Mohamed Rasmy

Senior Researcher, ICHARM/PWRI

Associate Professor, GRIPS

ICHARM: Delivering best available knowledge to local practices

Platform on Water Resilience and Disaster in Indonesia

Seamless Modeling Approach under Changing Climate:WEB-RRI Model development & Applications

Prec

ipita

tion

Inte

rcep

tion

Surf

ace

Stor

age

Evap

orat

ion

-tr

ansp

iratio

n

Infil

trat

ion

Gro

und

Wat

er

Flow

Surf

ace

Runo

ff

The water entering an area has to leave the area or be stored within the area. “conservation of Mass - zero-sum nature of the game”

HYDROLOGICAL PROCESSES FOR WATERSHED MODELS

P = Q + E ± ∆S

Where, P is precipitation, Q is runoff, E is evaporation and ∆S is the storage in the soil, aquifers or reservoirs.

OVERVIEW: RRI MODEL

3

Rainfall

DEM

Land Cover

Cross Sec.

Input

Discharge

W. Level

Inundation

Output

Sayama, T. et al.:, 2012.

(A) Only overland flow (B) Infiltration + Infiltration excess overland flow

(C) Saturated subsurface+ Saturation excess overland flow

A 2D diffusive wave model capable of simulating rainfall-runoff and flood inundation simultaneously. Sayama et al (2010)

Takasao and Shiiba (1988),

EVENT-BASED RAINFALL-RUNOFF MODELING

• IN MODELING SINGLE FLOODS• EFFECTS OF INTERCEPTION AND DEPRESSION STORAGE

ARE NEGLECTED.

• EVAPOTRANSPIRATION IS IGNORED ITS MAGNITUDE DURING FLOODING IS NEGLIGIBLE WHEN COMPARED TO OTHER FLUXES SUCH AS INFILTRATION.

• EFFECT OF THE STREAM-AQUIFER INTERACTION IS ALSO IGNORED RESPONSE TIME OF THE SUBSURFACE SOIL SYSTEM >>> RESPONSE TIME OF THE SURFACE OR DIRECT RUNOFF PROCESS.

WEB-RRI: Hydro-SiB2 with RRI Model

MERITS OF WEB-RRI MODEL1. Physical formulations for ET, interception, and soil moisture dynamics, which will

improve the accuracy of low flow estimation, the timing of flood onset, flood peak discharges, and inundation depths and extent improve the reliability of flood and drought related RA

2. As the model takes more inputs (e.g. radiations, temperature, humidity, wind speed, leaf area index) in addition to the precipitation, the model will produce reliable responses to the water cycle variability as well as climate change scenarios can be used for long term simulations and hydrological extremes of a catchment with a great confidence,

3. As the model inputs are compatible with numerical weather and climate modeloutputs, it can be coupled with their outputs directly to estimate the basin scale hydrological responses to the model predicted forcing data,

4. The model can reconstruct the actual conditions of hydrological parameters at each time steps (provided that input data is accurate enough), and then the model can be stopped at any time step and can be restarted from the previous history to reduce the computational burden of pre-running of the model in practical applications such as flood forecasting and seasonal predictions.

WEB-RRI Model Development

Locations of the study area and gauges: (a) a map of Java Island of Indonesia with the demarcation of the Solo River basin boundary and (b) dam, daily rain gauges, and the Cepu discharge point

Parameter Source

Rainfall Data River Discharge DataDEMSoil typeLand useVegetationOthers: air temp., humidity, wind, radiation, surface pressure

BBWSBBWSUSGSFAO

USGSNASA/MODISJMA/JRA55

WEB-RRI Model Calibration & Validation

Comparison between observed discharge and simulated discharge at the Cepu gauging station: (a) model calibration for 2007-2008 and (b) model validation for 2008-2009

WEB-RRI Model: Long-term Simulations

long-term observed discharges and simulated discharges from 1990 to 2009 (20 years) at the Cepu station

Flow Duration Curve of discharges from 1990 to 2009 (20 years) at the Cepu station

WEB-RRI Model: Peak Flow Simulation

WEB-RRI Model: Flood Inundation

Flood inundation extents for the 2007 flood event in the Solo River basin

WEB-RRI Model: Evapotranspiration

WEB-RRI well simulated ET component of water budget A portion of the errors was also attributed to irrigation practices conducted for

agricultural activities (paddy cultivation) in the middle to lower reaches during the dry period.

WEB-RRI model can be implemented for estimating past, monitoring present or predicting future agricultural droughts as well as for land-use and climate-change impact assessment studies.

Past Vs Future: Climatology of input data

Climate change simulation using MRI-3.2s data

Ranking order statistics Innovative trend analysis

The basin was assumed to have no dam (i.e. natural flow conditions) because of the unknown dam operation rule in the future climate

Downscaled rainfall is bias corrected Temperature and radiations data will be bias corrected Appropriate dam operational rule will be implemented to develop climate adaptation

strategies

10% increase compared to the past climate

Soil moisture & ET

• Root-sone soil moisture will be decreased by 25% during dry period due to reduction in the rainfall amount during dry period in the future climate.

• there is a constrain for evapotranspiration even though temperature will be higher in the future climate, resulting a reduction in evapotranspiration in the future climate

• Consequently, this effect will require more water to irrigate the agriculture in the future climate.

Monthly Discharge

• Max. increase in the river flow at Cepu will be in November of the future climate and the amount will be more than two times of the present situation. The month of December and March will also be showed increments of river flow by ~25% of the present climate conditions.

• In other months, flow will be decreased and the result are alarming on the vulnerability of drought conditions and associate risk to agriculture.

• The future direction of this study will accommodate data from other RCP scenarios that are under progress and will investigate the possible changes due to global warming in the Solo River basin.

End to End Approach to Climate Change Adaptation

18

Seamless Modeling Approach : IWRM under changing climate

Rainfall Prediction

Climate Modeling

Hyd

rolo

gica

l mod

elin

gC

rop

Mod

elin

gEc

onom

ic M

odel

ing

Clim

ate

mod

elin

g

The points to be considered for adaptation planning

• Extreme discharge will increase by 10% - Increase in flood damages to urban area & agriculture

• Early warning • Dam operation optimization to reduce flood risk• Land-use planning

• Dry months (May to October) will be become more dryer (>50 %)• Optimized dam operation for improve drought conditions and

agriculture productions• Review of irrigation practices – propose effective methods• Modification on crop calendar and crop type

Thank you for your kind attention !!!

abdul@pwri.go.jp