Hydrogeological and Morphological Characterization of Río Cuarto Maar Lake in Costa Rica: An analysis of lake geometry, water balance and groundwater interaction
(2026) In Engineering geology VTGM05 20261Division of Engineering Geology
Civil Engineering (M.Sc.Eng.)
- Abstract
- Volcanic crater lakes are important freshwater systems, but their hydrological functioning is often difficult to understand due to limited monitoring data and uncertainty in groundwater contribution. Río Cuarto Lake, located in the north part of Costa Rica, is a volcanic crater lake where the sources and movement of water are not fully known. This master’s thesis aimed to describe the lake’s morphology, water balance and water quality conditions and investigate if available hydrological and chemical observations could indicate interaction between groundwater and the lake.
The study methodology combined field measurements and spatial analysis to develop an overall understanding of the lake system. Bathymetric data was collected using... (More) - Volcanic crater lakes are important freshwater systems, but their hydrological functioning is often difficult to understand due to limited monitoring data and uncertainty in groundwater contribution. Río Cuarto Lake, located in the north part of Costa Rica, is a volcanic crater lake where the sources and movement of water are not fully known. This master’s thesis aimed to describe the lake’s morphology, water balance and water quality conditions and investigate if available hydrological and chemical observations could indicate interaction between groundwater and the lake.
The study methodology combined field measurements and spatial analysis to develop an overall understanding of the lake system. Bathymetric data was collected using sonar and GPS and used in GIS analysis to estimate depth, area and volume of the lake. A conceptual water balance was developed by using precipitation, evaporation, inflow and recharge estimates based on meteorological data and the Schosinsky soil water balance method. Water samples were collected from different depths and analysed in both field and laboratory to examine differences in water quality in the water column and to identify potential indicators of groundwater influence.
The results showed that Río Cuarto Lake has a steep-sided basin with a deep central area and stable stratification in the water column. Differences in water chemistry between surface and deeper water layers, together with the imbalance observed in the water balance calculations suggest that additional water sources besides direct rainfall and surface inflow could contribute to the lake system. However, uncertainties related to catchment area, simplified modelling assumptions and limited monitoring data limit the ability to prove groundwater interaction in the lake.
Overall, the study provides new baseline information on the hydrology and water quality of Río Cuarto Lake and highlights the importance of continued monitoring and improved hydrological measurements for understanding lake behaviour in volcanic environments over the long haul. (Less) - Popular Abstract
- Río Cuarto Lake in Costa Rica looks calm from the shore, but beneath the surface it is a deep volcanic crater lake with layered water and hidden water pathways that are not fully understood.
Río Cuarto Lake in northern Costa Rica is a small volcanic crater lake, but its hydrology is complex. The lake has few visible streams flowing in and out, which makes it difficult to understand where the water comes from and how it moves through the system. This master’s thesis investigated the lake’s shape, water balance and water quality. The aim was to improve the understanding of how Río Cuarto Lake functions and to examine whether the available measurements could indicate interaction between the lake and groundwater.
One clear result was that... (More) - Río Cuarto Lake in Costa Rica looks calm from the shore, but beneath the surface it is a deep volcanic crater lake with layered water and hidden water pathways that are not fully understood.
Río Cuarto Lake in northern Costa Rica is a small volcanic crater lake, but its hydrology is complex. The lake has few visible streams flowing in and out, which makes it difficult to understand where the water comes from and how it moves through the system. This master’s thesis investigated the lake’s shape, water balance and water quality. The aim was to improve the understanding of how Río Cuarto Lake functions and to examine whether the available measurements could indicate interaction between the lake and groundwater.
One clear result was that the lake is deeper than previously reported. By mapping the lake bottom with sonar and GPS from a paddleboard, the maximum measured depth was found to be about 74 metres. The lake also has steep basin walls and a deep central area, which can limit mixing between surface water and deeper water.
The water balance gave another important clue. The known water inputs, such as rainfall and visible inflows, were not enough to explain the higher measured outflow from the lake. This does not prove groundwater inflow, but it suggests that additional water sources may be involved, such as groundwater, small unmeasured inflows, or hidden pathways in the volcanic ground.
Water samples from different depths showed that the lake is divided into layers. The deepest water had a different chemical composition than the water closer to the surface, especially shown by higher electrical conductivity at 60 metres depth. Oxygen and redox conditions also changed with depth. This is relevant because layered volcanic lakes can sometimes experience sudden mixing events, known as rollover events. During such events, deeper water can move upward and change the water chemistry near the surface. In Río Cuarto Lake, previous studies have linked these events to changes in water colour, algal blooms and fish mortality.
The study provides updated information about the lake’s depth, shape, water balance and water quality. This can be useful for future monitoring, environmental assessment and water resource planning regarding volcanic lake areas. However, longer measurement periods, groundwater wells and more detailed hydrological and water quality studies are needed to confirm how important groundwater is for Río Cuarto Lake. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/student-papers/record/9236044
- author
- Starck, Maja LU and Bergkvist, Filip LU
- supervisor
- organization
- alternative title
- Hydrogeologisk och morfologisk karakterisering av maarsjön Río Cuarto i Costa Rica: En analys av sjöns geometri, vattenbalans och grundvatteninteraktion
- course
- VTGM05 20261
- year
- 2026
- type
- H3 - Professional qualifications (4 Years - )
- subject
- keywords
- bathymetry, water balance, groundwater–lake interaction, volcanic crater lake, water quality, hydrogeology, GIS, Río Cuarto Lake, Costa Rica
- publication/series
- Engineering geology
- report number
- ISRN LUTVDG(TVTG-5198)/1-84/(2026)
- language
- English
- additional info
- Examiner: Sara Johansson
- id
- 9236044
- date added to LUP
- 2026-07-01 11:25:48
- date last changed
- 2026-07-01 11:25:48
@misc{9236044,
abstract = {{Volcanic crater lakes are important freshwater systems, but their hydrological functioning is often difficult to understand due to limited monitoring data and uncertainty in groundwater contribution. Río Cuarto Lake, located in the north part of Costa Rica, is a volcanic crater lake where the sources and movement of water are not fully known. This master’s thesis aimed to describe the lake’s morphology, water balance and water quality conditions and investigate if available hydrological and chemical observations could indicate interaction between groundwater and the lake.
The study methodology combined field measurements and spatial analysis to develop an overall understanding of the lake system. Bathymetric data was collected using sonar and GPS and used in GIS analysis to estimate depth, area and volume of the lake. A conceptual water balance was developed by using precipitation, evaporation, inflow and recharge estimates based on meteorological data and the Schosinsky soil water balance method. Water samples were collected from different depths and analysed in both field and laboratory to examine differences in water quality in the water column and to identify potential indicators of groundwater influence.
The results showed that Río Cuarto Lake has a steep-sided basin with a deep central area and stable stratification in the water column. Differences in water chemistry between surface and deeper water layers, together with the imbalance observed in the water balance calculations suggest that additional water sources besides direct rainfall and surface inflow could contribute to the lake system. However, uncertainties related to catchment area, simplified modelling assumptions and limited monitoring data limit the ability to prove groundwater interaction in the lake.
Overall, the study provides new baseline information on the hydrology and water quality of Río Cuarto Lake and highlights the importance of continued monitoring and improved hydrological measurements for understanding lake behaviour in volcanic environments over the long haul.}},
author = {{Starck, Maja and Bergkvist, Filip}},
language = {{eng}},
note = {{Student Paper}},
series = {{Engineering geology}},
title = {{Hydrogeological and Morphological Characterization of Río Cuarto Maar Lake in Costa Rica: An analysis of lake geometry, water balance and groundwater interaction}},
year = {{2026}},
}