The remote sensing approach to assess the water demand in landscapes in the Southern of Portugal

Landscape irrigation management is an important factor for water conservation, especially in Mediterranean climate with dry and warm summers where the annual average temperature is 17 0 C and annual precipitation rarely exceeds 700 mm per year. A proper landscape irrigation management to optimize the water use efficiency is achieved by applying the correct amount of water to maintain visual quality of the plants without excessive losses due to deep percolation or runoff. In the absence of landscape water consumption records, vegetation indexes help to determine landscape water demand. Remote sensing provides a tool to assess the evolution of green quality in the landscape. This study aims to evaluate water demand in the Algarve urban landscape in 2016. High-resolution aerial images and climatic records were used to: i) identify and measure the irrigated landscape area; ii) differentiate hydrozones, which are areas covered by plants with similar water needs that were identified by color or patterning; and iii) compare the measured landscape water demand in those areas with vegetation indexes. Combining all information, a better understanding of trends in water demand for Algarve urban landscape was achieved. This is relevant due to the potential for climate change and projections for increasing drought.