LAWAMAD – Agricultural water management in Germany (Subproject C)

Background and Objective

Thejoint project LAWAMAD is tasked with analyzing options for improving water management in Germany's agricultural landscapes. The goal of enhanced water management is to significantly increase the availability of irrigation water for crop cultivation, for example, through the establishment of water retention basins. The LAWAMAD subproject C, focuses on a regionalized description of irrigation and an analysis of climate change-induced variations in irrigation demand.

The project's aim is to quantify these impacts of climate change on agricultural irrigation demand and to evaluate possible adaptation measures. For this purpose, a model-based method is being developed, which combines agricultural land use with climatic variables, soil type, and the simulation of practical irrigation decisions. The model development is based on past research projects in the federal states of Hessia, Bavaria, and North Rhine-Westphalia.

We distinguish between the following terminologies: The potential agricultural irrigation demand indicates the additional amount of water – per unit of space and time – needed to maintain soil water content at a level conducive to the growth of crops. This additional amount of water is determined based on objective criteria (climate, soil, crop, technology) and the principles of good agricultural practice in field irrigation. To derive the actual irrigation, it is necessary to consider economic and business factors as well as the availability of irrigation water.

Target Group

Policymakers, agricultural producers, advisors, regional water associations, chambers of agriculture, interested professionals and the general public, science

Approach

From this objective, the LAWAMAD subproject C "Regionalized Analyses of Irrigation Demand for Germany under Climate Change" derives the following work packages:

• Spatially explicit modeling of the status quo of irrigation   in Germany on a municipality resolution (WP 1)
• Development of a model to estimate potential irrigation demand in Germany (WP 2)
• Modeling of potential irrigation demand for the past (ex-post), and future development, incorporating regional climate projections (ex-ante) (WP 3)
• Estimate of actual irrigation by considering statistical data on irrigation infrastructure and economic parameters (WP 4)

The work is accompanied by an advisory board of 25 experts from science and federal authorities. The comprehensive expertise and regional knowledge of the experts are central components of knowledge generation and quality control in the project.

Data and Methods

An extensive spatial dataset of agricultural land use in Germany forms the input for modeling potential agricultural irrigation demand and deriving actual irrigation is. This includes climatic, soil physical, and phenological data, as well as real data on irrigation infrastructure. Furthermore, an extensive literature review is conducted on crop-specific factors (e.g., plant water requirements, root depth, etc.), the functioning of irrigation techniques, and agricultural water management or irrigation decision-making. These data are integrated into a model.

The developed model is based on combining soil water balance modeling with the principle of irrigation scheduling, enabling an objective and realistic calculation of agricultural irrigation demand. In developing the model, further criteria were considered (scaling from field to regional level, replaceability of input data, valid method that has already been used for a German case study) to ensure model suitability as a scenario tool.

Preliminary Results

The first results of the ongoing research project are presented in the report "Status Quo of Irrigation in Germany" (as of 2025), which unites all available statistical data on irrigation in Germany for the first time.

Initial insights into the expected model results are provided by past research projects. Studies for the federal statesof Hessia, Bavaria, and North Rhine-Westphalia show regionalized analyses of potential agricultural irrigation demand. These studies show a demand increase in the past due to already existing climatic changes. Future projections predict a continued increase in regions that have been irrigated previously and an expansion into regions currently not irrigated.