How To Develop An International Framework For Analysis Of Fluvial Morphological Processes

Transcription

1 ADVANCES IN RIVER SCIENCE CONFERENCE Swansea, April 2011 A new methodological framework for stream hydromorphological assessment, analysis and monitoring (IDRAIM) Massimo Rinaldi 1, Nicola Surian 2, Francesco Comiti 3, Martina Bussettini 4 1 Dipartimento di Ingegneria Civile e Ambientale, Università di Firenze 2 Dipartimento di Geografia, Università di Padova 3 Facoltà di Scienze e Tecnologie, Libera Università di Bozen-Bolzano 4 Istituto Superiore per la Protezione e la Ricerca Ambientale (ISPRA), Roma

2 EC Water Framework Directive: hydromorphology as one component of stream quality conditions Context EC Flood Directive: identification of measures to mitigate floods and related hazards Potentially conflicting objectives: - Quality - Safety

3 IDRAIM framework (sistema IDRomorfologico di valutazione, AnalisI e Monitoraggio dei corsi d acqua) Aim: to develop an overall methodological framework for analysis of fluvial morphological processes, integrating objectives of quality and safety, according to WFD and Flood Directive Project funded and developed in collaboration with: ISPRA, Istituto Superiore per la Protezione e la Ricerca Ambientale (Italian Environmental Agency)

4 IDRAIM framework Characteristics - Emphasis on geomorphic processes, sediment connectivity, trajectories of changes - Application to identification of possible strategies / actions for river management (target: public agencies) Existing methods River Styles Framework (Australia), Fluvial Audit (UK), SYRAH (France) Specific characteristics - Integration of morphological quality and fluvial dynamic hazard - Italian (european) context

5 Stage 1: General setting and initial segmentation Stage 2: Present morphological conditions and past channel evolution 2.1 Analysis of present and past conditions (A) Sediment sources; (B) Sediment connectivity; (C) Stream power; (D) Transport capacity; (E) Trajectories of changes; (F) Causes of channel evolution 2.2 Evaluation and analysis of morphological quality Morphological Quality Index 2.3 Evaluation and analysis of morphological dynamics hazard Morphological dynamics hazard index 2.4 Synthesis of problems Stage 3: Future trends 3.1 Analysis of future scenarios (A) Possible trajectories of future evolution (B) Implications on morphological quality (C) Implications on hazard 3.2 Monitoring and post-monitoring evaluation Stage 4: Integrated management 4.1 Priorities 4.2 Conflicts and integration of objectives 4.3 Classification, analysis and management of HMWB 4.4 Monitoring post - interventions

6 IQM (Morphological Quality Index) Recently approved as hydromorphological assessment method by Italian Legislation on WFD implementation Main characteristics and novelties 1. It is not a Physical Habitat Assessment method 2. Designed for WFD but not exclusive 3. Designed for geomorphologists 4. It evaluates the morphological quality (independently from ecological implications) Approaches and methods (1) Remote sensing and GIS analysis (2) Field survey

7 IQM (Morphological Quality Index) Terrace Clay outcropping Incision

8 Reference conditions: dynamic equilibrium

9 Phase 1: Segmentation (1) Physiographic units; (2) Confinement; (3) Channel morphology; (4) Other discontinuities Reach: scale of application of IQM (1 5 km)

10 Phase 2: Morphological assessment 1. Continuity A. Longitudinal B. Lateral A. Channel pattern Functionality 2. Morphology B. Cross-section C. Substrate Artificiality Channel changes 3. Vegetation

11 IQM indicators Functionality Continuity F1 Longitudinal continuity in sediment and wood flux F2 Presence of modern floodplain F3 Hillslopes stream connection F4 Processes of bank retreat F5 Presence of a potentially erodible corridor Morphology Channel pattern F6 Bed configuration valley slope F7 Forms and processes typical of the channel pattern F8 Presence of typical fluvial forms in the alluvial plain Cross-section configuration F9 Variability of the cross-section Bed substrate F10 Structure of the channel bed F11 Presence of in-channel large wood Vegetation F12 Width of functional formations in the fluvial corridor F13 Linear extension of functional vegetation Artificiality Upstream alteration of longitudinal continuity A1 Upstream alteration of channel-forming discharges A2 Upstream interception of sediment transport Alteration of longitudinal continuity in the reach A3 Alteration of channel-forming discharge in the reach A4 Interception of sediment transport in the reach A5 Crossing structures Alteration of lateral continuity A6 Bank protections A7 Artificial levees Alteration of channel morphology and/or substrate A8 Artificial changes of river course A9 Other structures of alteration of channel profile and/or substrate Interventions of removal A10 Sediment removal A11 Wood removal A12 Vegetation cutting V1 V2 V3 Channel changes Changes in channel pattern Changes in channel width Bed-level changes

12 Functionality F1: Longitudinal continuity in sediment and wood flux Class A Class B Class C

13 Artificiality A6: Bank protections

14 Channel changes - V1: Changes in channel pattern Class A Class C 1954 Class B

15 1. Very good (IQM = ) 2. Good (IQM = ) IQM=0.87 IQM= Moderate (IQM = ) 4. Poor (IQM = ) 5. Very poor (IQM = 0 0.3) IQM=0.60 IQM=0.43 Morphological Quality Index: IQM=1-IAM Morphological Alteration Index: IAM= Stot / Smax Total deviation: Stot = F1+ +F14+A1+ +A14+V1+ V3 IQM=0.04

16 IQM applications Unconfined Semiconfined Confined VERY GOOD GOOD MODERATE POOR VERY POOR Confined Braided wandering unconfined VERY GOOD GOOD MODERATE POOR VERY POOR VERY GOOD GOOD MODERATE POOR VERY POOR Single-thread unconfined

17 IQM applications 1,00 0,90 0,80 0,70 0,60 0,50 0,40 0,30 0,20 0,10 0,00 IQM V IQM A IQM F

18 Available material Guidebook for the evaluation of stream morphological conditions by the Morphological Quality Index (IQM) Illustrated Guide to the Answers Evaluation forms GB/Publications/Handbooks_and_Guidelines/Do cuments/manuale_66_2011.html