Groundwater management issues in the Greater Jakarta area, Indonesia

The Greater Jakarta occupies the northern zone of Java Island and the elevations of this plain vary from 0 to 1,000 m above sea level. It is one of the most developed basins in Indonesia and is located between 106° 33\u27-107° E longitude and 5° 48\u27 30"- 6° 10\u27 30" S latitude covering an area of about 652 km². The population of Jakarta at present is around 7.5 millions. As the water which is supplied by surface water only covers 30% of water demand, people are harvesting the available groundwater in the basin, which has already caused a negative impact on these resources itself both quantity and quality. The changing environment as consequence of the development has also brought undesirable effects to the quantity of groundwater. Therefore, the proper groundwater management of this area should be identifie

Kualitas Air pada Puncak Musim Kemarau di Daerah Rawa Danau Kabupaten Serang

Rawa Danau Serang merupakan rawa pegunungan yang menjadi andalan pemasok air di kawasan industri Cilegon dan sekitarnya. Selain air hujan, pasokan air ke Rawa Danau juga berasal dari mataair gunungapi di sekitarnya. Sumber air yang ada terdiri dari mataair, mataair panas, sumur gali, sumur bor dan sungai. Percampuran beragam sumber air tersebut dapat mempengaruhi kualitas air Rawa Danau, sehingga penelitian kondisi fisika dan kimia air menjadi penting untuk dilakukan. Pengukuran dilakukan pada kondisi puncak musim kemarau untuk menganalisis skenario terburuk dari curah hujan minimal dan kualitas air belum banyak dipengaruhi air hujan. Pada puncak musim kemarau, air di daerah penelitian cenderung bersifat asam dengan pH air berkisar 5,7-7,65. Hasil pengukuran dan analisis kimia air menggunakan AAS dan turbidimeter secara keseluruhan air masih memenuhi syarat untuk digunakan sesuai dengan peruntukannya. Analisis hidrogeokimia menggunakan diagram Piper menunjukkan bahwa tipe air Ca+Mg-HCO3. Rawa Danau Serang, which is a wetland in the mountain area, is the primary source of water for Cilegon and surrounding areas. Besides the precipitation, the main source of water in Rawa Danau is the mountain springs. The other water sources include springs, hot springs, dug wells, boreholes, and rivers. The mixture of those various sources of water might affect the quality of water.  Therefore, a study on the chemical and physical properties of the water is essential. We measured the water condition in the dry season to analyze the worst-case scenario of minimal rain. At the peak of dry season, water in the study area was acidic with pH ranging from 5.7 to 7.65. The results of chemical analysis of water using AAS and turbidimeter have indicated that, as a whole, the water from Rawa Danau was still meet the requirements for domestic use. Hydro-geochemical analysis using the Piper diagram has indicated that the type water is Ca + Mg- HCO3.

GROUNDWATER CHARACTERISTICS IN JAKARTA AREA, INDONESIA

ABSTRACT In the Jakarta area (Indonesia), excessive groundwater pumping due to the rapidly increasing population has caused groundwater-related problems such as brackish water contamination in coastal areas and land subsidence. In this study, we adopted multiple hydrogeochemical techniques to understand groundwater characteristic in the Jakarta area. Although almost all groundwater existing in the Jakarta basin is recharged at similar elevations, the water quality and apparent residence time demonstrates a clear difference between the shallow and deep aquifers. Due to the rapid decrease in the groundwater potential in urban areas, we found that the seawater intrusion in shallow aquifer and the shallow and deep groundwaters are mixing, a conclusion confirmed by major ions, Br−:Cl− ratios and chlorofluorocarbon (CFC)-12 analysis

PENJEJAK KELUARAN AIRTANAH DI LEPAS PANTAI (KALP) DI PANTAI UTARA SEMARANG DAN SEKITARNYA DENGAN 222RADON

ABSTRAK Pengambilan airtanah di kota Semarang di tahun 2009 mencapai 17,4 juta m3 setiap tahunnya dan terkonsentrasi di daerah Semarang Utara. Dampak yang timbul adalah  terjadinya krisis airtanah yang ditandai dengan penurunan muka airtanah sedalam hampir 20 meter pada daerah seluas 30 m2. Penurunan  muka airtanah tersebut mengakibatkan terkontaminasinya airtanah dalam (deep aquifer) termasuk intrusi air laut, penurunan permukaan tanah (land subsidence), dan banjir genangan (rob). Untuk mendeteksi kehadiran KALP yangberasosiasi dengan tidak adanya intrusi air laut, dilakukan penelitian dengan menggunakan isotop radon. Hasil penelitian menunjukkan tingginya level radon pada air laut di sebagian lokasi di lepas pantai, yang berasosiasi dengan aluvial pasir yang terendapkan di sekitar pantai. Kondisi ini mencerminkan adanya airtanah tawar secara lokal dalam jumlah terbatas ke lau

TRANSPORT AND TRANSFORMATION OF CHEMICAL COMPONENTS IN THE GROUNDWATER FLOW SYSTEM OF JAKARTA METROPOLITAN AREA

ABSTRACT The aim of this study is to examine the transport and transformation of chemical components within the groundwater flow in Jakarta area, and to evaluate the effects of accelerated urbanization on it. The collected data showed that the current hydraulic potential in the Jakarta metropolitan area is below sea level because of prior excess abstraction of groundwater. The distribution of Cl- and Mn2- concentration in groundwater suggests that the decline in hydraulic potential has caused the intrusion of seawater to shallow groundwater and the movement of shallow groundwater into deep groundwater. It implies an accumulation of contaminants in deep aquifers. On the other hands, the presentation of NO3--N in groundwater is suggested to be attenuated by the processes of denitrification and dilution in the coastal area

Sumber Daya Air Di Wilayah Pesisir & Pulau-Pulau Kecil Di Indonesia

xix 344 hal; 14,8 x 21 c

Sumber Daya Air Di Wilayah Pesisir & Pulau-pulau Kecil di Indonesia

Kawasan pesisir merupakan daerah yang selalu berkembang dengan tingkat pertumbuhan yang lebih cepat bila dibandingkan dengan daerah pedalaman, sehingga kawasan pesisir ini banyak dieskploitasi untuk berbagai tata guna, mulai dari yang tradisional seperti pertanian, perikanan dan kehutanan, sampai pada yang kontemporer seperti kawasan permukiman, kawasan industri dan kawasan wisata bahari.Kawasan pesisir Pulau Jawa dihuni lebih dari 50% penduduk. Pertambahan penduduk serta peningkatan kualitas hidup melahirkan tekanan lingkungan yang relatif berat sehingga berdampak terhadap lingkungan lain di luar lingkungan tersebut, dengan sendirinya lingkungan ini menjadi dinamik dan selalu berubah. Salah satu akibat dari perubahan ini adalah menurunnya kualitas air yang disebabkan oleh ketidakseimbangan antara laju eksploitasi dan imbuhan air di hulu. Oleh karena itu penelitian sumber daya air di wilayah pesisir ini diperlukan agar hasilnya dapat dipakai sebagai acuan dalam upaya meredam dan merehabilitasi kerusakan tata air.Selain kawasan pesisir, Indonesia memiliki banyak pulau-pulau kecil. Sumber daya air di pulau-pulau kecil ini jumlahnya terbatas karena dikelilingi dan dialasi oleh air laut sehingga rawan terhadap penyusupan air asin.Buku ini selain menyajikan sumber daya air di kawasan pesisir juga membahas beberapa penelitian sumber daya air di beberapa pulau kecil yang berada di wilayah Indonesia yang dapat menjadi referensi bagi perencanan pengembangan sebuah pulau kecil

A physical study of the effect of groundwater salinity on the compressibility of the Semarang-Demak aquitard, Java Island

This article is currently under review oin Journal of Geosciences, MDPI. Authors: Dwi Sarah, Lambok Hutasoit, Robert Delinom, Imam A. Sadisun, Taufiq Wirabuana -- Semarang-Demak and other cities along the coast of North Java are vulnerable to land subsidence. The presence of saline groundwater in the coastal region is thought to affect the high subsidence rate, in this case the compressibility of the aquitard layer. We aimed to analyze the effects of groundwater salinity on the compression characteristics of the Semarang-Demak clay using physical analysis. Methods included the determination of groundwater salinity, clay mineralogy and fabrics, and consolidation tests under various salinity conditions. The Semarang-Demak clay is dominated by smectite of high activity and saline clay exists at the depth of 10 to 35 m. Consolidation tests reveals that the increase of salinity increases the average consolidation rate and hydraulic conductivity up to 42% and 37.5%, respectively. Clay fabric analysis showed that the groundwater salinity modified the interconnectivity of pores by changing the fabric into parallel alignments, facilitating faster porewater dissipation, hence the clay is more readily compressed. These findings are useful for explaining the mechanism of the fast-subsiding coastal plains of North Java

SUBMARINE GROUNDWATER DISCHARGE MEASUREMENT ON THE SANDY UNCONFINED AQUIFER AT THE CARNAVAL BEACH, ANCOL (JAKARTA BAY)

Submarine groundwater discharge (SGD) is defined as all direct discharge of subsurface fluids into coastal zone. Components of SGD consist of fresh submarine groundwater discharge and the recirculated saline seawater discharge. SGD could act as a pathway for the transport of anthropogenic contaminants and nutrients to coastal waters. Measurement SGD at Carnaval Beach, Ancol, Jakarta was focussed on unconfined groundwater system. The method of quantified used automatic seepage meter for measured of SGD and installed conductivity temperature depth. The average SGD rate was 0.21 mm/min on March 20-31, 2009 consist of 19.05% fresh water, 80.95% recirculated seawater. April 1-23, 2009, the average SGD rate was 0.81 ml/min which consisted of 16.04% fresh water, 83.96% recirculated seawater. SGD fluctuation was opposite with the tide. As a result, submarine groundwater discharge at Jakarta coastal area was defined and can be measured to quantify