Simone Bizzi In collaboration with: Dr Andrea Nardini Technical Director of CIRF (Italian Centre for River Restoration) Model and evaluate geomorphology under different catchment management strategies

What is Geomorphology? “..the study of sediment sources, fluxes and storage within the river catchment and channel over short, medium and longer timescales and of resultant channel and floodplain morphology” (Newson and Sear 1993)

Geomorphology and river management? Annual expenditure on Flood Defence > £500 million WFD requirement to maximize habitat quality

Aims of the research Model and evaluate geomorphological features under different catchment managements strategies National Level Regional/River Basin Level Catchment/Coastal cell level Community Level Site/System level

Why River Habitat Survey? 10 years of experiences and more than samples only in England and Wales Assessments and decisions are taken using this dataset Feedbacks for the next versions

Is it the database suitable?

Problems to face Limited information in the variables Dynamic system in space and time Typology: Every river has its behaviour

Index (Targets – Geomorphological Features) Model approach More experiences in literature Geomorphology (CAESAR,REAS, HEC- RAS..) They require detailed and specific data Most of the time not catchment scale Evaluation phase most of the time is missing National Level Regional/River Basin Level Catchment/Coastal cell level Community Level Site/System level Modelling Evaluating Information (Causal Factors) Evaluation

Model approach Modelling Evaluating Phase 1: A cluster analysis able to find pattern in the data and structured them in a way suitable for the evaluation Information (Causal Factors) EvaluationIndex (Targets – Geomorphological Features)

Model approach Phase 2: A classification model able to give an output suitable for an evaluation Modelling Evaluating Information (Causal Factors) EvaluationIndex (Targets – Geomorphological Features)

RHS site Geomorphological Features (targets): Numbers of Bars Numbers of Pools and Riffles Type of Bank vegetations Numbers of woody debris Bankfull width CONCEPTUALIZATION

RHS site Natural variables (Causal Factors ) Slope Flow Regime Geology CONCEPTUALIZATION

RHS site CONCEPTUALIZATION Percentage of Land Use in the sub-catchment (Causal Factor ): Vegetated Urban Improved Grass Land Arable

RHS site CONCEPTUALIZATION Percentage of area in the sub-catchment obstructed by dams or artificial reservoirs (Causal Factor )

d1 d2 d3 d4 RHS site CONCEPTUALIZATION RHS sites Level of modification in the sites and upstream (Causal Factors) Hard Modification :  Resectioning  Bank and channels reinforcements  Embankments Soft Modification:  Weirs  Bridges  ford.. Culverts

d1 d2 d3 d4 RHS site i CONCEPTUALIZATION x i (t+1)= f( u RHS,i (t),u cat,i (t), Nat(t) ) x i = f( u RHS,i,u cat,i,Nat) STEADY STATE

Clustering Step

Natural Variables (VERTICAL path) Vs Anthropogenic Variables (HORIZONTAL path)

Clustering Step C1 C3 C2 Riffles and Pools BarsBank vegetation Mean C Mean C

Model capability ? ? C1 C3 Arable Urban Land Vegetat ed Grass land Mod. Up stream Mod. in the site C1 mean C1 std C2

SCENARIOS rate (% in Class C1) Scenario zero (untouched)100 Reduced Hard Interventions in the site (80%)85 Reduced Hard Interventions in the site and up-stream (80%)66 Land Use changes (-50% Arable - 20% Urban ->Vegetated)87 All together24 ? ? C1 C3 C2 Model capability

Scenarios rate (% in Class C1) P(x/ C1) P(x/ C2) P(x/ C3) Scenario zero (untouched) Reduced Hard Interventions in the site and up- stream (80%) ? ? C1 C3 C2 Model capability

The weakness of a site specific approach Flexible Geomorphological tool at national level RHS limits Conclusions

Future Directions Assessing the feasibility to add biology Developing a “site specific” case study to overcome some limitations intrinsic in the national level Analysing the level of “integrability” between these two different approach

Thank you for your attention!