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This study evaluates the flood hazard index in Kuala Langsa Village, Langsa City, Aceh, a region prone to frequent flooding due to its low-lying coastal location in eastern Aceh. It serves as a crucial link between North Sumatra and Aceh provinces. The area's significance underscores the importance of understanding and mitigating flood risks. By utilizing the coupled 1D/2D Hydraulic model, flood hazards are accurately predicted and mapped. The field data collection (as calibration) measures the maximum tidal water level based on information from residents affected by flooding on the land surface under their houses. Hydrological conditions during the December 2017 flood event are simulated using HEC-HMS. Hydraulic conditions are evaluated using HEC-RAS 6.4.1. The research aims to assess the flood hazard index in Kuala Langsa Village under spring tide conditions, considering variations in base flow and flood flow with return periods of 2 and 50 years upstream. The main results show that an FHI >2.62 (high) covers an area of 169.74 ha, 2.62 > FHI >2.23 (moderate) encompasses 172.60 ha, and FHI

River water environmental capacity (RWEC) is an essential indicator of sustainable development. However, there are several studies on the dependence of RWEC on hydrological and hydraulic factors, especially self-cleaning ability. This study aims to clarify the role of self-cleaning factors in RWEC formation in a specific river basin. The method used in this study employed a set of models, including hydrological and eco-hydrodynamic models, with an added set of water quality parameters. The proposed research framework was applied to a specific river basin for four selected pollutants: NH4+, NO3-, PO43-, and BOD. The results revealed that the self-cleaning factors contributed significantly to the increase in RWEC. Specifically, RWECNH4+ improved by 22.6 % in the wet season and 22.7 % in the dry season; RWECNO3- improved by 10.22 % and 13.08 % in the wet and dry seasons, respectively; RWECPO43- exhibited the most significant improvement (143 % and 73 %, respectively), RWECBOD in the dry season decreased slightly by about 9%, the wet season increased by 88.34%. Our results demonstrate the critical role of self-cleaning factors in improving the carrying capacity, leading to developing medium- and long-term plans to preserve ecosystems in river systems in different basins.

Málaga, a Mediterranean region, is increasingly prone to water-related risks, a situation compounded by the impacts of climate change. Urban development practices over the past decades have significantly exacerbated these risks. Our study offers a novel, scientifically derived methodology to evaluate municipal capabilities in managing hydrological risks through urban planning instruments. Leveraging a checklist applied through multicriteria analysis, we scrutinized the integration of theoretical and regulatory frameworks relating to hydrological risks in numerous municipalities. Our findings highlight a glaring deficiency in local Disaster Risk Reduction strategies in alignment with the Sendai Framework. Additionally, there's minimal incorporation of natural risk analysis and mapping into planning instruments. Our results spotlight Málaga's high institutional vulnerability due to its limited capacity in hydrological risk management, underlining the pressing necessity for land use policies informed by risk assessments and prioritizing citizen safety. This study significantly contributes to future urban planning initiatives, offering a roadmap toward more resilient communities amid escalating hydrological risks.

Study Region: Chari-Logone River basin, Lake Chad basin. Study Focus: The objective of this study was to better understand the hydrological functioning of the Chari-Logone basin under the effect of the high variability of rainfall which has affected the Sahel during the last sixty years. The study is based on hydro-climatic data for the period between 1960 and 2015 obtained from the national and international institutions. This work based on the following steps: 1) Average hydrological balances were estimated for different geographical areas, to identify the most productive parts of the basin. 2) The rainfall-runoff relation was compared for the wettest and driest decades of the study period, to identify the areas that contribute most to the amplification of the hydrological response to variations in rainfall. 3) The long-term period stability of the rainfall-runoff relation was evaluated for climatic conditions close to the average situation, in order to detect potential evidence of the anthropogenic impact. New Hydrologic Insights for the Region: During the period 1960–2015, the average water flow in the Chari-Logone basin (42 mm/year) represented only 5% of precipitation. Between the two climatically most contrasted wet (1960−1971) and dry (1982−1997) periods, the average flow differed by 75 % against a decrease of 15 % of precipitation. Our hydroclimatic data show no clearly detectable evidence of an anthropogenic impact responsible for a decrease in flows or a modification of the hydrological regime in the Chari-Logone basin.

Wastewater discharge and agricultural activities may pose microbial risks to natural water sources. The impact of different sources can be assessed by water quality modelling. The aim of this study was to use hydrological and hydrodynamic models to illustrate the risk of exposing grazing animals to faecal pollutants in natural water sources, using three zoonotic faecal pathogens as model microbes and fictitious pastures in Sweden as examples. Microbial contamination by manure from fertilisation and grazing was modelled by use of a hydrological model (HYPE) and a hydrodynamic model (MIKE 3 FM), and microbial contamination from human wastewater was modelled by application of both models in a backwards process. The faecal pathogens Salmonella spp., verotoxin-producing Escherichia coli O157:H7 (VTEC) and Cryptosporidium parvum were chosen as model organisms. The pathogen loads on arable land and pastures were estimated based on pathogen concentration in cattle faeces, herd prevalence and within-herd prevalence. Contamination from human wastewater discharge was simulated by estimating the number of pathogens required from a fictitious wastewater discharge to reach a concentration high enough to cause infection in cattle using the points on the fictitious pastures as their primary source of drinking water. In the scenarios for pathogens from animal sources, none of the simulated concentrations of salmonella exceeded the concentrations needed to infect adult cattle. For VTEC, most of the simulated concentrations exceeded the concentration needed to infect calves. For C. parvum, all the simulated concentrations exceeded the concentration needed to infect calves. The pathogen loads needed at the release points for human wastewater to achieve infectious doses for cattle were mostly above the potential loads of salmonella and VTEC estimated to be present in a 24-h overflow from a medium-size Swedish wastewater treatment plant, while the required pathogen loads of C. parvum at the release points were below the potential loads of C. parvum in a 24-h wastewater overflow. Most estimates in this study assume a worst-case scenario. Controlling zoonotic infections at herd level prevents environmental contamination and subsequent human exposure. The potential for infection of grazing animals with faecal pathogens has implications for keeping animals on pastures with access to natural water sources. As the infectious dose for most pathogens is more easily reached for calves than for adult animals, and young calves are also the main shedders of C. parvum, keeping young calves on pastures adjacent to natural water sources is best avoided.