Droughts Raise River Water Temperatures
A recent study unveils the impending rise in river temperatures due to reduced water flows and increasing atmospheric temperatures, posing significant challenges for aquatic ecosystems, wildlife, and human society.
With the ongoing global warming attributed to climate change and the projected increase in the frequency and severity of droughts, a recent study sheds light on the expected warming of rivers. This phenomenon presents significant challenges for aquatic ecosystems, biodiversity, and human society.
Water temperature plays a pivotal role in governing various physical, chemical, and biological processes within river ecosystems. Its significance is particularly evident for species incapable of regulating their body temperature, such as fish. Moreover, river temperature has implications for human health and serves as a vital resource for industrial, residential, and recreational purposes.
“Mechanisms Behind Increased River Water Temperatures in Droughts”
Scientists have identified three primary mechanisms responsible for elevating river water temperatures during droughts: input of energy from the atmosphere, the influence of physical characteristics of the river environment (such as shading and channel shapes affecting flow), and the varying contributions of different water sources. Groundwater, for instance, typically has a cooling effect on rivers during the summer months.
A review recently published in Hydrological Processes, conducted by the University of Birmingham in collaboration with the University of Nottingham and the Scottish Government’s Marine Directorate, underscores that the primary driver of elevated river water temperatures is the intense shortwave radiation experienced during hot and arid periods.
Impact of Drought-Related Factors on River Water Temperature
This, in conjunction with reduced water levels and volumes, as well as decreased flow velocities during droughts, will accelerate the warming of river waters. Nonetheless, the authors highlight that cooling effects resulting from groundwater inflow, the presence of shade along river channels, and the process of evaporation can ameliorate high temperatures under specific conditions.
Co-author David Hannah, who holds the position of Professor of Hydrology and serves as the UNESCO Chair in Water Sciences at the University of Birmingham, stated, “The increase in river water temperatures can have substantial and often adverse repercussions for aquatic life, affecting both individual species and entire ecosystems. Drought conditions frequently coincide with elevated atmospheric temperatures, and these patterns are expected to intensify and occur more frequently due to climate change. This has significant implications for river water temperatures due to the combination of intense solar radiation and reduced water flow rates.”
Mitigating High Temperatures in Rivers During Droughts Through Strategic Management
Nonetheless, specific management strategies, such as planting vegetation along riverbanks and engaging in river restoration efforts that involve restoring natural channel structures and reconnecting groundwater sources, have the potential to mitigate the impact of high temperatures during droughts, provided that these interventions are carefully targeted.
The researchers stress the need for more comprehensive, catchment-wide approaches to river restoration that take into account how the extremes in river water temperature can be mitigated while simultaneously delivering additional environmental and ecological benefits. They advocate for novel scientific methodologies that examine the interactions among the three mechanisms they have identified, with the aim of improving models’ abilities to predict the locations and timing of elevated river temperature extremes during droughts.
Dr. James White, the lead author from the University of Birmingham, added, “Our research underscores essential future research inquiries that will enhance our capacity to model the dynamics of river water temperature during droughts. This will assist river managers in devising strategies for the better management of thermal extremes through mitigation and adaptation measures.”
Read the original article on: Science Daily
Read more: Rising River Temperatures are Depleting Oxygen, Endangering Aquatic Ecosystems, Per a Recent Study
