Unusually low water levels in Asa streams

17 November 2022

Asa High-yield Experimental Forest was established in 2009 and covers an area of 1700 hectares, situated in close proximity to Asa Research Station. Spruce and pine dominates the forest and represent 95% of the total area. The aim of the high-yield experiment is to increase the growth of wood by 50 %, and at the same time avoid creating any negative effects on water chemistry, vegetation, recreational values, etc. Every second year stands within the experimental area are fertilized. Due to the fertilization, water samples are collected and analysed regularly from streams that represent the different catchments within the area, to ensure that there isn’t leakage of nutrients.

Apart from producing water chemistry data from the different catchment areas, the water monitoring program gives an opportunity to follow the water level and discharge through the seasons. This year the water level has differed in comparison to earlier years. It is common that the streams in the forest run dry for a period during the summer, but this year, there has hardly been water in the streams during autumn. As the photo below shows, there is at the moment (in early November) hardly any or only very low flow in the streams.

Low water leves in Asa stream. Photo: Erik Kristensen
Low water leves in Asa stream. Photo: Erik Kristensen

The graph below shows one of the streams drying up (i.e. very low discharge) by May and remaining that way into the autumn. March was extremely dry with minimal precipitation. Precipitation in the following six months was actually higher than the annual monthly average but it was still not enough to keep the stream flowing and make up for the lack of rain during March. The data is from an inlet stream to Lake Feresjön, where the water table has been low for a prolonged period, yet this year was even lower.

Inlet stream discharge and precipitation in 2022

Water leve data from the Lake Feresjön inlet streams can be found on SITES data portal, and soon it will also be possible to download all water level data and water discharge data from the catchment areas in Asa High-yield Experimental Forest.