Beach sands deposite identification using very low frequency method in the Benteng Lubuk, Krueng Raya coastal area

The 2D subsurface identification work of iron sands in Benteng Lubuk, Krueng Raya was successfully studied using the very low frequency method based on resistivity mode (VLF-R). This study aims to identify iron sand deposits in coastal areas using electromagnetic inversion. The inversion process shows a conductivity zone of iron sand area, where the resistive layer is strongly covered by a conductive layer above it. High resistivity values were found at 80-100 m stations. This layer has a resistivity value between 20000 – 40000 m and the conductivity value tend to be low. It is estimated that at this point there will only be manifestations of iron sand or sea water intrusion, due to the location of the track close to the coastline.

Aquifer Unit Management Plan (AUMP) For Groundwater Resources Management of Multi-layered Coastal Aquifer System

To address the vulnerability of coastal aquifer to over exploitation and sea water intrusion, a groundwater resources management plan titled as Aquifer Unit Management Plan (AUMP) is designed to provide valuable guidance for groundwater management of a multi-layered cuddalore coastal aquifer system located east coast of South India. The aquifer unit management plan is based on the summative examination of the aquifer unit disposition, response of hydraulic heads to recharge and discharge and effect of increased pumping on aquifer hydraulics. The safe hydraulic heads and annual exploitable potential were considered as the guiding factors to manage fresh groundwater resources of the coastal aquifer. The results show that the process of sea water intrusion has already started and with the present rate of pumping (1034.86 mcmy-1), the sea water intrusion risk has increased manifold all along the coast. The salient management strategies recommended are; restricting pumping to 695 mcmy-1, stepping up recharge activities in recharge zone, adopting water use efficiency methods and regulation in the coastal zone. AUMP is simple and can guide water managers to plan for sustainable groundwater withdrawal and safe guard the coastal aquifer from sea water intrusion and ensure sustainability of groundwater abstraction structures.

Sea Water Intrusion Monitoring on the Sendangbiru of the Southern Malang Coastal Area based on Geoelectrical Resistivity Data

The study was conducted with the objective to distinguish the presence of seawater intrusion layer or salt-water aquifer distribution along the data acquisition line at the locations. Data acquisition was conducted by using the Wenner-Schumberger configuration of geoelectrical resistivity. From this research, 4 lines and 4 points of vertical electrical sounding (VES) data for every line were obtained with the distance between electrode a as 10m. Based on the data processing, obtained depth up to 120m with the smallest resistivity value is 0.02Ωm and the largest is 6764.52Ωm. To make the distribution of resistivity values along the path line of the study, cross sections were made until a depth of 120m. Based on the cross-section, the low resistivity value (less than 1.5 Ωm) that interpreted as a seawater intrusion layer or salt water aquifer distribution is located at varying depths. There are intrusions for the SB1 cross section, there is an intrusion at a depth of 6m-7m as far as 10m, at a depth of 6m-8m as far as 10m for the SB2 cross section and at a depth of 22m - 26m as far as 25m for the SB3 cross section.

Pendugaan sebaran intrusi air laut melalui sungai di desa Ujungmanik kecamatan Kawunganten kabupaten Cilacap menggunakan metode geolistrik resistivitas konfigurasi Wenner

The estimation of the distribution of the sea water intrusion through the rivers in Ujungmanik Village, Kawunganten District, Cilacap Regency has been carried out using the Wenner configuration resistivity geoelectric. This research aims to estimate the distribution of sea water intrusion through rivers in Ujungmanik Village, Kawunganten District, Cilacap Regency based on geoelectric resistivity and conductivity data of groundwater. The geoelectric data acquisition was carried out on four lines. They were Wen1 Line, Wen2 Line, Wen3 Line, and Wen4 Line. Each line had a range of 200 meters. The results of geoelectric data processing showed that the subsurface rock structure consisted of sand, clay, sandy loam, and sandy clay. The Seawater intrusion shown by the sand layer occurred in all trajectories which had a range of resistivity value of 0.20 - 2.79 Ωm. Groundwater samples was carried out at fifteen points with the conductivity value varies between 1363 - 4145 µS / cm so that they can be classified that the water was fresh and brackish due to the sampling done in the rainy season. From this research it can be implied that the entire Ujungmanik area is evenly intruded by the sea water at the coordinates 7º38ꞌ15.62ꞌꞌLS 108°57ꞌ20.89ꞌꞌBT to 7º39ꞌ22.86ꞌꞌLS 108º56ꞌ35.33ꞌꞌBT.

Effects of Human Activities in the Coastal Zone of Laizhou Bay

The serious destruction of resources and environment in Laizhou Bay has attracted extensive attention of researchers. This study mainly analysed the changes of fish structure and environment in the coastal zone of Laizhou Bay caused by human activities. By consulting literatures and field measurements, the changes of dominant fish species, coastline and sea water intrusion were analysed. The results showed that dominant fish species in Laizhou Bay change from high-economic species to low-economic species under the influence of human activities, and the coastline erosion was serious, and the area of sea water intrusion was also increasing year by year. It is concluded from the research results that human activities had a significant impact on the structure of fish school and the environment. It is necessary to arrange human activities in an appropriate amount to reduce the overexploitation of resources in order to restore the fishery resources and environment in Laizhou Bay.

Geochemical variations due to salinization in groundwater along the southeast coast of India

In recent years, the extraction of groundwater (GW) in coastal aquifers has rendered the fragile aquifers more saline due to the sea water intrusion. Groundwater from the coastal aquifers of the Pudhucherry region were sampled to study the process of salinization. An integrated approach was adopted to identify the salinization process, by coordinating the results of borehole geophysics, rainfall pattern, water level variation, hydrochemical characters and multivariate statistical analysis. A total of 136 groundwater samples were collected during two different seasons, southwest monsoon (SWM) and northeast monsoon (NEM). The major cations and anions were analyzed adopting standard procedures. Resistivity and litholog indicate that the southeastern (SE) part of the study region has lower resistivity than in north. Based on electrical conductivity (EC) and total dissolved solids (TDS) values, most of the samples are potable, except for few samples from southeastern region. The study results indicated that higher values of Na, EC, K, SO4, Mg and Cl were observed during NEM, indicating leaching of salt into the aquifer and ion exchange process. The predominant hydrochemical facies of groundwater was Na-Cl and Ca–Mg–Cl type reflecting the saline water and the mixing process of saltwater and fresh groundwater, respectively. Though more number of samples with higher EC was noted in NEM, the results of PCA and correlation analysis indicate the predominance of leaching of salts and intense agricultural activities. The process of sea water intrusion was observed to be dominant during SWM.

Groundwater Monitoring Systems to Understand Sea Water Intrusion Dynamics in the Mediterranean: The Neretva Valley and the Southern Venice Coastal Aquifers Case Studies

Sea water intrusion (SWI) has been widely recognized as a global problem, significantly influencing coastal aquifers, mostly through reduced water quality and agricultural production indicators. In this paper, we present the outcomes of the implementation of two independent real-time monitoring systems, planned and installed to get insights on groundwater dynamics within the adjacent coastal aquifer systems, one located in the Neretva Valley, southeastern Croatia, the other located south of the Venice lagoon, northeastern Italy. Both systems are presented with technical details and the capacity to observe, store, and transmit (Neretva site) observed values in real-time. Analysis of time series reveals the significant influence of the sea level oscillations onto the observed groundwater electrical conductivity (EC) and piezometric head values, while precipitation rate is detected as a driving mechanism for groundwater parameters in shallow geological units. The installed monitoring systems are shown to be of great importance to provide qualitative and quantitative information on the processes influencing groundwater and surface water dynamics within two coastal systems.

Analysis of groundwater sufficienty for domestic and livestock requirements as an anticipation to sea water intrusion in Kebumen coast

This study has three objectives, i.e calculating the availability of groundwater in the study area, calculating water demand for domestic and livestock and evaluating the safe yield of groundwater extraction. To achieve these three objectives, groundwater availability, safe yield and actual utilization are calculated. Groundwater availability is calculated based on the multiplication of the area, aquifer thickness and the specific yield. Water demand for domestic is determined base on the number of population and the amount of water demand of each person in each day. Water demand for livestock is calculated based on the number of livestock and water consumption for each livestock in each day, while the safe yield is calculated based on the multiplication of area, annual groundwater level fluctuation and specific yield. The results of research showed that the availability of groundwater in the study area reached 440,517,770 m3/year, while the safe yield for its extraction was 76,641,600 m3/year. Because the water demand for domestic and livestock is 6,495,100 m3/year, so that the availability of groundwater in the study area is still sufficient to support water demand for these sectors. The water demand of the two sectors still have not exceeded the safe yield water extraction, so it will not cause decreasing of groundwater pressure which can cause to sea water intrusion.