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Located in a humid tropical monsoon region, Gin River Basin is frequently exposed to adverse flood impacts. Flood exposure assessments extending beyond traditional hazard assessments are crucial to understand these impacts. We examined flood hazard and exposure dynamics during three flood events in the basin, simulating flood hazard using the rainfall–runoff inundation model. Model parameters, including Manning’s roughness coefficients and soil depth were tuned through a trial-and-error approach using daily rainfall data. Two datasets with different spatial resolutions (∼300 m and 30 m) were used to identify exposed areas. Despite differences in hazard characteristics, the impact on human settlements remained similar, with household damages of 43.72% in 2017, 52.74% in 2016, and 76.65% in 2003. Coarser (∼300 m) land-use maps failed to capture smaller settlements in heavily damaged mid- and upstream areas, whereas high-resolution settlement maps identified them, predominantly located in agricultural and shrubland areas. These areas accounted for 69.3% of exposure midstream, 19.8% downstream, and 10.9% upstream, correlating with the heavy damage reported midstream. This highlights the importance of high-resolution settlement data for accurate flood exposure assessments, even in data-scarce basins. Socio-economic factors, disaster preparedness, and government support should be integrated into detailed flood risk assessments to develop effective mitigation measures.

Study region: Gin River Basin, Sri Lanka. Study focus: The individual and combined effects of climate and land-use changes on flood flow and inundation in the Gin River basin, Sri Lanka, were assessed. Downscaled, bias-corrected future precipitation projected by an ensemble of general circulation models (GCMs) under the Representative Concentration Pathway (RCP) 4.5 emissions scenario was input into a flood model developed using the Rainfall Runoff Inundation (RRI) model. Possible flood mitigation measures were identified based on flood simulations through the integrated assessment incorporating future climate and land-use projections. New hydrological insights for the region: The basin is projected to receive increased rainfall during the southwest monsoon (9.7 %) and second inter-monsoon (15.7 %) seasons, excluding March and April, in the future. Human settlements will expand in the downstream areas of the basin, while a significant share of agricultural land (27 %) in the basin will be converted into shrublands by 2050. High flows are predicted to increase by 16 % and 4 % at the upstream and downstream gauging stations, respectively, while mean river flow is expected to decrease by 25 % (upstream) and 34 % (downstream). In addition, a 3.5 % increase in annual maximum inundation extent is projected. However, the total inundation extent in the basin can be reduced by 1.3 % by regulating land-use changes, particularly the conversion of agricultural land into riparian forests.

Climatic variations caused by the excessive emission of greenhouse gases are likely to change the patterns of precipitation, runoff processes, and water storage of river basins. Various studies have been conducted based on precipitation outputs of the global scale climatic models under different emission scenarios. However, there is a limitation in regional- and local-scale hydrological analysis on extreme floods with the combined application of high-resolution atmospheric general circulation models’ (AGCM) outputs and physically-based hydrological models (PBHM). This study has taken an effort to overcome that limitation in hydrological analysis. The present and future precipitation, river runoff, and inundation distributions for the Lower Mekong Basin (LMB) were analyzed to understand hydrological changes in the LMB under the RCP8.5 scenario. The downstream area beyond the Kratie gauging station, located in the Cambodia and Vietnam flood plains was considered as the LMB in this study. The bias-corrected precipitation outputs of the Japan Meteorological Research Institute atmospheric general circulation model (MRI-AGCM3.2S) with 20 km horizontal resolution were utilized as the precipitation inputs for basin-scale hydrological simulations. The present climate (1979–2003) was represented by the AMIP-type simulations while the future (2075–2099) climatic conditions were obtained based on the RCP8.5 greenhouse gas scenario. The entire hydrological system of the Mekong basin was modelled by the block-wise TOPMODEL (BTOP) hydrological model with 20 km resolution, while the LMB area was modelled by the rainfall-runoff-inundation (RRI) model with 2 km resolution, specifically to analyze floods under the aforementioned climatic conditions. The comparison of present and future river runoffs, inundation distributions and inundation volume changes were the outcomes of the study, which can be supportive information for the LMB flood management, water policy, and water resources development.

Assessing water resources at a large river basin scale is important for having an idea of the water situation and efficient water resources management. What is the most appropriate approach to assess the water resources at a large river basin scale? This paper aims to develop a systematic review on water resources assessment at a large river basin scale, intending to present a new assessment method for the major river basins in Madagascar. This review investigates 40 articles from Google Scholar, Web of Science, and PubMed databases, from 2000 to 2022. This review has demonstrated the necessity of water resources assessment at a large river basin scale in Madagascar. An improvement in the use of multiple GCMs and SWAT models for water resources assessment within the basin was found necessary for appropriate water allocating regimes among upper and lower reaches. Water allocation and water scarcity at the basin level could be addressed by using the inter- and intra-basin approaches. The review concludes that a combination of the SWAT, multiple GCMs, and inter- and intra-basin approaches could be efficiently applied for assessing the water resources at a large basin scale. This review may be of benefit to scientists and water specialists. [ABSTRACT FROM AUTHOR]

We investigate the geometry of two-dimensional polygonal cracking that forms on the air-exposed surface of dried starch slurries. Two different kinds of starches, made from potato and corn, exhibited distinguished crack evolution, and there were contrasting effects of slurry thickness on the probability distribution of the polygonal cell area. The experimental findings are believed to result from the difference in the shape and size of starch grains, which strongly influence the capillary transport of water and tensile stress field that drives the polygonal cracking. [ABSTRACT FROM AUTHOR]