Water

Rural cut-slope construction constitutes a typical trigger of geological hazards in mountainous regions of developing countries, a risk exacerbated under climate change with the increased frequency and intensity of extreme rainfall events. This study developed an early identification framework for assessing landslide hazard potential associated with such construction, based on the Comprehensive Index Method (CIM). Using Fujian Province, China, as a case study, seven core influencing factors—including slope-wall distance, cut-slope height, and slope gradient—were selected to establish a differentiated weighting system. By integrating multi-source geospatial data, the framework enables automatic identification of potential hazards and risk classification. Results indicate that of the more than 144,000 potential hazard sites identified across the province, 21.20% were classified as medium-risk or higher-risk. High-risk sites display marked spatial clustering, predominantly located in inland counties of northwestern, central, and western Fujian, characterized by steep topography, frequent cut-slope activities, and extensively distributed clay soil layers—conditions highly sensitive to rainfall infiltration. Structural parameter analysis reveals that the vast majority of potential hazard sites exhibit typical engineering geological characteristics, including narrow slope-wall distance, steep cut-slope gradients, and moderate cut-slope height, collectively increasing the susceptibility to rainfall-induced instability. Validation based on two heavy rainfall events in 2024 (Super Typhoon Gaemi and the 9 June Wuping-Shanghang event) yielded identification match rates of 91.8% and 79.98%, respectively, with Kappa coefficients of 0.85 and 0.72, confirming the reliability and practical applicability of the method under extreme weather scenarios. The proposed framework offers valuable support for regional landslide prevention and climate adaptation planning in the context of ongoing climate change.

Nutrient deficiencies and pH fluctuations are among the major issues identified in most aquaponic studies. Studies have mainly used chemical fertilizers and pH adjusters to resolve these issues; however, a sustainable and environment friendly permanent solution is needed. In this novel pilot study, we incorporated coral carbonate media into a koi carp-lettuce aquaponic system-A (APA) to provide a continuous release of Ca²⁺, Mg²⁺, Fe, and P and to support accumulation in plant and fish biomass while maintaining neutral pH, in order to compare with the control aquaponic-B (APB). In APA, mean FCR, SGR, and PER were recorded as 1.57 kg feed·kg fish⁻¹, 0.58%·day⁻¹, and 1.77 kg feed·kg fish⁻¹ protein, respectively, in comparison with the control APB which showed mean FCR, SGR, and PER as 3.45 kg feed·kg fish⁻¹, 0.27%·day⁻¹, and 0.80 kg fish·kg protein⁻¹, respectively. Also, the mean plant mass obtained during this 28-day study was 5.28 and 4.40 kg with a fish weight gain of 0.51 and 0.22 kg for APA and APB, respectively. In this pilot-scale study (n = 2 independent systems per treatment), the observed plant and fish biomass in APA were 20.9% and 10.1% higher respectively than APB; these values show descriptive differences observed in this study. Nutrient analysis was found to show higher release and accumulation of key nutrients in APA. This study examined a low-chemical, sustainable approach for aquaponics by using reusable coral carbonate media to maintain neutral pH and to improve nutrient availability and productivity.

Integrating an end member catchment offers a mechanistic foundation for interpreting large basin hydrology. This critical aspect is rarely evident in Malawi’s river basin studies. This study characterizes the hydrochemistry of surface and groundwater and stable isotopes of water to gain a regional picture of how the Ruo River Transboundary Catchment (RRC) influences the Shire–Zambezi River Basin. Hydrochemistry (2013 to 2024) and stable isotope (2020 to 2022) data are used. Both Gibbs and Piper diagrams were used to interpret surface and groundwater facies and hydrogeochemical processes controlling mineralization of water. SI biplots were used to trace water sources, mixing signals, and evaporation trends. Low to moderate mineralization is noted in surface and groundwater sources, and electrical conductivity varied between 19 and 622 µS/cm and 31 and 1930 µS/cm for surface (12 sites) and groundwater (151 boreholes), respectively. Piper diagram analysis reveals a Ca-Mg-HCO₃ water type dominance. Gibbs plots suggested dissolution of silicate minerals and interaction of surface and groundwater. Stable oxygen (δ¹⁸O) and hydrogen (δ²H) isotope ratios in precipitation, surface, and groundwater exhibit a similar pattern, indicating a common meteoric input, variability in moisture source, and significant interaction of surface water and groundwater. SI plots indicate mixing of precipitation, surface, and groundwater of RRC. Finally, the Ruo River at flood stage reverses the flow of the Shire River sub catchments, impacting the water quality and quantity of the Zambezi, and, therefore, should be considered an important mixing end member in the Lower Shire Basin.