生态

 

HEC-WAT: A Planning Tool for Watersheds

HEC-WAT:一款流域规划工具

 

Adams, Lea, Chief – Water Resource Systems Division, USACE – Hydrologic Engineering Center, Davis, CA, lea.g.adams@usace.army.mil
Adams，Lea，美国陆军工程兵团水文工程中心水资源系统部门主管，加利福尼亚州戴维斯市，lea.g.adams@usace.army.mil

 

Lehman,William, Senior Economist, USACE – Hydrologic Engineering Center, Davis, CA，william.p.lehman@usace.army.mil
Lehman，William,美国陆军工程兵团水文工程中心高级经济分析师，加利福尼亚州戴维斯市，william.p.lehman@usace.army.mil

 

Introduction

介绍

 

The USACE Hydrologic Engineering Center (HEC) released Hydrologic Engineering Center Watershed Analysis Tool (HEC-WAT) Version 1.0 in September 2017. HEC-WAT is a flexible software application designed to support the field of water resources engineering. Because of its flexibility, the mission statement for HEC-WAT is necessarily broad: A water resources tool that integrates engineering and consequence software to support a wide range of USACE applications, including watershed and systems-based risk analysis.

 

2017年9月，美国陆军工程兵团（USACE）水文工程中心（HEC）发布了水文分析工具（HEC-WAT）的第一个版本（Version 1.0）。HEC-WAT是一软针对水资源工程领域开发出来的应用软件，因其灵活的适用性，决定了它具有广泛的应用场景。根据HEC-WAT的宗旨声明，HEC-WAT作为整合USACE众多的工程设计和模型演算软件的工具，旨在为这些软件提供更好分析支持，包括流域和基于系统的风险分析。

 

HEC-WAT was developed in response to a series of USACE policy documents stretching back to 2000 that established study guidelines requiring that the planning process “address the Nation’s water resources needs in a systems context” (Engineer Regulation 1105-2-100), and apply risk assessment methods (Engineer Regulation 1105-2-101). In short, these and other policy documents required USACE to evaluate projects more comprehensively and with consideration of risk and uncertainty.

 

水文工程中心（HEC）最初开发HEC-WAT的目的是为了响应美国陆军工程兵团（USACE）于2000年发布的一系列政策文件。这些政策文件制定的研究指南要求水资源规划编制“需要在一定系统条件下解决国家水资源问题”（工程师条例1105-2-100），并且要采用风险评估的方法（工程师条例1105-2-101）。简而言之，这些政策文件要求USACE评估项目时更加细节一些，多考虑风险问题和不确定性。

 

Beyond supporting USACE requirements, it’s readily apparent that study teams in the field of water resources should take a broad perspective when solving problems. With climate change, population growth and demographic shifts, the demands on our infrastructure to reduce our risk from extreme conditions of drought and flood are increasing. And to meet these demands, we have to more fully embrace integrated water resource management. HEC-WAT is a useful tool for evaluating projects from a more cohesive, watershed-scale perspective.

 

很明显，HEC-WAT除了为USACE的需求提供支持外，还要求水资源领域研究团队在使用HEC-WAT解决水资源问题时需要具备广阔的视野。诸如气候变化、人口增长和迁移、为减少极端干旱和洪涝风险，基础设施的需求量正在不断增大等。对了应对这些需求，必须要全面拥抱集成式的水资源管理。HEC-WAT正是在这样的需求背景下开发出来的，HEC-WAT从系统化、流域化的角度对项目进行评估，可以说是一款适应当下需求的工具。

 

This discussion focuses on using HEC-WAT as a planning tool at the watershed scale. The three key topics are: 1) integration of software that evaluates various aspects of water resources within a watershed; 2) spatial representation of watershed processes; and 3) incorporation of risk and uncertainty study methods. In addition, results are reviewed and several example project applications are described to illustrate different watershed planning use cases for HEC-WAT.

 

本文重点讨论在流域尺度上采用HEC-WTA作为水资源规划工具。主要分为3个主题：1）流域水资源要素的评估软件的集成，2）流域过程的空间表达，3）水资源风险与不确定性研究方法的结合。

 

Integration of Water Resources Software

水资源软件的集成

 

Currently, HEC-WAT integrates four primary pieces of HEC water resources software: HEC-HMS, HEC-ResSim, HEC-RAS and HEC-FIA. Each of these programs allows users to evaluate a specific aspect of water resources management within a watershed: HEC-HMS (Hydrologic Modeling System) models the rainfall-runoff transformation, HEC-ResSim (Reservoir System Simulation) models reservoir operations, HEC-RAS (River Analysis System) models river hydraulics and HEC-FIA (Flood Impact Analysis) models damage and life loss due to flooding. HEC-WAT integrates these software packages by facilitating the flow of information from one model to the next, eliminating the need for manual handoffs by a modeler. When a study team is evaluating a large number of planning alternatives (especially large-scale or complexal ternatives), creating the data communication pathways inside HEC-WAT can save a tremendous amount of time, as linking models only needs to be done once. Connecting models inside HEC-WAT can also eliminate errors that accidentally occur when users manually transfer data from one model to the next. HEC-WAT allows import of existing HEC models (e.g. HECHMS, HEC-RAS, etc.) to efficiently re-use available data, or users can build new individual HEC models within the HEC-WAT framework.

 

目前，HEC-WAT集成了水文工程中心（HEC）主要的4款水资源软件:HEC-HMS,HEC-ResSim,HEC-RAS以及HEC-FIA。这4个程序允许用户在流域尺度对水资源管理的特定要素进行评估：HEC-HMS（Hydrologic Modeling System）模拟降雨-径流转换，HEC-ResSim (Reservoir System Simulation)模拟水库调度，HEC-RAS (River Analysis System) 模拟河道水力工况，HEC-FIA (Flood Impact Analysis)模拟因洪涝造成的生命财产损失。HEC-WAT通过促进信息流在软件之间传递，将这4个软件包集成在一起，消除了软件操作人员的手动操作工作量。当研究团队对大量的规划方案进行评估时，特别是评估大尺度的复杂规划方案时，在HEC-WAT工具内部创建数据传递路径可以节省大量时间，因为耦合模型只需要设置一次就能完成信息流的传递，在HEC-WAT内部相互联系的模型还能消除由于用户在各软件之间手动输入传递数据出现的偶然失误。HEC-WAT还允许导入现有的HEC模型（例如 HECHMS, HEC-RAS等）以有效地重复使用可用的数据，也允许用户在HEC-WAT框架内新建一个独立的HEC模型。

 

 

Spatial Representation of Watershed Processes

流域过程的空间表达

 

The spatial component of a watershed-scale water resources study is often key to accomplishing the purpose of the study. One example that illustrates this concept is the application of HEC-WAT to evaluate potential modifications to reservoir operations within the Russian River,California, watershed (Figure 1). In this case, the study team analyzed the changes in flood frequency in the downstream communities of Healdsburg and Guerneville in response to various operational alternatives at Lake Mendocino in the upper watershed. The reservoir is located 50 to 80 miles upstream of the communities of concern, with a number of tributaries joining the Russian River along the way. In this case, the impact locations of concern were spatially distant from the project location within the watershed. The analysis also crossed modeling platforms, using stage-frequency results from HEC-RAS to evaluate flood risk impacts in response to reservoir operation changes modeled in HEC-ResSim. In this way, HEC-WAT supports both the spatial and cross-platform modeling components of watershed evaluations, providing a comprehensive analysis approach.

 

流域尺度水资源研究的空间组成往往是实现研究目的关键。这一点可以用以下案例来说明：HEC-WAT在评估加利福尼亚州俄罗斯河流域内水库调度潜在修正中的应用。在这个案例中，研究团队分析了俄罗斯河流域下游Healdsburg社区和uerneville社区的洪水频次与流域上游Mendocino水库调度方案之间的关系。Mendocino湖位于距离社区中心上游50至80英里处，同时，俄罗斯河沿途有众多支流汇入，在案例中，流域内研究人员关注的影响地点远离项目地点。案例采用HEC-WAT进行模拟，在HEC-WAT框架内可以建立耦合模型，应用HEC-RAS即时频率模拟结果评估洪涝风险的影响，从而对HEC-ResSim的水库调度变化做出响应。通过这种方法，HEC-WAT既支持水资源要素评估软件的耦合，又能提供更加细节的分析方法。

 

Russian River Watershed Risk and Uncertainty Methods

俄罗斯河流域风险和不确定方法

 

The HEC-WAT Flood Risk Analysis (FRA) compute type utilizes a Monte Carlo-style compute to support risk analysis. Hydrologic boundary conditions(precipitation and flow) are typically generated within a tool called the Hydrologic Sampler within HEC-WAT. Uncertainty in initial conditions and parameter values are sampled from uncertainty distributions specified by users within the individual HEC software programs. For example, starting reservoir pool elevations can be sampled within HEC-ResSim, initial loss rates within HEC-HMS, and uncertainty in structure first floor elevations within HEC-FIA. Within a standard FRA compute, hundreds or thousands of events are generated. Each flood event is hydrologically independent, and multiple flood events are organized into groups of events termed ‘realizations’ (consisting of a minimum of 500 events). Two types of uncertainty are sampled separately within HEC-WAT: knowledge uncertainty and natural variability. Knowledge uncertainty parameters are sampled once per realization, while natural variability parameters are sampled for each flood event within a realization.

 

HEC-WAT中的洪涝风险分析(FRA)模块采用蒙特卡罗算式为流域提供风险分析。模型的水文边界条件（降雨和流量）通常由HEC-WAT中一款做Hydrologic Sampler的工具生成。模型初始条件的不确定性和参数值从不确定分布中取样，这种不确定分布是由用户在独立的HEC软件程序中指定的。例如，水库的初始水位数值调用HEC-ResSim模型中的数值，初损率调用HEC-HMS模型中的数值，以及构筑物的首层标高调用HEC-FIA模型中的数值。一个标准的FRA模型，将产生成百上千个水文事件。每一个洪涝事件都是独立的水文工况模型，多个洪涝事件组成一个事件组团，称之为“实践计划”（最小由500个事件组成）。在HEC-WAT中有两种形式的不确定性参数是分开采样的，一种是常识不确定性参数，另一种是自然变异性参数。常识不确定性参数在每一个实践计划中取样一次，而自然变异性参数则在每个实践计划发生洪涝时取样。

 

 

Project Results and Example Studies

方案模拟结果和案例研究

 

HEC-WAT users can access standard results from the individual HEC software applications, as well as results specific to an HEC-WAT compute. Results for variables of interest generated during an HEC-WAT FRA compute can be viewed by individual event, or viewed collectively via histograms and frequency curves with uncertainty bounds. Depending on the variable, results can also be displayed spatially.

 

HEC-WAT的用户可以从独立的HEC软件应用获得标准的模拟结果表达，也可以从HEC-WAT中获得制定工况的模拟结果表达。在HEC-WAT的FRA模块进行计算时，各工况的模拟结果即时产生，可以通过独立事件查看，或者通过不确定边界的直方图和频率曲线集中查看。模拟时间的快慢取决于模型的变量，同时，模拟结果还可以在空间上进行展示。

 

HEC-WAT has been used on a number of watershed studies to date, including: a climate change evaluation of the Red River basin (North Dakota and Minnesota); a forecast-informed reservoir operations study in the Russian River watershed (California); and a reservoir operations and risk evaluation in support of the Columbia River Treaty (Pacific Northwest and Canada).

 

迄今为止，HEC-WAT已经应用于若干流域研究。例如，北达科他州和明尼苏达州红河流域气候变化评估；加利福尼亚州俄罗斯河水库调度预测预警研究；以及为《哥伦比亚河条约》提供水库调度与风险评估。

 

Summary

总结

 

HEC-WAT supports watershed-scale planning studies through: 1) integration of software that evaluates various aspects of water resources within a watershed; 2) spatial representation of watershed processes; and 3) incorporation of risk and uncertainty study methods. It generates standard results from the individual HEC software applications as well as risk analysis results from FRA computes, including spatially distributed results. HEC-WAT has been used to successfully evaluate a range of watershed planning studies, ranging from the effects of climate change to alternative reservoir operations.

 

HEC-WAT通过3种方式为流域尺度的水资源规划研究提供支持：1）流域水资源要素的评估软件的集成，2）流域过程的空间表达，3）水资源风险与不确定性研究方法的结合。

 

HEC-WAT从独立的HEC软件应用中生成的标准模拟结果，以及FRA模型的水资源风险分析结果，还包括空间分布结果。目前，HEC-WAT已经成功地用到一系列流域规划研究评估中，从气候变化的影响到水库调度均有所应用。

 

References

引用资料

 

Engineer Regulation 1105-2-100. 2000. Planning Guidance Notebook. U.S. Army Corps of Engineers.

工程师条例1105-2-100. 2000。规划指导手册，美国，陆军工程兵团

 

Engineer Regulation 1105-2-101. 2017. Risk Assessment for Flood Risk Management Studies. U.S. Army Corps of Engineers.

工程师条例1105-2-1001. 2017.洪涝风险评估管理研究，美国，工程师条例1105-2-100. 2000，陆军工程兵团