Date of Graduation
Spring 5-23-2026
Document Access
Project/Capstone - Global access
Degree Name
Master of Science in Environmental Management (MSEM)
College/School
College of Arts and Sciences
Department/Program
Environmental Management
Program
MSN project
First Advisor
Simon Scarpetta
Abstract
Saltwater intrusion is an increasingly critical threat to coastal groundwater systems worldwide, driven by chronic groundwater overdraft and exacerbated by projected intensified drought and sea-level rise associated with climate change. Despite the global relevance of this phenomenon, the spatial distribution and severity of saltwater intrusion vary across hydrological settings, reflecting differences in aquifer composition, extraction patterns, and management history. Understanding these spatial patterns is essential for prioritizing management interventions and protecting municipal water supplies and agricultural productivity in groundwater-dependent coastal regions. This study uses ordinary kriging and indicator kriging interpolation of aquifer chloride levels to assess the extent of saltwater intrusion in two vulnerable California regions: Pajaro Valley and Los Angeles County. The analysis revealed that Los Angeles County exhibits a more advanced stage of seawater intrusion, with predicted chloride concentrations ranging from 3.5 to 1,269.9 mg/L and exceedance probabilities approaching 96% at the 250 mg/L threshold in the southwestern coastal margin. In contrast, the Pajaro Valley displays a narrower salinity range, with concentrations between 14.1 and 218.2 mg/L and no monitoring location exceeding the 250 mg/L threshold. This research highlights that geostatistical kriging provides a framework for characterizing SWI risk across contrasting coastal aquifer systems. The exceedance probability maps produced by indicator kriging offer a particularly actionable tool for water managers, enabling the identification of priority intervention zones even in data-sparse or low-variability environments. Some recommendations to decrease saltwater intrusion are: expand and standardize the monitoring well network, and strengthen the injection barrier and managed aquifer recharge programs.
Recommended Citation
Diaz Miranda, Debbie Lisseth, "Saltwater intrusion in coastal aquifers of California Pajaro Valley and Los Angeles County" (2026). Master's Projects and Capstones. 2004.
https://repository.usfca.edu/capstone/2004
R script implementing Ordinary Kriging (OK) and Indicator Kriging (IK) models for chloride concentration mapping in Los Angeles County. Includes variogram fitting, spatial interpolation, and visualization of saltwater intrusion patterns.
Saltwater intrusion in coastal aquifers of California Pajaro Valley and Los Angeles County- OK and IK model for Pajaro Valley.Rmd (20 kB)
R script implementing Ordinary Kriging (OK) and Indicator Kriging (IK) models for chloride concentration mapping in Pajaro Valley. Includes variogram fitting, spatial interpolation, and visualization of saltwater intrusion patterns.
PV_GAMA.csv (7 kB)
Dataset containing Cl concentration records from Pajaro Valley, extracted from the California GAMA Program.
LA_GAMA.csv (266 kB)
Dataset containing Cl concentration records from Los Angeles County, extracted from the California GAMA Program.
PV_Boundary_Shapefile.zip (19 kB)
Shapefile defining the spatial boundary of Pajaro Valley. Used to clip and constrain the interpolation area in Ordinary Kriging (OK) and Indicator Kriging (IK) models for chloride concentration mapping
LA_Boundary_Shapefile.zip (2 kB)
Shapefile defining the spatial boundary of Los Angeles County. Used to clip and constrain the interpolation area in Ordinary Kriging (OK) and Indicator Kriging (IK) models for chloride concentration mapping.
