Analisis hidraulik loncat air pada lantai pemecah energi dengan endsill

Hydraulic jump is a natural phenomenon at the down stream of sliding gate. The occurrence of jump depends on the tail water depth and the Froude number. In many cases, the tail water depths are too low to provoke the occurrence of jump at the desired location. Many efforts have been done to dissipate the energy of hydraulic jump by constructing a stilling basin, baffle block, endsill or the combination of that, to avoid a local scouring. An endsill or a hump at the apron is introduced as a simple structure to dissipate energy of hydraulic jump. Base on momentum equation, an analytical solution of hydraulic jump in the upstream of endsill was developed. The same equation was developed by Forster and Skrinde using momentum equation and discharge equation through broad crested weir. Forster and Skrinde have developed also a diagram showing the relation among Froude number, ratio of sequent depth and initial depth of hydraulic jump, ratio of endsill height and initial depth of jump of an abrupt rise bed. In order to verify the proposed equation, some measurements of hydraulic jump variables for a single discharge were done in a small flume, the variation of Froude number is manipulated by applying difference gate opening. The results of experiments show that the proposed equation is valid for determining the ratio of sequent depth and its initial depth by knowing the height of endsill and the Froude number. This equation could be used also to predict the capability of endsill to reduce the specific force of the hydraulic jump. Keywords: hydraulic jump, endsill, momentum equatio

Kendala peningkatan budidaya tambak udang di pantai utara Jawa kasus Randusanga Kulon Kabupaten Brebes propinsi Jawa Tengah

ABSTRACT In the last decade, the developments of brakishwater shrimp culture become a primary sector of aquaculture that has important contribution to the national income. Some efforts in intensification of shrimp pond in North Coast of Java Island, in the last year, could not give any meaning on the rise of production. A degradation of environmental quality is suspected as the origin of the production loss. An appraisal of environmental sustainability to support shrimp culture sometimes is left behind for a reason of driving a high level of production. This condition usually led to deterioration of land and water resources. The target of production should be determined by considering the environmental sustainability. Randusanga Scheme in Brebes, Central of Java, is an example of shrimp culture that has an environmental degradation problem. After an evaluation of the land and water resouces condition, a new irrigation system that could improve the environmental quality is designed

Kontribusi Kemampuan Juru Pintu Pada Pengelolaan Pembagian air Irigasi

ABSTRAK Jaringan irigasi pada kenyataannya selalu mempunyai ketidakcocokkan dengan perancangan awal maupun adanya perubahan kondisi bangunan fisik selama pengoperasian yang sudah berlangsung. Ketidaksesuaian ini dapat pula terjadi pada perangkat lunak pengoperasiannya, misalnya rencana pemberian air yang terlalu jauh dari kebiasaan pengelolaan pemberian air sebelum ada jaringan teknis, atau. RPA I yang tidak mungkin dilaksanakan karena penyimpangan keadaan fisik jaringan tersebut di atas. Perubahan-perubahan yang terjadi pada pintu pembagi dan alat ukur debit yang dapat menimbulkan kesulitan pengaturan dan pengukuran oncoran air adalah hal yang paling sering terjadi. Juru pintu yang merupakan salah satu bagian dari mata ran tai pengelola irigasi sering mendapat beban yang paling besar oleh adanya ketidaksesuaian tersebut di atas. Tinjauan ini yang bertitik berat pada studi kasus di Proyek Irigasi CITAGAMPOR membahas peranan juru pintu dalam pengelolaan pembagian air irigasi, evaluasinya dan kemungkinan perbaikan tata kerjanya

Model matematik gelombang panjang dua dimensi

ABSTRAK Pemakaian komputer dalam bidang hidraulika sudah sangat maju terutama dalam hat simulasi fenomena aliran dan angkutan sedimen. Simulasi tersebut dimungkinkan karena semua persamaan diferensial parsial dapat diselesaikan secara numerik dengan cepat oleh komputer. Salah satu problema aliran yang dikemukakan adalah proses simulasi gerakan arus dua dimensi yang diakibatkan oleh pengaruh gelombang panjang misal pasang surut. Beberaper eara penyelesaian numerik telah dikenal salah satunya adalah metoda deferensi hingga yang didalamnyapun masih terdapal beberapa eara pendekatan hitungan deferensinya. Untuk model aliran dua dimensi tersebut ada yang memakai cars \u27Alternating Direction Implisit Method (ADP) ada yang memakai metoda pemisahan elemen, sehingga penyelesaian numeris setiap elemen persamaan aliran dilakukan secara terpisah (Method of Separation). Cara penyelesaian tersebut masing-masing mempunyai kelemahan, ADI dibatasi oleh \u27Courant Number\u27 yang keel sebagai pembatas stabilitas penyelesaian nuineriknya, tetapi AD! lebih Judah diselesaikan secara numeris daripada metoda kedua. Keywords: simulasi fenomena, sedime

Low cost irrigation, farm-level water management in waterlogged lowland. Nyamthoi, Kisumu, Nyanza, Kenya.

A special programme for food security \u27(SPFS) was launched in Kenya in 1995. For the past decade, Kenya\u27s agricultural production has no longer been able to keep pace with its population growth. The country is now faced with chronic deficits in maize, wheat, rice, oilseeds and sugar. In the past, the Government has given priority to the development of large scale, these top down systems, which have proven too excessively costly to construct and beyond the Government\u27s financial capacity to maintain. The current 7th national development plan gives high priority to commercially oriented smallholder schemes based on farmers\u27 own investment and operation, to generate employment, enhance food security and increase rural incomes. FAO assistance is requested to implement the SPFS, especially through pilot small-scale water control activities. A waterlogged lowland in the coast of Victoria lake, in Kisumu, was selected as demonstration area of innovative low-cost irrigation and drainage development and water management in waterlogged lowland. Simple water management in flood protection, water control, agricultural practices, reclamation, furrow and ridge land preparation were successfully introduced to the farmers. The project could convince the farmers that the flood could be managed without jeopardizing the environment and using low cost technology

Reliabilitas Rehabilitasi Kolam Pasang pada Jaringan Irigasi Pasang Surut Unit Tabung Anen, Kalimantan Selatan.

A new tidal irrigation system has been developed by Gadjah Mada University since 1970 to reclaim tidal swampy areas. In the natural condition, due to its bad drainage system, these lands are inundated by rain water and river water. A system of canal that used as a drainage canal during low tide and as irrigation canal during high tide is introduced. Due to the oxidation of acid sulphate soils, there were dispersion of leached acids to the canal. A system of reservoirs (kolam) are provided at the end of the canal to maintain the flow during drainage time and to store theremain acids materials in the canal that is pushed back by reverse flow to the kolam. After 30 years of services, the kolams are covered by sediment and could not function as needed. It was suspected to be the cause of land degradation and reduction of yields. Several farmers ask the rehabilitation of the kolam. A mathematical model is developed to evaluate the reliability of kolam rehabilitation by using HEC-RAS software. The results of simulation shows that the series of tertiary canal and kolam could regulate the flow and could help the canal system to dilute the acid water. Due to its hydro-topography condition (Land Type A), the land and the tertiary canals could act as a huge reservoir that can replace the purpose of kolam. The 126 km length of tertiary canals and 98% land that are inundated during high tide, could increase the cumulative volume of water flow through the canal by 1.671.462 m3, and the rehabilitation of kolam could only contribute about 196.074 m3. Keyword : tidal irrigation system, mathematical model, land reclamation

Deduksi logika dalam penelitian ilmiah

ABSTRAK Pada tahun terakhir ini kehidupan penelitian telah mulai terlihat semakin meningkat. Penelitian terapan maupun pengembangan i/mu dasar semakin dituntut guna mengikuti kebuluhan dunia pen¬didikan dan industri. Pada dasarnya penelitian ihniah bertujuan mendapatkan hubungan yang sistematik antara dua variabel atau lebih. Hubungan tersebut tentunya mengikuti proses alami yang berlaku pada variabel tersebut. Dalam usaha memformulasikan hubungan yang sistematis tersebut seseorang dituntut melakukan deduksi logika yang benar agar semua variabel ataupun variabel antara dapat diketahui sifat dan karakteristiknya. Salah satu cara yang handal yang sering digunakan dalam analisis hubungan antar variabel ialah statistika. Dengan statistika seseorang mencoba membuat jalan pintas menghubungkan dua variabel atau lebih misal dengan cara regresi yang kadang-kadang lanpa melihat formulasi fisiknya. Karena ketidak-jelasan data yang benar atau salah, seseorang dapat membuat analisis regresi dengan tujuan mendapatkan korelasi dua variabel yang paling balk. Suatu kurva regresi yang dihasilkan kadang¬kadang tidak sesuai dengan formulasi matematis hubungan antar dua variabel tersebut. Hasil yang demikian yang dapat membelokkan pengembangan ilmu ke arah yang tidak benar

Metoda Numerik untuk Penyelesaian Persamaan Gelombang Periode Panjang.

Gelombang periode panjang seperti pasang surut, resonansi, dan sebagainya menimbulkan arus di laut dan teluk. Untuk menghitung kecepatan arus dan perubahan muka air karena gelombang panjang tersebut digunakan metoda numerik. Metode numerik yang banyak digunakan adalah metode beda hingga ("finite difference") dan metode elemen hingga. Dalam tulisan ini disajikan salah satu metode beda hingga berdasar skema Leendertse ("Alternating Direction Implicit method", ADI), yang saat ini sedang dikembangkan di PA U di ilmu teknik

Studi model intrusi air asin di sungai juana hilir.

Penutupan Pintu Wilalung di sungai Serang dikhawatirkan akan mengurangi debit di sungai Juana yang akan memberi kesempatan intrusi air laut ke daerah pertanian. Sebuah studi telah dilaksanakan untuk mengetahui jarak jangkau intrusi air asin ini dan muara dengan beberapa penelitian lapangan. Dan untuk menghitung parameter-parameternya, hasil penelitian lapangan tersebut digunakan dalam hitungan angkutan massa dengan model stasioner. Parameter-parameter yang diperoleh diharapkan dapat dipakai untuk penelitian selanjutnya

Verifikasi Dan Kalibrasi Model Matematis Aliran Permukaan Dua Dimensi (Rma2), Pengaruh Eddy Viscosity Dan Kekasaran Dasar Pada Pola Aliran

The development of numerical models has provided some potentially useful engineering softwares especially for hydraulic engineering. A software called RMA2 in the BOSS SMS package is one of them that were supposed to be able to simulate 2D depth averaged surface water flow. A study has been conducted to verb the performance of the RMA2 software on flow influenced by tidal backwaters. The verification was done by comparing the result of flow simulation of dynamic backwater flow on a sinuous channel with a narrow section and the measured data on a physical model of flow on the same system. The measurement of flow velocity and flow pattern implemented particle image velocimetty method by using foam/patched floating tracer. Flow velocity data on several flow measurement stations were analysed quantitatively and the flow patterns were discussed qualitatively. The result of the study shows that the curves of velocity magnitudes on all measurement measured from the physical model and simulated by the mathematical model have very small differences. This result was achieved by implementing several zones in the computational domain with different roughness and diffusion coefficients. Both the mathematical and physical model shows similar pattern