Assessing Water Retention Potential in Agricultural Drainage Systems in Lower Austria

Agricultural drainage systems have been widely implemented to enhance crop productivity by managing excess water. However, with increasing weather extremes, including prolonged droughts and heavy precipitation, drained areas face new challenges, including the need for irrigation and a critical reassessment of water retention capabilities. Despite the importance of these systems, the extent of drained agricultural land in Austria, particularly in Lower Austria, remains largely unknown. Therefore, quantitative knowledge about the agrohydrological potential of drainage water management in the complex landscapes of Austria are urgently demanded.

This study aims to estimate the volume of water discharged through existing drainage infrastructure in agricultural regions of Lower Austria. By providing a foundational dataset, we seek to quantify the scale of drainage and evaluate its impact on soil water retention. The approach involves a two-step process. First, potentially drained agricultural areas are being identified by using existing resources such as the Austrian soil survey, cadastral soil assessments which provide spatial information on slope data, soil types, and land use.

Secondly, a raster-based water balance model is employed, using meteorological data and literature-based assumptions that attribute certain fractions of total runoff to drainage discharge. The model produces monthly estimates of drainage, emphasizing water retention beyond the vegetation period. These results are then upscaled to the identified drained areas.

Future repetitions of the model will incorporate increasing complexity, including detailed soil parameters and refined hydrological modelling techniques, such as the SWAP model. However, even initial estimations provide critical insights and serve as a starting point for understanding the interplay between drainage systems, water retention, and potential management strategies. This research underscores the importance of rethinking water management practices in agricultural systems to adapt to climate-induced challenges and improve sustainability.