Most of Indonesia’s pop­u­la­tion lives in areas with volcanic–alluvium geo­log­i­cal char­ac­ter­is­tics. Based on the nation­al hydro­ge­o­log­i­cal map of the Indone­sian Geo­log­i­cal Agency, areas with volcanic–alluvium geo­log­i­cal con­di­tions have high ground­wa­ter poten­tial and poten­tial for ground­wa­ter dam­age. This study aims to test the resilience of ground­wa­ter areas with volcanic–alluvial char­ac­ter­is­tics to pop­u­la­tion growth. The MODFLOW ground­wa­ter mod­el was built based on the site’s vol­canic and allu­vial geo­log­i­cal con­di­tions. This ground­wa­ter mod­el was test­ed against pump­ing sce­nar­ios based on pop­u­la­tion water demand in 2011–2020 and then pre­dict­ed pop­u­la­tion growth until 2030.

The result shows that ground­wa­ter resilience in volcanic–alluvium loca­tions has dif­fer­ent char­ac­ter­is­tics based on lithol­o­gy and pop­u­la­tion den­si­ty char­ac­ter­is­tics. Urban areas that are most­ly locat­ed in allu­vi­um areas tend to have a lin­ear ground­wa­ter decline pat­tern but have the sharpest ground­wa­ter decline gra­di­ent. In con­trast, sub­ur­ban areas in the allu­vi­um-to-vol­canic tran­si­tion area ini­tial­ly expe­ri­ence expo­nen­tial ground­wa­ter decline but change to lin­ear, while rur­al areas locat­ed in vol­canic areas that become the main devel­op­ment tar­get have expo­nen­tial ground­wa­ter decline char­ac­ter­is­tics.

To coun­ter­act the con­tin­u­ous deple­tion of ground­wa­ter, researchers con­duct­ed a sce­nario for opti­miz­ing sur­face water use. Based on the results of the sce­nario, a 60% reduc­tion in ground­wa­ter use is suf­fi­cient to stop con­tin­u­ous ground­wa­ter deple­tion. The results of this study can be used as a rec­om­men­da­tion for long-term water resources man­age­ment tar­gets for vol­canic and allu­vi­um areas that are being tar­get­ed for devel­op­ment.