Groundwater research in central Nicaragua

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 List of selected publications related to geosciences in Nicaragua

 

Department of Engineering Geology
Centro de Investigaciones Geocientíficas (CIGEO/ UNAN)

 

 
By José Alfredo Mendoza

The Department of Engineering Geology at Lund Institute of Technology (Sweden), and Centro de Investigaciones Geocientíficas, at the National Autonomous University of Nicaragua ( UNAN-Managua ) are developing the sub-project, Aquifer Vulnerability due to local contamination in the Río Sucio basin.

T he sub - project is part of a major programme , funded by the Swedish International Development Agency (Sida - SAREC , with the general goal of improve scientific capabilities of nicaraguan universities to solve scientifical  problems related to groundwater resources and environment.

This research aims to produce knowledge of groundwater resources in the water basins of Rio Sucio (a tributary of Rio Síquia) and Rio Mico, and to establish a base of information for sustainable use of water resources in human activities.

The specific objectives of the sub-project are:

Investigate and evaluate the hydrogeological characteristics of the aquifers and the pattern of flow transport within the Rio Sucio (Síquia) and Rio Mico microbasins.

E valuate the hydraulic relation between surface water, upper groundwater aquifers and deeper-seated aquifers
Geophysical and hydrogeologycal methods have been used to accomplish these objectives so far, the electrical resisitivity method has been extensively used in the area to map geological structures related to groundwater occurence. Chemical analysis of water from springs and streams, together with measurements of river flows have been carried out as well .

The area has been selected regarding the fact that Rio Mico and Rio Sucio basins, constitute two of the most environmentally damaged watersheds in the country. In these basins, human activities like gold mining, cattle grazing and the advancing agricultural frontier put a strong stress on the water basins. High levels of heavy metals used in gold mining, mainly mercury (Hg), have been found in river sediments, water and soils.

 
Women and children processing gold in Rio Sucio, close to Santo Domingo
Open pit in La Libertad
Old open pit mine in La Libertad
Old man tanning leather
Leather tanning in the south part of Rio Mico basin

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Hydrogeology

Little is known about the hydrogeology of central Nicaragua, but regarding the results achieved so far, groundwater occurence appears to be related to tectonic features (faults, fractures) and the strong weathering process in the area .

Measurings of stream flow are performed daily at three points of Rio Sucio, in an area close to the village of Santo Domingo, with the aim of assess the groundwater - surface water interactions in the area. This information is complemented with rain gauging.

An inventory of springs and water sampling for chemical analyses was performed in 2001, as part of a Minor Field Study. The results show that the water quality in the springs is good and young, but high values of lead (Pb) were found in a few of the sampled springs. Mercury (Hg) content in water of the main stream is high.

Geophysics

Geophysical methods are being used for studying the aquifers properties. A multi electrode resistivity/IP data acquisition system, the Lund Imaging System, has intensely been used for field investigations in the study areas. Different electrode arrays, likely Wenner and Wenner-Schlumberger, with several inter-electrode spacings are used for performing the Continuous Vertical Electrical Soundings (CVES). Furthermore, other geophysical methods will be used in this investigations .
Resistivity profile
This image shows the resistivity results of a Continuous V ertical Electrical Sounding (CVES) that crosses a stream and a quartz vein perpendicularly. Note the steep topography .

Complementary methods

Geophysical and hydrogeological methods have to be combined with other methods and tools to provide a comprehensive overview of the conditions in the area. Geographic information is valuable for this investigations, thus background and colected data is integrated in a Geographic Information System. Watertable levels in wells and positions of geological bodies are measured/located with a D-GPS (Differential-Global Positioning System). Topographical, geomorphological and cartographical data are also included when evaluating the colected information in this research.

The combination and analysis of diverse geographic data can provide important information for the study of hydrogeological and environmental problems
Old mine gallery
 
A underground system of  galleries and shafts used for gold mining during the XVIII s. serves to colect water for the village of Santo Domingo.

Publications

Resistivity imaging as a tool for groundwater studies in Santo Domingo, Nicaragua

Mapping a quartz vein using three electrode arrays at Santo Domingo

Geophysical methods for groundwater exploration in Ocotal, northern Nicaragua

 

Thesis  Projects

Saturated hydraulic conductivity measurements in the Río Artiguas watershed. By Magnus Eckeskog (2005)

Geology of the southern part of Río Artiguas. By Meyling Marianela Herrera Delgado (2005)

Surface water- groundwater water quality assessment on Rio Artiguas. By Ligia and Tania Espinosa (June-August 2004)

Geology of the northern part of  Río Artiguas. By Martha Sánchez (2005)

Investigation of Groundwater – Surface Water Interaction in the Drainage Basin of the River Sucio, Nicaragua. By Katarina Grunander and Elisabeth Nordenberg (2003)

Inventory of springs and hydrochemical investigations of groundwater in the drainage basin of Sucio river, Nicaragua. By Marie Aronsson and Cornelia Wallner  (2001)

 

List of selected publications related to geosciences in Nicaragua




José Alfredo Contact

For comments, questions or contributions please contact...

José Alfredo Mendoza
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Centro de Investigaciones Geocientíficas (CIGEO\UNAN, Managua) Colonia Miguel Bonilla #165 Apartado Postal A- 131, Managua,
Nicaragua
Tel + 505 270 3983 Fax + 505 277 0613
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Teknisk Geologi, LTH John Ericsson v. 1 Box 118, 22 100 Lund, Sverige
Tel +46 46 222 7423 Mobile 0709677231 Fax +46 46 222 9127