Ecohydrology is a fast-growing branch of science at the interface of ecology and geophysics, studying the interaction between soil, water, vegetation, microbiome, atmosphere, climate, and human society. This textbook gathers the fundamentals of hydrology, ecology, environmental engineering, agronomy, and atmospheric science to provide a rigorous yet accessible description of the tools necessary for the mathematical modelling of water, energy, carbon, and nutrient transport within the soil-plant-atmosphere continuum. By focusing on the dynamics at multiple time scales, from the diurnal scale in the soil-plant-atmospheric system, to long-term stochastic dynamics of water availability responsible for ecological patterns and environmental fluctuations, it explains the impact of hydroclimatic variability on vegetation and soil microbial systems through biogeochemical cycles and ecosystems under different socioeconomical pressures. It is aimed at advanced students, researchers and professionals in hydrology, ecology, Earth science, environmental engineering, environmental science, agronomy, and atmospheric science.