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Hydrological Modelling

Overview
Projecting stream flows in ungauged basins under future scenarios and quantifying changes to instream habitat

This service area broadly characterizes components of hydrology and hydrological modeling with linkages to stream flow, fish, and fish habitat. For convince this service area is split into general domains, each domain focuses on different applications and project types. Variations of some of these projects, programs, and analyses can be completed at a high-level as desktop a exercise, whereas others applications involve large teams of subject matter experts with field programs etc.

 

Hydrology Models to Forecast Stream Flows Under Future Scenarios:
  • Objectives: Hydrological modelling generally involves forecasting stream flows into the future under different scenarios. These scenarios could include hypothetical restoration alternatives, climate change, water management decisions, and so on. The general goal is to estimate monthly stream flows, floods and low flows:
    • Can we forecast stream flows for ungauged basins (near-term, long-term or seasonal averages)?
    • How will a hydrograph change under future scenarios with climate change?
    • How will changes to upland developments (i.e., land use) such as forestry, roads, agriculture, wildfires etc. change stream flows during critical seasons.
    • Hypothetical "what ifs" for hypothesis testing, etc.
  • Approach: Numerous hydrological models and tools exist for every application. My go-to approach is to use the collection of models available within the Raven Hydrological Framework. Other tools and applications can also support these projects and programs.
 
Hydraulic Models / Hydrodynamic Modelling:
  • Objective: In larger creeks and rivers it becomes important to start thinking about instream habitat as a three dimensional surface of varying depths and velocities with features such as banks, bars, side channels, boulders etc. Hydrodynamic models breakdown a stream reach into nodes (or cells) to generate high-resolution simulations of water flowing through a stream. This information is then used to help us understand how a given input discharge 
  • Approach: Involves the use of mathematical and computational models to understand water flow dynamics, including aspects like flow velocity, water level changes, and sediment transport (River2D; HEC-RAS-2D).

 

Instream Flow and Environmental Flow Needs:
 
Measuring Stream Flow, and Systems for Realtime Reporting:
  • Objective: The objective of hydrometric surveying is to obtain data on river discharge, stage, and/or velocity at one or more predefined locations. High-quality stage/discharge time series, collected under professional standards and practices, are worth their weight in gold. Stream discharge time series are foundational data inputs to all other modelling approaches described in this section. Stream flow data is also commonly used on its own (in the absence of any additional modelling) to guide water management decisions for fish and fish habitat.
  • Approach: The other service area subdomains (described above) offer some lenience or opportunity for creative capital. However, hydrometric surveys require strict adherence to professional standards and practices. This helps ensure that the information is as accurate as possible and that data quality can be clearly communicated using predefined and well-documented standards. In British Columbia, the Resources Information Standards Committee (RISC) sets criteria for hydrometric data collection, review, grading, and sign-off procedures by qualified professionals. Failing to follow these standards can not only jeopardize monitoring programs but may also invalidate any subsequent hydrological modelling or reporting work linked to licenses/regulatory obligations.
  • Key References: 2018 Manual of BC Hydrometric Standard V2  | WSC Levelling | WSC Measurement of Stage | WSC Stage Corrections | WSC Stage-Discharge Model Development and Maintenance | WMO Manual on Stream Gauging V1 Field Work & V2 Computation of Discharge | 2004 BC Assessment Methods of Instream Flow | 2014 US EPA Best Practices for Continuous
    Monitoring of Temperature and Flow in Wadeable Streams

 

Go-To Resources for Modelling and Analyses:

 

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