Water Resources Conditions and Possible Savings in Irrigation

SystemsProf Wim Bastiaanssen

Which tools are available to assist planning ?

Cheema – Ph.D. student TU-Delft

Remote sensingWater basin models

Groundwater flow modelsClimate models

Water accountingGIS data

Smart phoneSMS messages

Yesterday

Models are Required for Future Projection

PAST FUTURE

FUTURE: C

FUTURE: A

Policies:A, B, C

ObservationsRemote Sensing Simulation Models

FUTURE: B

Yesterday

Cheema – Ph.D. student TU-Delft

Conclusions day 1• The basic data needed for planning is

obsolete. Tools can assist with the derivation of real time and localized data

• The impact of certain interventions need to be understood, i.e. scenario analysis

• Water resources planning is a political process• More attention should be given to convert

information into evidence based decision making: data alone is not sufficient

From information to planning

Data

database

Ministries & AgenciesTargets

DefineScenarios

Tools

Impact &Advice

Parlement decisions

(Technical component only)

Fluctuation of the renewable water resources ?

Cheema – Ph.D. student TU-Delft

Yearly RainfallTRMMSatellite1998 to 2012

RainfMM validation over Pakistan

Rainfall trend 1998 to 2012

Cheema – Ph.D. student TU-Delft

Actual evapotranspiration Abyan

Modelling Recharge and Runoff for period 2000-2009 (SPHY model)

This are the renewable water resources

Cheema – Ph.D. student TU-Delft

• Integrate satellite data and ground stations• Downscale and calibrate local rainfall (250 m)• Compute actual evapotranspiration (250 m)• Validate evapotranspiration where feasible• Make water accounts for each basin• Assess renewable water resources• Determine degree of over-exploitation

How to improve the knowledge on renewable water recourses ?

Water accounting

Can we reduce the water demand for irrigation ?

Cheema – Ph.D. student TU-Delft

• Reduce abstractions of groundwater- Quota on water use, well licenses, stop subsidized diesel for pumps- Reduce crop ET by improved irrigation technologies- Reuse urban, industrial and irrigation water• Control agricultural areas- Control irrigated area (ha)- Control cropping intensity- Abandon certain crops - Land retirement• Enhance rainfed agriculture- New seeds- Better practices• ……

Cheema – Ph.D. student TU-Delft

irrigation efficiency improvement needs special attention

TRMM validation over PakistanIrrigation efficiency of 40 %

1000

400

500 350

300 450

Net withdrawal is 1000 – 750 = 250 mm

TRMM validation over PakistanIrrigation efficiency of 80 %

1000

800

500 350

140 210

Net withdrawal is 1000 – 350 = 650 mm, incremental ET is 400 mm

Control

your ET !

How to reduce crop evapotranspiration (ET) ?

Cheema – Ph.D. student TU-Delft

• Use drought tolerant crop varieties• Short duration crop varieties• Apply mulching of row crops and tree crops• Manage soil moisture within a preferred regime • Introduce drip systems that reduced soil evaporation • Apply a certain level of deficit irrigation that does not affect crop production

Cheema – Ph.D. student TU-Delft

Crop water stress will not necessarily reduce production

Large variabilityof Qat ET in Rada

Impose a certain level of water stress

Cheema – Ph.D. student TU-Delft

Actual ET Potential ET

Water

stress

For every water basin:

• Improve the knowledge of renewable water resources, and the intra-annual fluctuations

• Assess the level of over-exploitation and estimate the reduction need

• Reduce irrigation water demand by ET reduction measures (mm) and areal control (ha)

• Focus on areas where recharge fulfills > 100 mm/yr• Make water accounts current & future• Define scenario’s and interventions• Evaluate impact of scenario’s • Advice Members of Parlement

Thank you !