The hydrological cycle and a historical perspective of flooding

Jim Butterfield 1 Introduction to Past Perspectives

Emile Zola 'The ' 1880 novel based on Garonne flood of 1875

Ilkley 1900 Flood 1935 Flood 1676 Old Bridge replaces one swept away

Contrast with present world – continue to surprise us but now we have warning systems, forecasting, detailed measurement and reports on a global scale

Comprehensive flood records only in last 40 years ( some sites 100) so history of flooding limited to diaries, flood marks and newspaper reports ie Pepys, Gilbert White et al

Can we categorise floods – by impact, area affected, lives lost, people displaced, damage to buildings, agricultural losses, causes ( river flooding, flash flooding, combination of tidal and river flows, storm damage at coasts, catastrophes eg earthquakes, dam collapse and human actions )

Floods as we might recognise them date from 500 million years ago and occurred throughout our history and pre-history.

Flood myths widespread in many religions and cultures -Middle East, China, North America, India etc. Wrathful gods punish humans for their misdeeds – Judaism, Christianity, Islam

Noah - predated by Gilgamesh. (Black Seas flooding?)

First civilizations developed around irrigation and flood protection – before neolithic times, we walked away , if we could!

Gilgamesh Noah’s Ark, Dordrecht Hydrological Cycle

Continuous movement of water on, above and below the surface of the earth – between air, land and sea.

Water is forever on the move, repeatedly changing its state, with the cycle driven by evaporation and condensation. It is closely linked to the carbon nitrogen and sulphur cycles

Most of living biomass is water

Note the remarkable nature of water, which we tend to overlook because of our familiarity with it. It is fundamental to life on the planet and freshwater is fundamental to life on land

70% earth covered by oceans, which account for 86% evaporation and 78% precipitation and store 96.5% earth's water. Of the remainder, glaciers and ice- caps account for 1.7%, ground water 1.6%, freshwater lakes .01%, ground ice and permafrost .02% with the tiny fraction left divided between soil moisture, the atmosphere, marshland, rivers and biota

turnover times – immediate, hours, days, weeks, months, years. millennia and millions of years evapotransporation counts for 10% of all water entering the atmosphere

precipitation interception run-off evaporation evapotranspiration groundwater - water table, below which the ground is saturated – all porous spaces filled capilliary action porosity and permeability, rate of flow 30 metres a year typical, but varies -clay, very slow gravel, fast depth – varies, max several km below surface aquifers – re-charge rates and discharge rates

'vadose water' unsaturated zone - interceptions before reaching ground - field capacity movement generally down, but also horizontal. Soil characteristics critical.

Rivers – channel depth, width, roughness hydrology – measurement, measurement! Impact of digital technology etc

Some historical mentions

Major Floods mentioned by Withington -attributed to heavy rain,melting snow, tidal surges,storms, , dyke and dam bursts,mudslides, acts of war . Initial drownings followed by exposure, disease and starvation

838 AD storm surge – 2500 lost in also 1099, 1176, 1287, 1362 (widespread in N.Europe) loss of ports and settlements -further major floods in next two centuries 1570 AD Grote Mandrenke 100,000 lives lost ? Modern estimate 25000 between 1099 and 1570 nearly 3000 towns and villages lost in N.Europe January 1607 Somerset, Gloucestershire, S.Wales 200 square miles flooded and 2000 lives lost

China -1887 September – dykes on Hwang He burst and 1500 communities swept away – lives lost by frowning, starvation and disease – 900000 to 2'5 million (2 months before reports reached London)

Some historical mentions (contd)

1931 three years ended July with Huang He and Yangtze both bursting dykes - immense scale 40,000 suare miles and 50 million forced from their homes -900,000 to 4 million deaths – world's biggest natural disaster.

1938 Huang He dykes blown up by Chinese army – villages destroyed, major losses of life

1975 number of Great Leap Forward dams burst and perhaps 250,000lives lost

2004 1970 and 1991 Bangladesh floods

1953 North Sea storm surge = Netherlands and East Anglia

1927 Mississippi -200 levee breaches and flooding of 20,000 square miles (40 mile wide river – levee destruction to save urban areas)

United Kingdom – some notable floods

Peter Ackroyd 'London' 1090 London Bridge carried away 1579 Boats rowed in Westminster Hall early 1900's boats needed to enter houses in Lambeth but frequent floods expected, with reports of only the major ones

Pepys – travel hazards – broken road surfaces, quagmires but also 'dangerous waters' boats in Westminster and considerable damage in City of London on separate occasions

Thames floods 1928, 14 drowned and 'thousands' had to leave their homes but frequent reports of Thames Valley flooding

Gilbert White notes significant floods (crop lost, buildings damaged) -1771, 1777, 1784, 1786, 1786, 1789, 1792 frequent floods reported Holmfirth, Otley, Leeds, Shipley, York

Wilkipedia List of UK floods (does not include 1947)

1867 Great Sheffield Flood 1953 1953 Canvey Island 2002 Glasgow 2004 Boscastle 2005 Cumbrian rivers – Eden, Kent, Cocker, Derwent, Greta 2007 UK wide, but particularly Yorkshire. Sheffield badly hit 2009 UK wide 2013 North Sea flood 2013 Winter storms and prolonged rain – railway disruption and severance,inundation of agricultural land in Southern UK

Withington notes Thames barrier 1980's 4 times raised 1990's 35 times 2000-10 80 times

But note scale of our floods small compared with continental rivers! Flood Defences

Hunter/gatherers avoided wet areas or walked away if they could

Settled agriculture – need for flood defences, but related to control of water for irrigation – 'hydraulic civilizations' dykes/levees, canals and dams from 5000 bce – Nimrod's Dam

Human use of rivers and lakes – water essential for survival and food production, settlement of fertile deltas and flood plains, need for river connections for trade and transport, flat land for building, sources of power, sources of building materials, industrial uses and waste disposal

Anthropocene age? 'planetary wide re-plumbing of world's waterways – past 100 years – 48,000 large dams constructed and major rivers diverted - increased groundwater extraction – impact of growing population and economic growth

Flood defences (contd)

Construction of massive dams – Grand Coule, Hoover, Narmada,Three Gorges etc etc - controversial with large scale population displacement – but also dyke construction on very large scale ( effect may be to raise river bed well above surrounding land) but recognition that hard engineering has to be integrated within multi-purpose catchment area planning.

The Dutch example ; from 600 BC some settlement in fertile but marshy areas and occupation of 'terps' – most of them human built until Middle Ages -1200 identified- many demolished for soil nutrient contents – then dyke construction – 1250AD Omringdijk – 78 miles long – then sea wall building, wind pumps, canal and ditch construction with steam pumping from early 19th century. Cornelius Lely – Aftsluitsdijk built after 1916 storm and opened in 1932. 1953 – high rivers plus storm winds and very high – major disaster – Delta project. Coastal protection by dunes and sea wall – Petten and Hondsbosche sea dyke – sophisticated engineering alongside 'Room for the Rivers' policy – live with water rather than keep it all out.

Flood defences – organisation and policies

Dutch example – long history of co-operative organisation to protect communities living below sea-level and extend areas suitable for farming and settlement. Today – Directorate-General for Public Works and Water Management with Water Boards run by provincial governments – claim that the Dutch consensus model is unique -referred to as the 'polder model'

United Kingdom – pragmatic responses – Romans built sea walls, channels and drainage projects, which were inherited by people in the Middle Ages, with further drainage projects initiated by the medieval church. From 15th century foreign experts called in. Vermuyden schemes of mixed success and full drainage schemes had to await pumps. Enclosures. !9th and 20th century -drainage and reclamation – Thames Conservancy 1857 (previously City of London) Rivers v drains?

Before 1950, over 1000 water undertakings, reduced to 198 water undertakings by 1970, but also 1300 sewage authorities. Very fragmented, but 29 River Authorities established in 1965

organisation and policies (contd)

1973 – 10 Regional Water Authorities - multi-purpose water resource management, integrated river basin management – codes of practice introduced to encourage inter-disciplinary approach after 1979 -recognition of commercial aspects of water supply with privatisation of water supply and sewage disposal in 1989

1996 Environment Agency, with purpose of 'protecting the environment as a whole' and objective of 'sustainable development' Two directorates, one of which deals with Flood and Coastal Risk Management. 16 areas, grouped into 6 regions

By 1960's recognition of need for multi-purpose management, including conservation and recreation facilitation. But key issues change over time – 1960's river quality, 1970's water supply, but 1980's drainage for agriculture at cost of conservation -Halvergate Marshes Beginnings of co-operation between farmers, engineers and landscape managers – value of wetlands recognised. Flood Risk Management preferred term to Flood Defence

organisation and policies (contd)

River Basin Management Plans

Monitoring of planning applications in areas of flood risk

Flood forecasts Floodline

Lead Local Flood Authorities (2010 Act) eg Leeds strategy for and register of risk areas co-ordination with District Councils, Internal Drainage Boards, Highway Authorities Water companies and Planning Authorities note requirements to follow EU guidelines

Flood Study Day Some references.

E,C.Pilou Freshwater 1998 Gaia Vince Adventures in the Anthropocene 2014 Robert Arvill Man and Environment 1983 John Withington Flood 2014

Mike Dixon Ilkley Revisited 2010 Vaclav Smil Earth's Biosphere 2002

Jeremy Purseglove Taming the on-line Wilkipaedia – see History of Flood 1989 Floods, Flooding, Hydrological Cycle, Hydrology, Environment Agency etc

Elizabeth Kolbert The Sixth Leaflets and handbook from Dutch Extinction 2014 Coastal Exhibition Centre etc