Over half of the global population experiences water scarcity for at least one month during the year. Such situations of household water insecurity (HWI), where household water provisioning is reduced in such a way that affordability, adequacy, reliability, or safety is compromised to threaten human well-being, can be the result of complex interactions between humans and the water systems in which they live. To advance understanding regarding the cause-and-effect relationships between variable hydrological conditions and how humans experience domestic water provisioning, we conduct a systematic literature review to synthesize existing research and identify knowledge gaps of seasonal climate and hydrological influence on HWI. We incorporate a socio-ecological framework of drinking water services as well as process-based hydrological information to interpret results. Following the PRISMA 2020 systematic review guidelines, we retained 67 studies for final analysis. Examining studies by country as well as Major Freshwater Habitat, we find most study sites have been in sub-Saharan Africa (n=61, 89.7%) and in areas characterized by Tropical and Subtropical Coastal Rivers (n=37, 54.4%). Discussion of seasonality has centered on bimodal rainy/dry seasons; pre-monsoon, monsoon, and post-monsoon seasons; seasonal droughts and floods; winter snow and ice conditions; and seasonal migration. Water infrastructure, household characteristics, institutional factors, and water sharing practices mediate seasonal influences, either ameliorating or exacerbating its effects. To date, there have been few HWI seasonality studies in East Asia and the Pacific, Middle East and North Africa, North America, and Europe and Central Asia, and no studies in areas of Temperate Floodplain Rivers and Wetlands and Temperate Upland Rivers. Additionally, despite efforts to incorporate seasonality, most studies are cross-sectional, demonstrating an urgent need for more longitudinal studies to better characterize HWI within and between years. With climate change expected to disproportionately affect the portion of the global population that relies on seasonally varying environmental resources, it is critical to address these research gaps to ensure availability and sustainable management of water for all.

Regional climate change impacts show wide range of variations under different levels of global warming. Watersheds in the northeastern region of United States (NEUS) are projected to undergo most severe impacts from climate change in the forms of extreme precipitation events, floods and drought, sea level rise etc. As such, there is high possibility that hydrologic regimes in the NEUS may get altered in the future which can be absolutely devastating for managing water resources and ecological balance across different watersheds. In this study, therefore, we present a comprehensive impact analysis using different hydrologic indicators across selected watersheds in the NEUS under different thresholds of global temperature increases (1.50C, 2.00C and 3.00C). Precipitation and temperature projections from fourteen downscaled GCMs under RCP8.5 greenhouse gas concentration pathway are used as inputs into a distributed hydrological model to obtain future streamflow conditions. Overall, the results indicate that majority of the selected watersheds will enter into a wetter regime particularly during the months of winter while flow conditions during late summer and fall indicate a dry future under all three thresholds of temperature increases. The estimation of time of emergence of new hydrological regimes show large uncertainties under 1.50C and 2.00C global temperature increases, however, most of the GCM projections show strong consensus that new hydrological regimes may appear in the NEUS watersheds under 3.00C temperature increase.