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Papers by H. Biemans

Agricultural Water Management, 2022

LPJmL4 is a process-based model that simulates climate and land-use change impacts on the terrest... more LPJmL4 is a process-based model that simulates climate and land-use change impacts on the terrestrial biosphere, the water and carbon cycle and on agricultural production. The LPJmL4 model combines plant physiological relations, generalized empirically established functions and plant trait parameters. The model incorporates dynamic land use at the global scale and is also able to simulate the production of woody and herbaceous short-rotation bio-energy plantations. Grid cells may contain one or several types of natural or agricultural vegetation. A comprehensive description of the model is given by Schaphoff et al. (2017a, http://doi.org/10.5194/gmd-2017-145). The data presented here represent some standard LPJmL4 model results for the land surface described in Schaphoff et al. (2017a,). Additionally, these results are evaluated in the companion paper of Schaphoff et al. (2017b, http://doi.org/10.5194/gmd-2017-146). The data collection includes some key output variables made with di...

Map of the ratio irrigation/irrigation requirement showing (for values lower than 0.8) the areas ... more Map of the ratio irrigation/irrigation requirement showing (for values lower than 0.8) the areas where insufficient water availability limits the actual irrigation.

Proceedings of the National Academy of Sciences, 2013

Significance Humans alter the water cycle by constructing dams and through water withdrawals. Cli... more Significance Humans alter the water cycle by constructing dams and through water withdrawals. Climate change is expected to additionally affect water supply and demand. Here, model analyses of climate change and direct human impacts on the terrestrial water cycle are presented. The results indicate that the impact of man-made reservoirs and water withdrawals on the long-term global terrestrial water balance is small. However, in some river basins, impacts of human interventions are significant. In parts of Asia and the United States, the effects of human interventions exceed the impacts expected for moderate levels of global warming. This study also identifies areas where irrigation water is currently scarce, and where increases in irrigation water scarcity are projected.

Nature Communications, 2017

Safeguarding river ecosystems is a precondition for attaining the UN Sustainable Development Goal... more Safeguarding river ecosystems is a precondition for attaining the UN Sustainable Development Goals (SDGs) related to water and the environment, while rigid implementation of such policies may hamper achievement of food security. River ecosystems provide life-supporting functions that depend on maintaining environmental flow requirements (EFRs). Here we establish gridded process-based estimates of EFRs and their violation through human water withdrawals. Results indicate that 41% of current global irrigation water use (997 km3 per year) occurs at the expense of EFRs. If these volumes were to be reallocated to the ecosystems, half of globally irrigated cropland would face production losses of ≥10%, with losses of ∼20–30% of total country production especially in Central and South Asia. However, we explicitly show that improvement of irrigation practices can widely compensate for such losses on a sustainable basis. Integration with rainwater management can even achieve a 10% global net...

By 2050, 9 billion people will be fed through an increase in rain-fed and irrigated agricultural ... more By 2050, 9 billion people will be fed through an increase in rain-fed and irrigated agricultural land. The increase in water consumption will be the biggest challenge facing humankind. At the same time, climate change will disrupt the global water resources via changing precipitation and runoff patterns. It is fundamental to know how these changes in the food and water supply will occur, particularly when terrestrial and freshwater ecosystems are already degraded. We will study how and where new irrigated lands will be expanded with the coupled model LPJ-IMAGE. This model will allow us to predict the combined impact of climate change and land use change on water availability. Therefore, we will implement an environmental flow (EF) module into the Digital Global Vegetation Model (DGVM) LPJml. Allocation of water for freshwater ecosystem will be defined by assigning a high flow (HF) and a low flow (LF) to respond to freshwater ecosystem requirements following the Smakthin method (2004...

Forcing data to hydrological models is often presented as observations and therefore neglected as... more Forcing data to hydrological models is often presented as observations and therefore neglected as possible source of error in discharge calculations. This study quantifies the uncertainty in river discharge calculations caused by uncertainty in precipitation input for 300 river basins worldwide. For seven different global gridded precipitation datasets mean annual and mean seasonal precipitation at river basin scale are compared.

Hydrology and Earth System Sciences Discussions, 2013

Introduction 1.1 Problem statement 1.2 Objectives 1.3 General approach 1.4 Report outline 2. Mate... more Introduction 1.1 Problem statement 1.2 Objectives 1.3 General approach 1.4 Report outline 2. Material and methods 2.1 East Africa: countries and reference crop choice 2.2 Concepts and definitions 2.2.1 Yields and yield gaps 2.2.2 Water use productivity and water use efficiency 2.3 Data sources 2.4 Methods 2.4.1 Actual, rainfed and irrigated maize yields 2.4.2 Hydrological modelling 2.4.3 Matching irrigation water demand and availability 3. Results 3.1 Rainfall characteristics 3.2 Rainfed and irrigated maize production potentials 3.3 Yield gaps 3.4 Water use efficiency and water use productivity 3.5 Matching irrigation needs and availability 4. Discussion and conclusions 4.1 Limitations of the study 4.2 Major conclusions 4.3 Recommendations and follow-up References Appendix I. Country-specific irrigation use efficiencies p.

Agricultural Water Management, 2022

LPJmL4 is a process-based model that simulates climate and land-use change impacts on the terrest... more LPJmL4 is a process-based model that simulates climate and land-use change impacts on the terrestrial biosphere, the water and carbon cycle and on agricultural production. The LPJmL4 model combines plant physiological relations, generalized empirically established functions and plant trait parameters. The model incorporates dynamic land use at the global scale and is also able to simulate the production of woody and herbaceous short-rotation bio-energy plantations. Grid cells may contain one or several types of natural or agricultural vegetation. A comprehensive description of the model is given by Schaphoff et al. (2017a, http://doi.org/10.5194/gmd-2017-145). The data presented here represent some standard LPJmL4 model results for the land surface described in Schaphoff et al. (2017a,). Additionally, these results are evaluated in the companion paper of Schaphoff et al. (2017b, http://doi.org/10.5194/gmd-2017-146). The data collection includes some key output variables made with di...

Map of the ratio irrigation/irrigation requirement showing (for values lower than 0.8) the areas ... more Map of the ratio irrigation/irrigation requirement showing (for values lower than 0.8) the areas where insufficient water availability limits the actual irrigation.

Proceedings of the National Academy of Sciences, 2013

Significance Humans alter the water cycle by constructing dams and through water withdrawals. Cli... more Significance Humans alter the water cycle by constructing dams and through water withdrawals. Climate change is expected to additionally affect water supply and demand. Here, model analyses of climate change and direct human impacts on the terrestrial water cycle are presented. The results indicate that the impact of man-made reservoirs and water withdrawals on the long-term global terrestrial water balance is small. However, in some river basins, impacts of human interventions are significant. In parts of Asia and the United States, the effects of human interventions exceed the impacts expected for moderate levels of global warming. This study also identifies areas where irrigation water is currently scarce, and where increases in irrigation water scarcity are projected.

Nature Communications, 2017

Safeguarding river ecosystems is a precondition for attaining the UN Sustainable Development Goal... more Safeguarding river ecosystems is a precondition for attaining the UN Sustainable Development Goals (SDGs) related to water and the environment, while rigid implementation of such policies may hamper achievement of food security. River ecosystems provide life-supporting functions that depend on maintaining environmental flow requirements (EFRs). Here we establish gridded process-based estimates of EFRs and their violation through human water withdrawals. Results indicate that 41% of current global irrigation water use (997 km3 per year) occurs at the expense of EFRs. If these volumes were to be reallocated to the ecosystems, half of globally irrigated cropland would face production losses of ≥10%, with losses of ∼20–30% of total country production especially in Central and South Asia. However, we explicitly show that improvement of irrigation practices can widely compensate for such losses on a sustainable basis. Integration with rainwater management can even achieve a 10% global net...

By 2050, 9 billion people will be fed through an increase in rain-fed and irrigated agricultural ... more By 2050, 9 billion people will be fed through an increase in rain-fed and irrigated agricultural land. The increase in water consumption will be the biggest challenge facing humankind. At the same time, climate change will disrupt the global water resources via changing precipitation and runoff patterns. It is fundamental to know how these changes in the food and water supply will occur, particularly when terrestrial and freshwater ecosystems are already degraded. We will study how and where new irrigated lands will be expanded with the coupled model LPJ-IMAGE. This model will allow us to predict the combined impact of climate change and land use change on water availability. Therefore, we will implement an environmental flow (EF) module into the Digital Global Vegetation Model (DGVM) LPJml. Allocation of water for freshwater ecosystem will be defined by assigning a high flow (HF) and a low flow (LF) to respond to freshwater ecosystem requirements following the Smakthin method (2004...

Forcing data to hydrological models is often presented as observations and therefore neglected as... more Forcing data to hydrological models is often presented as observations and therefore neglected as possible source of error in discharge calculations. This study quantifies the uncertainty in river discharge calculations caused by uncertainty in precipitation input for 300 river basins worldwide. For seven different global gridded precipitation datasets mean annual and mean seasonal precipitation at river basin scale are compared.

Hydrology and Earth System Sciences Discussions, 2013

Introduction 1.1 Problem statement 1.2 Objectives 1.3 General approach 1.4 Report outline 2. Mate... more Introduction 1.1 Problem statement 1.2 Objectives 1.3 General approach 1.4 Report outline 2. Material and methods 2.1 East Africa: countries and reference crop choice 2.2 Concepts and definitions 2.2.1 Yields and yield gaps 2.2.2 Water use productivity and water use efficiency 2.3 Data sources 2.4 Methods 2.4.1 Actual, rainfed and irrigated maize yields 2.4.2 Hydrological modelling 2.4.3 Matching irrigation water demand and availability 3. Results 3.1 Rainfall characteristics 3.2 Rainfed and irrigated maize production potentials 3.3 Yield gaps 3.4 Water use efficiency and water use productivity 3.5 Matching irrigation needs and availability 4. Discussion and conclusions 4.1 Limitations of the study 4.2 Major conclusions 4.3 Recommendations and follow-up References Appendix I. Country-specific irrigation use efficiencies p.

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