Free Global DEMs and Flood Modelling—A Comparison Analysis for the January 2015 Flooding Event in Mocuba City (Mozambique)

Flood hazard and risk analysis in developing countries is a difficult task due to the absence or scarce availability of flow data and digital elevation models (DEMs) with the necessary quality. Up to eight DEMs (ALOS Palsar, Aster GDEM, Bare Earth DEM, SRTM DEM, Merit DEM, TanDEM-X DEM, NASA DEM, and Copernicus DEM) of different data acquisition, spatial resolution, and data processing were used to reconstruct the January 2015 flood event. The systematic flow rate record from the Mocuba city gauge station as well as international aid organisms and field data were used to define both the return period peak flows in years for different flood frequencies (Tyear) and the January 2015 flooding event peak flow. Both visual and statistical analysis of flow depth values at control point locations give us a measure of the different hydraulic modelling performance. The results related to the Copernicus DEM, both in visual and statistical approach, show a clear improvement over the results of the other free global DEMs. Under the assumption that Copernicus DEM provides the best results, a flood hazard analysis was carried out, its results being in agreement with previous data of the effects of the January 2015 flooding event in the Mocuba District. All these results highlight the step forward that Copernicus DEM represents for flood hazard analysis in developing countries, along with the use of so-called “citizen science” in the form of flooding evidence field data acquisition.

Analysis of Flood Potential and Risk on Agricultural Land in Pacitan Regency

Flood is a national disaster in Indonesia. Some of those factors, landform driven factors and non-driven factors in the form of land use management. Pacitan Regency has an alluvial landform that is vulnerable to flooding. BNPB states that the floods in 2018 continued on 07 March 2019, as a massive flood resulted in losses reaching > 600 billion. This study analyzed the potential and risk of flood in Pacitan Regency in 2018, in the past (1998 and 2008), and used it to projected future floods (2030). The research focused on land use change and its impact on flood potential and hazards. The potential and risk of flooding were analyzed using Paimin’s method. The parameter was analyzed from Landsat 5, 7, and 8 images in an unsupervised. The trend will be used for Business As Usual (BAU) analysis in 2030. As a comparison, land use analysis carried out based on Land Ability Class (KKL) and Spatial Planning (RTRW). Data validation using confusion matrix overall accuracy. As a result, there had been an increase of potential floods in high and very high levels (1998 to 2018) around 263.04 ha and 368.99 ha. This continues until 2030 (BAU), around 191.61 ha and 172.8 ha. Land use management with RTRW will increase the potential flooding at a very high level in 2030 + 1088.63 ha. The best land management is the KKL application which reducing the flood potential at a very high level + 1973.39 ha. Accuracy tests conducted at 100 points in 2018 showed that 88 model points matched the flooding event ( 88% accuracy).

Paleoenvironmental Conditions during the Paleocene–Eocene Transition Imprinted within the Glauconitic Giral Member of the Barmer Basin, India

The roughly 6 m thick limestone–green shale alternation within the lignite-bearing Giral Member of the Barmer Basin corresponds to a marine flooding event immediately after the Paleocene–Eocene transition. A detailed characterization of the glauconite using Electron Probe Micro Analyzer (EPMA), X-Ray Diffraction (XRD), Mössbauer and Field Emission Gun-Scanning Electron Microscope (FEG-SEM) reveals its origin in the backdrop of prevailing warm climatic conditions. The glauconite pellets vary from fine silt-sized to coarse sand-sized pellets, often reaching ~60% of the rock by volume. Mineralogical investigation reveals a ‘nascent’ to ‘slightly evolved’ character of the marginal marine-originated glauconite showing considerable interstratification. The chemical composition of the glauconite is unusual with a high Al2O3 (>10 wt%) and moderately high Fe2O3(total) contents (>15 wt%). While the K2O content of these glauconites is low, the interlayer sites are atypically rich in Na2O, frequently occupying ~33% of the total interlayer sites. The Mössbauer spectrum indicates 10% of the total iron is in ferrous form. High tetrahedral Al3+ of these glauconites suggests a high-alumina substrate that transformed to glauconite by octahedral Al-for-Fe substitution followed by the addition of K into the interlayer structure. The unusually high Na2O suggests the possibility of a soda-rich pore water formed by the dissolution of alkaline volcanic minerals. The Giral glauconite formation could have been a part of the major contributors in the Fe-sequestration cycle in the Early Eocene shelves. Warm climate during the Early Eocene time favored the glauconitization because of the enhanced supply of Fe, Al, and Si and proliferation of an oxygen-depleted depositional environment.

PENENTUAN POLA OPERASI PINTU PELIMPAH DALAM RANGKA PENGENDALIAN BANJIR BENDUNGAN DELINGAN, JAWA TENGAH

A spillway is one of many important components of a dam, which is operated to prevent the dam from overtopping. Spillway with gate structures requires to have a good operation pattern by considering a minimum critical height and outflow discharge to prevent any flooding events in the downstream part of the spillway channel. The case study in this research is the Delingan Dam which has two ogee spillways, four main sluice gates and four additional sluice gates. Located in Karanganyar District, West Java, Delingan Dam is considered as a vast infrastructure which is potentially threatening if the spillway’s operation is not optimal. This study aims to analyze the spillway gate operations’ pattern of Delingan Dam in order to control the flooding event. The methodology used in this study is flood routing by utilizing several scenarios in order to obtain the optimal simulation results. Five scenarios that were simulated on the designated flood discharge have various combinations on the number of gates and their opening, as well as the time in which the operation started. The results show that the operation only using ogee spillway still meets the criteria for minimum critical height and maximum allowable discharge for return period of 25, 50, and 100 year.As the discharge with 1000 year return period, half of PMF, and PMF,the recommended operation is, foremost, to occupy the main gate in which results in the peak outflow discharge of 23.65 m3/s, 62.4 m3/s, and 140.9 m3/s, with the minimum critical height of 1.45 m, 1.41 m, and 1.35 m, respectively. However, this operation is not adequate for the half of PMF, and the PMF discharge, since the capacity in the spillway channel is estimated about 24.7 m3/s.Keywords: spillway, flood control, spillway gate operation, the delingan dam

EXPERIMENTAL INVESTIGATION INTO FACTORS AFFECTING THE TRANSIENT FLOW OF FLUID THROUGH AN ORIFICE IN REALISTIC CONDITIONS

During operations, damage can occur with a resulting ingress or egress of fluid. The incoming water affects the reserve buoyancy and it can also change stability and hull girder loading. During a flooding event it is vital that the flow through the damaged orifice and the movement of floodwater around the structure can be predicted quickly to avoid further damage and ensure environmental safety. The empirical measure coefficient of discharge is used as a simplified method to quantify the flooding rate. In many internal flow applications the coefficient of discharge is estimated to be 0.6 but recent research shows that it can vary considerably when applied to transient flooding flows. This paper uses an experimental setup to investigate how changes to the orifice edges and position within the structure affect the flow. It is then used to investigate the coefficient in a more realistic scenario, a static compartment in waves.

Biogeochemical impacts of flooding discharge with high suspended sediment on coastal seas: a modeling study for a microtidal open bay

Freshwater, suspended sediment matter (SSM), and nutrients discharged from rivers into the ocean have large impacts on biological production. In particular, during floods, coastal areas are greatly stirred up and large amounts of nutrients are supplied to the sea surface. We investigate the biogeochemical impact of flooding river discharges containing a large amount of SSM by conducting numerical simulations for a specific flooding event of the Yura River, Japan. Parameters are varied over wide ranges of SSM properties and nutrient content in riverine water. Two qualitatively different regimes of the riverine plume, hypopycnal and hyperpycnal, appear within realistic parameter ranges. Compared with the reference case without SSM, the surface salinity (nutrients) within the riverine plume becomes lower (higher) in hypopycnal cases and higher (lower) in hyperpycnal cases within a few days after the flooding discharge. These results suggest the necessity of properly taking into account the effect of SSM in assessing the influence of high river discharges on coastal biogeochemistry. It is the case not only for the specific river and event we are dealing with but also for other flooding events and other rivers and connecting coastal seas.

Evaluation of Humanitarian Supply Chain Resilience in Flood Disaster

Frequent natural hazards such as flooding and the devastating consequences of severe events make the humanitarian supply chain particularly important in alleviating the suffering of those communities impacted by such events. However, the ambiguity of information and the different goals of stakeholders demand that the humanitarian supply chain must be resilient. This research adopts the use of literature review and expert opinions to identify the indicators that affect the resilience of the humanitarian supply chain using the flood event in Hechuan District, China in 2020 as an example. Based on the combination of fuzzy Decision-making Trial and Evaluation Laboratory and Analytic Network Process (fuzzy-DEMATEL-ANP), the interrelationships between the indicators and the weights of each indicator are calculated. The research results indicate that decision-makers in the humanitarian supply chain should vigorously coordinate the cooperation among stakeholders, ensure the effective transmission of information, and formulate forward-looking strategic plans. At the same time, these key decision makers should also be aware of the need to adjust their strategies at different stages of the flooding event in order to achieve a flexible humanitarian supply chain that responds to the varying demands over the course of a flooding event. The results of this study will help professionals involved in humanitarian supply chains to develop strategies and plans to become more resilient thus helping to reduce losses from natural hazards such as floods.

AGENCIES' MANAGEMENT PREPARATIONS AND PROPOSED EVACUATION ROUTES FOR FLOOD DISASTER: A CASE STUDY OF MELAKA

The research focuses on the flooding event in Melaka. Flooding has been occurring so frequently in Melaka that assessing the management and preparation for flooding needs to be undertaken. Alor Gajah, Melaka has been selected as a case study because frequent flooding events in the district affected many people. Using FGD as a data collection method, the result showed there is no management structure of flooding events beyond the district level and a proper training for the community is required before the structure can be developed. The original hierarchy and functions under Directive 20 should be maintained. This research suggested a proper institutionalisation of flood management and flood rehabilitation structure for Alor Gajah's district.

Bankruptcy filings, flooding, real estate prices and Leading Index

PurposeFlood damage to uninsured single-family homes shifts the entire burden of costly repairs onto the homeowner. Homeowners in the United States and in much of Europe can purchase flood insurance. The Netherlands and Asian countries generally do not offer flood insurance protection to homeowners. Uninsured households incur the entire cost of repairing/replacing properties damaged due to flooding. Homeowners’ policies do not cover damage caused by flooding. The paper examines the link between personal bankruptcy and the severity of flooding events, property prices and financial condition levels.Design/methodology/approachA fully modified ordinary least squares (FMOLS) regression model is developed which uses personal bankruptcy filings as its dependent variable during the years 2000 through 2018. This time-series model considers the association between personal bankruptcy court filings and costly, widespread flooding events. Independent variables were selected that potentially act as mitigating factors reducing bankruptcy filings.FindingsThe FMOLS regression results found a significant, positive association between flooding events and the total number of personal bankruptcy filings. Higher flooding costs were associated with higher bankruptcy filings. The Home Price Index is inversely related to the bankruptcy dependent variable. The R-squared results indicate that 0.65% of the movement in the dependent variable personal bankruptcy filings is explained by the severity of a flooding event and other independent variables.Research limitations/implicationsThe severity of the flooding event is measured using dollar losses incurred by the National Flood Insurance program. A macro-case study was undertaken, but the research results would have been enhanced by examining local areas and demographic factors that may have made bankruptcy filing following a flooding event more or less likely.Practical implicationsThe paper considers the impact of the natural disaster flooding on bankruptcy rates filings. The findings may have implications for multi-family properties as well as single-family housing. Purchasing flood insurance generally mitigates the likelihood of severe financial risk to the property owner.Social implicationsNatural flood insurance is underwritten by the federal government and/or by private insurers. The financial health of private property insurers that underwrite flooding and their ability to meet losses incurred needs to be carefully scrutinized by the insured.Originality/valuePrior studies analyzing the linkages existing between housing prices, natural disasters and bankruptcy used descriptive data, mostly percentages, when considering this association. The study herein posits the same questions as these prior studies but used regression analysis to analyze the linkages. The methodology enables additional independent variables to be added to the analysis.

After the Flood: A Multidisciplinary Investigation of Human Remains Found in a Floodplain and First Record of Raft Spiders Colonizing a Corpse

In the analysis of any forensic case, the estimation of time, cause and manner of death is affected by post-mortem changes. These are inextricably linked to both intrinsic characteristics of the body and a variety of external factors, mainly environmental, such as the presence and types of scavengers. While there are several research and case-studies on terrestrial environments, there is scant knowledge regarding aquatic environments, either stable or cyclical/seasonal. At present, no case studies have considered human remains discovered in the mud, following a flooding event. This case study describes a body discovered in a floodplain area in northern Italy. After a flood event, the water progressively drained out, leaving the body in the mud. Besides the unique conditions of the remains, of particular interest was the colonization by larvae of Calliphora vomitoria (L.) (Diptera: Calliphoridae) and raft spiders, Dolomedes fimbriatus (Clerck) (Araneae: Pisauridae), for thefirst-time recorded colonizing a corpse. The multidisciplinary approach to such an investigation is described.