Groundwater Assessment at Santiago Island (Cabo Verde): A Multidisciplinary Approach to a Recurring Source of Water Supply

Abstract

Groundwater resources are in many parts of the world the only source for private domestic, agricultural and public water supply. Subsurface has also become major recipient of wastewater and solid waters especially in the developing countries. Overexploitation of coastal aquifers and pollution are among the main problems related to groundwater resources assessment and management in Santiago Island (Cabo Verde). Brackish groundwater is the only available water type in the region that is being provided to numerous parts of the Island such as Praia Baixo, Montenegro, and Charco for agriculture and human supply. Solute and isotope data obtained in different groundwater systems were used in the identification of groundwater resources degradation. In order to understand the influence of the anthropogenic activities on the water quality and the main origin of the salts in groundwater, a statistical approach (Principal Components Analyses-PCA) was performed on the physico-chemical data. The results obtained indicate waterrock interaction mechanisms as the major process responsible for the groundwater quality (mainly calcium-bicarbonate type), reflecting the lithological composition of the subsurface soil. Also, anthropogenic contamination was identified, in several points of the island. Isotopic techniques (δ 2 H, δ 18 O and 3 H content) combined with geochemistry provided comprehensive information on groundwater recharge, as well as on the identification of salinization mechanisms (e.g. seawater intrusion, salt dissolution, and marine aerosols) of the groundwater systems, at Santiago Island.

Water Supply and Access to Safe Water in Developing Arid Countries

“…Given the limited potential of the surface water resources, supply is strongly dependent on groundwater sources. However, excessive pumping is promoting saltwater intrusion, which affects such groundwater resources (e.g., Carreira et al 2010;Gonçalves et al, 2015). So, nowadays seawater desalination is a national strategy to help the development of the public water supply service (Marques et al 2011).…”

Assessment of hydrochemical trends in the highly anthropised Guadalhorce River basin (southern Spain) in terms of compliance with the European groundwater directive for 2015

“…More strongly evaporated groundwater samples reflect higher pumping rates and often present higher salinisation values with more enriched isotope values, due to evaporation effects (Carreira et al 2010). Trends related to this kind of process are easy to explain using such graphs, and therefore, we make use of them to detect upward trends in salinisation.…”

Groundwater flow in a relatively old oceanic volcanic island: The Betancuria area, Fuerteventura Island, Canary Islands, Spain

“…No other values for the shield basalts are available in FVI as well as in the other few similar outcrops in the Canary Islands. In Santiago Island, Cape Verde archipelago, to the South of the Canaries, wells drilled in submarine basalts yield up to 960 m 3 /d (Carreira et al, 2010), while in FVI the highest yield is 430 m 3 /d, in both cases subjected to important pumping drawdown in highly penetrating wells, of some tens of meters, and part of this yield comes from in-the-well water storage. The expectable maximum value of transmissivity is at most a few tenths of m 2 /d.…”