Design Flood Discharge Research Articles

PERBANDINGAN ANALISA DEBIT BANJIR PADA SUNGAI MENCONGAH KABUPATEN LOMBOK BARAT

Many unit hydrograph concepts are used to carry out the transformation from rainfall to flow discharge. The data needed to derive a measured unit hydrograph in the watershed under consideration is automatic rainfall data and discharge recording at certain observation points. A hydrograph can be described as a graphic presentation of one of the elements of flow and time. The purpose of the design flood discharge analysis is to evaluate the magnitude of the design flood discharge at various return periods of 2, 5, 10, 20, 25, 50, 100 years. This research is a case study using rainfall data for 10 years, namely 2014-2023. Next, an analysis of the maximum daily rainfall in the Mencongah watershed (watershed) was carried out, climatological data obtained from the relevant agencies. After analyzing the rainfall data obtained in the field, the maximum annual rainfall in the Mencongah watershed was obtained based on the results of data analysis from the Mencongah station, which was 229 mm, while the average rainfall was 167.9 mm, a large value.PMP (Probable Maximum Precipitation) on the Mencongah river is 85.37 mm, the design flood discharge with return periods of 2, 5, 10, 20, 25, 50 and 100 years using the Hapers method is obtained respectively: 72.21 m³; 180.525 m³, 361.05 mm, 722.101 m³, 902.626 m³, 1805.252 m³, 3610.504 m³,while the Melchior method discharge is 191,517 m³; 478,793 m³; 957,586 m³; 1915.171 m³; 2393,964 m³; 4787 m³; and 9575.855 m³

Design of Automatic Flood Control System in Kulon Progo, Special Region of Yogyakarta, Indonesia

The construction of Yogyakarta International Airport has resulted in land use changes and increased the topography in the area by up to 9 m, which has led to potential flooding. A spatial analysis was conducted on the flow direction after the airport's construction, specifically in the West Carik watershed. It was discovered that the flow direction was uncertain and trapped upstream of the airport. A polder system with automation is proposed as a solution to the drainage problem. An automation system is designed for pump operation with the objective of improving efficiency. The system is expected to reduce the volume of water in the polder by reducing human involvement and providing ease in monitoring. The results of hydrological analysis with a 50-year return period flood resulted in a design flood discharge of 11.73 m3/s. The polder has a storage capacity of 63,312 m3, a depth of 4 m, and a surface area of 1.58 ha. It requires a total pump capacity of 8.4 m3/s, consisting of three pump units, with one unit having a capacity of 1.8 m3/s and two units with 3.3 m3/s. One additional pump with a capacity of 3.3 m3/s is also planned as a backup pump. The pump automation system simulation employs an Arduino UNO as the controller, water level sensor, and relay. This system successfully fulfills the desired operational system for the pump. In the actual implementation, a Programmable Logic Controller (PLC) is required as the controller, with water level sensors, relays, and contactors as inputs and outputs.

Effect of Flow Discharge on Sedimentation in Paneki River

Introduction: Paneki River has the potential for sedimentation caused by flow discharge. The condition of the river is getting wider every day which will threaten the risk of flooding if there is heavy rain with high intensity. The purpose of this study is to determine the return time flood discharge and basic sediment transport discharge in the Paneki river which can be used as a reference in planning sediment control buildings. Method: This research method includes primary data collection and secondary data collection, data management including calculating width, slope, design rainfall, design flood discharge, sieve analysis, and specific gravity. Then proceed to calculate the return time flood discharge using the Nakayasu synthetic unit hydrograph method and basic sediment transport using the Meyer-Peter and Muller method. Results and Discussion: From this research, the result of the 2-year return time flood discharge is 121.306 m3/det, for 5-year return time flood discharge is 185.069 m3 /det, for 10-year return time flood discharge is 209.261 m3 /det, for 25-year return time flood discharge is 312.359 m3 /det, and for 50-year return time flood discharge is 373.566 m3 /det. The results of basic sediment transport discharge per cross-section ranged from 0.0000861 m3 /det to 0.005641775 m3 /det. Conclusion: The study shows that sedimentation is influenced by flow discharge. The results of the calculation of flow discharge (Q) and bottom sediment transport (Qs) in Paneki River using the Meyer-Peter and Muller method resulted in Qs varying from 0.0000861 m³/det to 0.016551197 m³/det, according to the measured flow discharge. The greater the flow discharge, the greater the sediment transport, indicating a direct relationship between flow discharge and sedimentation.

UAV Mapping for Flood Routing in Steep and Densely Vegetated Areas: Insights from the Contok River Basin, Garang Watershed, Indonesia

This research utilizes photogrammetry to assess flood routing dynamics in the Contok river basin, a sub-watershed with a challenging landscape characterized by steep slopes, dense vegetation, and meandering patterns. The objectives are to assess Unmanned Aerial Vehicle (UAV) mapping accuracy, evaluate the river's capacity for design flood volumes, quantify the impact of land cover changes on surface runoff, and provide insights for early warning systems and watershed conservation strategies. The study area, encompassing the Contok River Basin, a sub-watershed of the Garang Watershed, covers 7,413 km² and includes a stream length of 5,274 meters in Semarang City, Central Java, Indonesia. This research employed image processing of aerial photographs and satellite imagery. Aerial photos captured using UAV data were utilized to derive elevation data and cross-sectional profiles of the Contok River, essential for understanding channel morphology and hydraulic characteristics. Concurrently, satellite imagery was used for land cover analysis, identifying vegetation and built-up areas that influence surface runoff dynamics. Hydrological analysis was performed to quantify discharge magnitudes, simulated against river cross-sections to evaluate flood behavior under varying scenarios. Our proposed UAV mapping provides adequate accuracy for small and local areas. Furthermore, it remains reliable for flood routing analysis. We discovered that the capacity of the Contok River channel in the downstream area allows it to convey design flood discharges up to a 50-year return period, contrary to the upstream area, it overflows. Notably, the shift from vegetated to built-up and agricultural areas significantly contributes to the 10.6% increase in surface runoff. This research highlights the role of UAV-based photogrammetry in assessing and mitigating flood hazards amidst evolving land cover patterns. It also enhances the understanding of flood dynamics and thus provides insights that will serve as a reference for flood early warning systems, flood management practices, and watershed conservation.

Drainage Network Performance Mapping in the Tukad Ngenjung Sub-System Based on Geographic Information Systems (GIS)

The aim of this research is to determine the condition and performance of the drainage network. The method used in this research is a quantitative descriptive method based on field observations. The results of this research based on hydrological and hydraulic calculations show that in the Tukad Ngenjung Sub System drainage network, out of a total of 52 channels, 42 channels are unable to accommodate the design flood discharge with a return period of 2 years and there are 45 channels that are unable to accommodate the design flood discharge with a 5 year return period. For channels that are unable to accommodate flood discharge, the design should be given more attention or repairs should be carried out by the relevant parties, so that the runoff that occurs in the channel can be resolved.

English English

River diversion is a procedure carried out prior to constructing a dam. It is conducted by diverting water from the main river so that the main dam construction work can be executed at a specifically dry area. In Meninting Dam, the diversion system consists of two main structures, namely cofferdam and diversion tunnel that is equipped with a navigation structure at the upstream part of the tunnel. During the construction, cofferdam experienced overtopping on June 17, 2022. The overtopping most likely occurred because of the diversion tunnel’s inability to divert the actual flood effectively during the construction. Therefore, this research aimed to analyse the effectiveness of Meninting Dam’s proposed diversion tunnel against design flood discharge for a return period of 25 years. The data used in this research were the updated version of the ones used to design the whole construction of Meninting Dam’s diversion system, while the flow conditions along the diversion tunnel were analysed using HEC-RAS. At the same time, the analysis was also carried out using the Level Pool Routing Method as a comparison. The analysis results show that the design flood discharge for a return period of 25 years in Meninting Dam Watershed is 265,62 m3/s. This causes the water level along the diversion tunnel reach el. +165,95 m above sea level. Taking into account that the cofferdam crest elevation is at +170,00 m above sea level, it could be concluded that Meninting Dam’s proposed diversion tunnel, which is 4 m wide and 4 m tall is able to divert the design flood discharge for a return period of 25 years effectively. The investigation results in Meninting Dam Watershed show that the main cause of the overtopping was heavy precipitation. This caused the increasing water level at the upstream part of the cofferdam that resulted to its inability to function properly, taking into account that it was still under construction when it occurred

ANALISIS KAPASITAS AIR PADA SALURAN DRAINASE DI JALAN ANTASURA DAERAH PEGUYANGAN KAJA DENPASAR UTARA

ANALISIS KAPASITAS AIR PADA SALURAN DRAINASE DI JALAN ANTASURA DAERAH PEGUYANGAN KAJA DENPASAR UTARA

A watershed-scale multi-approach assessment of design flood discharge estimates used in hydrologic risk analyses for forest road stream crossings and culverts

Flood peak magnitudes and frequency estimates are key components of any effective nationwide flood risk management and flood damage abatement program. In this study, we evaluated normalized peak design discharges (Qp) for 1,387 hydrologic unit code 16 to 20 (HUC16-20) watersheds in the White Mountain National Forest (WMNF), New Hampshire and in five Experimental Forest (EF) regions across the United States managed by USDA Forest Service (USDA-FS). Nonstationary regional frequency analysis (RFA) and single site frequency analysis (FA) with long-term high-resolution observed streamflow data along with the deterministic Rational Method (RM) and semi-empirical United States Geological Survey regional regression equation (USGS-RRE) were used. Additionally, a hydrologic vulnerability assessment was performed for 194 road culverts as a result of extreme precipitation-induced flooding on gauged and ungauged watersheds in the Hubbard Brook EF (HBR) within the WMNF. The RM outperformed the USGS-RRE in predicting Qp in the gauged and ungauged HUC16-20 watersheds of WMNF and in three other small, high-relief forest headwater watersheds—Coweeta Hydrologic Lab EF’s watershed-14, and watershed-27 in North Carolina and HJ Andrews EF’s watershed 8 in Oregon. However, the USGS-RRE performed better for larger watersheds, such as the Fraser EF’s St. Louis watershed in Colorado and the Santee EF’s watershed 80 in South Carolina. About 31 %, 26 %, and 56 % of the culverts at the HBR site could not accommodate the 100-yr Qp estimated by RFA, RM and USGS-RRE, respectively. Based on the chosen RIs and techniques, it is determined that except for one culvert with diameter = 0.91 m (36 in.), none of the culverts with diameter of 0.75 m (30 in.) or larger are hydrologically vulnerable. Our results suggest that the observation based RFA works best where multiple gauges are available to extrapolate information for ungauged watersheds, otherwise, RM is best-suited for smaller headwater watersheds and USGS-RRE for larger watersheds. Results from the hydrologic vulnerability analysis revealed that replacing undersized culverts with new culverts of diameter ≥ 0.75-m will improve flood resiliency, provided that the structure is geomorphologically safe (with minimal effects of debris flow, erosion, and sedimentation) and allows for both bank-full discharge and necessary fish passage within that design limit. This study has implications in managing road culverts and crossings at Forest Service and other forested lands for their resiliency to extreme precipitation and flooding hazards induced by climate change.

COMPUTATIONAL SIMULATION OF SEDIMENT MOTION STABILITY PROCESS ON BRIDGE ABUTMENT DUE TO CRIB PLACEMENT (CASE STUDY: HARAPAN RIVER, JAYAPURA REGENCY)

Erosion occurs when the flow of velocity in a channel exceeds the threshold velocity that causes the bed material to move. This phenomenon is observed in the Harapan River, resulting in significant impacts, such as riverbed lowering and narrowing due to the presence of water structures (bridge abutments) spanning across the river. The objective of this study is to investigate the sediment motion stability around bridge abutments before and after the installation of cribs in order to prevent structural failures. Sediment sampling was conducted at six points around the bridge abutments, using the Pebble Count method along zigzag paths. The grain size of the bed material was classified according to the Sturgess classification standard, and the material dispersion process was analysed using the Hjustorm curve. Design rainfall was transformed into design flood discharge, which was then simulated using the Two-Dimensional Hydrodynamic, comparing the river conditions before and after crib installation. In abutments without cribs, erosion occurred in direct contact with the abutment on the right side for each sediment grain diameter. However, in abutments with cribs, erosion still occurred, but it did not directly contact either abutment despite the presence of a crib. The crib prevented and protected the abutments from being eroded by the riverbed.

RAINFALL ANALYSIS FOR CREATING INTENSITY-DURATION-FREQUENCY (IDF) CURVE OF PONTIANAK CITY

Pontianak is a lowland area prone to flooding if it rains with high rainfall intensity. Analysis of the planned flood discharge is needed to overcome the flood problem. The design flood discharge analysis can be calculated using the rational method, which requires rain intensity data in terms of duration and frequency, which can be described as an IDF curve.This research was conducted by calculating the average daily maximum rainfall after conducting consistency and homogeneity tests on the rainfall data used and determining the selected distribution based on the results of statistical parameters. The rain design with various return periods is calculated with the desired distribution that matches Pontianak City. The rainfall intensity calculation uses the Mononobe method because the rainfall data owned is daily rainfall data.The analysis results show that the Log Pearson Type III distribution corresponds to the data distribution in Pontianak. From the IDF curve, it can be seen that high rainfall intensity lasts for a short duration; this can prove the general nature of rain that the faster the rain stays, the higher the rainfall intensity and vice versa. The IDF curve can assist in calculating the design flood discharge.

Analisis Banjir Metode Hidrograf Satuan Sintetis SCS dan Nakayasu DAS Pesung, Batam

Design discharge is discharge with a certain return period which is used as a reference or parameter in a water building construction planning. Calculation of the design discharge can be done by using the synthetic unit hydrograph method. The calculation of the planned discharge using the Nakayasu and SCS-CN synthetic unit hydrographs aims to compare the calculation of the maximum discharge in the Pesung Watershed, Batam. The design discharge analysis was carried out without calibrating with AWLR data (observed flow) due to the unavailability of AWLR data at the study site. Thus, in this study using HDRO (high direct runoff) as a comparison. The purpose of this study is to estimate the magnitude of the design flood discharge in the Pesung Watershed, Batam City. The methods used in this calculation of the flood hydrograph is using an empirical formula, namely SCS Synthetic Unit Hydrograph and Nakayasu. The results of the HDRO calculation analysis show that the largest flood discharge occurs in the Nakayasu synthetic unit hydrograph method with details of the SCS synthetic unit hydrograph method, the peak time (Tp) is obtained at 4.46 hours, with a return period flood discharge of 5 – 50 reaching 215,488 – 584,308 m3/ s. Whereas in the Nakayasu synthetic unit hydrograph method, the peak time (Tp) is obtained at 1.47 hours, with a return period flood discharge of 5 – 50 years reaching 360.526 – 986.535 m³/s.

Analysis of Annual Rainfall Distribution and Planned Rain Intensity at 11 (Eleven) Rain Post Stations in Serang District

This research aimed to find the best rainfall probability model and planned rain intensity using the Mononobe formula for 11 rain stations in Serang Regency. Annual rainfall data is processed and evaluated as secondary data using the rain data consistency test method, the Gumbel probability distribution, the Normal probability distribution, the Log Normal probability distribution, and the Pearson Type III Log probability distribution. The consistency test results reveal that the rainfall data is consistent. The Gumbel probability distribution is used to examine the design rain intensity based on the analysis. This study is intended to guide estimating the design rainfall intensity to develop the design flood discharge and run-off calculations. Suggestions for future research include improving the accuracy of rain data processing and making longer-term data available to provide a more accurate frequency analysis

PENINJAUAN SISTEM POLDER GROGOL DALAM MENGHADAPI BANJIR

Floods that often occur due to high rainfall inflicts social problems and other social impacts on the community. Therefore. a capable drainage system is necessary which comprises drainage channels with adequate capacities as well as pumps with sufficient capacities and operational rules. The study focuses on hydrological and hydraulical analysis on the system of Polder Grogol, West Jakarta. The estimation of design flood discharge employs Soil Conservation Service method with 5 years return period for Semeru and Makaliwe channels. The results of hydraulical analysis shows both channels are still adequate in draining design flood discharge. However, the existing pumping system is no longer sufficient to keep the reservoir’s water level below the bottom of reservoir’s inlet channel. There are several options to lower the reservoir water level. In this study, the approach is to add a new pump with the capacity of 0,25 m3/s wihout changing the formation of existing pumps. The analysis results reveals the additional pump manages to lower the reservoir water level below the targeted elevation.

Analisis Debit Banjir Rancangan Dan Kapasitas Tampang Sungai Di Sekitar Kawasan Sempadan Sungai Sokong Kabupaten Lombok Utara

In line with the North Lombok Regency (KLU) government program to prioritize handling and structuring residential areas and disaster-prone areas in the Pemenang-Tanjung sub-district in 2022, it is necessary to carry out several technical studies to support the program. One of the technical studies that can be carried out is an analysis of the design flood and river capacity around the Sokong River section in Tanjung Village, which is a location that is classified as densely populated, with slums and residential areas close to the river border. This study aimed to determine the magnitude of the design flood discharge and the cross-sectional capacity of the Sokong river section. The method used in this study is a hydrological analysis using the Nakayasu Synthetic Unit Hydrograph method to determine the amount of design flood discharge for the 25-year return period (Q25th) and analysis of river cross-sectional capacity using Hec-RAS 4.1.0 software. The results of the analysis show that the Q25th that occurs along the Sokong River section is 131.32 m3/s and the simulation results use Hec-RAS 4.1.0 software. shows that the capacity of the Sokong River segment cannot accommodate the Q25th. Therefore, it is necessary to plan the arrangement of residential buildings around the border area of ​​the Sokong River by raising the elevation of the building to be free from flood inundation.

The Concept of a Zero Runoff System (ZROS) in reducing the volume of rainwater runoff using infiltration wells at the Syiah Kuala University

High rainfall with a very high intensity can cause inundation. The purpose of this study was to determine the magnitude of the designed flood discharge that occurred, and the number of infiltration wells needed to reduce rainwater runoff. This research uses data of maximum 10 years of daily rainfall for observation. The results showed that the rainfall intensity for the 5 years return period was 47.24 mm/hr resulting in a design flood discharge of 2.27 m3/second. The average well water level is 5.08 cm with an average soil permeability value of 5.03 cm/hour. Infiltration wells are designed with a depth of 1.5 m with a diameter of 1.4 m. The use of wells is calculated based on 2 types, type 1 (lined well walls) and type 2 (non-lined walls) in each roof class. The total area of roof covering 15.38 ha requires ± 2.678 type 1 wells, or ±2.440 type 2 wells which can reduce rainwater runoff by 17% (type 1) or 30% (type 2) of the total flood discharge of the Syiah Kuala University.

Evaluation of Krueng Tripa River Capacity in Ujung Krueng Village, Nagan Raya Regency, Indonesia

Flood events are very common in the lowlands as often happens in Ujong Krueng Village, Tripa Makmur District. This study aims to determine the magnitude of the design flood discharge using the Nakayasu method and evaluating the cross-sectional capacity of the Krueng Tripa River in Ujong Krueng Village. The data used are both primary and secondary. Primary data consists of measurements of river slope, river flow velocity, river depth and river width, while secondary data consists of rainfall data, Krueng Tripa watershed maps and Krueng Tripa River situation maps. The results of the design flood discharge calculation using the Nakayasu method show that the 2-year return period (RP) is 3237.46 m3/s, the 5-year RP is 4389.53 m3/s, the 10-year RP is 5177.08 m3/s, the 10-year RP is 5177.08 m3/s, the 25-year RP is 6199.32 m3/s, the 50-year RP is 6979.04 m/s, and the 100-years RP is 7778.23 m3/s. From the results of hydraulic analysis on the section of the Krueng Tripa river in Ujong Krueng Village using the HEC-RAS 6.1.0 software, it shows that in the 2-year return period, on pias 1, 7 and 8 experienced overflows on both sides while on pias 2, 3, 4, 5 and 6 only overflow on the right side. In the return periods of 5th, 10th, 25th, 50th - year and 100th, all the streams had overflowed, the highest overflow reached 4.84 m, while the lowest overflow reached 0.30 m.

Evaluasi Saluran Drainase Jalan Pitulua Kecamatan Rante Angin Kota Lasusua Kabupaten Kolaka Utara

This study aims to determine whether the drainage canal can control/accommodate flood discharge. This research was conducted in the Pitulua Street area, Rante Angin District, Lasusua City and began in October 2021. The type of research is descriptive quantitative case study approach. The object of this research is the drainage channel of Jalan Pitulua, Rante Angin District, Lasusua City. The results of this study note that the drainage channel with an existing capacity of 1.6854 m3/s (right), 1.863 m3/s (left) can accommodate the design flood discharge of 1.511 m3/s (Q2), 1.614 m3/s (Q5) and 1.677 m3/s (Q10)

PERENCANAAN BENDUNG TETAP UNTUK JARINGAN IRIGASI BANDA MUSAJIK D.I GUMARANG KECAMATAN PELEMBAYAN KABUPATEN AGAM

Banda Musajik, which is located in Jorong Alahan Anggang, Nagari Tigo Koto Silungkang, Agam Regency, West Sumatra Province, is one of the irrigation networks in D.I Gumarang, under the authority of the UPTD Balai SDA and BK North Sumatra Province. The service area is 30 ha, the water source comes from Batang alahan anggang. Weir planning is based on the design flood discharge with a return period of 100 years. The discharge plan uses 10 years of rainfall data. Rainfall stations that affect the Alahan Anggang watershed are Gumarang Station and Kampuang IV Station. The area's average rainfall was determined by the Thiessen Polygon method, the planned rain by the log normal method and the frequency analysis test using the chi square test. Maximum flood discharge (Q100) 13.54 m3/s. The effective width of the dam is 11.42 m, one flush door is 0.80 m wide, one pillar is 0.50 m thick. The type of lighthouse is round with a radius of 0.80 m and a height of 1.52 m. The stilling pool is planned for the Vlugter type with the height of the weir, the length of the pool floor and the radius of the weir of 3.74 m. The length of the flood embankment from the weir to the upstream is 19 m with a height of 0.50 m from the flood water level. From the analysis of the forces acting on the body of the weir, the number of vertical forces (ΣRV) is 5,916 T, the number of horizontal forces (ΣRH) is 8,397 T, the number of holding moments (ΣMT) is 352,678 T.m, the number of overturning moments (ΣMG) is 344,87 T.m. stability of the weir body against overturning 1.31 1.3 , against shear 1.42 1.3, Eccentricity ( e ) 5.05 78.74 Maximum stress 1.90 78.74, minimum stress -0.36 78.7, the design of the weir body is safe against shearing, overturning, and the bearing capacity of the ground.Key words : Hydrological analysis, Hydraulic design of weir, Weir stability.

Analysis of drainage network capacity in Rawa Jaya Area, Ilir Timur I, Palembang

Palembang is a lowland which is dominated by swamp areas.. The problem of flooding in this area stems from a drainage network system that is almost cut off, causing high rainfall and water not flowing properly into the river. This study aims to analyze the drainage network system’s performance based on the channel’s capacity to the channel’s condition in analyzing the hydrology using the probability distribution method. The frequency suitability test was carried out using Smirnov-Kolmogorov and Chi-Square. The results showed that the rainfall was 116.74 mm/hour and the design flood discharge (Qr) at the ten-year return period was 3.684 m3/second. The carrying capacity of the discharge channel (Qs) is smaller than the value of Qr. Indicates that the existing drainage channels cannot accommodate the flood discharge, resulting in flooding. The channel at point 4 leads to the discharge channel; the capacity value of Qs is 4.0296 m3/second, while Qr is 3.684 m3/second. The calculation results can be estimated that the channel discharge capacity is smaller than the planned flood discharge, so the drainage channel capacity cannot accommodate flood flows.

Analysis of the Effect of Land Use on Flood Discharge in the Pangkajene River Basin, Pangkajene Regency and the Islands

Changes in land cover that occur have an impact on hydrological conditions in a watershed. The hydrological condition referred to by the amount of watershed output is the discharge which describes the amount of water. This study aims to determine the effect of changes in land cover on river flow in the Pangkajene watershed. Data were analyzed using hydrological analysis and land use change. The results showed that there was an increase in design flood discharge of ±18.83 m³ in each return period. Changes in land use that occur are the area of rice fields, ponds, and settlements increases while the area of forest decreases. The increase in the value of flood discharge is not significant because changes in land use have not changed much either.