Kajian Banjir dan Perubahan Dasar Sungai Banger Akibat Penutupan Regulator Gate, Kota Pekalongan, Provinsi Jawa Tengah

Dalam sistem pengembangan daerah Provinsi Jawa Tengah, Pemerintah provinsi menetapkan Kota Pekalongan sebagai salah satu wilayah strategis untuk pertumbuhan ekonomi. Meskipun memiliki potensi yang signifikan, Kota Pekalongan masih perlu mencari solusi untuk mengurangi banjir yang merupakan masalah berulang. Banjir di Kota Pekalongan disebabkan oleh gelombang pasang (rob) dan luapan banjir yang terjadi di sungai-sungai yang melintasi kota. Menurut Bappeda Kota Pekalongan, pada tahun 2020 terjadi genangan banjir seluas 1.177,86 hektar. Untuk mengatasi masalah banjir, pemerintah telah membuat beberapa infrastruktur pengendalian banjir di Kota Pekalongan, diantaranya regulator gate dan tanggul parapet. Pembangunan regulator gate ini bertujuan untuk mengatur aliran yang masuk ke sistem Sungai Loji, sehingga kedepannya seluruh aliran ke Sungai Banger sepenuhnya. Studi ini mensimulasikan banjir di wilayah Kota Pekalongan untuk menilai dampak pembangunan regulator gate dan tanggul sungai khususnya di sekitar Sungai Banger menggunakan HEC-RAS 6.4 dengan dibagi menjadi 4 skenario. Simulasi dilakukan dengan debit banjir periode ulang 25 tahun dan 50 tahun. Hasil studi ini menunjukkan area terkena banjir sebelum pembangunan regulator gate adalah 710,06 hektar, dan setelah pembangunan regulator gate, area banjir berkurang menjadi 363,02 hektar. Banjir yang tersisa terjadi di muara Sungai Banger, tetapi setelah normalisasi penambahan tanggul parapet dilakukan, banjir di Kota Pekalongan dapat diselesaikan

Close-range photogrammetry method for SF6 Gas Insulated Line (GIL) deformation monitoring

Close-Range Photogrammetry (CRP) technology advanced rapidly along with the development of camera sensors. CRP has many advantages over other methods in terms of technical data acquisition, product quality, and cost. Because of these advantages, the CRP method can be used in various applications. In this study, the CRP method is used to monitor the deformation of the SF6 Gas Insulated Line (GIL) object between two substations of the Indonesian National Electricity Service in Kuningan Barat, South Jakarta. Planning was carried out with a simulation using 3D field data obtained from reconnaissance process. During the survey, photo data was collected using a smartphone and processed to form a 3D model. The simulation produced a configuration of control points, check points, and camera stations that have the best Strength of Figure (SoF) values. In the planning process, camera pre-calibration is carried out to get the best camera orientation parameter values from several experiments. The planning results are used in the next stage, namely field data acquisition and data processing. The data acquisition process was carried out for two sessions. This is done to see the changes in coordinates that occur between these sessions. Data processing was carried out by following the classical photogrammetric stages. The results obtained from this study are the average accuracy produced by Close-Range Photogrammetry method for measuring deformation which is below a tolerance of 3 mm. With this method, deformation measurements can be carried out quickly, accurately, and at a relatively lower cost than other observation methods

On the acceleration of land subsidence rate in Semarang City as detected from GPS surveys

Land subsidence is not a new phenomenon for Semarang the capital city of Central Java Province with recent population of about 1.5 million. Some report said the subsidence in Semarang probably is occurring for more than 100 years. Geodetic surveys such as GPS Surveys can detect land subsidence accurately. Land subsidence in Semarang exhibits spatial and temporal variations with the typical average rates of about 3 to 10 cm/year until recently it seem the acceleration existed in some region of the city. This acceleration will increase the risk of negative consequences from the land subsidence. This paper present and discuss the acceleration of land subsidence in Semarang as detected from GPS Surveys. The surveys have been conducted in 2008, 2009, 2010, 2012, 2016 and 2017. From 2008 to 2012 the subsidence generally follow linier rates while from 2012 to 2017 seem they are accelerating. The northern eastern region of Semarang along the coastal area still exhibits relatively higher rates of subsidence along with acceleration in rates compare to others region. Ground water exploitation is suspected to be the causes of that land subsidence phenomenon in Semarang cit