Flooding on River Niger and Benue - nwp · Flooding on River Niger and Benue Causes, ... Flood Risk...

Flooding on River Niger and BenueCauses, Remedies and Proposed Actions

Hans van Poppel & Mathijs van Ledden PhD MBAJuly 7, 2013

River Niger Dredging 14 May 2013

0. Table of Contents

1. Introduction

2. River Niger3. Flooding - causes4. Flooding - remedies5. Conclusions and Outlook

6. Proposed Action Plan7. Questions and Discussion


1. Introduction� Hans van Poppel

� Director Asia and West-Africa� MSc from Delft University of Technology, Water

Management & Hydrology (1986)� Flood protection programmes in Thailand, Indonesia,

Ghana, Netherlands� Project Director Thailand National Flood Mitigiation

Plan (in progress)� Jeen Kootstra, Resident Director Nigeria

� Royal HaskoningDHV� Working also under name of NEDECO (Netherlands

Engineering Consultants);� Merger Royal Haskoning and DHV 2012;� Present in many river basins around the world� Active in Nigeria since 1953;� Active on/with River Niger since 1950.


2. River Niger – system characteristics

Niger Mississippi RhineLength (km) 4,180 3,800 1,233Basin (x 106 km2) 2.1 3.2 0.17Average flow (m3/s) 5,600 16,000 2,000


2. River Niger - HistoryRecent floods:E.g. 1954/1955, 1994/1995, 2012

Important River Information:� Hydrological studies 1950s;� Hydro-Climate stations 1970s;� Masterplan/Design Dredging 2006–2009;

Infrastructural works:� Kainji Dam 1958-1969;� Jebba Dam 1984;� Capital dredging 2009 – 2010;� Maintenance dredging 2011 – 2012;� Under discussion: dredging support & flood prevention (Committee

on River Niger Dredging and Flood Prevention)


2. River Niger – Flood Risk� Flood 2012: 363 killed, $ 17 billion

loss, 2.3 million displaced

� Public investment in flood risk reduction pays off is lesson learned in many deltas around the world

� Example New Orleans

� Niger River Basin will become much more attractive for private investors

The Day, 27th May


3. Flooding – Causes07/2012, south-west08/2012, middlebelt09-10/2012, delta


3. Flooding – Causes

� Limited discharge capacity� Upstream high discharge

� Excessive rainfall;� High runoff;� Tributaries;

� Narrow/shallow floodplain;� Properties in floodplain

� Blockage downstream� Bottlenecks (bridges, city banks)� High(er) sea level


4. Flooding – Remedies

� Upstream retention� Vegetation;� Landscaping;� Dams;� Retention reservoir;

� Decongestion� Shoal removal/dredging� Floodplain lowering/widening;� Widening at bottlenecks

� Levee raise� Local flood risk reduction


4. Example - Retention

� Upstream control flood storage reservoirs (dams)

� Throttling outlets (orifice) to regulate flows released downstream

Flood reservoir

Rectangular orifice-controlled flow release

Dam


River Rhine NL River Niger

4. Example – River Widening


4. Example – Dredging

Warri

Ajaukuta

Wide River Channel

Narrow River channel

River Niger ~698km


� Overall river discharge capacity is not sufficient

� There is no single cause of the problem, a quick and easy fix therefore does not exist

� A mix of short-term and long-term measures (increasing retention, conveyance, local protection)

� Engineering - funding - governance

5. Conclusions and Outlook


Short term (prior to Aug-Sep 2013):� Identify critical areas/infrastructure/assets (public/private) (June 2013)� Develop concrete measures to reduce risk in these areas (June - July 2013)� Develop assessment tools (June – Aug 2013) (Example:Thailand)

Mid term (2013-2016):� Identify bottlenecks in river system (River Stress Test)� Implement “no regret” measures with highest return� Develop more sophisticated tools for detailed analysis

Long-term (2013 onwards):� Develop of LT Integrated River Basin Management Strategy� Liaise with stakeholders� Governance / Funding

6. Proposed River Niger Action Plan


7. Questions and Discussion

Flooding on River Niger and Benue - nwp · Flooding on River Niger and Benue Causes, ... Flood Risk...

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