Springs can be described as discharge points which are supplied by spring water or in other words ground water. Groundwater itself is supplied through various sources including melt water, surface waters and precipitation.
In Aeisha Aggarwal and Kathy L. Young’s hydrology research on ‘Surface-groundwater exchange between a wetland, sandur, and lava field in southeastern Iceland', the authors evaluate properties of groundwater that are affected by precipitation events in the areas of the Southeast Iceland to get a better understanding of seasonal spring vulnerability to climate change. Spring hydrology studies are critical for understanding hydrological, chemical and ecological implications for the ecosystems spring water can affect.
For springs to function properly groundwater has to be replenished at an appropriate rate or springs may stop producing their valuable spring discharge. Alternatively, permafrost aggradation can lead to the freezing of the spring outlets preventing them from functioning properly. These permafrost aggradation events would likely cause groundwater supply to be re-routed to new seepage outlets. Presently, no permafrost is found in this spring location.
Aggarwal and Young point out the importance of the stable groundwater supply noting that: “The flow and longevity of the spring-fed systems are tied to the forces that recharge the groundwater system connecting to the springs. Where groundwater is recharged by glacial-melt waters, the retreat of glacial margins can result in changing flow paths and water availability."
The research was conducted to gain a better understanding of spring feeding ecosystems and the role they play maintenance of coastal wetlands in Southeast Iceland. To evaluate impacts of heavy rainfalls on spring discharge, the researchers chose stable isotope, hydrograph analysis and water temperature changes as the variables to be examined. The study site was located at the Hvoll farm (Figure 1) in Southeast Iceland and comprised of a mixture of dry grassy meadows, wetland meadows, small pools and streamlets.
The study site also included presence of postglacial basalt and rubbly lava fields, Núpahruan and Brunahraun branches of the Laki lava field. Brunná River, a glacial-fed stream is also located on the site of the study, which cuts diagonally through the Hvoll farm. Water in the river is supplied by the glacial melt waters from the Skeiðará lobe of the Vatnajökull ice cap. The structure of the lava fields provides routes for water to penetrate and travel through in a fairly unrestricted way. Aggarwal and Young were able to identify over 50 springs in the area of the study site out of which a sub-sample of six springs were selected for further examination (Figure 2).
Springs that are fed by shallow aquifers carry a low storage capacity and periodicity that would better represent changes in groundwater-recharge events such as rainfall and snowmelt. A tipping bucket rain gauge was used to assess rainfall occurrence in the study site area. To evaluate the spring discharge rate, the research used a water velocity meter with the assumption that discharge measured in the streams running through the study site area represented the discharge of the springs. Hydrographs were used to plot water levels and rainfall throughout the time of the study. This was done to evaluate the effects of precipitation on the water level and temperature values collected. Finally, analysis of isotopic composition was performed to determine the change in water quality following rainfall events. "Water chemistry has been used to determine recharge locations with mixed results. The quality of water will change as it interacts with rock and surface waters, dissolving anions, cations, and trace elements. The isotopic composition of the water will also change as water travels along various pathways. Differences in isotopic composition between precipitation and surface waters were identified over 59 years ago,” notes the authors in their study.
The importance of analyzing such changes in groundwater-fed springs is clear as they will be less vulnerable to forces of evaporation, which will continue exhibiting stronger effects with increasing air temperatures. Vatnajökull – the largest ice cap in Iceland, is expected to lose 20-30 percent of its glacial mass by the end of the century. This will cause rivers like the Brunná River to receive large amounts of melted runoff increasing its discharge. After its initial increase that discharge will begin to drop as glaciers become depleted. Spring-fed systems on the other hand are expected to stay supplied with a constant input of water from the rainfall and surface runoff making them an important source of water to hydrological systems in Iceland.
Aiesha Aggarwal is a Master of Science (MSc) graduate in Physical Geography and is now working as Conservation Researcher and Analyst at The Couchiching Conservancy. The Government of Canada provided logistical funds through the Northern Scientific Training Program. Read Aggarwal’s MSc Thesis in YorkSpace.
Kathy L. Young is a Professor in EUC and Environmental Science Coordinator. This paper was originally published by IWA Publishing. It is an Open Access work, and the terms of its use and distribution are defined by the Creative Commons licence selected by the authors.