Transboundary Aquifers between Baja California, Sonora and Chihuahua, Mexico, and California, Arizona and New Mexico, United States: Identification and Categorization

In 2016, research suggested there might be up to 36 transboundary aquifers located along the border between Mexico and the U.S. The main contribution of this study was to put together the available segments already existent in the literature without considering the validity of the criteria used to define the boundaries of those segments. In 2018, updated research reported 33 hydrogeological units (HGUs) crossing the boundaries between Mexico and Texas. This later analysis included the homogenization of geological nomenclatures, standardization of geological and hydrogeological criteria, using a specific methodology to correlate, identify, and delineate each HGU. The purpose of this paper is to use this latter methodology and expand the same analysis to include the transboundary aquifers between Baja California/California, Sonora/Arizona, and Chihuahua/New Mexico. Results of this study indicate that a total of 39 HGUs have been identified in this region which accounts for an approximate shareable land of 135,000 km2 where both countries share half of the area. From the total shareable area, around 40% reports good to moderate aquifer potential and water quality, of which 65% is in the U.S. and 35% on the Mexico side. Border-wide, the total number of HGUs in the border region between Mexico and the United States is 72, covering an approximate area of 315,000 km2 (180,000 km2 on the U.S. side and 135,000 km2 on the Mexico side). The total area that reports good to moderate aquifer potential as well as good to regular water quality ranges between 50 and 55% (of which approximately 60% is in the U.S. and the rest in Mexico).

ANALISA POTENSI AKUIFER DI KECAMATAN RUMBAI PESISIR KOTA PEKANBARU DENGAN MENGGUNAKAN METODE GEOLISTRIK ATURAN SCHLUMBERGER

The analysis of aquifer potential has been done in the Rumbai Pesisir District of Pekanbaru City by using the Schlumberger configuration geoelectric method. Data was taken from four villages in Rumbai Pesisir Subdistrict, in Lembah Damai, Limbungan, Limbungan Baru and Meranti Pandak. The result obtained using progress software showed that each location has aquifer with different layer and thickness. The highest aquifer resistivity is located in Lembah Damai Village with a resistivity value of 549.50 Ωm in the third layer, while aquifer with the lowest resistivity value is located in Meranti Pandak Village with a resistivity value of 15.69 Ωm in the third layer. The highest thickness aquifer located in Meranti Pandak Village with a thickness of 48.47 m in the third layer, while the lowest thickness aquifer located in Limbungan Baru Village with a thickness of 11.51 m in the second layer. The Result from lithology of each path shows that flow pattern of water flowing from Lembah Damai Village to Limbungan Village, then Meranti Pandak Village and then Limbungan Baru Village. The results of the analysis of aquifers potential indicate that underground water reserves in the Rumbai Pesisir District of Pekanbaru City are 17.13 x 109 m³.

Aplikasi Metode Geolistrik untuk Pendugaan Air Bawah Tanah Desa Karanganyar Kecamatan Bantaran Kabupaten Probolinggo Jawa Timur

Desa Karanganyar, Kecamatan Bantaran, Kabupaten Probolinggo merupakan salah satu daerah kekeringan. Daerah ini tersusun oleh lapisan produk Gunungapi Tengger yang terdiri dari tuff, breksi gunungapi, lava, dan lahar. Kondisi tersebut memungkinkan daerah tersebut mengalami krisis akan air tanah karena lapisan produk gunungapi memiliki karakteristik impermiabel atau kedap air. Untuk itu diperlukan penelusuran mengenai informasi dasar tentang letak keberadaan air tanah dengan cara survey geofisika menggunakan metode geolistrik resistivitas. Penelitian ini bertujuan untuk mengkaji potensi keberadaan air tanah di lokasi penelitian dan mengetahui kondisi litologi bawah permukaan dengan metode geolistrik tahanan jenis menggunakan konfigurasi Wenner dan Schlumberger. Berdasarkan hasil penelitian diketahui litologi penyusun di daerah pengukuran berupa batuan vulkanik (lempung tuffan, tuff, lahar tuffan, breksi, dan lava). Batuan yang berpotensi mengandung akuifer yaitu batuan lahar tuffan. Batuan lahar tuffan tersebar di ketiga titik pengukuran sehingga ketiga titik tersebut memiliki potensi akuifer. Pada titik KRA-1 akuifer yang dapat dijumpai diduga terdapat pada kedalaman 37,1 – 102,3 meter dengan nilai resistivitas 60,3 – 171,5 ohm meter, titik KRA-2 pada kedalaman 92,8 – 143,9 meter dengan nilai resistivitas 50,2 – 62,9 ohm meter, dan titik KRA-3 pada kedalaman 63,4 – 133,15 meter dengan nilai resistivitas 62,6 – 119,5 ohm meter.Kata Kunci: Karanganyar; Bantaran; Probolinggo; geolistrik; akuifer ABSTRACT Karanganyar Village, Bantaran District, Probolinggo Regency is one of the drought areas. This area is composed of layers of Tengger Volcano products consisting of tuff, volcanic breccias, lava, and lava. These conditions allow the area to experience a crisis of groundwater because the volcanic product layer has impermiable or waterproof characteristics. For this reason it is necessary to search for basic information about the location of the presence of groundwater by geophysical survey using the resistivity geoelectric method. This study aims to examine the potential presence of groundwater in the study site and determine the conditions of subsurface lithology with the geoelectric resistivity method using the Wenner and Schlumberger configurations. Based on the research results, it is known that the lithology of the constituents in the measurement area is volcanic rock (tuffan clay, tuff, lava tuffan, breccia, and lava). Rocks that have the potential to contain aquifers are tuffan lava rocks. Tuffan lava rocks are scattered in all three measurement points so that all three points have an aquifer potential. At the point of KRA-1 aquifer that can be found is suspected to be at a depth of 37.1 - 102.3 meters with a resistivity value of 60.3 - 171.5 ohm meters, a KRA-2 point at a depth of 92.8 - 143.9 meters with a value of resistivity 50.2 - 62.9 ohm meters, and KRA-3 points at depths of 63.4 - 133.15 meters with resistivity values of 62.6 - 119.5 ohm meter.