Pemetaan Zona Kerentanan Airtanah Pesisir Formasi Batugamping Terhadap Pencemaran Nitrat Di Kecamatan Sepulu Madura

Fomasi litologi akuifer batugamping mempunyai karakteristik media aliran berupa celah, rekahan, dan lorong pelarutan, sehingga memiliki potensi mengalirkan airtanah dengan kecepatan tinggi. Produktivitas yang tinggi ini mengakibatkan sumber pencemar di permukaan dapat dengan cepat meresap ke sistem akuifer dan bercampur dengan airtanah; kondisi inilah yang memicu kerentanan tinggi. Salah satu langkah pengelolaan airtanah pesisir adalah penentuan zona kerentanan airtanah terhadap pencemaran. Dengan demikian, tujuan penelitian ini adalah untuk mengetahui tingkat kerentanan airtanah pesisir terhadap pencemaran di formasi batugamping menggunakan metode COP dengan pendekatan intrinsik dan metode EPIK dengan pendekatan perkembangan karst. Hasil penilaian menggunakan kedua metode tersebut menunjukkan tingkat kerentanan rendah hingga sangat tinggi. Pemetaan metode COP menghasilkan dua kelas kerentanan: rendah (95% dari luas wilayah) dan sedang (4%), sedangkan metode EPIK menghasilkan zona indeks kerentanan yang lebih panjang dengan empat kelas kerentanan, yaitu rendah (1,23%), sedang (17,82%), tinggi (17,82%), dan sangat tinggi (21,65%). Dibandingkan dengan COP, EPIK menghasilkan kelas kerentanan yang lebih tinggi karena pengaruh koefisien pembobot pada formula penghitungannya. Hasil penilaian kerentanan divalidasi dengan indikator limbah domestik berupa senyawa nitrat (NO3). Uji laboratorium menunjukkan kandungan nitrat (NO3) airtanah yang bervariasi dari 0,12 mg/l (terendah) hingga 9,80 mg/l (tertinggi). Variasi ini masih berada di bawah baku mutu air minum tetapi di atas baku mutu air limbah domestik atau melebihi kadar nitrat di alam. Berdasarkan hasil validasi, zona kerentanan berkorelasi dengan kandungan nitrat (NO3). Pada zona kerentanan yang tinggi, ditemukan kadar nitrat yang tinggi pula.ABSTRACTA limestone aquifer is lithologically characterized by three flow media: fissures, fractures, and dissolution channels, thus creating the potential to drain groundwater at a high rate. This high productivity, however, means that the groundwater is highly vulnerable to pollution. If a pollutant source is present on the surface, it can quickly seep into and mix with the subsurface system. Among the widely proposed management strategies is groundwater vulnerability zoning. This study was intended to determine the degrees of coastal groundwater vulnerability to pollution in a limestone formation with two methods: COP intrinsic vulnerability) and EPIK (karst development-based vulnerability). The assessment results showed that the vulnerability produced with both methods varied from low to very high. In the mapping, COP produced two levels: low (95% of the total area) and medium (4%), while EPIK generated a longer vulnerability index zone with four levels: low (1.23%), medium (17.82%), high (17.82%), and very high (21.65%). Compared to COP, EPIK results in a higher vulnerability class due to the weighting values in its vulnerability assessment. The results were validated with a domestic waste indicator: the presence of nitrate (NO3). Laboratory tests showed NO3 concentrations in the range 0.12 of 9.80 mg/l. These figures are still below the quality standard for drinking water but above that of domestic wastes or exceeding the maximum NO3 content found in nature. The validation revealed that the vulnerability zone is correlated with NO3 levels: the higher the vulnerability class of the zone, the higher the nitrate content.

A Modified AVI Model for Groundwater Vulnerability Mapping: Case Studies in Southern Italy

Many methods for evaluating the aquifer’s vulnerability to pollution have been developed in the past four decades by using geographic information system (GIS) tools. However, even if the aquifer vulnerability concept is well defined and the methods have been constantly tested and compared, the problem of the choice of the best “standard” method remains. To meet these objectives, aquifer vulnerability maps are of crucial importance. The choice of method depends on several factors, including the scale of the project, the hydrogeological characteristics of the area, and data availability. Among the many methods, the AVI (Aquifer Vulnerability Index) method has been widely used as it considers only two physical parameters. The AVI Index represents the hydraulic resistance of an aquifer to vertical flow, as a ratio between the thickness of each sedimentary unit above the uppermost aquifer (D, length), and the estimated hydraulic conductivity (K, length/time) of each of these layers. The AVI Index has a time dimension and is divided into five classes. In order to avoid a widespread presence of the higher vulnerability classes, especially in shallow aquifers, the AVI classification has been modified using statistical methods. The study reports the application of the modified AVI method for groundwater pollution vulnerability, in three different areas of southern Italy, highlighting the limitations of the method in alluvial aquifers and the differences with other methods.

Groundwater Vulnerability towards Pollution in Area Around the Piyungan Landfill, Bantul Regency, D. I. Yogyakarta

The Piyungan landfill is located in Bantul Regency, Daerah Istimewa Yogyakarta, still uses an open dumping system. The open dumping system produced more quantity of leachate from other systems. Leachate spreads to the ground and seeps into the ground to the groundwater surface. These conditions have an impact on the environment. This study aims to assess the groundwater vulnerability to leachate contamination in the area around the Piyungan landfill. The research method used is survey and mapping, and data analysis is carried out using the Le Grand method. Geographic Information System (GIS) is also used to visualize data into maps. The Le Grand method considers as many as 5 physical environmental parameters, including the groundwater depth, absorption above ground, aquifer permeability, groundwater slope, and horizontal distance of wells with pollutant sources. Next, scoring is carried out for each of these parameters, and then a groundwater vulnerability map is made using the overlay method. The results of the study were three classes of the potential vulnerability of groundwater pollutions. That were large pollution potential (may or may be polluted), medium pollution potential (maybe polluted but slightly), and small pollution potential (very difficult to pollute).

First Application of the Integrated Karst Aquifer Vulnerability (IKAV) method. Potential and Actual vulnerability in Yucatan, Mexico

Groundwater vulnerability maps are important decision support tools for water resources protection against pollution and helpful to minimize environmental damage. However, these tools carry a high subjectivity along the multiple steps taken for the development of such maps. Additionally, the theoretical models on which they are based do not consider important parameters such as pollutant concentration or pollutant residence time in a given section of the aquifer, solely focusing the analysis on a theoretical travel time from a release point towards a target. In this work, an integrated methodology for the evaluation of potential (intrinsic) and actual vulnerability is presented. This integrated method, named IKAV, was developed after the analysis of several study cases and the application of multiple intrinsic groundwater vulnerability methods in a selected study area. Also, a solute transport model served as the basis to define additional parameters for vulnerability analysis for areas severely affected by anthropogenic practices. A defined workflow and several criteria for parameters and attributes selection, rating and weighting assignment, and vulnerability classification are presented. The first application of the IKAV method was carried out in the Yucatan karst, demonstrating to be a reliable method for vulnerability estimation. Results demonstrated the scope of the IKAV method to highlight important regional conditions, minimizing the subjectivity, and expanding the analysis of vulnerability.

Groundwater Vulnerability to Pollution in Kediri City, East Java Province, Indonesia

Groundwater is a water resource that is still a mainstay for humans. The need for groundwater increases with the growth of population and the development of the industrial and agricultural sectors. The residents of Kediri City still use wells from shallow aquifers to fulfill their water needs. Shallow aquifers are prone to pollution due to the influence of shallow groundwater depths and human activities. The purpose of this study is to determine the vulnerability of groundwater pollution in Kediri City. Groundwater vulnerability was conducted by the GOD method (Groundwater Occurrence, Overlaying Lithology, and Depth of Groundwater) that consists of 3 parameters, namely the groundwater confinement, the type of overlying strata, and the depth of the groundwater level. The analysis results show that the level of groundwater vulnerability according to the GOD method in Kediri City consists of moderate and high classes. The western and the eastern part of Kediri City is classified as a high level of vulnerability. In contrast, in the middle of Kediri City, it tends to experience a moderate level of vulnerability.