Penanggulangan Banjir Kali Kedurus Hilir Dengan Menggunakan Model Matematika

Sistem Pematusan Kedurus merupakan salah satu sub-sistem pematusan dari 22 subsistem pematusan di Kota Surabaya. Oleh karena muara Kali Kedurus adalah Kali Surabaya maka sub-sistem Kedurus ini sangat dipengaruhi oleh elevasi permukaan air di Kali Surabaya yang dikendalikan oleh operasional Dam Jagir, Pintu Air Wonokromo dan Dam Gunungsari yang berada di Kali Surabaya. Untuk memenuhi pasokan air baku PDAM Ngagel sebesar ≥ 6 m^3/dt diperlukan elevasi + 3.20 pada duga Pintu Dam Jagir. Elevasi ini lebih tinggi daripada elevasi permukaan air Kali Kedurus sehingga sistem drainase Kedurus tidak bisa mengalirkan air ke Kali Surabaya dan akibatnya terjadi genangan seluas ±400 Ha di Kecamatan Wiyung dan sekitarnya (Surabaya Drainage Master Plan 2018, 2000). Oleh karena perbedaan kepentingan antara kontinuitas pemberian air untuk PDAM Ngagel sebesar ≥ 6 m^3/dt dan penanggulangan banjir sistem drainase Kedurus maka diperlukan suatu kajian untuk mendapatkan solusi antara dua kepentingan tersebut. Kajian dilakukan dengan menggunakan model matematika. Hasil analisa, model matematik satu dimensi Hec-Ras bisa diterapkan untuk Kali Kedurus dengan angka kekasaran Manning untuk P .0 - P .17 (bagian tebing : 0.017, main channel : 0.025), P .18 - P .48 (bagian tebing :0.017, main channel: 0.025), P.49 - P.85 (bagian tebing: 0.033, tnain chanel: 0.033). Dari simulasi Model Hec-Ras terkalibrasi untuk kondisi debit banjir rencana Kali Kedurus menunjukkan bahwa debit banjir puncak Kali Kedurus di muara sebesar 49.14 m3/dt atau 59.5% Q_20(debit banjir rencana dengan periode ulang 20 tahun) Kali Kedurus (Q_20 Kali Kedurus = 82.531 m3/dt). Selain itu, pada penampang P.56 - P.85 (terletak pada 5600 m - 8500 m dari . muara di Kali Surabaya) mengalami peluapan. Dengan mempertimbangkan kapasitas Kali Surabaya dan Kali Kedurus; direncanakan debit banjir Kali Kedurus di muara sebesar 40% Q_20 Kali Kedurus, alternatif yang dapat diambil adalah membuat kolam penampungan yang dapat menampung sebagian debit banjir dari Kali Kedurus Hulu sebelum masuk ke Kali Kedurus Hilir. Output Model Hec-Ras menunjukkan bahwa debit banjir puncak Kali Kedurus di muara sebesar 35.40 m3/dt atau 42.89% Q-20 Kali Kedurus dengan adanya kolam penampungan. Kondisi ini masih harus disertai normalisasi sa1uran dari P.78 - P.85 (terletak pada 7800 m - 8500 m dari muara di Kali Surabaya) ================================================================================================================================== Kedurus drainage system is one of the twenty two drainage sub-systems in Surabaya.As the downstream of Kali Kedurus is Kali Surabaya, it is significantly influenced by water level elevation of Ka1i Surabaya which is controlled by Jagir dam, Gunungsari dam and Wonokromo flood gate. To fulfill water supply of PDAM Ng&gel amounting ≥ 6 m^3/sec, water level elevation + 320 on Jagir dam is badly needed. This elevation is higher than that of Kali Kedurus so that Kedurus drainage system is unable to discharge to Kali Surabaya. Consequently, the area of ± 400 hectares in Wiyung sub-district and its surroundings is flooded unavoidably (Surabaya Drainage Master Plan 2018. 2000). The different need between the continuation of water supply for PDAM Ngagel ≥ 6m^3 /sec and Kedurus drainage system for flood prevention brings a serious problem. Therefore, a feasible study is required to be conducted to give best solution for the above need. The study is conducted by using mathematical model. And the result is that mathematical model of Hec-Ras one dimension can be applied for Kali Kedurus with Manning roughness for P.O - P.l7 (river bank: 0.017 main channel: 0.025), P.l8- P.48 (river bank: 0.017, main channel: 0.025), P.49- P.85 (river bank: 0.033, main channel: 0.033).From calibrated Hec-Ras simulation model for design flood condition of Kali Kedurus shows that peak flood discharge in downstream part is:49.14 m3/sec or 59.5% Q_20 (flood discharge with 20 years return period) Kali Kedurus (Q_20 Kali Kedurus = 82.531 m^3/sec). Besides that, overflow occurs on P.56- P.85 (located at 5600 m - 8500 m from the outlet to Kali Surabaya). By making consideration of Kali Kedurus and Kali Surabaya capacities, it is planned to make Kali Kedurus flood discharge in downstream part 40% Q_20.Another way that can be taken is to make returning basin that will be able to accommodate some flood discharge from upstream part of Kali Kedurus before flowing down to Kali Kedurus downstream. The out-put of Hec-Ras model shows that flood peak discharge of Kali Kedurus in downstream part is 35.40 m^3 /sec or 42.89% Q_20 Kali Kedurus with returning basin. This condition must be accompanied by drainage normalization of Kali Kedurus from P.78- P.85 (located at 7800 m - 8500 m from the outlet to Kali Surabaya

Kajian Tentang Penggunaan Keterangan Ahli Hukum Pidana dalam Praktik Pembuktian Perkara Pidana

Keterangan ahli adalah keterangan yang diberikan oleh seseorang yang memiliki keahlian khusus tentang hal yang diperlukan untuk membuat terang suatu perkara pidana guna kepentingan pemeriksaan. Khusus dalam praktik perkara pidana , terkadang dalam pembuktian penuntut umum atau terdakwa menggunakan keterangan dari ahli hukum pidana. Dijelaskan dalam KUHAP tidak ada Pasal yang melarang penggunaan keterangan ahli pidana. Keterangan ahli pidana terkadang atau sangat sering digunakan dalam pembuktian praktik perkara pidana, muncul suatu masalah atau penolakan dalam praktik penggunaan keterangan ahli pidana dalam pembuktian praktek pidana.Tujuan dari penelitian ini adalah untuk mengetahui kedudukan keterangan ahli dalam praktik perkara pidana dan urgensi penggunaan keterangan ahli hukum pidana dalam praktik perkar pidana

Analysis of Waikelo Port Breakwater Failure through 2D Wave Model

Waikelo Port is located in South West Sumba of East Nusa Tenggara. The port facilities are protected by breakwater with a vertical wall construction and it was built in a relatively deep ocean at -15m of Low Water Sea Level (LWS). On 21 of January 2012, an earthquake with magnitude of 6.3 Richter scale occurred around Sumba Island and it caused cracking in the concrete wall of breakwater. Then, 4 days after on 25 st January 2012, a heavy wind of 20–23 knots generated a high wave around 4.0–5.0m in Sumba strait. These high waves caused a critical damage on the west part of the breakwater. The damage of port facilities were getting worse when a storm called Lua hit on March 2012. This study was conducted to observe the effect of the extreme event in the failure of breakwater. The result of two-dimensional (2D) wave model shows that the wave heights in the area of breakwater are varied 3.80 to 4.0m. It is quite greater than the wave design of 50 years return period (= 2.00m) which was used in breakwater design and calculation. This observable fact confirms that the failure of breakwater was caused by the continuous extreme events that exceed the design criteri

Analysis of Climate Variability and Trends in The Context of Climate Changes: Case Study in Terengganu

Uncertainty of climate extreme nowadays causes an alteration in the local climate trend and variability. Terengganu, Malaysia recorded series of extreme drought and flood events throughout a year affected by North-East monsoon which will change the next climate pattern. Thus, it will affecting the long-term planning and sustainability that related to the water resources in the long-term. The objective of this study was to analyse the trend changes of rainfall and temperature at Kuala Terengganu, Malaysia due to climate changes impact. The trends changes were analysed using Man-Kendall and Sen’s Slope. The climate projection result shows the annual mean temperature is expected to have decreasing trend until end of century. However Mar to June are expected to bit higher than historical reach to 29oC by RCP8.5. Then it will be dropped to 24oC (-5% from historical) during Northeast monsoon. Consistent to the annual rainfall, it was expected to have increasing trend over time. The highest increasing trend was expected to occur on Nov to Dec more than 40% by RCP8.5

Analysis of Climate Variability and Trends in The Context of Climate Changes: Case Study in Terengganu

Uncertainty of climate extreme nowadays causes an alteration in the local climate trend and variability. Terengganu, Malaysia recorded series of extreme drought and flood events throughout a year affected by North-East monsoon which will change the next climate pattern. Thus, it will affecting the long-term planning and sustainability that related to the water resources in the long-term. The objective of this study was to analyse the trend changes of rainfall and temperature at Kuala Terengganu, Malaysia due to climate changes impact. The trends changes were analysed using Man-Kendall and Sen’s Slope. The climate projection result shows the annual mean temperature is expected to have decreasing trend until end of century. However Mar to June are expected to bit higher than historical reach to 29oC by RCP8.5. Then it will be dropped to 24oC (-5% from historical) during Northeast monsoon. Consistent to the annual rainfall, it was expected to have increasing trend over time. The highest increasing trend was expected to occur on Nov to Dec more than 40% by RCP8.5

Flood Modeling of Jatiroto River Using HEC-RAS to Determine Effective Flood Control Alternatives

Jatiroto River, located on the border of Lumajang and Jember Regencies, is one of the rivers with a risk of flooding. This is due to changes in land use and high sedimentation. For this reason, flood control efforts are needed to reduce disaster risk. This study aims to conduct flood modeling on the Jatiroto River and propose the most effective flood control. In this paper, the flood modeling uses HEC-RAS 5.0 with Q25y and Q50y obtained from analyzing rainfall data from 9 rainfall stations. The first modeling was carried out to produce a flow hydrograph on the upstream river section. The second modeling is carried out for the downstream river section with lateral flow from the Jatiroto tributaries. The flood modeling results show that the existing cross-sectional capacity of the Jatiroto River cannot accommodate Q25y, so it overflows in several cross-sections, especially the downstream section.By normalizing the river's cross-section and constructing an embankment in the downstream area, the flow simulation results on flood modeling show that the flood discharge at 25 years and 50 years does not overflow in all cross sections. Therefore, the normalization and construction of embankments become the effective flood control option in the Jatiroto River

Analysis of climate variability and trends in the context of climate changes: Case study in Terengganu

Uncertainty of climate extreme nowadays causes an alteration in the local climate trend and variability. Terengganu, Malaysia recorded series of extreme drought and flood events throughout a year affected by North-East monsoon which will change the next climate pattern. Thus, it will affecting the long-term planning and sustainability that related to the water resources in the long-term. The objective of this study was to analyse the trend changes of rainfall and temperature at Kuala Terengganu, Malaysia due to climate changes impact. The trends changes were analysed using Man-Kendall and Sen’s Slope. The climate projection result shows the annual mean temperature is expected to have decreasing trend until end of century. However Mar to June are expected to bit higher than historical reach to 29oC by RCP8.5. Then it will be dropped to 24oC (-5% from historical) during Northeast monsoon. Consistent to the annual rainfall, it was expected to have increasing trend over time. The highest increasing trend was expected to occur on Nov to Dec more than 40% by RCP8.5

Dam break studies using hydrologic and hydraulics model for Chereh Dam, Kuantan, Pahang, Malaysia

This current study is evaluating the risks of Chereh Dam failure. A dam break study basically consists of rainfall analyses; hydrologic modeling; dam breaching analysis and inundation mapping of the resultant flood. Precipitation analyses and development of Intensity Duration Frequency (IDF) curve has been prepared and published in Urban Storm water Management Manual by the Department of Irrigation and Drainage of Malaysia. In here, hydrologic modeling was performed with the HEC-HMS (Hydrologic Modeling System). The results of hydrological analysis revealed that the observed and simulated flow hydrographs in the calibration and confirmation exercises were reasonably close. Furthermore, dam breaching analysis and inundation mapping was executed with the HEC-RAS (River Analysis System). Dam break analysis result will be used to arrange policy of the state or city government in order to minimize the hazards of Chereh Dam failure