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The Winongo River originates in the Opak River and has many potential hazards such as flooding, cold lava floods and riverbank landslides, so a disaster risk analysis is necessary. The research area is located in the headwaters of the river which passes through the villages of Sendangadi, Sinduadi, Trihango, Bener, Tegalrejo and Pakuncen. The method used is semi-quantitative and qualitative, using tabular data and numerical assessment of land use, population and river hydrology. With the AHP (Analytical Hierarchy Process) method which determines the best choice from several supporting data. The method of determining disaster risk by weighting follows the Regulation of the Director General of BNPB Year 2012. A disaster risk assessment using the AHP method obtained a score of 1.1 in Sendangadi Village, 1.6 in Sinduadi Village. Trihanggo has a value of 1.1, Bener has a value of 1.3, Tegalrejo has a value of 1.4, and Pakuncen has a value of 1.5. Sendangadi and Trihango villages have the lowest risk level with the same value of 1.1. From the results of the disaster risk analysis it has been found that in all sub-districts that are flowed by the upstream Winongo River, they have a low level of risk., Sungai Winongo berhulu di Sungai Opak dan memiliki banyak potensi bahaya seperti banjir, banjir lahar dingin, dan longsor tebing sungai sehingga perlu dilakukan analisis risiko bencana. Daerah penelitian terletak pada hulu sungai yang melewati Kelurahan Sendangadi, Sinduadi, Trihango, Bener, Tegalrejo dan Pakuncen. Metode yang digunakan adalah semi kuantitatif dan kualitatif, dengan menggunakan data tabular dan penilaian numerik penggunaan lahan, populasi dan hidrologi sungai. Dengan metode (Analytical Hierarchy Process) AHP yang menentukan pilihan terbaik dari beberapa data pendukung. Metode penentuan risiko bencana dengan pembobotan mengikuti Peraturan Dirjen BNPB Tahun 2012. Kajian risiko bencana dengan metode AHP didapatkan skor 1,1 di Desa Sendangadi, 1,6 di Desa Sinduadi,. Trihanggo memiliki nilai 1,1, Bener memiliki nilai 1,3, Tegalrejo memiliki nilai 1,4, dan Pakuncen memiliki nilai 1,5. Desa Sendangadi dan Trihango memiliki tingkat resiko terendah dengan nilai yang sama yaitu 1,1. Dari hasil analisis risiko bencana yang telah didapatkan bahwa di semua kelurahan yang dialiri Sungai Winongo bagian hulu mendapatkan tingkat risiko rendah.

Water construction developments are increasing over time with the aim of preventing floods, raising water levels, and helping water resource management. However, in the planning process, debit data for 20 years is very difficult to obtain. Therefore, there is a Synthetic Unit Hydrograph (SUH) method to help analyze without using rainfall data and only using watershed characteristics for hydrological analysis. In this study, we will analyze the synthetic unit hydrograph parameters using the Nash and Soil Conservation Service (SCS) methods and compare them with data from the Gemawang AWLR in the Code River sub-watershed. A comparison was made to find out which method is suitable for the Code River sub-watershed at the AWLR Gemawang station. The suitability index or R² of the two methods shows results that are close to one or very related. The regression angle of the variation SCS method obtained an angle of 38˚, at the time of rising 36.5˚ and at recession time of 38.6˚. The Nash variation method gets 40.1˚ for one hydrograph data, 40.6˚ for rising time and 43.3˚ for descending time. &nbsp, Pembangunan konstruksi keairan seiring berjalannya waktu semakin meningkat dengan tujuan mencegah banjir, menaikkan tinggi muka air, maupun membantu manajemen sumber daya air. Tetapi pada perencanaannya butuh data debit selama 20 tahun yang sangat sulit didapat. Oleh karena itu adanya metode Hidrograf Satuan Sintetik (HSS) untuk membantu menganalisa tanpa menggunakan data curah hujan dan hanya menggunakan karakteristik DAS untuk analisa hidrologi. Pada penelitian ini akan menganlisa parameter hidrograf satuan sintetik dengan menggunakan metode Nash dan Soil Conservation Service (SCS) dan membandingkan dengan data dari AWLR Gemawang di Sub-DAS Sungai Code. Perbandingan dilakukan untuk mengetahui metode mana yang cocok untuk sub-DAS Sungai Code di stasiun AWLR Gemawang. Indeks kesesuaian atau R² dari kedua metode menunjukkan hasil yang mendekati satu atau sangat berhubungan. Sudut regresi metode SCS variasi didapatkan sudut 38˚, pada waktu naik 36,5˚ dan waktu resesi 38.6˚. Metode Nash variasi mendapatkan 40,1˚ untuk satu data hidrograf, 40,6˚ untuk waktu naik dan 43,3˚ untuk waktu turun.

Bank protection structure is applied generally as a countermeasure of the bank erosion problem. The structures, such as groynes, revetments and so on, will success to protect the riverbank locally. However, usually the structures will change the cross-sectional geometry, which lead to change the flow pattern or others hydraulics parameters. Furthermore, the structure will produce another bank erosion problem in another place, especially in case that the flow is a dominant factor in riverbank erosion problem. The horizontal two dimensional bed deformation analysis of the Sesayap River is performed. The advantage of the dredging method is discussed. The dredging of bars is the appropriate choice for the countermeasures of bank erosion of the Sesayap River at Malinau, when we considered the financial efficiency and bed degradation along both banks.

Countermeasures of the bank erosion problem considering the horizontal two dimensional flow patterns and bed deformation are discussed in this paper. Numerical analysis is performed using the horizontal two-dimensional bed deformation model which the equations are written in general coordinate system. The presence of the mid-channel bar in the river is one of the factors causes the riverbank erosion in the rivers. The results from the numerical model indicate that dredging of the mid-channel bar with the appropriate level reduces the bed degradation near the bank toe, especially at the lee area. Revetment can protect the bank directly. However, the installation of revetment makes the bank line smoother. As a result, the flow velocity to the opposite bank becomes faster and the possibility that local scouring is accelerated along the opposite bank increases.

The purpose of this paper is to study the erosion characteristics of cohesive sediment by both non-cohesive sediment and clear water. The results of flume experiment and the dynamic shear stress on the bed are discussed. The flume experiments were conducted with non-cohesive sediment is supplied on the cohesive sediment. The transport rate of the non-cohesive sediment supply is varied from 0 to 150% of the equilibrium sediment transport rate. The results indicate that, when bed is composed of 100% cohesive sediment, the bed degradation depth with sediment supply are more than without sediment supply or in clear water and the erosion rate is decreased with increase in sediment discharge. Because the dynamic shear stress on the bed is decreased with increase in sediment discharge.

It is often observed banks which have the alternate layers between cohesive sediment layers and non-cohesive sediment layers in natural rivers (ex. the Sesayap River, East Kalimantan Province, Indonesia and so on). In this study, mathematical model of bank erosion process for banks with both the cohesive and the non-cohesive layers is developed. Furthermore, the model is installed into the horizontal two dimensional channel deformation model. The governing equations of the channel deformation model are written in boundary fitted moving general coordinate system. The results indicate that the horizontal shift speed of banks changes with time very much. When the bottom layer is not exposed to the flow, the speed of bank erosion is very slow. However, when bed near the bank is eroded with time and bottom layer starts to be exposed to flow, the bank erosion rate increases rapidly and it is considered that a severe disaster is caused. The calculated horizontal shape of bank lines is not so smooth and local curvature of bank lines becomes small.