Djoko Legono
Fakultas Teknik, .lurusan Teknik Sipil Universitns Gadjah Mada, Yogyakarta

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KAJIAN PENGELOLAAN AIR IRIGASI BENDUNG PIJENAN Umar, Fauzan; Legono, Djoko; Nurrochmad, Fatchan
Civil Engineering Forum Teknik Sipil Vol 17, No 2 (2007): MEI 2007
Publisher : Civil Engineering Forum Teknik Sipil

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Abstract

Bantul Regency is about 506.85 km2 consists of 16,440 ha paddy fields and 34,245 ha upland fields. The Pijenan weir is one of weirs located in Bedog river in Bantul Regency. The weir provides irrigation water for Jigutan command area (Pijenan Upstream) of 2.074 ha. Kebonongan command area was previously irrigated from Kamijoro free intake in Progo River. The Kamijoro free intake did not properly function properly due to the sediment deposited in 1969. This condition requires supply taken from Pijenan weir. Irrigation water supply taken to Kebonangan command area can be carried out if irrigation water to Jigutan command area has been optimum. Optimally utilized irrigation water for Jigutan command area is necessary based on the crop pattern and crop variety in order to maximize the farmers? profit. Based on the restitution of irrigation management policy, farmers free to decide which crop variety will be cultivated in accordance to paddy-paddy-palawija pattern. Paddy as the main crop and palawija (corns, beans, peanuts, onion, and chilly) can be cultivated anytime in order to gain the maximum profit based on the available water in Jigutan command area. The optimization analysis of irrigation water allocation for Jigutan command area was performed using the linear program. Water allocation for Jigutan command area of 100% and 50% of available water resulted in optimum cultivation area of 822.88 ha with profit of Rp 7.688.517.507,00 and 612.88 ha with profit of Rp 6.743.877.335,00. The crop intensity with water allocation of 100% and 50% was 278% (197% paddy and 81% palawija) and 207.05% (114.05 paddy and 93% palawija), respectively. These results described that the optimum area of paddy crop cultivation is significantly sensitive to irrigation water allocation compared to the palawija market price. This explains why the profit obtained by the farmers is dependent from the palawija variety. Results of the optimization of irrigation water allocation of 100% and 50% of the available water to Jigutan command area provides annual supply to Kebonongan command area for 155.233.586 m3 and 75.316.444 m3, respectively.
MITIGASI BENCANA ALIRAN DEBRIS SUNGAI BELANTING SECARA NON STRUKTURAL DESA BELANTING KECAMATAN SAMBELIA KABUPATEN LOMBOK TIMUR – NUSA TENGGARA BARAT Legiarto, Ahad; Legono, Djoko; Haryono, Haryono
Civil Engineering Forum Teknik Sipil Vol 18, No 3 (2008): SEPTEMBER 2008
Publisher : Civil Engineering Forum Teknik Sipil

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Abstract

Belanting village, situated in the foot of Rinjani mountain range and crossed over by Belanting River, is a fast-growing village. Almost all of its inhabitants are migrants who came there on their own support. On January 21, 2006, a disaster strucked: debris flow came, taking people?s lives and creating havoc to local infrastructures. One of the difficulties in the area is that the lack of non-structural disaster mitigation. At this rate, a study is required concerning the awareness of local inhabitants of the threat posed by debris flow hazard. The objective of the study is to identify the level of local people?s understanding on debris flow disaster, to be functioned as determining basis for disaster management pattern by non-structural mitigation. Data were collected from questionnaires and interviews for 80 respondents. The resulting questionnaire data were then analyzed using SPSS (Statistic Pocket for Social Science). Result of the analysis indicates that 52.5 per cent of respondents have not understood the threat of disaster. In the meantime, the interviews indicate that religious leaders (Tuan Guru) hold high social status. Based on the result of the analysis and interviews, there is a need for a strategy in non-structural mitigation program and, as far as the study is concerned, socialization during public religious learning regarded as more effective and efficient efforts.
PENGELOLAAN SEDIMEN KALI GENDOL PASCA ERUPSI MERAPI JUNI 2006 Rahmat, Ali; Legono, Djoko; Kusumosubroto, Haryono
Civil Engineering Forum Teknik Sipil Vol 18, No 2 (2008): MEI 2008
Publisher : Civil Engineering Forum Teknik Sipil

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Abstract

The Gendol River, with its catchment area of 66 km2 and the river length of about 22 km, originates from the south east of Mount Merapi. Nineteen sabo dams have been built in order to anticipate and control sediment disaster. The most upstream dam is Kaliadem (+1.100 msl) and the most downstream dam is consolidation dam of GE-C0 (+163 msl). Sand mining occurs at several points along the river and cause environmental damage. In order to conserve environment and to maintain sediment balance a proper sediment management is required. The research is conducted based on sediment balance. The analysis of transportable sediment volume (VS) is conducted using empirical formula of Takahashi (1991) and Mizuyama (1977). Over flow sediment volume (VE) was analyzed using empirical equation of Shimoda (1995). Sediment balance was analyzed based on maximum daily rainfall (R24) with 25 years return period. The result of the study shows that the sabo system in Gendol River effectively works to control lahar flow. As a conclusion, the existing sabo dams are able to maintain sediment balance in Gendol River. The possible amount of sand mining is estimated about 1.253.422 m3 and the allowable daily sand mining volume is estimated about 836 m3 per day.
KAJIAN PENANGANAN BANJIR KALI CILIWUNG DKI JAKARTA DITINJAU DARI ASPEK HIDRO-EKONOMI (STUDI KASUS PADA RUAS CAWANG – PINTU AIR MANGGARAI) Waluyadi, Heriantono; Jayadi, Rachmad; Legono, Djoko
Civil Engineering Forum Teknik Sipil Vol 17, No 3 (2007): SEPTEMBER 2007
Publisher : Civil Engineering Forum Teknik Sipil

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Abstract

Every year in a rainy season, flood inundates several areas along Ciliwung River, especially in the Cawang ? Manggarai reach. Flood in this reach is caused by land use changing in upstream area and narrower the river width in the downstream area. Several planning will be implemented to reduce the flood, which are normalization with widening river, revetment and dike construction also diversion channel from Ciliwung River to East Banjir Kanal. To determine the benefit of every flood control structure the integrated and comprehensive considerations is required. The study of performance of flood management planning with hydro-economy approach that considers hydrologic, hydraulic and economic aspect is conducted in this study. The aim of this study is to determine the benefit of every flood control structure. Before determining the benefit of flood control structure, the expected annual damage must be calculated, the calculation is based on discharge-probability of exceedence curve, discharge-stage curve and stage-damage curve. The relation from above three curves will be needed for damage-probability of exceedence curve. As a result from this curve the expected annual damage and the benefit of flood control structure can be determined. The results of analysis are that the benefit of flood control structure for normalization, diversion channel with 2,5 m in width gate, diversion channel with 3,0 m in width gate and diversion channel with 3,5 m in width gate are Rp. 20 billion, Rp. 16.1 billion, Rp. 18.9 billion and Rp. 20.1 billion respectively.
ANALISIS KEANDALAN DATA PENAKAR HUJAN OTOMATIS SEBAGAI ACUAN KOREKSI PERKIRAAN HUJAN RADAR Hambali, Roby; Legono, Djoko; Jayadi, Rachmad
Jurnal Teknik Pengairan Vol 10, No 2 (2019)
Publisher : Jurusan Teknik Pengairan, Fakultas Teknik, Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/ub.pengairan.2019.010.02.09

Abstract

The reliability test of automatic rain gauge data in the Mt. Merapi region is highly needed considering that the data is used as a reference to correct the X-band MP radar rainfall estimates error. Rain gauge stations containing unreliable data need to be eliminated so that radar rainfall estimates can be adjusted based on reliable data only. This paper discusses the technique of examining the reliability of rain gauge data using a two-way analysis of variance. The method used in variance analyzing is the Scheffe test, where the difference in the mean value of the two rain gauge stations is compared with the critical value of the Scheffe test. The criteria appointed to declare 'reliable' is if the number of stations that have a significant difference with the reviewed station is less than two. A total of 5939 10-minute rainfall intensity data from 21 rain gauge stations in the Mt. Merapi region were used in the analysis. The results show that six of the 21 rain gauge stations contain unreliable data to use as a reference for correcting radar rainfall estimates. The Scheffe test is considered excellent and straightforward to apply to find out the variance of mean values between rain gauge stations.
ANALISIS TRANSPOR SEDIMEN SERTA PENGARUH AKTIVITAS PENAMBANGAN PADA SUNGAI SOMBE, KOTA PALU, SULAWESI TENGAH Pratama, Muhammad Iqbal; Legono, Djoko; Rahardjo, Adam Pamudji
Jurnal Teknik Pengairan Vol 10, No 2 (2019)
Publisher : Jurusan Teknik Pengairan, Fakultas Teknik, Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/ub.pengairan.2019.010.02.02

Abstract

Sedimentation problems occuring in Sombe River is a phenomenon of sediment grainsor particles entrained from the riverbank avalanche. The problem is exacerbated when there is moderate to high intensity rainfall, causing sediment material transported by a flood. Moreover, sand mining activities also affect the changes in the riverbed. The research aims to identify and estimate the quantity of sediment transport and the effect of the mining activities on the riverbed changes in Sombe River. In this research, direct measurement in Sombe river and observation of the mining activities in Sombe River are conducted to collect sediment samples and river morphology data. Thenceforth, the collected data will be analyzed using Rottner and Van Rijn method. According to the result of the calculation, the average of sediment discharge in Sombe River with a return period of 1 year, 2 years, 5 years and 10 years are Rottner method is 2.1 x 10 7 - 3.8 x 10 7 Tons/year; Van Rijn method is 4.0 x 10 7 ? 6.9 x 10 7 Tons/years.
METODE UJI KETELITIAN UNJUK KERJA ALAT UKUR DENGAN PENERAPAN PERSAMAAN DISTRIBUSI NORMAL (CONTOH KASUS LASER DOPPLER ANEMOMETER) Laksitaningtyas, Agatha Padma; Legono, Djoko; Yulistiyanto, Bambang
Jurnal Ilmiah Teknik Sipil Jurnal Ilmiah Teknik Sipil, Vol. 24, No. 1, Januari 2020
Publisher : Department of Civil Engineering, Udayana University

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Abstract

Statistics and probability is one of the methods used in digital signal processing to measure.  Digital signal processing functions to measure, classify and process into data component that offend an object. Determining the ratio of signal power to noise at the reception of input and output systems is very important to estimate the quality and capacity of signal reception from an instrument Laser Doppler Anemometer (LDA) device. LDA is an example of a measuring instrument that functions to measure the speed that will issue frequencies so as to produce a signal. The basic problem in signal measurement is how to distinguish the true fundamental signal from noise. The purpose of this study is to test the accuracy testing of the performance of a measuring tool to determine the noise from a signal issued by an LDA. The analysis used is using the normal distribution equation which will produce a boundary value for the signal and noise. The test is carried out on two open channels in the laboratory in the form of U and S shaped channels. In U Channel there are four test points, while for S Channel there are eight test points. For each point was done three times testing. The accuracy test of the LDA signal reading shows that the frequency of the signal reading on the U channel is 92.47% with a noise value of 7.53%. The accuracy test of the LDA signal reading shows the signal reading frequency on the S channel is 93.74% with a noise value of 6.26%.
Laboratory Study on Comparison of the Scour Depth and Scour Length of Groundsill with the Opening and Groundsill without the Opening Hairani, Ani; Legono, Djoko
Journal of the Civil Engineering Forum Vol. 2 No. 1 (January 2016)
Publisher : Department of Civil and Environmental Engineering, Faculty of Engineering, UGM

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jcef.26838

Abstract

River bed control structure what so called groundsill or bottom sill is built for controlling a river bed to remain stable against degradation. Unlike other river obstacles, the presence of groundsill might cause sediment retention upstream of the structure; hence it reduces the supply of sediment to the downstream part of the river. At some extent, the above situation might create unexpected negative impact, not only cease the sediment migration but also disable fish migration, as well as the utilization of river for navigation. This paper presents the hydraulic investigation on various models of groundsill, i.e. groundsill without the opening and groundsill with a certain type of the opening. Series of laboratory experiments were conducted on an open channel flow of 0.75m width and longitudinal slope of 0.05%. There were two types of groundsill, i.e. groundsill without the opening with 0.75m width and 0.05m height, and groundsill with the opening of 0.39m width and 0.005m height of crest at the opening and 0.05m at the wings. Various flow rates were then introduced, necessary data were taken, and the hydraulic phenomena were studied. The results showed that groundsill without the opening produced non-dimensional (relative to the channel width) scour depth of 0.036, and scour length of 0.253. Groundsill with the opening produced scour depth of 0.013 and 0.024 near the downstream end of the wing section and the opening respectively. The scour length of the groundsill with the opening is 0.080 and 0.293 near the downstream end of the wing section and the opening section respectively. Moreover, it can be noted that the presence of the scour depth and scour length of the groundsill with the opening was generally much smaller rather than that of groundsill without the opening. The above results give the evidence that groundsill with the opening is much friendlier and also more suitable for the environment needs.Keywords: control structure, environmentally sound, groundsill, hydraulic phenomenon
PENERAPAN OPTIMASI PARAMETER PADA METODE EXPONENTIAL SMOOTHING UNTUK PERKIRAAN DEBIT Santosa, Budi; Suharyanto, Suharyanto; Legono, Djoko
MEDIA KOMUNIKASI TEKNIK SIPIL Tahun 18, Nomor 1, PEBRUARI 2010
Publisher : Department of Civil Engineering, Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (2378.929 KB) | DOI: 10.14710/mkts.v18i1.7855

Abstract

Exponetial smoothing is a technique that is very easy to apply and very effective as forecasting tool. However it requires the estimation of a parameter in order to get good acceptable result. The paper present the optimization is performed by using LINGO 11. The Resulted parameter gives predicted values closestto the observed data, and produces very good prediction as indicated in the MAE and MSE values better than other methods. Keywords : Discharge prediction, Parameter optimization, Exponential smoothing   Abstrak   Exponential smoothing adalah suatu metode yang sangat mudah untuk diterapkan dan sangat efektif dalam peramalan. Akan tetapi, penerapan metode Exponential smoothing ini memerlukan perkiraan parameter smoothing yang tepat. Dalam paper ini disajikan teknik optimasi parameter untuk memperkirakan parameter smoothing yang menghasilkan error yang minimum. Dalam optimasi yang digunakan LINGO 11. Parameter yang dihasilkan memberikan hasil prediksi yang paling dekat dengan data observasi , serta memberikan hasil yang lebih baik sebagaimana ditunjukkan dengan nilai MAE dan MSE dibanding dengan metode lain. Kata-kata Kunci : Perkiraan debit, Optimasi parameter, Exponential smoothing
SEDIMENT BYPASS MODELLING OF VOLCANIC RIVERS (A CASE STUDY: BOYONG RIVER, MERAPI MOUNT, INDONESIA) Legono, Djoko
MEDIA KOMUNIKASI TEKNIK SIPIL Volume 14, Nomor 2, Edisi XXXV, JUNI 2006
Publisher : Department of Civil Engineering, Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (314.151 KB) | DOI: 10.14710/mkts.v14i2.3941

Abstract

Sedimen yang diangkut oleh sungai-sungai yang berasal dari gunung berapi sering mempunyai jumlah yang sangat banyak sehingga dapat mengundang permasalahan berupa daya rusak yang ditimbulkan ataupun bahkan dampak negatif lainnya. Penanggulangan yang telah ditempuh selama ini adalah dengan cara membangun bangunan pengendali sediment atau bangunan sabo yang ditujukan untuk mengurangi besarnya daya perusak tersebut dengan cara menahan laju aliran sediment yang mengalir ke hilir. Dalam hal suplai sedimen dari gunung berapi tersebut relative besar maka kehadiran bangunan sabo terlihat nyata manfaatnya. Namun pada saat dimana suplai sedimen berkurang, maka kehadiran bangunan sabo sering dinilai sebagai penyebab utama terjadinya degradasai dasar sungai di ruas-ruas sungai sebelah hilir bangunan sabo. Paper ini membahas hasil studi tentang efektivitas suatu bangunan pengalihan sedimen (sediment bypass), dalam rangka mengurangi besarnya suplai sedimen yang masuk pada suatu sungai,  yang kemudian dialihkan pada sungai yang lain. Studi dilakukan dengan mengambil kasus Kali Boyong dan Kali Kuning yang berhulu di puncak Gunung Merapi, Daerah Istimewa Yogyakarta. Teori pendekatan imbangan sedimen diaplikasikan pada suatu geometri bangunan pengalihan, yang selanjutnya diperbandingkan dengan hasil pengujian model fisik. Hasil studi menunjukkan bahwa aplikasi persamaan imbangan air (konservasi massa) pada bangunan pengalihan sedimen mempunyai nilai yang mendekati dengan hasil yang diperoleh dari pengujian model fisik. Hasil studi dapat digunakan untuk menentukan geometri yang sesuai dengan rencana penetapan jumlah pengalihan sedimen dari Kali Boyong ke Kali Kuning.Kata kunci: bangunan pengalihan sedimen, daya perusak, imbangan sedimenPermalink: http://www.ejournal.undip.ac.id/index.php/mkts/article/view/3941[How to cite: Legono, D., 2006, Sediment Bypass Modelling of Volcanic Rivers (A Case Study: Boyong River, Merapi Mount, Indonesia), Jurnal Media Komunikasi Teknik Sipil, Volume 14, Nomor 2, pp. 142-149]