Controls on the hydro-geomorphological impact of the 2017 El Nino Costero floods, northern Peru

Overview

Between January and April 2017 El Nino Costero (coastal El Nino) generated catastrophic floods in the Piura region of northern Peru impacting over 1.7 million people resulting in 178 deaths, 77,300 homes destroyed or damaged and the displacement of 10,000 people (USAID, 2017). Risk to life, infrastructure and property is considerably enhanced when flood waters are charged with sediment and floating debris. Enhanced stream powers during high magnitude floods drive erosion and deposition of sediment which in turn bring about significant changes in channel cross-sectional geometry and major river channel avulsions into populated areas. Increased supply of sediment to fluvial systems through natural or anthropogenic processes can also have a major impact on downstream river channel dynamics resulting in localised aggradation and the downstream passage of sediment waves. Such hydro-geomorphological activity poses a major hazard to population and infrastructure in both developed and developing nations.

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Image Captions

Piura City.jpg – “Over flight of Piura City after the El Nino Costero flooding” Photo: Andrew Russell
Hydro-geomorphic changes of the Rio Piura.jpg – “Example of hydro-geomorphic changes of the Rio Piura after El Nino Costero flooding” Photo: Andrew Russell

Methodology

This project provides a systematic examination of the impacts of the 2017 El Nino Costero floods in terms of: (a) river channel geomorphological change; (b) sediment flux; (c) anthropogenic channel modification; and (d) comparability with past floods. Remote sensing (aerial photos and satellite imagery) and field data acquisition will provide input to analysis of flood dynamics using hydraulic modelling and GIS-based analysis.

Project Timeline

Year 1

1. Review of existing studies of flood geomorphological and sedimentary impacts from Peru and elsewhere. Review of hydraulic model(s).
2. Stakeholder mapping of the key actors engaged in flood management and identification of associated grey literature sources (e.g. strategic plans, evaluations).
3. Geomorphic mapping of channel change on the Rio Piura using remotely-sensed data.
4. Acquisition of secondary data sets (Aerial photos, LiDAR, DEMs).
5. Planning and organisation of field season 1.
6. Field expedition – Season 1 (Aug-Sept, 2021) Geomorphology, sedimentology, crowd sourced information & stakeholder interviews.
7. Processing and analysis of geomorphological & sedimentary data from field season 1.

Year 2

1. Interpretation and synthesis of data from remotely-sensed, field based geomorphological mapping and sedimentary analysis.
2. Planning and organisation of field expedition . Geomorphology, sedimentology, crowd sourced information)
3. Field expedition – Season 2 (Including stakeholder workshop) (Aug-Sept., 2022).
4. Processing and analysis of geomorphological & sedimentary data from field season 1.
5. Begin hydraulic modelling activities using field data in conjunction with secondary data.

Year 3

1. Complete analysis and interpretation of field data from field season 2.
2. Complete hydraulic modelling of 2017 flood.
3. Present results at an international conference (AGU Fall 2022)
4. Begin write-up of thesis.

Year 3.5

1. A reconstruction of the 2017 El Niño Costero in the Rio Piura including hydraulic and sediment dynamics.
2. Modelling of previous El Niño Costero floods and also future high magnitude floods on the Rio Piura using updated topographic data which incorporates major post 2017 flood engineering work.
3. Completion of write-up of thesis and feedback documents/presentations to stakeholders.

Training
& Skills

The student will be trained in remote sensing techniques, GIS, and surveying (dGPS & TLS) techniques. These will be coupled with in-field geomorphological mapping, hydraulic modelling, sedimentology, and palaeohydrological reconstruction using logging techniques. In addition, there will be opportunities to develop you Spanish language in order to engage with local stakeholders and to crowd source data.

References & further reading

Goldstein, P.S. & Magilligan, F.J. (2011) Hazard, risk and agrarian adaptations in a hyperarid watershed: El Niño floods, streambank erosion, and the cultural bounds of vulnerability in the Andean Middle Horizon. Catena 85, 155-167.

Morera S.B., Condom T., Crave, A., Steer P., & Guyot, J.L. (2017) The impact of extreme El Niño events on modern sediment transport along the western Peruvian Andes (1968-2012). Nature Scientific Reports, 7, 11947. DOI:10.1038/s41598-017-12220-x

Rein, B. How do the 1982/83 and 1997/98 El Niños rank in a geological record from Peru? (2007) Quaternary International, 161, 56-66.

Tote, C. et al. (2011) Effect of ENSO events on sediment production in a large coastal basin in northern Peru. Earth Surf. Process. Landforms, 36, 1776-1788.

Waylen, P.R. and Caviedes, C.N. (1986) El Niño and annual floods on the north Peruvian littoral. Journal of Hydrology, 89, 141-156.

Mettier, R., Schlunegger, F., Schneider, H. (2009) Int J Earth Sci (Geol Rundsch) 98, :2009-2022.

Further Information

Dr Andrew Henderson
School of Geography, Politics & Sociology
Newcastle University

Tel: +44 (0) 191 208 3086
E-mail: andrew.henderson@ncl.ac.uk

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