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This study assesses the geographical distribution of agricultural water scarcity in Bangladesh in order to streamline the adaptation measures. The agricultural water scarcity was assumed to be a system with five subsystems, namely, groundwater depth, surface water availability, rainfall availability, groundwater salinity for irrigation, and surface water salinity for irrigation. The catastrophe-theory-based multi-criteria decision making approach was used for the estimation of agricultural water scarcity index from five subsystem indices. The obtained results showed that agriculture in about 6.3% of the area of the country is experiencing very high-risk water scarcity, 19.1% with high water scarcity, 37.2% with moderate water risk, and the rest is low or no risk of water scarcity for agriculture. Results showed that the western part of Bangladesh was more vulnerable to agricultural water scarcity. The analysis of the results showed that higher agriculture water scarcity in the northwest region resulted from water unavailability, and in the southwest region it was closely related to poor water quality. The severe areas of water scarcity are very similar to those that are usually regarded as water-scarce. The approach presented in this study can be used for rapid but fair assessment of water scarcity with readily available data, which can be further improved by incorporating other factors related to water scarcity.

Graphene has piqued the interest of many researchers due to its superior mechanical, thermal, and physiochemical properties. Graphene nanoplatelets with covalently functionalized surfaces (CF-GNPs) were employed in turbulent-heated pipes to undertake thermal and economic studies. CF-GNPs and distilled water were used to make the current nanofluids at various mass percentages, such as 0.025, 0.05, 0.075%, and 0.1 wt.%. In the range of 6,401 Re 11,907, the thermal system was heated up to 11,205 W/m2 under fully developed turbulent flow conditions. Field emission scanning electron microscopy (FE-SEM), zeta potential, nanoparticle sizer, and field emission transmission electron microscopy (FE-TEM) were used to examine the morphological features and characterise the particles. In addition, the current thermal system’s economic performance was assessed to estimate its price-to-operate ratio. There was a 16.10% reduction in heat exchanger size for 0.025 weight percent, 0.05 weight percent, 0.075 weight percent, and 0.1 weight percent. In addition, the power needed for the base fluid was 422 W, which was then lowered to 354 W, 326 W, 315 W, and 298 W for 0.025 wt.%, 0.05 wt.%, 0.075 wt.%, and 0.1 wt.%, respectively.