DEL095 – 11203050/11203051 Development of process-based tools for assessing reservoir sediment management considering river ecosystem

Aanleiding van het project

Dams and reservoirs are functional assets of river basins, particularly in areas with strong seasonal variations in rainfall-runoff patterns, where they can regulate river flow to prevent flooding, as well as in areas with ever-growing water and energy demand due to growth of economy and population. However, it is obvious that any intervention in a natural system induces adverse impacts on the ecosystem. Additional negative impacts of dams and reservoirs can also be attributed to poor planning, mismanagement, inefficient operation and improper consideration (or negligence) of impact mitigation options and conditions.
The major environmental problem of dams in a river basin is the disturbance in natural flow dynamics and sediment transport, for example shortage in downstream flow and sediment supply leading to micro- to large-scale morphological changes and changes in species habitats. These changes do not only impact riverbeds, floodplains and settlements, but also aquatic and riparian habitats (e.g. wetlands and fish spawning areas) and ecological processes (e.g. fish migration cues). On the other hand, the reservoirs themselves suffer from sedimentation problems, and one of the main sediment-induced problems is storage loss. Globally, the total storage in reservoir is around 7000 km3. Due to sedimentation, we lose around 57 billion m3 per year (according to ICOLD 2009). The available water storage per capita is decreases since 1980. This means the solution we have so far is not sustainable.
Sedimentation in reservoirs decreases their lifespan and has severe impact on the reservoir purposes. The trapping of sediment, in reservoirs, creates shortages in sediment supply downstream. This has implications for river morphology and creates ecological problems in the reservoir and the river system (changing temperatures, sediment starvation, blocking fish migration, altering habitats, etc.). The shortage of sediment creates different bed characteristics which might not

Doel van het project

The main aim of this project is to further deepen, broaden and integrate our knowledge and improve our tools (add-ons and coupling) to be able to link the dam and sediment management operation with ecology. Followings are some of the aims and objectives of the proposed project:
1) To implement new functionality in our modelling tool to improve the morphological replication and prediction with dam operation that could be more useful to assess river environment and habitats
2) To improve and test our tool to replicate efficient and optimal sluicing and flushing operation of the system of reservoirs in a cascade
3) To improve and integrate our tools (morphology, dam operation and ecology) that could be used to address the problems of mitigating negative ecological effects and maintaining sustainable aquatic ecosystems.
4) To apply new developments (like Delft3D-Flexible Mesh and Delta-Shell) and make our tools more user-friendly
This allows quantitative assessment of implications and impacts of dam and reservoir operation and management scenarios on river morphology and ecology. This will help to determine the optimal management strategy for green and sustainable development of river system with reservoirs.

Omschrijving van de activiteiten

Component-1: Research/model improvement/Testing (Fundamental and industrial research)
Task 1.1:
Implementing new approach and
(a) unctionality for computation of spatial and temporal variation of porosity and consolidation considering cohesive sediment in Delft3D4 software
(b) Testing of the new functionality in Delft3D4 morphological model with RTC
Task 1.2:
(a) Implementing a routine for exchange of information in Delta-Shell environment for better and user-friendly integration for coupled morphology and habitat modelling
(b) Testing of the new implementation to compute relevant ecological statics
Task 1.3:
Implementing and testing improved coupling of morphology, habitat and Real-Time Control Tool (RTC) in D-FM model
Component-2: Application and validation (Experimental development)
Task 2.1:
Application and validation of the new functionality in Delft3D4 morphological model with RTC for a real-world case (Funagira Reservoir in Japan)
Task 2.3:
Real-world application of coupled model (morphology + habitat + RTC) in D-FM to Funagira reservoir morphological model with habitat assessment
Task 2.4:
Application of the improved model in a cascade system of dams

Verwachte resultaten

Volgnr
Wat
Wanneer (jaar)
1
Proposal, inventory and data collection memo
2018
2
Update of Delft3D code with a new approach of spatial porosity and computation of consolidation
2018/2019
3
Delft3D4 model testing and application case with RTC, morphology and habitat suitability assessment
2019
4
Implementation and validation of HABITAT model using Delft3D-Flexible Mesh and Delta-Shell
2019
5
Memorandum with the results and a conference/journal paper will be written (together with J-Power)
2019

Innovativiteit

Process-based modelling tools such as Delft3D, Delft3D-Flexible Mesh (D-FM) and HABITAT models are still not yet commonly used in the dam (hydropower, multi-purpose) sector to quantify and mitigate the environmental impacts of their operation. Previous studies (Tenryuu River, Mekong River, Koshi River, etc) show that proper integration of sediment and ecological management measures require dynamic coupling of 2D/3D modelling tool. Existing tools do not provide enough functionality to use them in practice, where dam operators base their environmental operations mostly on trial and error. This study will not only increase the capabilities in modelling these processes in a physics based manner, but also introduce tools that allow improved and smarter ways to integrate sediment management and ecosystem to optimize the dam operation. These technologies allow dam operators to adjust the general sediment management strategy while more accurately predicting the environmental consequences (on a short- and long-term).
To enable dynamic morphological computation and habitat assessment in Delta Shell, the expected development will provide smooth way for quick ecological computations of the habitat suitability in order to build the meta-model. The workflow in HABITAT will be optimized through Python scripting. For several years now, the functionality of Python scripting in HABITAT has been available. This is due to generic developments in Delta Shell. Until now, this functionality has been largely neglected due to limited knowledge on Python by HABITAT users and the lack of predefined scripts to be used in analyses. However, this functionality can be used to automate the model setup, create uniformity in response curves and speed up computations.

Valorisatie

Welk product (zie boven)?
Wie gaat het gebruiken?
Wie gaat ervoor zorgen, en hoe?
Delft3D4 with new functionality
All model users for further research and applications in projects
Deltares will maintain it by applying in more case studies/ projects and regularly improving it.
Delft3D-FM with Habitat in Delta-Shell
All model users for further applications in projects
Deltares will maintain it by applying in more case studies/ projects and regularly improving it.
Scientific paper and public-wiki
Open to all
Deltares and J-Power can jointly work and improve in future as well.

Link naar projectresultaten…