Hydraulic Habitat Modelling and MappingDave Mould

Structure

• What is hydraulic habitat modelling and mapping?

• Hydraulic modelling (in 2 slides……)

• 3 case studies

– As part of the design process

– Investigation tool to build evidence

– Impartial appraisal

• Summary

Hydraulic habitat

The combination of river depth, velocity and substrate determines the available physical habitat for aquatic species.

Therefore, hydraulic models can then be used in combination with knowledge of the habitat requirements of species/life stage of interest to determine habitat availability. Can also inform on sediment dynamics.

1D modelling

Max vel

Island

2D modelling

APR Project 15. Two dimensional modelling in Urban and Rural Floodplains

Case study 1 - Design

Case study 1 - Design

Case study 1 - Design

Case study 1 - Design

Case study 1 - Design

Case study 2 – Evidence

EA science project SCSC0120077

Case study 2 – Pershore weir

Case study 2 – Evidence

Q95 Depth. On-weir HEP Q95 Depth. Depleted reach Q95 Velocity. On-weir HEP Q95 Velocity. Depleted reach

Difference = post installation minus pre installation.

Case study 2 – Evidence

Q20 Depth. On-weir HEP Q20 Depth. Depleted reach Q20 Velocity. On-weir HEP Q20 Velocity. Depleted reach

Difference = post installation minus pre installation.

Case study 3 - Appraisal

Pool and run

Shoulder

Vegetation management

Case study 3 - Appraisal

Case study 3 - Appraisal

Case study 3 – Pool and run Pre change adult Brown Trout habitat Post change adult Brown Trout habitat

Pre change Brown Trout spawning habitat Post change Brown Trout spawning habitat

Run

Pool

Run

Pool

Run

Pool

Run

Pool

Case study 3 - Shoulder

Pre-change 0+ Cyprinid habitat Post-change 0+ Cyprinid habitat

Case study 3 – Veg removal Pre-change 0+ Cyprinid habitat Post-change 0+ Cyprinid habitat

Pre-change Brown Trout spawning habitat Post-change Brown Trout spawning habitat

Case study 3 – Crisp summary

Total Habitat Suitability (THS) Q95 Q70 Q50 Qmean Q10

Adult BT 2665 4085 4495 4761 5178 1+ BT 2685 3689 3939 4318 5247

0+ BT 4798 5011 4559 3913 2197 BT Spawning 2791 3523 4202 4698 5360

0+ Cyp 862 1568 1596 1607 2019

Habitat Quality Q95 Q70 Q50 Qmean Q10

Adult BT 26 32 35 36 37

1+ BT 26 29 31 33 38 0+ BT 47 40 36 30 16 BT Spawning 27 28 33 36 39 0+ Cyp 8 12 12 12 15

Summary

Pros ConsAcross whole flow regime and range of species/life stages.

Cost of survey data vs scale of the modelling

Spatial & crisp outputs Often limited knowledge of requirements of many species

Results in a data poor situation Uncertainty in model results

Play tunes with model topography

Optimisation of designs