Overland hydrology modeling Goran Pejanovi Assistant director - - PowerPoint PPT Presentation

Overland hydrology modeling

Goran Pejanović Assistant director National Hydrometeorological Service of Serbia (host of the SEEVCCC)

Hydrologic cycle and its modeling

• atmosphere model:
• land surface model:
• hydrology model:
• ocean model

precipitation snowmelt subsurface runoff

• verland flow

underground flow river discharge

• available high-resolution datasets on:

topography land use, land cover soil types, soil texture vegetation cover cloud microphysics soil moisture evapotranspiration interception surface runoff infiltration

Hydrological models

• statistical models

simple equations, lot of parameters that should be calibrated correlation between precipitation amount and river discharge

• conceptual models
• physically based models

differential equations based on physical lows, but often oversimplified (kinematical approximation), fewer parameters for calibration

• dynamically treat overland and underground flow
• be universal (easy to apply on any watershed, short and long term integrations)
• be computationally efficient

Hydrological model should:

• be a callable routine within an atmospheric model

HYdrology PROgnostic Model

• atmosphere:

NCEP’s Numerical Mesoscale Model NMM-E non-hydrostatic model

• land:

NOAH land surface scheme

• hydrology:

HYPROM2d: surface runoff HYPROM1d: river routing

• datasets:

HYDRO1km USGS topography FAO soil texture data USGS landuse data

=       − + ∂ ∂ + ∂ ∂ + ∂ ∂ + ∂ ∂

x fx

S S x h g y u v x u u t u =       − + ∂ ∂ + ∂ ∂ + ∂ ∂ + ∂ ∂

y fy

S S y h g y v v x v u t v

( ) ( )

= + ∂ ∂ + ∂ ∂ + ∂ ∂

• H

y hv x hu t h

Governing equations:

A B C D E F

d

A-B-C-D-E-F

h – points u – points river points

• Reference:

Nickovic et al., 2010, HYPROM Hydrology Surface-Runoff Prognostic model, Water Resources Research, 46, W11506

• Dynamical treatment of overland flow

(NO kinematical approximation!)

• Numerically stabile implicit time scheme for

the friction term

• New numerical scheme for preventing grid

decoupling noise

• Horizontal advection scheme is mass

conserving and positive definite

l

W

l

W

l

W

precipitation surface runoff interc. snow melt evaporation baseflow

LSM as a vertical hydrology component

Liquid water content forecast: Darcy’s Law

ex w l w l

R z W K z t W +       + ∂ ∂ ∂ ∂ = ∂ ∂ γ

saturated conductivity saturated diffusivity porosity (max. soil moisture content) Clapp-Horneberger constant

ws

K

ws

γ

s

W b

3 2 +

        =

b s l ws w

W W γ γ

2 +

        =

b s l ws w

W W K K

diffusivity conductivity

Case study: the Savinja river, flash flood event

T and V at 850 hPa, 1Nov1990

• acc. rainfall

26 Oct – 6 Nov1990

accumulated precipitation (mm) forecast hour (h) forecast hour (h) river discharge (m^3/s)

watershed: 1850 km2 model .vs. observations

Case study: the Moraca river

7th Feb. 2003 5th Feb. 2003

watershed: 3200 km2 heavy rain event: example of model’s dynamics

surface runoff and streamlines

0.20 0.465 porosity 8.17 2.45 x 10‐6 0.113 x 10‐4 Clay Loam (09) 2.79 CH constant 1.41 x 10‐4 sat. conductivity 0.136 x 10‐3

• sat. diffusivity

Bedrock (15) parameter

River discharge sensitivity to soil types

Water budget components: six months accumulations

precipitation runoff evaporation snow melt

November 2002 – April 2003

One year runs: river discharge

year: 2003 year: 2008 model .vs. observations

BIAS: - 2.43 MAE: 35.48 RMSE: 55.48 CC: 0.94 FEC: 0.87

Case study: the Skadar lake, climate simulations

the Skadar lake watershed: 5180 km2 RCM-SEEVCCC: resolution ~35km, A1B SRES/IPCC scenario NMM-E nesting: resolution ~8km control year: 2003 simulation: 2020 - 2030 modeled river discharge

• n the Bojana river

• Dynamical treatment of overland flow
• Suitable for long term and flash flood simulations
• Computationally efficient
• Applicative to small and large watersheds
• No calibration needed
• Off-line and on-line mode

HYPROM example for the Danube watershed

HYPROM conclusions:

• Couple with NMM-B + LISS
• Dynamical treatment of

subsurface flow (if possible)