Massive hydropower dams in the Mekong river basin (MRB) have triggered substantial debate and international attention due to its utmost importance on maintaining ecology and biodiversity. Although numerous studies have been conducted to assess the consequences of existing and proposed dams, the combined effects of dams on biodiversity and ecosystems have received limited attention. In this study, we focused on the dam’s locations and suitability on the overall Mekong River Network in order to comprehend the environmental and ecological integrity of the MRB as a whole. Overall, we identified harmful dams on their associated sub-basins based on the notion of connectivity. The vulnerability of ecosystems and biodiversity in the MRB is well recognized, and our findings generally provide additional theoretical support for their protection.

Study regionHeeia watershed, Oahu, Hawaii, USA.Study focusHydrological models are useful tools for assessing the impact of climate change in watersheds. We evaluated the applicability of the Soil and Water Assessment Tool (SWAT) model in a case study of Heeia, Pacific-island watershed that has highly permeable volcanic soils and suffers from hydrological data scarcity. Applicability of the model was enhanced with several modifications to reflect unique watershed characteristics. The calibrated model was then used to assess the impact of rainfall, temperature, and CO2 concentration changes on the water balance of the watershed.New hydrological insights for the study regionCompared to continental watersheds, the Heeia watershed showed high rainfall initial abstraction due to high initial infiltration capacity of the soils. The simulated and observed streamflows generally showed a good agreement and satisfactory model performance demonstrating the applicability of SWAT for small island watersheds with large topographic, precipitation, and land-use gradients. The study also demonstrates methods to resolve data scarcity issues. Predicted climate change scenarios showed that the decrease in rainfall during wet season and marginal increase in dry season are the main factors for the overall decrease in water balance components. Specifically, the groundwater flow component may consistently decrease by as much as 15% due to predicted rainfall and temperature changes by 2100, which may have serious implications on groundwater availability in the watershed

Although the soil and water assessment tool (SWAT) is a physically based hydrologic simulator, it has many parameters that cannot be measured directly in the field, but must be obtained through a model calibration process. Model calibration is thus an essential task to obtain the optimal parameter values, which match simulations with observations as closely as possible. This study used the Zenne River Basin (Belgium) as a case study, which experiences high spatial heterogeneity in terms of geological formation, groundwater recharge, and rainfall-runoff responses. Therefore, the objectives of this paper were to calibrate the SWAT model on the basis of different calibration techniques and identify which technique is suitable for such a heterogeneous basin so that the calibrated SWAT can be used as a tool for integrated management of the Zenne River Basin. Prior to calibration, the sensitive parameters were identified on the basis of a detailed sensitivity analysis (SA) of the Latin hypercube one-fac...

The Brahmaputra River (BR) is a heavily braided river, due to various intricate paths, high discharge variability and bank erodibility, as well as multi-channel features, which, in turn, cause huge energy dissipation. The river also experiences anastomosing planform changes in response to seasonal water and sediment waves, resulting in a morphology with extreme complexity. The purpose of this study was to provide detailed and quantitative insights into the properties of planform complexity and dynamics of channel patterns that can complement previous studies. This was achieved by investigating the applicability of the anastomosing classification on the Brahmaputra river’s planform, and computing disorder/unpredictability and complexity of fluctuations using the notion of entropy and uniformity of energy conversion rate by the channels, by means of a power spectral density approach. In addition, we also evaluated their correlation with discharge as a dynamic imprint of river systems on alluvial landscapes, in order to test the hypothesis that river flow may be responsible for the development of anastomosing planforms. The analysis suggests that higher discharge values could lead to less complex planform and less fluctuations on the alluvial landscape, as compared to lower discharge values. The proposed framework has significant potential to assist in understanding the response of complex alluvial planform under flow dynamics for the BR and other similar systems.