Nadjadji Anwar

Fractal Characteristic Analysis of Watershed as Variable of Synthetic Unit Hydrograph Model

Fractal characteristic of watershed is an important parameter which influences the formation of synthetic unit hydrograph. Based on a previous study, hydrology response of watershed expressed in hydrograph form could be well presented by hydrology network characteristic as a form of fractal characteristic of watershed [1]. Fractal characteristic of watershed was stated as fractal dimension which was presented in three parameters i.e. river branch ratio (RB), river length ratio (RL) and watershed river area ratio (RA). The purpose of this research was to analyze fractal characteristic and to verify its fractal dimension stability as preliminary research to prepare variables which would be used to develop synthetic unit hydrograph model in the future. Analysis was undertaken using two methods i.e. Horton’s Coefficient Ratio and Box Counting Dimension. Analysis result revealed that fractal dimension of river network from 8 watersheds calculated using those two methods could give almost the same result, ranged from 1 to 2. Fractal dimension from calculation also showed similarity with study conducted by Tarboton et al. [2], Balkhanov et al. [3], Khanbabaei et al. [4], obtaining that fractal dimension of river network is generally in the range of 1 to 2.

A framework of knowledge management for successful group decision in design process

Knowledge acquires collaboration in producing innovations. Diversities, i.e. expertise, backgrounds, and also resources, are essential for the collaboration. Hence, the activities of sharing, transferring and also exchanging resources between diverse participants become vital in realizing the innovation. This circumstance is recently found in the design process of buildings. The development of buildings requirements leads to complexities in its design. Collaboration is fundamentally needed to attain best design. Knowledge Management found to be essential factor for the collaboration practices. The practices are also known as Group Decision. This study intends to discover issues, roles, and impacts of Knowledge Management towards successful Group Decision in design process. Literature review is used to build the conceptual model, and the conceptual model is empirically confirmed to designers and consultants of high-rise buildings. The empirical data is analyzed by using correlation and regression analysis. The results of this study are conceptual and empirical model of Knowledge Management towards successful Group Decision. Both models can be used to support the development of Computer Supported Collaborative Design in supporting the achievement of successful Group Decision works.

Model test variations of baffled block installation pattern in energy dissipator USBR type III for reduce flow energy

Energy dissipator serves to stabilize the flow of water for preventing any scouring. Scouring can endanger the geometry of downstream river situated at the riverbed and river bank. The change in stream conditions from supercritical to subcritical leads to a hydraulic jump that is used by energy dissipator to reduce the flow energy. Type of energy dissipator which is frequently used is stilling basin equipped with baffled blocks. Baffled blocks serve to generate hydraulic jump and reduce the flow velocity. However, the effectiveness of stilling basin in stabilizing the flow water is lacking. This is proved by the occurrences of scouring on downstream riverbed and riverbank of the weir even though it has been supported by stilling basin. Based on the problem, the research about the installation of baffled block pattern has been done. Model 0 was a model made based USBR type III stilling basin while model 1 was variation model where the baffled block installation was adjusted so that it is located between chute block. The dimension of the baffled block model 1 has modified to adjust the location. The study was conducted by analyzing the hydraulic flow parameters (flow velocity, Froude number and energy specific) on upstream and downstream of energy dissipator. Based on the analysis, it can be concluded that average downstream flow velocity for model 0 was 34.14 cm/sec while for model 1 was 29.18 cm/sec. Thus, model 1 could reduce the flow velocity 1.85% more effectively than model 0. The average downstream Froude number for model 0 was 0.30 while for model 1 was up to 0.26. Thus, model 1 could reduce the Froude Number 0.52% more effectively than model 0. The average energy loss for model 0 was 50.69% whereas model 1 was 51.20%. There is an increase in energy loss by 0.52% from model 0. Thus, model 1 has more effective baffled block pattern installation in stabilizing the water flow than USBR type III model.Energy dissipator serves to stabilize the flow of water for preventing any scouring. Scouring can endanger the geometry of downstream river situated at the riverbed and river bank. The change in stream conditions from supercritical to subcritical leads to a hydraulic jump that is used by energy dissipator to reduce the flow energy. Type of energy dissipator which is frequently used is stilling basin equipped with baffled blocks. Baffled blocks serve to generate hydraulic jump and reduce the flow velocity. However, the effectiveness of stilling basin in stabilizing the flow water is lacking. This is proved by the occurrences of scouring on downstream riverbed and riverbank of the weir even though it has been supported by stilling basin. Based on the problem, the research about the installation of baffled block pattern has been done. Model 0 was a model made based USBR type III stilling basin while model 1 was variation model where the baffled block installation was adjusted so that it is located between ch...

A synthetic unit hydrograph model based on fractal characteristics of watersheds

ABSTRACT Synthetic unit hydrograph (SUH) is one of the rainfall-discharge transformation models that are still popularly used today primarily for estimating flood discharge for water resources planning and management. The advantage of this model is that it is able to estimate the discharge based on the sequence of time in an occurrence of rainfall, and thus the correlation between time and discharge in the form of hydrograph can be obtained. The fundamental weakness of SUH is that they are likely to produce deviations for watersheds that do not have the hydrological characteristics similar to the watersheds used as the basis for the model’s development. These deviations are estimated as a result of the assumptions used to establish the concept of unit hydrograph and the complexity of the factors affecting hydrograph, particularly the nature of rainfall and watershed characteristics that are not accommodated in the model, including fractal characteristics of watersheds that are considered highly influential on the formation of a hydrograph. This research was conducted at eight watersheds in Central Sulawesi-Indonesia to develop and construct an SUH model. The model was constructed by using some parameters based on a combination of main fractal and morphometric characteristics of a watershed. This research successfully formulated a peak time equation (Tp) as a function of the length of the main stream (L), the ratio of stream length (RL) and the density of stream network (D) with a determination coefficient (r2) of 99.8%, a base time equation (Tb) as the function of area of a watershed (A) and slope of main stream (S) with a determination coefficient of 98.2%, a peak discharge equation (Qp) as a function of peak time and a simple single curve equation derived from Gamma Distribution Equation. The validation of SUH models at eight watersheds in Central Sulawesi shows that all the main hydrograph parameters evaluated showed a very good performance.

Construction safety monitoring based on the project’s characteristic with fuzzy logic approach

Construction workers accident is the highest number compared with other industries and falls are the main cause of fatal and serious injuries in high rise projects. Generally, construction workers accidents are caused by unsafe act and unsafe condition that can occur separately or together, thus a safety monitoring system based on influencing factors is needed to achieve zero accident in construction industry. The dynamic characteristic in construction causes high mobility for workers while doing the task, so it requires a continuously monitoring system to detect unsafe condition and to protect workers from potential hazards. In accordance with the unique nature of project, fuzzy logic approach is one of the appropriate methods for workers safety monitoring on site. In this study, the focus of discussion is based on the characteristic of construction projects in analyzing “potential hazard” and the “protection planning” to be used in accident prevention. The data have been collected from literature review...

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.

Parameters Estimation of Synthetic Unit Hydrograph Model Using Multiple Linear and Non-linear Regressions

The use of synthetic unit hydrograph model (SUH) is remain popular used to transform rainfall into run off for water resources development. The typical feature of this model is that the main equation represents the shape of the curve expressed by the relationship between time and discharge. In addition, the SUH model is also expressed in three parameters i.e. peak time (TP), peak discharge (QP), and base time (TB), representing the hydrograph curve equation. In general, SUH model is developed based on morphometry parameters of watershed, especially watershed area (A), main river length (L) and main river slope (S). Another approach in hydrograph modelling is based on the fractal characteristics of watershed. This study aims to develop a synthetic unit hydrograph model based on a combination of morphometry and fractal characteristics of watersheds. The three model parameters (TP, QP and TB) were predicted using multiple linear regression and compared with multiple nonlinear regression. The results of the analysis show that the two methods showed excellent performance. The estimation of SUH parameters using linear regression resulted peak time equation (TP) as function of river length (L), ratio of river length (RL) and density of drainage network (D) with determination coefficient of 99.8%, a base time equation (TB) as the function of watershed area (A) and river slope (S) with determination coefficient of 98.2%. Using multiple non linear regression, estimation of SUH parameters formulated peak time equation (TP) as function of river length (L), ratio of river length (RL) and ratio of watershed area (RA) with determination coefficient of 99.9%, a base time equation (TB) as the function of watershed area (A) and ratio of watershed area (RA) with determination coefficient of 97.9%. Peak discharge equation (QP) is stated as a function of peak time and a simple single curve equation derived from Gamma Distribution Equation.

NEW INDEX FOR LAGOON BY THE CHANGE OF WATER QUALITY

New index for showing the condition of lagoon is developed by testing the water quality in sea water and water in soil layer on site and after five days. The water quality is changing by the stored condition such as under the sun or no sunshine and aerated condition or sealed condition from the air. The change of water quality between on site and after five days under the four different conditions combined two conditions shown above can give some index of the situations in lagoon. The parameters measured for water quality are DO, COD, NH4, NO2, NO3, PO4, PH. And also temperature, salt density, turbidity, numbers of bacteria and numbers of microorganism are measured simultaneously. The index is made by these measured parameters with showing the vector diagram and correlation diagram between these parameters. The fields for observation are Sanbannse lagoon in Tokyo bay in Japan and Lamong bay in Surabaya, Indonesia, observation is continuing from 2005 to 2008. The former area is corresponding to the temperate zone and the last is corresponding to the tropical zone. So the authors can make the some index which shows the condition of lagoon by analyzing the relations between the change of these parameters and activity of creature.