Characterizing the Stormwater Runoff Quality and Evaluating the Performance of Curbside Infiltration Systems to Improve Stormwater Quality of an Urban Catchment

The conveyance of stormwater has become a major concern for urban planners, considering its harmful effects for receiving water bodies, potentially disturbing their ecosystem. Therefore, it is important to characterize the quality of catchment outflows. This information can assist in planning for appropriate mitigation measures to reduce stormwater runoff discharge from the catchment. To achieve this aim, the article reports the field data from a typical urban catchment in Australia. The pollutant concentration from laboratory testing is then compared against national and international reported values. In addition, a stochastic catchment model was prepared using MUSIC. The study in particular reported on the techniques to model distributed curbside leaky wells with appropriate level of aggregation. The model informed regarding the efficacy of distributed curbside leaky well systems to improve the stormwater quality. The results indicated that catchment generated pollutant load, which is typical of Australian residential catchments. The use of distributed storages only marginally improves the quality of catchment outflows. It is because ability of distributed leaky wells depended on the intercepted runoff volume which is dependent on the hydrological storage volume of each device. Therefore, limited storage volume of current systems resulted in higher contributing area to storage ratio. This manifested in marginal intercepted volume, thereby only minimum reduction in pollutant transport from the catchment to outlet. Considering strong correlation between contributing impervious area and runoff pollutant generation, the study raised the concern that in lieu of following the policy of infill development, there can be potential increase in pollutant concentration in runoff outflows from Australian residential catchments. It is recommended to monitor stormwater quality from more residential catchments in their present conditions. This will assist in informed decision-making regarding adopting mitigations measures before considering developments.

Study on behavior of ponding time based on characteristics of infiltration rate and rainfall intensity with varying return period

Runoff management is based on two main concepts: controlling runoff discharge and managing concentration (Tc). Tc is closely related to understanding ponding time (tp), which is associated with estimating the length of tp on a land surface. The present study aims to investigate the behavior of tp due to varying infiltration rates (f) and rainfall intensities (i) with different return periods (Tr). The ponding time (tp) was derived from graph analysis of infiltration rate and rainfall intensity with Tr 2, 5, and 10 years. Infiltration measurements were conducted at 8 points using a double-ring infiltrometer. Meanwhile, rainfall data were obtained from 2010 to 2019. The observed tp (tpobs ) was derived through overlying between infiltration rate curve and rainfall intensity. In contrast, empirical tp (tpemp ) was estimated using Horton’s formula. The result confirms that the infiltration rate followed an exponential curve and varying rainfall intensities. Infiltration rates give vary in tp where the longer Tr, the faster the initial time of tp. There was fairly good consistency between tpobs and tpemp as shown by relatively high-value R2 >0.6) for Tr 2, 5, and 10 years. It indicates that the Horton’s formula has reliable to estimate tp in the study area.

KAJIAN KAPASITAS TAMPUNGAN KOLAM RETENSI DI PERUMAHAN SARIMAS, KELURAHAN SUKAMISKIN, KECAMATAN ARCAMANIK, KOTA BANDUNG

The flood was triggered by a decrease in absorption zones as population growth, activity and land requirements for housing or economic activities increased. To overcome the flood, Bandung City created a conservation pond as one of the flood prevention measures designated as one of the most frequent flood forest prevention measures in Sarimas. The purpose of this study is to assess of the capacity of the retention pool in Sarimas housing, Sukamiskin sub-district, Arcamanik subdistrict, Bandung city.Based on a runoff discharge analysis conducted with rain on the 10-year obtained a maximum of water runoff discharge using the method of synthetic hydrograph unit (HSS) Nakayasu of 20.52 m3. The traceability of the flow path carried out still leaves a significant volume of the water tank, with the capacity of the outlet remaining up to 5.01 m3/s capacity for the pump.

Analysis of sheet erosion component variability on four complex hillslopes and consecutive storms under laboratory conditions

Understanding of rainfall-runoff processes in arid and semi-arid regions, such as runoff discharge (Q) and sediment concentration (SC) in hillslopes with different geometries, can offer better insights into hydrological processes. Consequently, considering intra- and inter-storm dynamics of Q and SC during consecutive storms (CSs), on hillslopes of various geometric shapes, has not been accurately and scientifically studied. The current research was planned to study the response of the sheet erosion components. The experiments were performed on four complex hillslopes (CHs) including straight-parallel, straight-convergent, concave-convergent, and convex-convergent under five CSs with rainfall intensity of 45 mm/h on a sandy loam soil in a 1 × 2 m2 plot under laboratory conditions. The results showed that the individual effects of the CSs and CHs and their interactive effects on Q and SC were significant (P ≤ 0.00). However, Q was more influenced by the CSs (ηp2 = 0.65) and SC was more affected by the CHs (ηp2 = 0.77). Moreover, analysis of the hydrographs (HGs), sedigraphs (SGs), and sediment rating loops (SRLs) observed in four CHs during five CSs indicated the diversity in the behavior of the SC (from 2.32 to 68.68 g/L) in comparison with variations in Q (from 14.68 to 38.38 mL/s).

ANALISIS KAPASITAS SALURAN DRAINASE DI KECAMATAN KELAPA GADING

Flood is a disaster caused by various factors. Floods have caused many losses, ranging from disruption to daily activities to the loss of a person's life. Kelapa Gading is an area that is often hit by floods. This indicates that there are many factors that can cause flooding in Kelapa Gading. This study aims to find the factors that cause Kelapa Gading to be frequently flooded and solutions to reduce flooding in the area. There are several factors that needs to be examined, rainfall, drainage capacity, and drainage conditions. Drainage capacity will be calculated using the Manning method to determine the discharge from the existing drainage channel. Then it will be compared with the discharge caused by rainfall. From the results of the analysis, it is known that 12 of the 32 channels reviewed are not able to accommodate runoff discharge. After the analysis, it can be concluded that the factors that cause flooding are from the capacity of the drainage channels and external factors such as the presence of sediment at the bottom of the channel or the channel is obstructed by road construction. The solutions to this problem, deepening drainage channels or making infiltration wells in flood-prone areas. ABSTRAKBanjir adalah sebuah bencana yang disebabkan oleh berbagai faktor-faktor. Banjir telah menyebabkan banyaknya kerugian, mulai dari gangguan untuk melakukan aktivitas sehari-hari sampai dengan hilangnya nyawa seseorang. Kecamatan Kelapa Gading merupakan wilayah yang sering dilanda banjir. Hal tersebut menandakan ada banyak faktor yang bisa menyebabkan terjadi banjir di daerah Kelapa Gading. Penelitian ini bertujuan untuk mencari faktor-faktor yang menyebabkan daerah Kelapa Gading sering dilanda banjir dan solusi untuk mengurangi banjir di daerah Kelapa Gading. Ada berberapa faktor yang perlu diteliti yaitu curah hujan, kapasitas drainase, dan kondisi drainase. Kapasitas drainase akan dihitung menggunakan Manning method untuk menentukan debit dari saluran drainase eksisting. Kemudian akan dibandingkan dengan debit yang diakibatkan oleh curah hujan. Dari hasil analisis yang diperoleh diketahui bahwa 12 dari 32 saluran yang ditinjau tidak mampu menampung debit limpasan. Setelah analisis dapat disimpulkan faktor-faktor yang menyebabkan banjir ada dari kapasitas saluran drainase dan faktor luar seperti adanya sedimen di dasar saluran atau saluran terhambat oleh pembangunan jalan. Solusi untuk menangani hal tersebut ada dua yaitu memperdalam saluran drainase atau membuat sumur resapan pada daerah yang rawan banjir.

Estimating Flood Inundation Depth Along the Arterial Road Based on the Rainfall Intensity

This study identifies the rainfall intensity that causes the flood along the arterial road connecting Malang to Surabaya, East Java, Indonesia, estimates flood occurrences based on the recorded rainfall data, and proposes the normalization of the side ditch to reduce flood occurrences. The Nakayasu synthetic unit hydrograph was used to analyze the runoff discharge, and the Hydrologic Engineering Center’s River Analysis System software was used to analyze the water level profile of the side ditch. The regression method was used to determine the relationship between the rainfall intensity and inundation depth along the arterial road. Analysis results show that floods occur if the rainfall intensity is ≥1.01 year return period. To estimate the flood inundation depth, simple linear regression was conducted herein. Furthermore, it was observed that flood occurrences can be avoided by normalizing the side ditch cross section with a fully rectangular shape having a channel bottom elevation equal to the existing elevation.

The Performance of Physically Based and Conceptual Hydrologic Models: A Case Study for Makkah Watershed, Saudi Arabia

Population growth and land use modification in urban areas require the use of accurate tools for rainfall-runoff modeling, especially where the topography is complex. The recent improvement in the quality and resolution of remotely sensed precipitation satisfies a major need for such tools. A physically-based, fully distributed hydrologic model and a conceptual semi-distributed model, forced by satellite rainfall estimates, were used to simulate flooding events in a very arid, rapidly urbanizing watershed in Saudi Arabia. Observed peak discharge for two flood events was used to compare hydrographs simulated by the two models, one for calibration and one for validation. To further explore the effect of watershed heterogeneity, the hydrographs produced by three implementations of the conceptual were compared against each other and against the output of the physically-based model. The results showed the ability of the distributed models to capture the effect of the complex topography and variability of land use and soils of the watershed. In general, the GSSHA model required less calibration and performed better than HEC-HMS. This study confirms that the semi-distributed HEC-HMS model cannot be used without calibration, while the GSSHA model can be the best option in the case of a lack of data. Although the two models showed good agreement at the calibration point, there were significant differences in the runoff, discharge, and infiltration values at interior points of the watershed.

Study on Implementation of ITK Campus Drainage Master Plan (Case Study: Faculty of Mathematics and Natural Sciences)

Two main building Kalimantan Institute of Technology was established on an area of 3500 m2 on October 6, 2014 which serves as the infrastructure for teaching and learning activities of students. The rapid increase in the number of students each year results in an increase in the number of buildings as facilities for teaching and learning. This is the background for the development of the Kalimantan Institute of Technology area by adding five more lecture buildings to support teaching and learning activities for 3500 students. The expansion area for five more lecture buildings is currently under construction in the area of ​​the Faculty of Mathematics and Natural Sciences. The function of the land area has been change due to building construction resulted in an increase in runoff discharge. This condition certainly affects the region if not handled properly. Increased runoff discharge will affect inundation or flooding in the area if it is not equipped with a drainage system as needed. This research is one alternative solution given. This research is in the form of a study on the implementation of a drainage master plan that aims to obtain drainage dimensions such as drainage width, drainage length and drainage depth by observing runoff due to rainwater using the concept of environmentally friendly drainage. The research obtained from the dimensions of tertiary canals with dimensions of 0.10-0.30 meters, secondary channels 0.30-0.45 meters and primary channels 0.35-0.70 meters with the discharge area of ​​the Faculty of Mathematics and Natural Sciences ITK is 1.18 m3/ sec.

Evaluation of Dimensions and Drainage Performance Office in the Aceh Tamiang Area Kuala Simpang

The Aceh Tamiang office area is one of the office areas in Kuala Simpang which consists of various offices in the Aceh Tamiang area. The purpose of this research is to identify the drainage condition of the existing primary drainage channel which accommodates runoff discharge, the shape and direction of the flow in the inundation channel in the Aceh Tamiang Kuala Simpang office area, which is expected to help solve the problem of flooding in the 832 m3 / second. And for the channel capacity in this primary drainage drainage of 0.829 m3 / sec, the value is smaller than the planned flood discharge (Qr). Rainfall intensity (I) of 126,432 mm / hour. The plan flood discharge (Qr) for a 5-year return period yields 2,551 m3 / second and the value for channel discharge capacity (Qs) is obtained from the calculation of 2,216 m3 / second. This value is smaller than the value of the planned flood discharge.area. From the results of research conducted by the Aceh Tamiang Kuala Simpang office area is a location with a fairly high degree of rainfall, with a rainfall intensity (I) of 126,432 mm / hour and a flood discharge plan for a 5-year return period obtained a result of 0.