Rakshan Roohi
La Trobe University, Australia
Title: Assessment of wateruse of different landcovers using Surface Energy Balance Algorithms for Rainfed Agriculture (SEBARA) in western Victoria, South Australia
Biography
Biography: Rakshan Roohi
Abstract
Evaporation and transpiration components of the energy balance are influenced by many factors especially in water-limited ecosystems: surface temperature, soil moisture, vegetation type and growth stage, and atmospheric advection and therefore are the most difficult ones to estimate. Any shift in landuse/Landcover (LULC) can disturb the hydrological balance and thus put stress on the water resources. Following the principals of energy balance equation, Surface Energy Balance Algorithm for Rainfed Agriculture (SEBARA) has been devised to estimate the evapotranspiration (ET) of different LULCs in western Victoria using medium spatial resolution Landsat data. ET estimates of four LULCs: crops, plantations, natural vegetation and pastures revealed that generally the crops and plantations have 12-20% higher evapotranspirtation rate than the natural vegetation and pasture which is due to lower surface albedo and emissivity, resulting in lower outgoing longwave radiation. As a consequence, the higher available net radiation and lower soil heat flux in crops and plantations result in higher ET rate. It is observed that the tree roots can reach extend down to 12m to access groundwater which is deeper than the 6-8m previouly measured. The younger plantation with an open canopy has lower ET than the older plantation, but similar to the pastures and natural vegetation. The cultivated oats have similar evapotranspiration rate as that of old plantation. Overall the ET from pastures is lowest however, the rate depends upon the pasture species. The estimated ET compares well with ET measured using flux tower and adjusted sapflow readings (accuracy > 95%).