Putih River Research Articles

Pemetaan Banjir Kawasan Sungai Gadjah Putih dan Evaluasi Kinerja Saluran Drainase RW 14, Sumber, Banjarsari, Surakarta

Floods often occur due to river water overflowing to the surface. Flooding can also be caused by land development which increases surface runoff and impacts the drainage system. This can cause a decrease in the performance of the drainage channel. This research aims to map floods caused by runoff from the Gadjah Putih River, and the performance of existing drainage channels in RW 14 Sumber, Banjarsari, Surakarta. The rain data used is rain data from the Pabelan, Mojolaban, and Baki rain stations from 2000 to 2019. The Gumbel method is used to analyze rain return periods, runoff discharge analyzed by using Rational Method. Runoff discharge is explained at return periods of 2, 5, and 10 years, producing discharges of 8.15 m3/s respectively; 9.76 m3/day; and 10.61 m3/day. Floods are mapped using HEC-RAS by conducting steady flow analysis. The results of the flood mapping of the Gadjah Putih River showed that the area that experienced flooding at the return period of 2, 5 and 10 years respectively was 50,326.77 m2; 56,865.37 m2; 60,756.82 m2. Drainage performance analysis compares hydrology and hydraulic calculations. The analysis resulted drainage performance in RW 14 Sumber show that at the 2 year discharge period, 34 types of channels are safe, and 11 types of channels require repair; in the 5 year discharge period, 30 types of channels are safe, and 15 types of channels require repair; at the 10 year discharge period, 25 types of channels are safe, and 20 types of channels require repair.

Effect of Debris Flow Event on the Affected Areas in Putih River, Indonesia

Debris flow is a natural phenomenon that can cause some damage and fatalities. Debris flow from Mount Merapi frequently happens through the Putih River, so it is necessary to do research. Anticipating the occurrence of debris flows can be done with predictions to reduce the number of casualties and material losses. This research used a simulation method based on Ashida, Takashi, and Mizuyama equation that applied the Nakayasu synthetic unit hydrograph through modeling on SIMLAR V2.1 application by modifying the hyetograph pattern and the rain intensity value. The test result contained flood area, velocity, volume, flow height, and the value of degradation and aggradation that happened in each simulated pattern. The velocity value in simulation with rain intensity of 56.8 mm and one peak hyetograph is 1.36 m/s, and in simulation with rain intensity of 56.8 mm and two peak hyetograph is 1.42 m/s. It means the parameter increases by 4.4%. Based on the results, it can be concluded that the hyetograph pattern is very influential on the impact of lava floods. The increase in the hydrograph value is also directly proportional to the increase in flow velocity. The value of rain intensity and rain pattern also affects the number of areas affected by the lava flood. The increasing value of the intensity and pattern of rain is also directly proportional to the increase in the area affected by flooding.

Geological aspect analysis for micro hydro power plant site selection based on remote sensing data

<span>Geological characters analysis is essential for micro hydropower plant (MHP) development planning. This paper presents an analysis of the geological aspect to determine the layout of MHP components based on remote sensing data as part of a solution to addressing power shortages in Sungai Are District, South Ogan Komering Ulu Regency, South Sumatra Province. Remote sensing and topographic map were extracted to identify the potential site. The topographic map and geological analysis were used to calculate the potential of electrical energy and the geological hazard risk, particularly floods and landslides. The results of the study identified four potential sites. Site 1 (Luas River, Ulu Danau Village) and site 3 (Putih River, Gintung Village) are suitable for MHP with a low cost of construction. Site 2 (Pecah Pinggan Village) and site 4 (Simpang Luas Village) are prone to flooding and landslides that makes it suitable for MHP but with a high cost of construction. Based on the geological aspect analysis, it is possible to optimize the hydropower capacity, by adding the volume of water flow from several nearby tributaries channeled into the hydropower flow system through civil construction engineering or by making a cascade design on the tailrace water flow.</span>

Simulation of debris flows in the watershed of the Putih River, Indonesia using SIMLAR 2.1

In 2010, the eruption of Mount Merapi produced a huge volcanic material for debris flows. One area affected by the debris flows is the watershed of Putih River. To predict the impact caused by debris flows can be done by using software such as the Simulation Lahar (SIMLAR) 2.1. In this paper, debris flow modelling will be carried out using SIMLAR 2.1 in conditions without sabo dams and using sabo dams. This simulation aims to determine the effectiveness of the sabo dams in reducing the impact of debris flows. The data used are rainfall data, DEM and sediment data in Putih River. The results show that the sabo dam building can slow down the velocity of debris flow. In addition, sabo dams also function as a barrier to riverbed erosion in the Putih River watershed. Based on the results above, it can be concluded that SIMLAR 2.1 can predict the impact of debris flows in the Putih River watershed.

A Study of the Hazard Level and Vulnerability of the Society Against Debris Flow of Merapi in the Putih River Watershed, Indonesia

Mount Merapi is one of the most active volcanoes in Indonesia with a relatively fast period of around 2-7 years. The impact of hazards arising from a fire eruption, such as primary hazards, namely hazards that occur directly, secondary hazards, namely hazards that occur indirectly or take place after an eruption, tertiary hazards, namely environmental damage around the volcano. This study aims to determine the value of the hazard level and vulnerability to debris flow in the Putih River watershed. The research method used in this study is to use the scoring and weighting method. The results obtained from the scoring and weighting methods, Srumbung and Mranggen villages have a debris flow hazard with a total value of 2.6 which falls into the high hazard level category. The results show that Srumbung Village obtained a total value of 7.92 which is included in the medium level of vulnerability category. Parameters that have a big influence on the level of community vulnerability to debris flows in the two villages are social aspects with a value of 3 and economic aspects with a value of 2.4.

Identification of Physical and Mineralogical Properties of Riverbank Material at Sand Mining Landslide Sites of Kali Putih River, Blitar

Kali Putih River is a river that is often affected by the eruption of Mount Kelud. The resulting large deposits of volcanic sand materials cause exploitation through uncontrolled sand mines. This will have an impact on potential hazards caused by environmental damage; for example, there have been several cases of riverbank landslides. Based on previous studies, it is important to study the identification of physical characteristics and mineralogy of riverbank materials through laboratory testing. The Gs value was found to be within 2.650-2.697, which can be classified as gravel or sand. According to the AASHTO standard, the classification is coarse-grained soil. By USCS classification, all samples were determined as well-graded sand. Based on the JGS standard, these samples can be classified as Volcanic Soil (VS) and Volcanic Sand (SV). SEM results showed that the grain samples had low sphericity with angular to sub-angular and a bladed-oblate granular form. From X-RD analysis, the mineral composition of samples was dominated by anorthite (CaAl2Si2O8) and albite (Na(AlSi3O8)). Associated with Bowen's Reaction, these compounds are common in young materials when the weathering process is still progressing.

Analysis of Local Spatial Data Infrastructure to Support Volcanic Mudflow Mitigation along Putih River, Magelang Regency, Central Java Province, Indonesia

One of the most devastating disasters in Indonesia was the Mount Merapi eruption in 2010. After the eruption there still exists the secondary hazard of volcanic mudflow, which has caused damage and casualties. Volcanic mudflow is a mixture of pyroclastic material and rainwater, meaning that in the rainy season the area along rivers becomes a high volcanic mudflow hazard, including the area along Putih River in Magelang Regency, Central Java Province. The development of Spatial Data Infrastructure (SDI) plays an important role in disaster management, especially in disaster mitigation efforts. Building an SDI which shares information on spatial conditions in the area along the Putih River could save many lives and reduce the risk from volcanic mudflow. This research was conducted employing interview surveys, field surveys and secondary data collection at government institutions. The results of the analysis have provided a geoportal prototype as an information gateway for the mitigation of volcanic mudflow along the Putih River and the reduction of disaster risk both for the government and community.

Sosialisasi dan Simulasi Tanggap Bencana Gunung Meletus dan Banjir Desa Sumberagung Kecamatan Gandusari

Geographically, Sumberagung Village is located near an active volcano, Kelud Mountain. With such geographical conditions, it is very possible that natural disasters occur, ranging from volcanic natural disasters and cold lava floods in the Kali Putih River Region. With the frequent occurrence of disasters it is necessary to increase the readiness in dealing with disasters in the Sumberagung Village community, it is very necessary to conduct socialization to provide insight and knowledge to the community. The method used is to conduct direct socialization in the field, giving questionnaires, and coupled with literature studies from various sources, to conduct socialization to elementary / MI students in Sumberagung Village, Gandusari District, Blitar Regency. To improve disaster response and be smart in absorbing information on elementary / MI children as an early step, it is very necessary to socialize and simulate the SD / MI children in Sumberagung Village. The entire community and SD / MI students in Sumberagung Village have a very good response to the socialization activities and disaster response simulations that have been carried out, so that they are ready to assist and support the installation of placards for evacuation routes in Sumberagung Village, Gandusari District, Blitar Regency.

Evaluation of infrastructures and riparian area toward the potency of debris flow effect in Putih river watershed, Indonesia

Putih River is one of the rivers which was affected by debris flow after the eruption of Mount Merapi in 2010. The impact of the damage included riparian areas and infrastructures took place along the river. This research aims to evaluate the condition of riparian area in Putih river watershed with the established rules of Indonesian government and conditions of infrastructures that constructed along the river. The research was carried out by field survey that supported by Survey123 for ArcGIS and data processing using ArcGIS software. Based on the results, it shows that Jumoyo village had the largest of riparian area with 2.1 Ha for riparian area by 5 m width and 10 Ha for riparian area by 50 m width. The result also showed that Jumoyo village had the highest approximate population number within the riparian areas with 656 people for riparian area with 5 m width and 1465 people for riparian area with 50 m width. From the field survey result, it shows that there are 35 buildings/infrastructures in Putih River, consisting of 2 dams, 11 bridges, 1 ground sill, 20 sabo dams, and 1 sand pocket.

Potential use of crushed pyroclastic rocks from mount Kelud as alternative backfill materials

Pumice and scoria are pyroclastic rocks that can be found where volcanic mountains appear. In Indonesia, pumice and scoria are found in large deposits in the area of Mount Kelud at Kali Putih River in Blitar Regency, Province of East Java. Thus, it is important to evaluate their potential uses as alternative backfill materials. Standard Proctor compaction tests were conducted to determine the maximum dry density (MDD) and optimum moisture content (OMC) to evaluate their compaction properties. Constant head permeability tests were also conducted to determine the coefficients of permeability. Direct shear tests were also applied to investigate the shear strength characteristics of these materials. The results showed that the MDD values of scoria are slightly higher than pumice. The OMC values of pumice and scoria are 23% and 15.5%, respectively. The internal friction angle of pumice and scoria are higher than natural sand, which are approximately 55-64º and 46-59º respectively. Pumice and scoria with different relative densities had coefficients of permeability that ranged from 0.0003 to 0.002 cm/s and 0.001 to 0.002 cm/s respectively. Due to their mechanical properties, it can be concluded that these materials have potential as alternative backfill materials.

Temporal Changes in Runoff Characteristics of Lahars After the 1984 Eruption of Mt. Merapi, Indonesia

After a volcanic eruption, in situations where pyroclastic material generates thick ground cover, even small amounts of rainfall can trigger lahars; this effect sometimes continues for many years. For hazard mitigation against lahar disasters after an eruption, it is essential to evaluate the current risk of occurrence and estimate any possible temporal changes for the future. Putih River is one of the rivers where lahars occurred frequently after the 1984 eruption of Mt. Merapi. In this study, the characteristics of lahars and floods in the Putih River after the 1984 eruption and their change over the years were analyzed, focusing on the runoff characteristics of lahars. Irrelevant rainfall and discharge data for analyzing runoff characteristics of lahars were excluded in preprocessing. The magnitude and occurrences of lahars decreased annually during the four years following the eruption. The maximum runoff rate of lahars was approximately 12 during the 1984–1985 rainy season and decreased yearly after this. A judgement graph was employed to track the temporal changes of lahar- triggering rainfall characteristics. For the 1984–1985 and 1985–1986 rainy seasons discriminant lines, which discriminate between rainfall events triggering lahar flow with peak discharge > 900 m3/s and other rainfall events, were drawn on the judgement graph.

Hydraulic and Hydrologic Modeling of Steep Channel of Putih River, Magelang District, Central Java Province, Indonesia

Hydrologic and hydraulic modeling are important to be conducted to examine the watershed response based on a rainfall input, especially over disaster-prone watershed such as Putih River watershed in Magelang, Central Java Province. A GIS-based grid-based distributed rainfall-runoff model was used to simulate the rainfall-runoff transformation. A two-dimensional hydrodynamic flow modeling was then carried out to simulate the flood processes on the stream and floodplain area. A sensitivity analysis was conducted on infiltration rate, Manning’s n value, and rainfall intensity. Infiltration rate, Manning’s n value, and rainfall intensity give considerable effects to the resulted flow hydrographs. The modeling results show that the results of hydrologic-hydraulic modeling is in good agreement with the observed results.

Guppy fish (Poecilia reticulata Peters) population structure in Gajah Putih River, Surakarta, Central Java

Panjaitan YK, Sucahyo, Rondonuwu FS. 2016. Guppy fish (Poecilia reticulata Peters) population structure in Gajah Putih River, Surakarta, Central Java. Bonorowo Wetlands 6: 103-109. The study of fish population structure is one strategy to know the condition of fish population and water pollution level in a waters area. Guppy fish (Poecilia reticulata Peters) can live in various conditions of water quality, especially in rivers. The Gajah Putih River flowing through Surakarta, Central Java is the habitat of guppy fish. The number of residential and factory activities that dump waste into the Gajah Putih River, causing a decrease in river water quality. Research on the population structure of Guppy fish in Gajah Putih river, Surakarta City was conducted between September and December 2014. Sampling was done purposively where the Guppy fish was found. There are 10 locations along the Gajah Putih River for sampling, each 300m away. At each location, a random sample of 30 fish was collected, then sorted by age and sex. There are also measurements of energy reserves in fish samples, as well as physical and chemical factors of water. Based on temperature, DO, pH TS and COD, the environmental conditions of the Gajah Putih River waters can still be tolerated by Guppy fish. The difference of environmental parameters between stations is relatively small, so it does not affect the difference of population structure of Guppy fish between stations.

Geo-disaster Laharic Flow along Putih River, Central Jawa, Indonesia

In 2011, laharic flow transporting volcanic materials had significantly occurred along Putih River, causing severe damage in Jumoyo area, Magelang, Central Java, Indonesia. The disaster happened frequently until April 2011. The approximately 150 million cubic meter of volcanic materials expelled from 2010 Merapi eruption has been assumed as main cause of recent laharic flow. Although pyroclastic deposit mostly flew to south and southeastern direction through Woro, Gendol, and Opak Rivers, laharic flow apparently flew to the west – westward directions through Putih and Pabelan Rivers. This study will explain the mechanism of such disaster along Putih River from sedimentological point of view.
 
 Transport mechanism of laharic flow along river is strongly controlled by the slope and type of fluids. In the upper stream area, debris flow commonly occurs as gravity flow in the steep slope. To the downstream area, where more river and surface water infiltrates the volcanic material transportation, laharic flow mechanism transforms to hyperconcentrated flow. In the gently slope area, laharic flow decreases in concentration but increase in amount because of the accumulation influx from several river flows. Hyperconcentrated flow in Putih River is mostly generated by accumulation of river flow in the tributary area. In such area, loose volcanic materials are eroded easily by surface water. Rill and gully erosion bring volcanic material into main channel of Putih River, followed by intensive vertical erosion along upper stream that will produce bigger accumulation of volcanic material within laharic flow in the downstream area. Several sabo dams along the Putih River were damaged during early period of laharic flow due to this transportation mechanism.
 
 At the downstream of in Gempol Village, Jumoyo Area, the main channel of Putih River is shifting northwestward significantly due to Gendol Hill. On the other hand, river body in this settlement area is narrower compared to the upper stream area just before turning point. Both condition cause laharic flow to spill out from the channel and form an unconfined sheet debris flow with a 500 m width and around 2-4 m thick sediments. Although energy of transport is reduced significantly, but this flow is still able to transport abundant volcanic material ranging from silt to boulder. Traditional market and hundreds of houses were buried and the main road from Yogyakarta to Magelang city has been disconnected for several times due to this disaster.
 
 Keywords: Putih River, Laharic flow, Jumoyo

Developing building-damage scales for lahars: application to Merapi volcano, Indonesia

Lahar damage to buildings can include burial by sediment and/or failure of walls, infiltration into the building and subsequent damage to contents. The extent to which a building is damaged will be dictated by the dynamic characteristics of the lahar, i.e. the velocity, depth, sediment concentration and grain size, as well as the structural characteristics and setting of the building in question. The focus of this paper is on quantifying how buildings may respond to impact by lahar. We consider the potential for lahar damage to buildings on Merapi volcano, Indonesia, as a result of the voluminous deposits produced during the large (VEI 4) eruption in 2010. A building-damage scale has been developed that categorises likely lahar damage levels and, through theoretical calculations of expected building resistance to impact, approximate ranges of impact pressures. We found that most weak masonry buildings on Merapi would be destroyed by dilute lahars with relatively low velocities (ca. 3 m/s) and pressures (ca. 5 kPa); however, the majority of stronger rubble stone buildings may be expected to withstand higher velocities (to 6 m/s) and pressures (to 20 kPa). We applied this preliminary damage scale to a large lahar in the Putih River on 9 January 2011, which inundated and caused extensive building damage in the village of Gempol, 16 km southwest of Merapi. The scale was applied remotely through the use of public satellite images and through field studies to categorise damage and estimate impact pressures and velocities within the village. Results were compared with those calculated independently from Manning’s calculations for flow velocity and depth within Gempol village using an estimate of flow velocity at one upstream site as input. The results of this calculation showed reasonable agreement with an average channel velocity derived from travel time observations. The calculated distribution of flow velocities across the area of damaged buildings was consistent with building damage as classified by the new damage scale. The complementary results, even given the basic nature of the tools and data, suggest that the damage scale provides a valid representation of the failure mode that is consistent with estimates of the flow conditions. The use of open-source simplified tools and data in producing these consistent findings is very promising.

High-spatial-resolution imagery helps map deposits of the large (VEI 4) 2010 Merapi Volcano eruption and their impact

The 26 October–23 November 2010 eruption is Merapi’s largest event (VEI 4) over the past 140 years. We used high-spatial-resolution (HSR) imagery from GeoEye, Pleiades, IKONOS, and SPOT5 satellites to assess the extent and effects of the pyroclastic density currents (PDCs) and subsequent lahars. We have tracked the geomorphic and structural (fracturing) changes of Merapi’s summit crater and dome between 2008 and 2012. The 4 September 2011 GeoEye image shows that due to the explosive eruption, the summit area lost about 10 × 106 m3. The eruption enlarged the SSE-trending Gendol breach to be 1.3 × 0.3 × 0.2 km. The 2010 tephra and PDC deposits covered about 26 km2 in the two catchments of Gendol and Opak Rivers on Merapi’s south flank, i.e., 60–75 % of the total PDC deposit area, with a total bulk volume of 45 × 106 m3. The tephra-fall deposit covered an area of about 1300 km2 with a range in volume of 18–21 × 106 m3. Supervised and object-oriented classification on HSR imagery enables us to map in detail the PDC deposits across the Gendol-Opak catchment. We delineated 16 spectrally and/or texturally distinct units of PDC deposits and compared them with previously published results. They encompass high-energy surge deposits within ca. 8 km of the summit, valley-confined PDC deposits channeled as far as 16.5 km in the Gendol River, and widespread overbank PDC with ash-cloud surge deposits on valley margins. Additional high-resolution data are provided to map and analyze flooded areas due to lahar activity in 2011–2012 on the south and west flanks. Subsequent overbank lahars impacted selective small areas in the populated ring plain, devastating villages along the Putih River on the southeast flank and the Gendol River. We have analyzed the morphometric parameters (channel cross-sectional capacity, longitudinal rate of channel confinement, and channel sinuosity) of the Gendol-Opak River channels that govern overbank and avulsion of lahars in the ring plain. The paper demonstrates the potential of HSR satellite imagery to outline tephra, PDC, and lahar deposits; map the geomorphic and structural evolution of the summit area of persistently active composite cones; and thus improve hazard assessment for Merapi, a volcano whose summit, slopes, and drainages have changed more since October 2010 than at any other time since 1931.

SNAKE LINE ANALYSIS FOR LAHAR FLOW WARNING SYSTEM (CASE STUDY IN PUTIH RIVER, MOUNT MERAPI)

Lahar flow in the region of Mount Merapi after an eruption of 2010 is still considered potentially to happen and threat the region along the river from the upstream. The development of warning criteria against the potential occurrence of lahar flow is a thing that should be done continuously to accommodate dynamics data availability (rainfall data and lahar flow occurrence data), although with limited data. This study aims to develop lahar warning system applying snake line as a rain phenomenon in Putih catchment area which will affect the occurrence of lahar flow and to evaluate the success rate of snake line for deciding the warning system. This study used the main reference from Guidelines for Development of Warning and Evacuation System against Sediment Disasters in Developing Countries released by Ministry of Land, Infrastructure and Transport Infrastructure Development Institute – Japan (2004). This research was conducted through several stages, i.e. secondary data collection in the form of rainfall data, lahar flow occurrence data, making correlation graph between rainfall intensity and working rainfall, determination of critical line, warning line and evacuation line. The results show that standard rainfall for warning and evacuation alert in Putih River are 22 mm, and 49 mm, respectively. The accuracy of warning criteria and the evacuation criteria against snake line for warning line is 30%, evacuation line is 61% and the critical line is 83%. The behavior of snake line that indicates lahar flow occurrence in Putih River forming an angle of 40o up to 45o.

Debris flows and flash floods in the Putih River after the 2010 eruption of Mt. Merapi, Indonesia

Debris flows and flash floods in the Putih River after the 2010 eruption of Mt. Merapi, Indonesia