Development of constructed wetlands in agricultural landscapes using remote sensing techniques

In Sweden, drainage and the construction of water infrastructure have influenced agriculture in the last few centuries both positively and negatively. Recently, a trend has set in where wetlands are constructed to retain water, retain and reduce nutrients and to enhance the biodiversity. This study aimed to use remote sensing techniques to study landscape water retention over time. In this pilot study, water retention structures in Gotland (57 degrees 28'35.0 '' N18 degrees 29' 13.9 '' E) and Kalmar Lan (56 degrees 39'41 '' N16 degrees 21'46 '' E) for 2000/2001 and 2020 were identified and analyzed using Landsat data. In this study, it was found that the number of water retention structures (>0.8 ha) increased from 44 to 101 for Gotland Lan and from 44 to 127 for Kalmar Lan. Most water retention structures were <4 ha and were located in mid- and downstream areas. A comparison of the remote sensed results with the Swedish Meteorological and Hydrological Institute (SMHI) database showed a disagreement of the spatial coordinates of the wetlands in the database with the water retention structures. This pilot study has shown that remote sensed data can be used to identify water retention structures, although higher resolution imagery would be highly advisable in these kinds of studies.

Automated summary

In Sweden, drainage and water infrastructure construction have had both positive and negative impacts on agriculture in the last few centuries. A recent trend in constructing wetlands for water retention, nutrient reduction, and biodiversity enhancement has been observed. This pilot study utilized remote sensing techniques to identify and analyze water retention structures in Gotland Lan and Kalmar Lan, showing an increasing trend in the number of structures, predominantly located in smaller areas and downstream regions. The study also highlighted discrepancies between remote sensing data and the Swedish Meteorological and Hydrological Institute database, emphasizing the importance of higher resolution imagery in similar studies.