Factors Determining the Natural Fresh‐Salt Groundwater Distribution in Deltas

Most river deltas are densely populated areas with intensive agriculture. The increased shortage of fresh surface water that results from rising demands are expected to lead to increased groundwater pumping, which leads to sea water intrusion. To correctly project the future of fresh groundwater res...

Full description

Saved in:
Bibliographic Details
Published in:Water resources research 2021-01, Vol.57 (1), p.n/a
Main Authors: van Engelen, Joeri, Bierkens, Marc F. P., Delsman, Joost R., Oude Essink, Gualbert H. P.
Format: Article
Language:English
Subjects:
Agriculture
Aquifers
Boundary conditions
Chemical analysis
Deltas
Distribution
Geology
global sensitivity analysis
Groundwater
Groundwater resources
Groundwater salinity
Hydraulic conductivity
Hydrogeology
Intensive farming
Inversions
Mathematical analysis
paleo‐groundwater flow
Population density
Pumping
Rivers
Saline water intrusion
Salinity
Salinity effects
Salt water intrusion
Salts
Seawater
Sensitivity analysis
Shortages
Simulation
Surface water
System effectiveness
Transgressions
Uncertainty
variable‐density groundwater model
Water analysis
Water resources
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Most river deltas are densely populated areas with intensive agriculture. The increased shortage of fresh surface water that results from rising demands are expected to lead to increased groundwater pumping, which leads to sea water intrusion. To correctly project the future of fresh groundwater resources in deltas, knowing the current fresh‐salt groundwater distribution is a prerequisite. However, uncertainties about these distributions and their drivers are large. To understand these uncertainties, we conducted a global sensitivity analysis of a complex three‐dimensional variable‐density groundwater model of a synthetic delta, simulating the effect of the last glacial low stand and the subsequent marine transgression. The analysis is unique in its wide range of geometries, hydrogeological parameterizations, and boundary conditions analyzed, making it representative for a large number of deltas worldwide. We find that the aquifer hydraulic conductivity is the most uncertain input and has a strong nonmonotonous effect on the total salt mass onshore. The calculated fresh‐salt groundwater distributions were classified into five classes and compared to real‐world case studies. We find that salinity inversions occur in deltaic systems with high representative system anisotropies as a remnant of a marine transgression. These salinity inversions were observed in half of the real‐world cases, indicating that their fresh‐salt groundwater distributions are not in a dynamic equilibrium. We conclude that it is very likely that past marine transgressions are still reflected in the current fresh‐salt groundwater distributions in deltas. This makes paleo‐groundwater modeling a prerequisite for effective simulation of present‐day groundwater salinity distributions in these systems. Plain Language Summary Most river deltas are densely populated areas with intensive agriculture. The increased shortage of fresh surface water that results from rising demands are expected to lead to increased groundwater pumping, which, in turn, will lead to a more salinized groundwater system. To correctly project the future of fresh groundwater resources in deltas, knowing the current fresh‐salt groundwater distribution is a prerequisite. However, uncertainties about the current fresh‐salt groundwater distributions and their drivers are large. To understand these uncertainties, we conducted a lot of simulations of a complex three‐dimensional groundwater model of a synthetic delta, simulatin
ISSN:0043-1397
1944-7973
DOI:10.1029/2020WR027290