STUDI EROSI DAN CIRI HIDROLIKA ALIRAN PERMUKAAN LAHAN (Erosion Study and Hydroulic Flow on Land Surface)

The purposed of the study is to identify of characteristics hydraulic flow and erosion as real picture on incipient motion of sediment transport. The study id conducted in types of soil namely Alfisol and Entisol. They have a wide range utilization and a high erosion susceptibility. Simulation has been conducted by dropping eight different rain height to undisturbed soil block samples with 2.500 square cm, width and 10 cm thickness and with 9% and 17% land slopes. The results shows that surface run off not play detachment of soil particle if equal with rain pellet and dispersion of water, but its transport sediment. Surface run off on plot standard in two kind of soil (Alfisol and Entisol) is laminar sub critics with Reynold number 140,2 and 136,2; Froude Number 0,940 and 0,980; drag force 9,02 and 4,44 N/m. Whereas 17% slope is super critics with Reynold Number 206,2 and 76,1; Floude Number 1,219 and 1,286 and drag force 14,79 and 9,76 N/m. Key Word: Erosion, Hydraulic characteristic, sediment transport

Aliran kerapatan di sungai akibat intrusi air asin.

ABSTRACT Fresh water have less density than salt water. If these two fluids with different densities are _flowing in a channel, then a mixed flow may occur. The Interaction between fresh and salt water depends on the Mixing Ratio .411 as a product of the fresh water flow and the tide period over the tidal prism (1..lassie,1976). Three types of mixed water flows in a river were previously considered, i.e., fully mixed flow, partially mixed flow and stratified flow. The type of mixed flow can be, e.g., characterized by dimensionless Estuary Number E (Harleman dan Abraham,1966) which depends on the Froude Number, or by Mixing Coefficient (Furumoto and Awaya,1988) also depending on the Stratified Froude Number, as well as by Gradient Richardson Number K (French,1986) where the flow in an open channel is classified in a range between homogenous and stratified by density gradient. The numerical simulation was developed from volume continuity, salinity continuity and momentum equations. Those equations are consider with kinematic viscosity and diffusion. The .field measurements have been taken in several cross sections of Lamong River in Indonesia (Anwar, et al, 1992) as well as Nanakita River in Japan (Uehara,1984). Analysis were done by identifying those rivers by the mixing conditions and numerical simulations. According to the mixing conditions, Lamong River was concluded to be fully mixed flow since having small mixing ratio and, on the contrary, Nanakita River was concluded to be stratified flow with highly mixing ratio. The result of numerical simulation is that the Officer\u27s Equation (of kinematic viscosity and diffusion) is recommended to be used for fully mixed flow conditions such as Lamong River, on the other hand, the Van Rees\u27s Equation is recommemded to be used for fully stratified flow types such as Nanakita River. Key word: Aliran kerapatan , itrusi air asin, kecepatan alira

The Concept and Development of Land Value Assessment

Problem in land acquisition increasingly complex, this problem can be related directly to the land acquisition process from planning to project delivery, as well as indirect effects of the reasonableness of the value of the land. Land value is expected to accommodate attributes as physical development and infrastructure projects in a more comprehensive city, thus the value of the land can represent a reasonable condition and can be estimated in accordance with the development that is influenced by multiple attributes (discrete and continuous) as well as the spatial effect of the gradient measured geographical. Based on a review of empirical, conceptual and literature, the value of land is affected by several variables that can be explaned as follows: supply and demand ; highest and best use ; phisic, legal, social and economic. The method can combine the data value of the land and the land characters are more accurate and spatially, it is necessary to use Computer-Assisted Mass Appraisal (CAMA) and Geographic Information System (GIS

Optimasi Pola Tanam Menggunakan Program Linier (Waduk Batu Tegi, Das Way Sekampung, Lampung)

Waduk Batu Tegi terletak di DAS Way Sekampung,SWS Way Seputih-Way Sekampung, Batu Tegi, Kecamatan Air Naningan, Kabupaten Tanggamus, Lampung. Waduk ini berfungsi sebagai penyedia air untuk irigasi, penyedia air baku, dan Pembangkit Listrik Tenaga Air (PLTA). Dengan keterbatasan volume air yang tersedia di waduk, dilakukan optimasi agar dapat mengoptimalkan kebutuhan air untuk irigasi yang menentukan intensitas tanam suatu lahan, air baku untuk sektor domestik dan non-domestik, dan potensi PLTA. Tujuan dari optimasi pola tanam adalah menentukan harga maksimal hasil panen yang dapat dihasilkan suatu lahan dengan jenis tanaman yang berbeda. Optimasi dalam kasus ini dilakukan dengan menggunakan program linier program bantu Quantity Methods for Windows. Perhitungan optimasi dengan pola tanam rencana dilakukan agar optimasi berupa intensitas tanam menghasilkan panen yang lebih maksimal jika dibandingkan dengan pola tanam eksisting. Dari hasil analisis yang telah dilakukan, didapatkan kesimpulan bahwa debit andalan 80% waduk yang terbesar adalah 76,7 m3/detik yang terjadi pada Bulan Februari dan yang terkecil adah 4,30 m3/detik yang terjadi pada Bulan Oktober, model alternatif pola tanam yang menghasilkan luas lahan dan keuntungan hasil panen paling optimum adalah Alternatif 5, besar kebutuhan air untuk irigasi dari alternatif 5 adalah 346,2 x 10 6 m3dalam satu tahun, besar kebutuhan air untuk air baku saat kondisi jam puncak pada tahun 2010 adalah 27,69 m3 x 10 6 m3 dan kebutuhan air untuk PLTA adalah 734,8 m3 x 10 6 m3, serta keuntungan maksimal yang didapatkan dari hasil produksi lahan sawah dengan menggunakan pola tanam alternatif 5 adalah Rp 1.890.843.057.506,00

Kajian Model Fisik Pengaruh Freeboard dan Susunan Buis Beton sebagai Pemecah Gelombang Tenggelam Ambang Rendah (Pegar) dalam Mereduksi Gelombang

The Research Center and Development of Water (Puslitbang) is currently developing the Submerged Breakwater in shallow sea area (PEGAR). The author is interested to examine the material that  easily obtained in the field of RCP concrete cylinder. The observation is how it to be ability in function as submerged breakwater an go green and low cost. The physical model of wave transmission test is how the response to the structure in ability to damping of wave as the breakwater function. In this research breakwater used is submerged breakwater type by using concrete cylinder (buis beton). The purpose from this research is to know how the response of breakwater structure to the waves through it, with some variation of the structure by creating a structure with three variations of the arrangement and freeboard that is the relative depth with the crest width is constant. The wave generated test in this study is using regular waves in wave flume at FTSP Civil Engineering Department of Institute Technology Ten November. From the analysis of the effect of the installation of submerged breakwater by using concrete cylinder to the wave damping value, it can be concluded that the factors that are very influential is the freeboard and the composition of concrete cylinder. Scenario A (rigid vertical massive) is capable of producing the smallest value of kt is 0.33. As for scenario B (rigid horyzontal massive) with a damping value of 0.5, while the scenario C (rigid permeable) is only able to  produce kt value of 0.71. Scenario A is better than scenario B and C Because the position of arrangement of A is very good used to damp wave in small or big freeboard conditions

THE EFFECTIVENESS NUMBER OF BAFFLE BLOCKS TO REDUCE ENERGY IN TUKUTAHA TRANSITION CHANNELS

One of the causes of damage to the weir structure is scouring. Scouring may occur along the weir channel. Scouring occurs due to the high flow velocity and high specific energy. One of the methods used to reduce specific velocity and energy is by installing baffle blocks in parts that have high-velocity and energy. The addition of baffle blocks is carried out at a place that has a high-velocity, namely the transition channel. To see the effect of baffle block variation on velocity and energy, a study was conducted. The study was conducted with four baffle block type models. The type 0 model is a baffle block installation pattern based on the initial design. Type 1 model is designed based on the planning of The Colorado State University (CSU) rigid boundary basin. Type 2 model is designed by reducing the number of baffle blocks from the initial design of 102 baffles to as many as 75 baffles. while the 3 channel type model transitions without baffle blocks. Based on the analysis of % energy loss in the transition channel, the type 0 model produces the largest energy loss. The type 0 model at maximum discharge has a % energy loss 10.821% greater than the type 1 model, 14.889% greater than the type 2 model and 33.02 % greater than the type 3 model

Analysis of Main Morphometry Characteristic of Watershed and It’s Effect to The Hydrograph Parameters

Until today, the development of synthetic unit hydrograph model is still based on morphometry characteristic of watershed or combine with other parameters. According to Sri Harto (1985), There are at least four main characteristic morphometry of watershed which highly influenced to the hydrograph and can be easily quantified namely watershed area (A), main river length (L), main river slope (S) and form factor (FB). This research aim is to analyze and verify these four factors and it’s effect to the three of hydrograph parameters i.e. peak time (TP), peak flow (QP) and base time (TB). This research was carried out in eight watersheds in Central Sulawesi Province Indonesia as the base of variable preparation to develop synthetic unit hydrograph model. Main morphometry analysis of watershed was conducted by using geographical information system (GIS) software, referring to Indonesia Topographic Map (RBI) data combined with Digital Elevation Model-Shuttle Radar Topographic Mission (DEM-SRTM) data, to determine the area (A), main river length (L), main river slope (S) and form factor (FB) of every analyzed watershed. The research showed that eight observed watersheds had an area (A) of 23.88 km2 to 144.73 km2, main river length (L) of 10.31 km to 28.69 km, main river slope (S) of 0.03422 to 0.10812 and form factor (FB) of 0.21 to 0.49. From correlation analysis, It seen that the watershed area affected very well to peak flow (QP) with correlation coefficient of 0.98. The main river length also affected very well to the peak time (TP) with correlation coefficient of 0.99. Two others morphometry parameters namely main river slope (S) and form factor (FB) did not show the effect which could be concluded. These two parameters showed low correlation coefficient

Comparative Analysis of Water Resources Management Service Costs for Delta Brantas Irrigation Area

A proper fuction of irrigation system needs sustainable water resource management, supported by Water Resources Management Service Costs (BJPSDA). BJPSDA is a partial reimbursement of the cost required for water resource management activities, especially for operation and maintenance activities, must be calculated and set by water resources management. There are two methods that are used to calculate BJPSDA, which is BJPSDA in accordance with the Regulation of the Minister of Public Works and Public Housing No. 18/PRT/M/2015 and BJPSDA using basic service fee by considering the quality of service and value of economic benefits modelling. This study was conducted by comparing two BJPSDA methods in the Delta Brantas Irrigation Area and will be analyzed descriptively. BJPSDA of irrigation in accordance with Regulation of the Minister of Public Works and Public Housing No. 18/PRT/M/2015 is Rp. 255,-/m3, as cost recovery.. BJPSDA of irrigation value using basic service fee by considering the quality of service and value of economic benefit modelling amounted Rp. 338,-/m3, calculated from basic service fee amounted Rp. 177,-/m3, added with NME for agriculture water in Delta Brantas Irrigation Area amounted Rp. 161/m3, as a water value

Peramalan Keseimbangan Air (Water Balance) untuk Manajemen Sumber Daya Air di DAS Sungai Rejoso Kabupaten Pasuruan, Jawa Timur

Tujuan studi untuk memperkirakan ketersediaan sumber daya air 30 tahun kedepan dan menjadi acuan dasar peramalan keseimbangan air. Metode yang dilaukan analisa kebutuhan air, seperti metode pembangkitan data dengan formula pada Microsoft Excel dan menghitung kebutuhan debitnya menggunakan metode di SNI 19-6728.1-2002 Analisa irigasi terdapat 3 skema Pola Tata Tanam, sehingga menggunakan Cropwat 8.0. Analisa ketersediaan air ada beberapa metode yang akan digunakan. Metode tersebut yaitu Metode Aritmatika dan Metode Thomas Fiering. Hidrograf Satuan Sintesis SCS (Soil Conservations Services), metode RMSE dan metode NASH terdapat dalam HEC-HMS 4.8. Studi ini menghasilkan nilai RMSE sebesar 0,3 dan NASH sebesar 0,936. Selain itu juga memberi saran untuk menggunakan Pola Tata Tanam ke-2 (Polowijo2-Padi-Polowijo1) dengan skema 4 (Debit Ketersediaan Total) yaitu nantinya terjadi surplus sebesar 195