Groudwater flow system and water quality in a Coastal plain aquifer in Northwestern Nicaragua
The Departments of León and Chinandega in northwestern Nicaragua are agricultural regions that were under cotton cultivation for almost thirty years (1950’s-1980’s), and more recently mainly under sugarcane. Water supply for the population of almost 700,000 inhabitants comes mainly from groundwat...
|Main Author:||Delgado Quezada, Valeria|
The Departments of León and Chinandega in northwestern Nicaragua are
agricultural regions that were under cotton cultivation for almost thirty years
(1950’s-1980’s), and more recently mainly under sugarcane. Water supply for the
population of almost 700,000 inhabitants comes mainly from groundwater. The
principal aquifer in the region is a shallow unconfined alluvial unit underlain by
fractured volcanic rocks. Several hydrogeological and chemical studies have
identified significant water quality impacts by pesticides and nitrate, but none of
the studies have investigated the depth of impact in the aquifer. This information
is important in order to ensure new potable water supply wells are drilled deep
enough and to ensure the unimpacted deeper aquifer is protected in the longterm.
Monitoring wells were installed at five different depths at three locations
roughly along the groundwater flow direction. Precipitation, groundwater, and
surface water samples were collected during two sampling events. Agrochemical
impact in the aquifer was observed at depths of up to 12 m below the water table
at all three sites and originates mostly from the historical application of pesticides
in the cultivation of cotton. Isotope composition confirmed that in general
groundwater at increasing depth in the aquifer is recharged at increasingly higher
elevations although some mixing of local and regional flow systems is evident.
This has important implications in terms of aquifer protection and management