Hydrological assessment is critical to the successful implementation of adaption measures. In this study, projections of seven global circulation models (GCMs) associated with high and medium–low Representative Concentration Pathways (RCP 8.5 and RCP 4.5) for the period 2021–2040 and 2081–2100 were adopted to assess changes on runoffs in the Gilgel Abbay watershed, the upper Blue Nile basin. A weather generator was employed to generate daily temperature and precipitation to drive a hydrological model for impact assessment. Despite the projected magnitude of changes varied among different GCMs and RCPs, increasing runoffs in wet-season and decreasing in dry-season are observed in both periods, mainly attributed to the change in projected precipitation. Such changes are profound in cases of RCP 8.5 with respect to those of RCP 4.5 and in cases of 2081–2100 with respect to those of 2021–2040. Although the increasing runoffs would provide greater inflow to Lake Tana, the increase of precipitation in wet-season would imply a higher possibility of flash floods. On the other hand, decrease runoffs in dry-season further intensify existing shortage of irrigation water demand. These changes will have deleterious consequences on the economic wellbeing of the country and require successful implementation of adaption measures to reduce vulnerability.

Climate change and population growth are increasing the frequency of flooding and drought, resulting in conflict over water resources. Social impact assessments (SIA) of the allocation and management of water resources provide a way of reducing and resolving such conflicts. This article first explores the nature of SIA for water environments through an inductive analysis of the cases mentioned in more than 30 papers. Next, it identifies important advantages of SIA over integrated water resources management (IWRM) practices and indicates that while IWRM solves water-related issues to improve social well-being, it cannot entirely grasp the overall social impact of planned interventions. Following this, it analyzes the water environment governance structures in Taiwan, using questionnaire responses from water environment management professionals to discuss challenges of effectively implementing water environment SIA. The questionnaire covers 26 detailed tasks of SIA advocated by Vanclay et al. This research is the first to have evaluated the difficulty of the tasks. The survey results can be used as a reference for the implementation of SIA in other regions. The results show that (1) the water environment SIA is indeed necessary; (2) Taiwan’s water environment professionals need to improve from their current lack of understanding of SIA; (3) it is difficult to implement the water environment SIA; (4) it is necessary for SIA to clarify and integrate the authorities and responsibilities of relevant government departments; (5) the professionals believe the myth of quantification of SIA; and (6) water environment SIA must be integrated with the existing IWRM. Finally, we emphasize the need to integrate SIA and IWRM in a mutually complementary way, and illuminate the need for an integrated SIA framework for water environment management.

With improvements in data quality and technology, the statistical downscaling data of General Circulation Models (GCMs) for climate change impact assessment have been refined from monthly data to daily data, which has greatly promoted the data application level. However, there are differences between GCM downscaling daily data and rainfall station data. If GCM data are directly used for hydrology and water resources assessment, the differences in total amount and rainfall intensity will be revealed and may affect the estimates of the total amount of water resources and water supply capacity. This research proposes a two-stage bias correction method for GCM data and establishes a mechanism for converting grid data to station data. Five GCMs were selected from 33 GCMs, which were ranked by rainfall simulation performance from a baseline period in Taiwan. The watershed of the Zengwen Reservoir in southern Taiwan was selected as the study area for comparison of the three different bias correction methods. The results reveal that the method with the wet-day threshold optimized by objective function with observation rainfall wet days had the best result. Error was greatly reduced in the hydrology model simulation with two-stage bias correction. The results show that the two-stage bias correction method proposed in this study can be used as an advanced method of data pre-processing in climate change impact assessment, which could improve the quality and broaden the extent of GCM daily data. Additionally, GCM ranking can be used by researchers in climate change assessment to understand the suitability of each GCM in Taiwan.

Climate change research has emerged over the past few decades as a vibrant field of inquiry with significant impact on society, economics and politics. Analysing the context of past climate change research is necessary to check progress, gaps, needs and to optimise the benefits of future development. This paper analyses nearly 6000 government-funded climate change research projects in Taiwan from 1993 to 2020 based on data in Government Research Bulletin (GRB), supplemented by reviewing Taiwan’s science and technology policies to obtain a constructive research discourse. While the Taiwan government has continued to actively promote climate change research following the IPCC (the Intergovernmental Panel on Climate Change), it suffers from uneven development of research fields, lack of social and interdisciplinary/transdisciplinary research, and a gap between scientific research and decision-making. While these individual issues can be addressed, they stem from a core factor: the lack of determination and commitment of politicians and government to implement recommended mitigation/adaptation policies. This is one of very few papers investigating climate change research from a national perspective and the first focusing on Taiwan, and is of potential interest to researchers, policymakers and members of the general public concerned about national-scale climate change research.