Using real-time observations and land surface modelling for improved irrigation and water resources management in Mediterranean climate

Abstract

Irrigated agriculture is essential to sustain crop production and livelihoods of the rural population in semi-arid and arid regions such as the Mediterranean. Meanwhile, unsustainable irrigation practices, population growth, and climate change are increasing agricultural water demand while exacerbating water scarcity. Effective measures to reduce agricultural water consumption while sustaining a high level of crop production and securing environmental sustainability are therefore urgently needed. <br /> This thesis aims at increasing the availability of environmental data and advancing the representation of agricultural systems in land surface models to improve local and regional scale irrigation and water resources management in the Mediterranean. <br /> In the first part, the use of a low-cost weather station to deliver reliable and timely data for environmental monitoring, research, and modelling is assessed. Performance and data quality of multiple stations are examined in terms of inter-sensor variability and in comparison to a high-performance weather station. <br /> The second part of this thesis focusses on improving the representation of typical Mediterranean crops in the Community Land Model version 5. A new sub-model to model deciduous fruit orchards is developed encompassing crop phenological stages, biomass growth and partitioning into different plant organs as well as typical management practices. The development is then tested using extensive field measurements from an apple orchard. <br /> Finally, the new sub-model is used to assess irrigation and water management in a small Greek catchment dominated by irrigated apple orchards. First, simulated crop growth and soil moisture dynamics are examined in relation to irrigation and compared to observations from two monitored apple orchards. Thereby, further model improvements are made to represent the local irrigation practices. Subsequently, the model is applied at regional scale to determine irrigation requirements and examine the impact of different irrigation deficit scenarios on yield and crop water use efficiency as well as to assess the water saving potential in the catchment.