groundwater

The Hydrogeology of Curaçao: an electrical resistivity study

Abstract

Worldwide, coral reef health is declining rapidly due to both global stressors (climate change) and local stressors (pollution). Reef maintenance on Curaçao focusses on reducing local stressors including terrestrial pollution. One f low path for terrestrial pollution is via submarine groundwater discharge (SGD). Yet, on the island of Curaçao these hotspots of submarine groundwater discharge have not yet been located, let stand quantified. With this research we aimed to increase our understanding of groundwater flow on the island. This will serve as a foothold for future SGD research. To do so, we have conducted 9 electrical resistivity tomography (ERT) measurements to understand (1) the heterogeneity of the lava formation, the main aquifer, (2) the saltwater-fresh water interface at the coast, and (3) the groundwater flow at geological interfaces. To assist in the interpretation of the data we measured groundwater levels and the discharge of Hato spring, in addition to observing local geological outcrops. We discovered that the lava formation is a very heterogenous aquifer due to variety in degree of weathering of the pillow basalt. As a result of the heterogenous permeability, the extent of seawater intrusion in the coastal lava formation is strongly variable. Yet, the lava formation does form a better barrier for sea-fresh water mixing than the limestone terraces. The midden formation (sedimentary rock) forms a thin aquifer near the surface. And, at the interface of lava and midden formation, the groundwater flow is hampered. As a result, the groundwater is confined within the lava formation until the lava formations reservoir “overflows”. The same occurs at the interface of the lava formation and the diorite intrusion. The next step in SGD research is quantifying the seaward groundwater flux where the lava formation is in direct contact with the sea or limestone formation. Here seaward groundwater flow is not hampered by the midden formation or the intrusion and thus forms hotspots of Submarine (polluted) Groundwater Discharge.

Date
2022
Data type
Research report
Theme
Research and monitoring
Report number
MSc Thesis
Geographic location
Curacao

Community extinction: the groundwater (stygo‑)fauna of Curaçao, Netherlands Antilles

Abstract

The research aimed to recollect specimens from Curaçao of the genus Halosbaena belonging to the rare crustacean order Thermosbaenacea, a genus with a relictual Tethyan distribution. It resulted in recording the apparent extinction of the entire, species-rich, subterranean fauna on the island that had occurred within a period of 43 years up to 2015. The composition of the groundwater fauna on Curaçao was sampled in 2015 for comparison with sampling undertake 43 years previously. Despite using the same sampling methods previously used and comprehensive coverage of the available sampling sites, no stygofauna specimen was collected from sampling in 2015 in contrast to more than 50 species collected from the initial sampling in 1973. It is hypothesised that this faunal extinction was associated with the oil industry, but it is unclear whether it resulted from petroleum pollution of groundwater drawdown or recharge. This record of the extinction of an entire ecosystem, rather than merely some members of it, is perhaps unique, but is concerning amongst the more diffuse extinction events happening globally.

Date
2022
Data type
Scientific article
Theme
Research and monitoring
Journal
Geographic location
Curacao

Bonaire's Southern Wetlands Management Plan

EXECUTIVE SUMMARY

The southern wetlands of Bonaire represent a unique environment for the island. Consisting of a wide variety of habitat types including caves, karsts, dry tropical forests, coastal areas, salt pans and mangroves. The Ramsar site Pekelmeer lies completely in this area, as well as a small portion of the buffer zone of the Ramsar site Lac Bay.

Culturally, a number of Bonaire’s historic monuments and tributes to its past can be found as you drive around the perimeter, from ruins of old salt pans to the remains of slave huts and gravestones. Maintaining and respecting these sober reminders of Bonaire’s history is vital to ensuring the sacrifices of the enslaved populations are not forgotten. It would be impossible to separate the historic and cultural identity of Bonaire from this area.

Economically the southern wetlands represent commercial opportunities for salt extraction by Cargill Salt Works as well as a significant driver of tourism, whether it is history enthusiasts, cyclists, kiteboarders, recreational fishers, scuba divers or bird watchers.

The cultural and economic value of this area is only surpassed by its environmental value. The southern wetlands are recognized internationally as an Important Bird Area (IBA), as a site of regional importance by the Western Hemisphere Shorebird Reserve Network, as an area important for sea turtle nesting and as a Ramsar site. The Ramsar site Pekelmeer, which encompasses most of the southern portion of the wetlands, is critical to a number of threatened, endangered or keystone species. Pekelmeer offers a much-needed rest stop for a number of migratory bird species while also serving as an important breeding ground for the Caribbean Flamingo and five different tern species. Furthermore, the southern wetlands constitute most of the natural habitat of the rare and endemic Bonaire Sabal Palm.

This management plan offers a description of the southern wetlands (chapter 1), a legal and legislative overview (chapter 2), a description of resources and utilities (chapter 3), an explanation of the spatial development plan (chapter 4), an overview of conservation target habitats (chapter 5), an analysis of threats and issues (chapter 6), an outline of management actions and strategies (chapter 7), and provides recommendations for the management plan evaluation and review (chapter 8). Conserving this unique wetland will be a major challenge. A critical first step is to designate Pekelmeer as a protected area under island and national legislation, and appoint a management authority.

Date
2022
Data type
Research report
Theme
Governance
Education and outreach
Legislation
Research and monitoring
Geographic location
Bonaire