Application of GIS-Base GALDIT for vulnerability assessment to saltwater intrusion of Holocene coastal aquifer: a case of Quang Nam - Da Nang city, Vietnam

Abstract

Groundwater is an essential resource which is influenced by salt water due to the groundwater exploitation in Holocene aquifer of Quang Nam - Da Nang. Hence, the measures for preventing saltwater intrusion and better groundwater management are required. In this study, GALDIT method was utilized to identify the salt water intrusion (SWI) vulnerability zones using monitoring data in Holocene aquifer of Quang Nam - Da Nang. The results of GALDIT method indicated that Da Nang and Hoi An cities were in the high SWI vulnerability zones. The moderate SWI zones were dominant and low vulnerability zones were at the southern part of the study area. The analysis of the monitoring data showed the occurrence of SWI far inland, up to the distance of 12.5 km from the sea shore and suggested the impact of human activities on SWI. The analysis of monitoring data together with GALDIT index indicated that the important of the groundwater abstraction depth or the occurrence of fresh-salt groundwater interface should be considered to improve the result of GALDIT method for the prevention of SWI. In short, the GALDIT used in this study is an important approach for the prevention of SWI in the study area.

Zrozumienie mechanizmów pochodzenia słonej wody w przybrzeżnych warstwach wodonośnych obszaru Da Nang (środkowy Wietnam)

“…Saltwater origin and mechanisms in coastal aquifers in Vietnam have been studied extensively and the main causes identified are groundwater exploitation [9]; inter-aquifer leakage due to diffusion and density flow or high hydraulic gradient [10].…”

Assessment of Pleistocene Aquifer Vulnerability to Saline Intrusion in the Coastal Region of Ba Ria-Vung Tau Province Using GIS and Entropy-GALDIT

“…In Vietnam, in recent years, many researchers have become interested in using the GALDIT model to assess the vulnerability of coastal aquifers to saline intrusion [18][19][20][21]. However, the majority of research still applies the original weights of the method framework and has not shown the spatial distribution visualization of each component parameter.…”

“…According to the parameters, "the height of groundwater level", "the distance from the study site to the saline line", and "the impact of existing status of seawater intrusion", the very high vulnerability zones were close to the saline boundary and had a large water-lowering funnel. Similarly, Phan Nam Long and Huynh Tien Dat [19] also applied GALDIT based on GIS to assess groundwater vulnerability due to seawater intrusion in Quang Nam and Da Nang. They identified areas of high vulnerability distributed along the coast and in densely populated areas near rivers.…”