Project TR37010: UrbanDrainage Systems as Key Infrastructure in Cities and Towns Soil Water BalanceComponents and Methods for Calculation PhD Student: Željko Vasilić Mentor: Miloš Stanić Belgrade, 26.04.2013.
Outline: • Introduction • Soil water balance • Evapotranspiration • Infiltration • Conclusions
About project TR 37010 • „UrbanDrainage Systems as Key Infrastructure in Cities and Towns“ • Funded by Ministry of Science • Experimental catchments for investigation of urban runoff
About project TR 37010 Parking area Oil separator • Experimental catchment – Belgrade Infiltration tank
About project TR 37010 • Experimental catchment – Belgrade
P ET Soil Water Balance E P-Pint Qsurf • Water balance components (for unsaturated soil) INF unsaturated GWR saturated • Evapotranspiration • Infiltration Process of water penetrating from the ground surface into the soil.
Evapotranspiration modelling ETp – potential ET0 – Reference Ea– actual • Factors driving the process • Energy • Meteorological factors (T, Humidity, Wind speed..) • Other factors affecting Ea • Soil characteristics and conditions • Vegetation characteristics • Environmental conditions
Evapotranspiration modelling • Methods for calculation • Energy balance method • Aerodynamic method • Combined method • Methods for calculation of ETp • Blaney– Cridle eq. • Pristley – Taylor eq. • Penman – Monteith eq.
Penman Monteith method • Assumes horizontal surface. Modification (Allen,2006):
Penman Monteith method • Results data from meteo station SmederevskaPalanka Lat 44o22’N ; Lon 20o57’ E; Altitude 121.0 m Total annual ET Orientation South Orientation North
Inflitration modelling Basic equation for unsaturated flow Continuity equation (z direction): Momentum equation: Combination gives (Richard’s eq.):
f(t) (mm/h) Infiltration modelling fo α1 • Other methods • Simple methods • Horton equation • Philips Equation α2>α1 • Based on approximate theory • Green Ampt method • (k=const.,sharp boundary wetting front,semi-infinitive domain…) fc t(h) Darcy’s law: Continuity eq.: Combined: Horton’s method
Inflitration modelling Implementation of Simplified Green Ampt model Darcy’s law: Continuity eq.: Combined (with assumptions):
Conclusions and future work • Slope and orientation of the surface can significantly affect evapotranspiration • Infiltration can be calculated using methods of different complexity • After the measured data from the experimental catchments are obtained all methods will be tested