land uses sediment production and delivery.
土地利用变化导致的加速侵蚀和沉积物产量增加是一个关键的环境问题。资源管理者和决策者需要空间明确的工具来帮助他们预测由于未铺砌道路和其他类型的土地扰动而导致的沉积物产生和输送变化。由于发展速度快以及对近岸珊瑚礁群落的潜在破坏，这在加勒比地区的大部分地区是一个特别重要的问题。本研究的具体目标是：（1）开发一个基于地理信息系统（GIS）的沉积物预算模型；（2）使用该模型评估未铺砌道路对美属维尔京群岛圣约翰三个流域沉积物输送速率的影响；（3）将预测的沉积物产量与现有数据进行比较。圣约翰侵蚀模型（STJ - EROS）是一个基于ArcInfo的程序，它使用经验沉积物产生函数和输送比率来量化流域尺度的沉积物产量。该程序由六个输入例程和五个计算沉积物产生和输送的例程组成。输入例程具有允许用户调整控制沉积物产生和输送的关键变量的界面。其他五个例程使用预设的侵蚀速率常数、用户定义的变量以及来自九个数据层的值，来计算未铺砌道路行车道、路堑边坡、河岸、树木倒伏和未受干扰的山坡的流域尺度沉积物产量。STJ - EROS应用于圣约翰三个不同发展水平的流域。自然条件下预测的沉积物产量范围为2至7Mgkm(-2)yr(-1)，而当前条件下的产量速率范围为8至46Mgkm(-2)yr(-1)。据估计，未铺砌道路使拉梅舒尔湾的沉积物输送速率增加3至6倍，使鱼湾增加5至9倍，使肉桂湾增加4至8倍。未受干扰和当前条件下预测的流域尺度沉积物产量都在测量的沉积物产量和海湾沉积速率范围内。STJ - EROS的结构和用户界面意味着该模型可以很容易地应用于其他地区，并用于评估未铺砌道路和其他土地利用对沉积物产生和输送的影响。
