Water is gradually becoming scarce in Afghanistan like in many other regions of the globe. The objective of this study was to evaluate the spatial changes in the availability and sustainability of water resources in Afghanistan. The Terrestrial Water Storage (TWS) data of the Gravity Recovery and Climate Experiment (GRACE) satellite obtained from three different institutes, having 1° × 1° spatial resolution for the period 2002–2016 was used for this purpose. Sen’s slope method was used to assess the rate of change, and the Modified Mann–Kendall test was used for the evaluation of the significance of trends in TWS. After, the concept of reliability–resiliency–vulnerability (RRV) was used for assessing the spatial distribution of sustainability in water resources. The results revealed a significant decrease in water availability in the country over the last 15 years. The decrease was found to be highest in the central region where most of the population of the country resides. The reliability in water resources was found high in the northeast Himalayan region and low in the southwest desert; resilience was found low in the central region, while vulnerability was found high in the south and the southeast. Overall, the water resources of the country were found most sustainable in the northeast and southwest and least in the south and the central parts. The maps of water resource sustainability and the changes in water availability produced in the present study can be used for long-term planning of water resources for adaptation to global changes. Besides, those can be used for the management of water resources in a sustainable and judicious manner.

The sustainability of water resources is fundamental for basin management, especially in regions where changing hydrological conditions due to climate extremes are prevalent. This study presents a comprehensive assessment of the Kabul River Basin (KRB) sustainability using the Standardized Runoff Index (SRI) as a runoff indicator. By integrating the concepts of reliability, resilience, and vulnerability (RRV), this research aims to provide a granular understanding of water sustainability within the basin. Utilizing future climate projections derived from the mean ensemble of Global Climate Models (GCMs) of Coupled Model Intercomparison Project Phase 6 (CMIP6) under two shared socioeconomic pathways (SSP2-4.5 and SSP5-8.5), the Soil and Water Assessment Tool (SWAT) model simulated surface runoff for the KRB. Employing a grid-based approach, this study uncovers the internal variabilities within the basin, recognizing that individual grid points may present distinct water availability characteristics. Historical analysis indicated a decline in the KRB’s sustainability, attributed to increased vulnerability and reduced reliability and resilience. Future projections emphasize the basin’s susceptibility to runoff variations, particularly in downstream areas characterized by dense populations and intense agricultural activities. These findings accentuate the need for strategic water resource management within the KRB to address localized vulnerabilities and ensure sustainable water availability amidst climatic uncertainties.

The global climate models (GCMs) of Coupled Model Intercomparison Project phase 6 (CMIP6) were used spatiotemporal projections of precipitation and temperature over Afghanistan for three shared socioeconomic pathways (SSP1-2.6, 2-4.5 and 5-8.5) and two future time horizons, early (2020-2059) and late (2060-2099). The Compromise Programming (CP) approach was employed to order the GCMs based on their skill to replicate precipitation and temperature climatology for the reference period (1975-2014). Three models, namely ACCESS-CM2, MPI-ESM1-2-LR, and FIO-ESM-2-0, showed the highest skill in simulating all three variables, and therefore, were chosen for the future projections. The ensemble mean of the GCMs showed an increase in maximum temperature by 1.5-2.5^oC, 2.7-4.3 ^oC, and 4.5-5.3 ^oC and minimum temperature by 1.3-1.8 ^oC, 2.2-3.5 ^oC, and 4.6-5.2 ^oC for SSP1-2.6, SSP2-4.5, and SSP5-8.5, respectively in the later period. Meanwhile, the changes in precipitation in the range of -15-18%, -36-47% and -40-68% for SSP1-2.6, SSP2-4.5, and SSP5-8.5, respectively. The temperature and precipitation were projected to increase in the highlands and decrease over the deserts, indicating dry regions would be drier and wet regions wetter.

The water reticulation system for LRT3 Station 6, New Klang Valley Expressway is analysed and modelled in this research using EPANET 2.2 software. The study examines the difficulties posed by population growth and urbanization, which increase water demand and strain the distribution system. The objective is to create a Dead-End system model in EPANET 2.2 that provides crucial data for water reticulation design. The consulting firm in charge of the LRT3 project provides information, including water demand and elevation. Using a statistical test, the EPANET model is validated and compared to head loss equations (Hazen-Williams and Darcy-Weisbach’s). The validated model provides hydraulic information including pressure, velocity, conduit diameter, and total head loss. The study region has a daily water demand of 5,680 litres, revealing unique insights into water usage patterns and needs. The water pressure level study shows that most network sites maintain appropriate pressure levels over the 7.5-meter threshold, maintaining the water distribution system's operation and optimum performance to satisfy customer needs. This data assists water supply engineers, architects, planners, and technicians in analysing and optimizing LRT3 Station 6's water distribution network. The research contributes to the sustainable administration of water resources in urban development initiatives.

Estuaries, where freshwater rivers meet ocean saltwater, are vital coastal ecosystems characterized by water layer stratification. Human activities, including dredging, industrial waste disposal and coastal development, disrupt estuarine dynamics, leading to altered salinity levels and ecological threats. Sudden salinity changes, often driven by these activities, jeopardize estuarine species adapted to specific salinity conditions, potentially causing biodiversity decline and ecosystem collapse. This research focuses on two cases: Case 1 examines an unaltered estuary, replicating natural conditions, while Case 2 introduces a constriction pattern mimicking real-world estuaries influenced by geological or human-made features. Systematic salinity monitoring along multiple stations, including longitudinal, transverse and vertical directions, reveals a significant correlation between estuary shape and salinity distribution. In Case 2, a central constriction substantially impacts saltwater and freshwater mixing time, resulting in downstream salinity variations. These findings have broader implications, informing environmental conservation, climate adaptation, resource management and infrastructure design. Additionally, they advance fluid dynamics and environmental science, potentially fostering innovation across disciplines. In summary, this research offers practical solutions for the preservation and sustainable development of estuarine ecosystems.