Spatial Upgrading of Riverbank Slums Towards Sustainability of Watershed Infrastructure

Information about the eruption of Mount Lawu in Central Java Province in 1885 and Mount Merapi in D.I. Yogyakarta in 2010 became a source for estimating the presence of magnetic minerals which underwent a sedimentation process in the Bengawan Solo River from upstream (Wonogiri) - downstream (Bojonegoro). The results we get of the magnetic susceptibility distribution of the Bengawan Solo sediments reveal that the sediment from the upper reaches of the Bengawan Solo River has a low frequency magnetic susceptibility value in upstream of around 1,080.23×10−8 m3/Kg - 2,780.77×10−8 m3/Kg, the middle part is 74.40×10−8 m3/Kg - 1,735.90×10−8 m3/Kg, and downstream 17.57×10−8 m3/Kg - 1,620.53×10−8 m3/Kg. The value of magnetic susceptibility decreased significantly from upstream to downstream. High susceptibility indicates the sample contains metal elements. In determining iron oxide, we use X-Ray Fluorescence assisted by X-Ray Diffractometer testing to determine magnetic minerals. X-Ray Fluorescence confirm metal oxide in the sample. There are Al and Fe confirm the presence of magnetic properties in sedimentation. The Vibrating Sample Magnetometer confirmed that the Bengawan Solo sediment has a magnetic saturation about 0.06 - 9.50 (emu/g), a magnetic remanent around 0.001 - 0.575 (emu/g) and coercivity field of around 10 - 60.15 (Oe). X-Ray Diffractometer pattern confirm the mineral structures, namely Coesite, Magnetite, Cristobalite, Portlandite, Quartz, Anatase, Goethite, Tridymite, Gibsyte, Stishovite, Grasullaria, Labradorite and Wuestite. These results indicate the novelty of sediments from Bengawan Solo, Central Java to East Java. HIGHLIGHTS We found several important points in this research: The Bengawan Solo River is formed from several formations and lifting from faults The Bengawan Solo River is rich in minerals formed from metal oxides The magnetic value decreases with the distance from Mount Lawu The Bengawan Solo River has confirmed ferromagnetic properties from the S-type hysterisis curve With low magnetic remanent values, low saturation magnetism and high magnetic corrosivity GRAPHICAL ABSTRACT

The agricultural sector is still a priority in the development of the agricultural economy in Indonesia. Bojonegoro Regency has a priority in agricultural development through food commodities, especially rice plants and makes Bojonegoro Regency a food barn. This makes rice fields close to the Bengawan Solo River get irrigation from the Bengawan Solo River. The purpose of this study is to determine the influence of production factors on rice yield in the Bengawan Solo Downstream Watershed, Bojonegoro Regency. The sample used was 60 farmers who were purposive taken. The analysis method used uses the Cobb Douglas production function method. The production factors used are land, fertilizer and seeds. The study revealed that the model effectively explained the variation in rice production within the study area. Among the production factors analyzed, land was found to have the most significant influence on rice output. This finding indicates that larger cultivated areas tend to result in higher rice production. The results highlight the importance of optimizing land use and managing agricultural resources efficiently to enhance rice productivity in the downstream area of the Bengawan Solo watershed, Bojonegoro Regency.

Permanent surface water is defined as area of the Earth continental surface corresponding to an accumulation of water, showing slight variations in water levels, retaining most of their volumes over the year and that do not dry up. Bengawan Solo watershed, especially in the downstream area is situated in East Java, Indonesia and is recorded as the longest and the largest river on Java Island. Thus, this river becomes one of the biggest water resources in Java, Indonesia. As a water resources, it is important to identify spatial distribution of permanent surface water in Bengawan Solo River. Synthetic Aperture Radar (SAR) is an effective way to detect surface water over large areas. Sentinel-1 is a new available SAR and its spatial resolution and short temporal baselines have the potential to identify permanent surface water. Thus, we propose an identification of permanent surface water using Sentinel-1 data. The quantitative evaluation shows relevant results with overall accuracy of more than 97%, F-measure provides value 0.79, also very low False Positive Rate and commission error. There are also morphological and land use change detected in the area. These results are encouraging and the first step for monitoring Bengawan Solo River.

Flood is disaster often occur in most parts of Indonesia. Besides human factors, regional factors are also main cause. According to the National Board for Disaster Management (BNPB) data, flood-prone areas are Central Java (Bengawan Solo and Pemali River), East Java (Sat Sampean and Bengawan Solo River), Jakarta (Ciliwung, Angke, Pesanggrahan River), Jambi (Batanghari River), West Java (Citarum, Citanduy River). Based on data over past two years, the number of flood events in Indonesia has always exceeded 500 causes. By 2015 775 incidents, 115 dead, 317,683 displaced, and 2016 546 incidents, 75 dead, 105,302 displaced. Based on the data, needed to have a pre-flood warning tool will give notice if the river state has potential to cause flooding when it rains. This background provided us with the idea to create design and prototype of FRESTI (Flood Prediction Using Sensor Integrated based on Internet of Thing and Radio Frequency to Solve Environmental Issue).The early detection function of flooding by FRESTI is achieved by embedding rain sensors, water debit, river slope and water level sensors. The parameters will measure flood potentially and give early warning. FRESTI features a siren will react when receiving data sent using radio frequency. These sirens will be placed close to resident’s settlement as warning alarm. In addition, FRESTI is equipped with monitoring system based internet of things that transmit data from internet which can be accessed by people continuously and real time. In the experiment, FRESTI will be placed in area through which large river flows frequently flooded for data retrieval and conducted cooperation with BNPB. The experimental data is expected to reduce the number of victims died caused by flooding.

Putat Boro River is one of the main drainage systems of Surakarta city which drains into Bengawan Solo river. The primary problem when flood occur is the higher water level of Bengawan Solo than Boro River and then backwater occur and inundates Putat Boro River. The objective of the study is to obtain operational method of Putat Boro River floodgate to control both inflows and outflows not only during flood but also normal condition. It also aims to know the Putat Boro rivers floodgate operational function to reduce inundation. Putat Boro river water level variation and Bengawan Solo river water level variation were used for simulation of Boro river floodgate routing. The simulation used 10-year inflows, 50-year inflows, and 100-year inflows return period and Boro water level variation are +82.50 m, +83.00 m and +84.00 m. The results of the study show that the effective opening of floodgate are 0.35 m - 0.55 m for +82.05 m of Bengawan Solo water level, 0.50 m – 0.65 m for +82.55 m of Bengawan Solo water level and 0.70 m – 0.85 m for +83.48 m of Bengawan Solo water level, for reducing water level of Boro river flooding. Keywords : Flood, drainage systems, floodgate and flow routing.

Bengawan Solo Watershed is one of the largest watersheds in Indonesia. This watershed flows in many areas both in Central Java and East Java. Therefore, the water resources condition greatly affects many people. This research will be conducted on prediction of climate change effect on water resources condition in terms of rainfall conditions in Bengawan Solo River Basin. The goal of this research is to know and predict the climate change impact on water resources based on CCAM (Conformal Cubic Atmosphere Model) with downscaling baseline (historical) model data from 1949 to 2005 and RCP 4.5 from 2006 to 2069. The modeling data was validated with in-situ data (measurement data). To analyse the water availability condition in Bengawan Solo Watershed, the simulation of river flow and water balance condition were done in Bengawan Solo River. Simulation of river flow and water balance conditions were done with ArcSWAT model using climate data from CCAM, DEM SRTM 90 meter, soil type, and land use data. The results of this simulation indicate there is (i) The CCAM data itself after validation has a pretty good result when compared to the insitu data. Based on CCAM simulation results, it is predicted that in 2040-2069 rainfall in Bengawan Solo River Basin will decrease, to a maximum of only about 1 mm when compared to 1971-2000. (ii) The CCAM rainfall prediction itself shows that rainfall in Bengawan Solo River basin will decline until 2069 although the decline itself is not significant and tends to be negligible (rainfall is considered unchanged) (iii) Both in the DJF and JJA seasons, precipitation is predicted to decline as well despite the significant decline. (iv) The river flow simulation show that the water resources in Bengawan Solo River did not change significantly. This event occurred because the rainfall also did not change greatly and close to 0 mm/month.

The Bengawan Solo River stretches from the Central Java region to East Java, making it the longest river on the island of Java, where Bengawan Solo has become the economic pulse for residents, especially in Central and East Java, which crosses trade, office areas, densely populated settlements, and industries. These various activities produce waste, which has an impact on water quality pollution. The purpose of this study aims to determine the status of the water quality standard of the Bengawan Solo River. Data used from the Solo Bengawan River Basin by using data from the January-March 2020 period through 12 monitoring points were analyzed using the STORET Method. Each parameter is analyzed using Peraturan Pemerintah no. 82 Tahun 2001 and the results most of the parameters did not meet the quality standards, including TDS, TSS, DO, Nitrite, Phosphate, COD, BOD, Lead, Copper, Total Coliform and Fecal Coliform. The results of the STORET assessment analysis show that the Bengawan Solo River is included in class 4 by 41.6% in moderate polluted conditions and the remaining 58.4% in heavily polluted conditions. The STORET Method calculation results according to classes I, 2 and 3 are 100% points in Poor condition (≥-30) which is a heavily polluted condition indicating the status of water quality is not in accordance with the standard applied by Keputusan Gubernur Jawa Timur No 61 concerning river use in East Java.
 Keywords: Water quality, Bengawan Solo, STORET Method

Abstract. Andriyono S, Rukminasari N, Hidayani AA, Zakaria IJ, Alam MDJ, Kim HW. 2023. Diversity of dinoflagellate cysts isolated from estuarine sediments of the Bengawan Solo and Brantas rivers, Indonesia. Biodiversitas 24: 1083-1091. Dinoflagellates are a major part of the phytoplankton and are commonly found in freshwater, brackish, and marine habitats and are major components that play an important role in marine ecosystems. Dinoflagellate cysts (dinocysts) are produced by dinoflagellates in an unfavourable environment and can be preserved well in sediments for long periods. More than 200 dinoflagellate species have been observed to produce resting cysts. That cyst is associated with the maintenance, discontinuation, and repetition of annual blooms. This study identified dinoflagellate cysts based on the morphological characteristics collected from the estuaries of the Brantas and Bengawan Solo rivers. Analysis of cyst diversity in the two regions shows that the Bengawan Solo River mouth has a higher Shannon-Wiener index compared to the Brantas river mouth. The type of dinoflagellate cyst that dominates at the mouth of the Bengawan Solo River is Protoperidinium obtusum, while that at the mouth of the Brantas River is Polykrikos schwartzii. Shade graph analysis shows a number of species to be found only in the estuary of the Bengawan Solo River, namely Zygabikodinium lenticulatum, Polykrikos kofoidii, Protoperidinium pentagonum, Gymnodinium catenatum, and Votadinium sp. Based on the results of this study, it is necessary to carry out DNA characteristic tests of isolated and cultured species to document genetic information. In addition, this information is very important in the management of coastal areas around the estuaries of the Bengawan Solo and Brantas rivers to prevent dinoflagellate population explosions that may have negative impacts on various sectors.

This study investigated the influence of land use change and climate change on changes in streamflow in the Bengawan Solo River (BSR, 16 389 km2) basin, Indonesia. We applied the excess water and energy approach to three tributaries of the BSR, namely Pidekso, Madiun and Kening rivers, which represent the up-, mid-, and downstream parts of the BSR, respectively. This study used hydrological data from 1982−2013 and land use data for the years 1994 and 2013. The results show that from 1982 to 2013, the annual streamflow of the Pidekso and Madiun River increased, while in the Kening River it decreased. Based on attribution measures, the increasing streamflow trend in the Pidekso and Madiun rivers is mainly attributed to land use change, while the decreasing streamflow trend in the Kening River is mainly attributed to climate change. These conclusions are supported by statistical analyses and land use change analysis.

Bengawan Solo River water is a source of drinking water and raw materials for the government of Surakarta city, but the water has been mixed with domestic, industrial, and agricultural wastes. The waste contains estradiol-17 derived from urine and feces, both from livestock and humans as well as industries around the sub-watershed Bengawan Solo River. The content of estradiol-17 in the Bengawan Solo sub-watershed is quite high. This study is the first conducted in Bengawan Solo River to look at natural estrogens that are very rarely studied in the environment, which are likely could cause several health effects in humans and wildlife due to their relatively strong estrogenic potential and high levels in wastewater and river water. Therefore, research on the elimination of these compounds using effective, energy-efficient, and low-maintenance technologies for water treatment such as phytoremediation is highly expected. The purposes of this study were to identify estradiol, to measure the estradiol levels through HPLC tests as well as to test the effectiveness of phytoremediation with Portulaca plant as biological agents. The results show that the water of Bengawan Solo River contained estradiol substances ranging from 3.88 ppm to 5.76 ppm. The Portulaca plant species was effective at eliminating estrogenic waste up to 99.89%.

Bengawan Solo River has been flown since prehistoric times. It had its headwaters at the downstream of the ancient Mount Merapi in southern Java and downstream into the South Coast, and then moved to its estuary on the North Coast. The Bengawan Solo River has potential role in the past as an economic medium, for trading and transportation route which had served in all the regions of Java. This vital function however, is not widely exposed. Exploration of river history of the Bengawan Solo has not been fully revealed and still under further research. The method used to reveal the river’s function is used historiographical method by emphasizing several literatures sourced from textbooks, scientific journals, and others. Through this study, it is known that the Bengawan Solo River had served vital functions as a basis for economic activity, trade, and transportation route which was from the Majapahit Kingdom to the 19th century. The vitality of the river needs to be used as one of the historical learning materials at the high school to rise awareness about local history potential, especially in Surakarta. Therefore, the qualitative method indicators from G. Moedjanto and Soejatmoko is used to analylze local history consciousness. To examine the data validity, triangulation and data analysis techniques were used, in the form of the interactive model from Miles dan Hubermen. According to the result, it highlights two important aspects of local history learning materials in schools, namely geomorphological development and fulfillment of economic functions. This learning is important to arise historical consxiousness in the context of locality among all students.

The mass media is often informed of successfully constructing communities. Many books and journals have written about the success of mass media in constructing the communities. This study, however, examines how the mass media failed to construct the communities of Ledok Wetan and Sumbangtimun Villages, Bojonegoro Regency, East Java, Indonesia in the case of Bengawan Solo floods. The failure was not due to the failure of Berger and Luckmann’s theory (2012) of the construction of social reality, but because the communities considered that floods from the longest river in Java were not harmful to human life and not economically harmful. Because of this assessment, the public does not feel worried about doing harmful things, such as throwing garbage into Bengawan Solo. At the same time, the mass media also did not assess the Bengawan Solo floods that occur every rainy season every year, go through 3 cities and 17 districts, and involve thousands of refugees as a serious problem. National mass media did not report the flood problem of Bengawan Solo, while the local media only reported when the flood occurred, between two to seven days. There is no news that aims to inform, educate, and influence the community to better anticipate the floods of the Bengawan Solo, to minimize their impact. In fact, newspapers distributed in the flood victims’ communities do not report about flood news. Keywords : Failure, Mass Media, Construction, Flooding, Bengawan Solo River

A disaster is an unexpected and often sudden event that causes destruction, serious damage, and human suffering. According to the Law of the Republic of Indonesia Number 24 of 2007 concerning Disaster Management, disasters are caused by natural factors and/or non-natural and human factors so that disasters can result in loss of life, environmental damage, loss of property, and psychological impacts. Bojonegoro Regency which has the widest area crossed by the Bengawan Solo river and 24,753 hectares of its area is a watershed so that almost every year Bojonegoro Regency is flooded when the Bengawan Solo river overflows. Floods in Bojonegoro Regency almost occur every year. Where the flood that occurred in Bojonegoro Regency was caused by the overflow of the Bengawan Solo river. As much as 63% of the total population of Bojonegoro Regency is exposed or at risk of flooding in 2012 to 2020. This study is to determine the Delta (Δ) risk of flood-prone areas in Bojonegoro Regency based on trends in land use change with a multitemporal perspective in Bojonegoro Regency. This study uses the latest methods, especially in terms of spatial modeling, namely TIN and Raster databases. The first step is to predict the trend of land use in Bojonegoro Regency. Which is then continued to identify flood hazards and land use vulnerabilities. Flood disaster-prone areas each year are predicted based on the previous stages using the Analytic hierarchy process which then produces disaster risk in each prediction year. The last step is to calculate the amount of change or Delta (∆) of Flood Disaster Risk in Bojonegoro Regency. The results of this study are Delta (∆) Low Flood Disaster Risk: experienced a change of -1.62% or decreased by 49.66 Ha from 2020 to 2040. Delta (∆) Moderate Flood Disaster Risk: experienced a change of 2.85% or experienced an increase of 17.67 Ha from 2020 to 2040. Delta (∆) High Flood Risk: experienced a change of 23.96% or an increase of 31.99 Ha from 2020 to 2040.

The tourism sector is growing rapidly and emerging as a key driver of regional development. One approach to fostering tourism is establishing Tourism Villages, such as Panta'nakan Lolo Village, which capitalizes on its tourism potential. As a tourist village, it features iconic attractions like Ke'te Kesu. Tourism development has driven increased accommodations alongside physical and spatial changes in the settlement environment. These include new construction, spatial reorganization, and changes in tourism activities and management. This study examines spatial changes in Panta'nakan Lolo Village's settlements before and after its designation as a Tourism Village. Using a qualitative method, data were collected through field surveys, in-depth interviews, and documentation. Spatial-temporal analysis identified changes in land use patterns during 2012, 2018, and 2024. Additionally, settlement patterns were assessed using the Nearest Neighbor Analysis approach with ArcGIS software. The results reveal significant spatial transformations linked to the village’s tourism development. These changes include expanded built-up areas, integration of tourism elements into settlements, and the rise of tourism-related activities and management systems.

Bengawan Solo experiences flooding almost every year and it has been a big problem since it causes damage and losses affecting many people in the area. Sragen is the Regency with the greatest loss due to flooding of the Bengawan Solo River which is the longest river in Java Island with 16,100 km2 basin area. Dykes are the structural intervention usually proposed to deal with flood water. The objective of this study is to conduct an assessment of dyke height requirement in order to reduce flood risk in Sragen Regency along Bengawan Solo River. The assessment is based on risk level according to regulations of the Head of National Disaster Management Agency Number 2 in 2012, regarding the general guidelines for the assessment of disaster risk. Hazard levels are obtained from the relationship between hazard index parameters and exposed population index. Loss levels are obtained from the relationship between the hazard level parameter and the loss index. Flood risk level is determined from the level of losses and capacity. For mitigation purposes, flood risk reduction analysis has been conducted through a structural approach by simulating dyke construction around the Bengawan Solo River. Several scenarios of dyke height (2m, 4m, and 6m) have been simulated to assess flood inundation.