Water in the Netherlands Water management in a densely populated delta and the role of controlled drainage Jan van Bakel

Professional career Graduated in 1976 in Wageningen (Hydrology) In 1976: employee of ICW as head of Department Numerical Modeling In 1986 Ph.D. ‘Planning, design and operation of surface water management systems: a case study’ From 1991-1995: consultancy company TAUW 1995-2009: employee Staring Centre -> Alterra Since 01-10-2009 consultant (zzp’er); see www.debakelsestroom.nl Expert in Agrohydrology Member of the board of the Dutch Hydrological Association (NHV) 21-9-2018 trip USA nov 2011

Deltaic country Napoleon: Ems Scheldt Rhine Meuse 21-9-2018 trip USA nov 2011

21-9-2018 trip USA nov 2011

Precipitation and evapotranspiration Yearly vaules (mm) Monthly values Precipi-tation Reference crop evapotr. Average 827 543 10%-value 626 500 90%-value 1065 584

Precipition and evaporation Yearly values (mm) Monthly values For Agriculture: mostly too wet, sometimes too dry Precipitation Reference crop evapotr. Average 827 543 10%-value 626 500 90%-value 1065 584

Trends Before WW II: land reclamation on a small scale After WW II: promotion of land reclamation and improvement, to secure food production (autarky) Intensification of agriculture (Rudy Rabbinge) Environmental problems (nutrients, pesticides) Environmental and water management plans Emphasis on restoration of water systems: water is leading. Romantic hydrology! Climate change: threats and chances Recently: use of technology can help to do the job Controlled Drainage (CD) is a very promising candidate!

The main water topics (tasks) Safety first 4 water tasks: Water quality: environmental issue Water shortage: both for agriculture and nature Water surplus: for agriculture and civilians Salinisation : for agriculture (and nature) 21-9-2018 trip USA nov 2011

Things are changing… Climate change Land subsidence in 2050 Demographics Land use Water use 21-9-2018 trip USA nov 2011

Controlled Drainage (CD) Farmers didn’t care about N and P loads to surface waters unless .. Farmers didn’t care about peak discharges unless … Farmers didn’t care about drought effects on nature But the times ….. CD with smaller drain spacing and higher drainage base offers new possibilities 21-9-2018 trip USA nov 2011

Types of drainage (1) Phreatic level Drainagebase controlled dr. Undrained 1,00 m Phreatic level Conventional dr. Drainagebase controlled dr. 0,60 – 0,90 m 1,00 m 1,10 m Phreatic level drains

Types of drainage (2) Conventionally drained, made composite afterwards 1,00 m 1,00 m Phreatic level 0,60 m drains collector Composite, controlled drainage; smaller drain spacing 1,00 m 1,00 m 0,60 m collector

Some model results (from SWAP) for CD, without forecasting Groundwater depths Water quality Peak drainage fluxes 21-9-2018 trip USA nov 2011

Model results with SWAP for groundwater levels, CD with 30 cm variation and fixed data

Model results with SWAP on groundwater levels CD

N and P loads on surface waters N: denitrification P: immobilisation Induced seepage accounted for by Δh/seepage resistance, calculated by a regional model N kg/ha/yr P Undr. Conv. CD 21-9-2018 trip USA nov 2011

Peak discharges Standard Undr. discharge cap. CD Conv. Highest discharge (mm/day) CD Conv. 21-9-2018 trip USA nov 2011 years

In conclusion Water management in the Netherlands has a ‘rich’ tradition The economic developments after WW II caused a distortion of water systems Climate change will enhance the problems The restoration can be done in a ‘romantic’ and/or technological way Controlled drainage, with the use of new technologies and techniques (remote control, now- and forecasting), has much potential 21-9-2018 trip USA nov 2011

More information ‘Water in the Netherlands’: www.nhv.nu (jan.van.bakel@hetnet.nl) ‘Water Policy in the Netherlands’, 2009. Reinhard and Folmer (eds). www.rffpress.org/water SWAP-model: www.swap.alterra.nl 21-9-2018 trip USA nov 2011

Water in the Netherlands Water management in a densely populated delta and the role of controlled drainage Thank you for your attention!