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Ecohydrology of Water-controlled Ecosystems addresses the connections between the hydrologic cycle and plant ecosystems, with special emphasis on arid and semi-arid climates. This important topic is treated by building suitable mathematical models of the physics involved and then applying them to study the ecosystem structure and its response to rainfall and climate forcing in different parts of the world, including savannas, grasslands and forests. It investigates the vegetation response to water stress (drought), the hydrologic control on cycles of soil nutrients, and the dynamics of plant competition for water. The book also offers insights into processes closely related to soil moisture dynamics, such as soil-atmosphere interaction and soil gas emissions. This book will appeal to advanced students and researchers from a large range of disciplines, including environmental science, hydrology, ecology, earth science, civil and environmental engineering, agriculture and atmospheric science.

Highly organized vegetation patterns can be found in a number of landscapes around the world. In recent years, several authors have investigated the processes underlying vegetation pattern formation. Patterns that are induced neither by heterogeneity in soil properties nor by the local topography are generally explained as the result of spatial self‐organization resulting from “symmetry‐breaking instability” in nonlinear systems. In this case, the spatial dynamics are able to destabilize the homogeneous state of the system, leading to the emergence of stable heterogeneous configurations. Both deterministic and stochastic mechanisms may explain the self‐organized vegetation patterns observed in nature. After an extensive analysis of deterministic theories, we review noise‐induced mechanisms of pattern formation and provide some examples of applications relevant to the environmental sciences.

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The recent intensification of international trade has led to a globalization of food commodities and to an increased disconnection between human populations and the land and water resources that support them through crop and livestock production. Several countries are not self-sufficient and depend on imports from other regions. Despite the recognized importance of the role of trade in global and regional food security, the societal reliance on domestic production and international trade remains poorly quantified. Here we investigate the global patterns of food trade and evaluate the dependency of food security on imports. We investigate the relationship existing between the trade of food calories and the virtual transfer of water used for their production. We show how the amount of food calories traded in the international market has more than doubled between 1986 and 2009, while the number of links in the trade network has increased by more than 50%. Likewise, global food production has increased by more than 50% in the same period, providing an amount of food that is overall sufficient to support the global population at a rate of 2700-3000 kcal per person per day. About 23% of the food produced for human consumption is traded internationally. The water use efficiency of food trade (i.e., food calories produced per unit volume of water used) has declined in the last few decades. The water use efficiency of food production overall increases with the countries' affluence; this trend is likely due to the use of more advanced technology.

Abstract. In the present paper we describe some methods for verifying and evaluating probabilistic forecasts of hydrological variables. We propose an extension to continuous-valued variables of a verification method originated in the meteorological literature for the analysis of binary variables, and based on the use of a suitable cost-loss function to evaluate the quality of the forecasts. We find that this procedure is useful and reliable when it is complemented with other verification tools, borrowed from the economic literature, which are addressed to verify the statistical correctness of the probabilistic forecast. We illustrate our findings with a detailed application to the evaluation of probabilistic and deterministic forecasts of hourly discharge values.