Wseep
Ea


Must be measured in rain gauges. In how many?
How to interpolated/extrapolated?
Inverse of the Distance Weight
Regression Model
THIESSEN POLYGON

Depends on:
 Atmospheric conditions (HR, Temperature, radiation & wind)
 Available soil water (above wilting point)
 Transpiration surface (Leaf Area Index – LAI)
 Depends on plants Development and soil
cover.
http://www.fao.org/docrep/X0490E/x0490e06.htm

Rn is the net radiation, G is the soil heat flux, (es - ea) ris the
vapour pressure deficit of the air, r a is the mean air density at
constant pressure, cp is the specific heat of the air, D is the
slope of the saturation vapour pressure temperature
relationship, g is the psychrometric constant, and rs and ra are
the (bulk) surface and aerodynamic resistances.

Richards Equation

http://www.mohid.com/wiki/index.php?title=Module_PorousMedia#Water_retenti
on

10cm
30cm
50cm
1 m
70cm
2 m
Tempo
T oalha F reática
P-V
Primavera-Verão
ETR
P-V
P-V
P-V
Chuva
1º ANO
2º ANO
3º ANO
Outono-Inverno
O-I
Rega
50cm
O-I
O-I
O-I
35cm
15cm
MOHID Land
Watershed
Water
Content
Runoff
Rain Intensity
IST – MARETEC 2008



Is the Rain that does not infiltrate.
Flows at soil surface, can infiltrate (and
sometimes exfiltrate.
Flow is controlled by friction.








Hydrology
Vegetation (evapotranspiration, nutrients, pesticides,
erosion,….)
Mineralisation of Organic matter in the soil (bacterial loop)
Irrigation
Salts dynamics/chemical equilibrium
Rivers,
Reservoirs/lakes,
Estuaries and Coastal Lagoons.



All models compute Evapo-transpiration on the
same way. Differences on results depend on the
detail of the input data.
Process oriented models (e.g. Hydrus, Mohid,
Mike, RZWQM) compute percolation using the
Richards Equation. They need fine grids.
Other models use coarse grids and empirical
formulations to compute flow (e.g. SWAT, HSPF,
BASINS).







Meteorological data processor,
Climate (seasonal/daily solar evolution),
GIS,
Chemical Equilibrium,
Plants Optimal Growth,
Management Practices,
Graphical interfaces.


Production of plants is the major role of
catchments.
Diffuse pollution is mostly due to plant growth
improvement:
 Fertilisation, Phyto-sanitation, irrigation.
http://www.fao.org/docrep/009/a0100e/a0100e05.htm
N2
CO2
NH4+
CH4
ANAEROBIC
BIOMASS
LABILE OM
Psol
REFRACTORY
OM
NO3
-
AEROBIC
BIOMASS
CO2
AUTOTROPHIC
BIOMASS
NH4+
Urea
NH3
Psol
Pfix


http://www.mohid.com/wiki/
http://en.wikipedia.org/wiki/MOHID_Land
Distributed vs partially distribuited
models
MOHID Land
SWAT
1D Drainage network
Q
t

2
2 2
 H
 Q 
Q n 
 2 4/3   0

  gA 
x  A 
A Rh 
 x
2D Overland flow
2/3
Q 
A. R h
H / x
n
HRU
3D Porous Media

t
 h z 
  K (h) 


  xi  xi 
Watershed picture to
farm plots;
Vegetation and Erosion
Flush events
Precipitation
Variable in
Time
& Space
CN, Lag time
Processos de qualidade da água em Rios
CO2
O2
Nitrato
Respiração
Amónia
Nutrientes
Consumo
Ortofosfato
Sílica
Bactérias
Produtores Primários
Excreção
Consumo
Morte
Detritos / MO
Deposição
Sedimentos
Produtores Secundários

Kinematic wave equation
 (equilibrium between gravity and friction)

Trapezoidal shape for channels in both models
•Rch is the hydraulic radius for a given depth
of flow (m),
•slpch is the slope along the channel length
(m/m),
•n is Manning’s “n” coefficient in channel
•vc is the flow velocity (m/s).
If inertia is
important:
2
2 2
 H
 Q 
Q n 

 2 4/3   0

  gA 
t
x  A 
A Rh 
 x
Q
MOHID Land
Watershed
Water
Content
Runoff
Rain Intensity
IST – MARETEC 2008
MOHID Land
River
Sediment
Rain Intensity
WQ
models in
river
IST – MARETEC 2008







wperc,ly is the amount of water percolating to the underlying
soil layer on a given day (mm H2O),
SWly,excess is the drainable volume of water in the soil layeron a
given day (mm H2O),
Δt is the length of the time step (hrs),
TTperc is the travel time for percolation (hrs).
SATly is the amount of water in the soil layer when
completely saturated (mm H2O),
FCly is the water content of the soil layer at field
capacity (mm H2O),
Ksat is the saturated hydraulic conductivity for the
layer (mm·h-1).





Qgw,i is the groundwater flow into the main
channel on day i (mm H2O),
Qgw,i-1 is the groundwater flow into the main
channel on day i-1 (mm H2O),
αgw isthe baseflow recession constant,
Δt is the time step (1 day), and
wrchrg is theamount of recharge entering the
aquifer on day i (mm H2O).

CN – Curve Number (0% -100% runoff)
 O CN is a function of: i) permeability, ii) land use
and iii) previous soil water content. CN can
change between 0.0 (no runoff) and 100 (all
precipitation transformed into runoff).
A
High infiltration rates.
B
Moderate infiltration rates.
C
Low infiltration rates.
D
Very low infiltration rates.

S – Soil water retention parameter
(mm H2O)
 1000

S  25 , 4 
 10 
 CN


Q surf 
R
R
 0,2 S 
2
day
day
 0 ,8 S 
Knowing Qsurf (acumulated runoff) it is
possible to estimate infiltration
IST- MARETEC 2009
1.
Com base na topografia foram geradas 700 sub-bacias para
a RH6 com áreas entre 0.001 km2 e 100 km2
2.
1
Sub-bacias foram geradas em função das massas de água
Precipitação
Precipitation
1
IST- MARETEC 2009
Flow
1. Cada sub-bacia comporta-se como
uma Unidade de Resposta
Hidrológica (HRU) com o mesmo
uso de solo, tipo de solo e declive
1
RH6
Tipologia A2
Estuário mesotidal homogéneo
com descargas irregulares de rio
• Estuário do Sado
6 massas de água
• Estuário do Mira
3 massas de água
8
IST- MARETEC 2009
28
IST- MARETEC 2009
Poucos dados - estações da Sado WB1
Poucos dados - estações da Sado WB2
Poucos dados - estações da
Sado WB2 (individualmente
e com a média das estações)
Canal de Alcácer
IST- MARETEC 2009