《Journal of Hydrologic Engineering》杂志刊登“人工水库的大小和土地利用/土地覆盖模式对最大降水和洪水的影响：以美国河流上的Folsom大坝为例”

作者：WondmagegnYigzaw, Faisal Hossain and Alfred Kalyanapu

刊物：Journal of Hydrologic Engineering，2012年9月29日

关键词：大坝；变入渗能力模型；可能最大降水；可能最大洪水；土地利用/土地覆盖

摘要：大坝的设计通常用可利用的历史数据进行频率的分析。这种方法的局限在于在设计中不能预见的物理上合理的因素导致的洪水频率的潜在转变。例如，由于来自于水库和土地利用/土地覆盖的强烈的局部大气反馈，相较于其他因素来说未来洪水极值可能改变。通过可能最大降水和流域的水文特性估算可能最大洪水，可能的最大洪水时大坝水力特性的关键设计参数。考虑到降雨径流过程的非线性，一个需要回答的关键问题是，水库大小和土地利用/土地覆盖如何修正极端洪水模式，特别是通过可能的最大降水修正得到的可能最大洪水。利用美国某一具有一个大的人造水库的圈中流域作为典型例子（即Folsom大坝），这次研究应用分布式的变入渗能力模型来从大气反馈模拟的不同的土地利用/土地覆盖情景（有坝之前，当前情景，非灌溉，双水库）中模拟可能的最大洪水。利用区域大气模型系统对大气反馈进行数值模拟来得到可能最大降水。区域大气模型系统产生的可能最大降水通过变入渗能力模型模拟得到可能最大洪水。对有坝之前和当前状态的可能最大洪水的对比显示可能最大洪峰流量能减少大约105 m3/s；当前状态和非灌溉状态的可能最大洪水的对比显示灌溉的发展使可能最大洪峰流量减少大约125m3/s。另一方面，水库大小对可能最大降水几乎没有任何影响，因此也不会对可能最大洪水没有影响。在设计的下游堤防容量可以处理大坝的泄洪能的地方，像该案例，这样的减少预示着对下游的洪水风险的一个可能的影响，任何洪水管理协议应该考虑这种情况。现代大坝设计和运行应当考虑一种集成的大气-水文模拟方法来估算因大坝带来的土地利用/土地覆盖变化导致的极端主动潜在的降水变化，这个例子也支持这种观点。

Impact of Artificial Reservoir Size and Land Use/Land Cover Patterns on Probable Maximum Precipitation and Flood: The Case of Folsom Dam on American River

Authors: WondmagegnYigzaw, Faisal Hossain and Alfred Kalyanapu

Journal: Journal of Hydrologic Engineering, posted ahead of print September 29, 2012

Key words:Dams, Variable Infiltration Capacity (VIC) model, probable maximum precipitation (PMP), probable maximum flood (PMF), land use and land cover.

Abstract:The design of the dams usually considers available historical data for analysis of the flood frequency. The limitation of this approach is the potential shift in flood frequency due to physically plausible factors that cannot be foreseen during design. For example, future flood extremes may change, among other factors, due to strong local atmospheric feedbacks from the reservoir and surrounding land use and land cover (LULC). Probable Maximum Flood (PMF), which is the key design parameter for hydraulic features of a dam, is estimated from Probable Maximum Precipitation (PMP) and the hydrology of the watershed. Given the non-linearity of

the rainfall-runoff process, a key question that needs to be answered is “How do reservoir size and/or LULC modify extreme flood patterns, specifically probable maximum flood via climatic modification of PMP?” Using the American River Watershed (ARW) as a representative example of an impounded watershed with a large artificial reservoir (i.e., Folsom Dam), this study applied the distributed Variable Infiltration Capacity (VIC) model to simulate the PMF from the atmospheric feedbacks simulated for various LULC scenarios (Pre-dam, Current Scenario, Non-irrigation, and Reservoir-double). The atmospheric feedbacks were simulated

numerically as PMP using the Regional Atmospheric Modeling System (RAMS). The RAMS-generated PMP scenarios were propagated through the VIC model to simulate the PMFs. Comparison of PMF results for Pre-dam and Current Scenario conditions showed that PMF peak flow can decrease by about 105 m3/s; while comparison of Current Scenario with Non-irrigation PMF results showed that irrigation development has increased the PMF by 125m3/s. On the other hand, the reservoir size had virtually no detectable impact on PMP and consequently on PMF results. Where downstream levee capacity is already under-designed to handle a dam’s spillway capacity, such as for the case study, such increases indicate a likely impact on downstream flood risk that any flood management protocol must adapt to. The premise that modern dam design and operations should consider an integrated atmospheric-hydrologic modeling approach for estimating proactively potential extreme precipitation variation due to dam-driven LULC change is well supported by this case study. 

原文链接：http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29HE.1943-5584.0000722