Abstract:
Climate change in Norway is occurring gradually, yet its consequences are
becoming increasingly evident. There is a steady rise in average temperatures, an
increase in annual precipitation and runoff, as well as a growing intensity of extreme
weather events. Various regions of the country are experiencing more frequent and
intense rainfall, which directly affects the hydrological regime and the formation of
surface runoff. These climatic shifts raise concerns due to their impact on freshwater
sources, especially during periods of heavy precipitation, when higher levels of bacterial
contamination, increased water turbidity, and intensified coloration are observed; this
indicates elevation of concentrations of organic matter and suspended particles in the
water.
Amid growing climate risks, there is a pressing need for thorough regional
analyses of how these changes affect water quality. Such analyses form the foundation
for timely upgrades to water treatment facilities, as the increasing burden on filtration
and disinfection systems could compromise their effectiveness, particularly in smaller
settlements. By the end of the 21st century, the situation is expected to worsen, with
forecasts indicating a further rise in waterborne pollutants due to soil erosion, runoff
from agricultural lands, and urbanized areas.
According to climate research, the rise in air temperature, especially when
combined with changes in precipitation patterns, will significantly influence hydrological
processes [1]. Precipitation in Norway is expected to become predominantly convective
in nature, occurring more frequently and with greater intensity [4]. This will pose new
challenges for water supply systems, particularly in maintaining consistent drinking
water quality. Norway has already experienced an increase in the average annual
temperature of about one degree Celsius since the early 20th century [1]. This trend
is accompanied by shifting snowmelt seasons, increased winter and spring runoff, and
changes in the amount and distribution of precipitation. A particularly noticeable rise
in precipitation occurred after the 1970s, amounting to approximately an 18% increase
compared to initial values.
