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The Yakima River Basin (Basin) in south-central Washington is a prime example of a place where competing water uses, coupled with over-allocation of water resources, have presented water managers with the challenge of meeting current demand, anticipating future demand, and preparing for potential impacts of climate change. We took a decision analysis approach that gathered diverse stakeholders to discuss their concerns pertaining to climate change effects on the Basin and future goals that were collectively important. One main focus was centered on how climate change may influence future salmon populations. Salmon have played a prominent role in the cultures of Basin communities, especially for tribal communities that have social, cultural, spiritual, subsistence, and economic ties to them. Stakeholders identified the need for a better understanding on how the cultural, spiritual, subsistence, and economic aspects of the Confederated Tribes and Bands of the Yakama Nation could be affected by changes in salmon populations. In an attempt to understand the complexities of these potential effects, this paper proposes a conceptual model which 1) identifies cultural values and components and the interactions between those components that could influence tribal well-being, and 2) shows how federal natural resource managers could incorporate intangible tribal cultural components into decision-making processes by understanding important components of tribal well-being. Future work includes defining the parameterization of the cultural components in order for the conceptual model to be incorporated with biophysical resource models for scenario simulations. [ABSTRACT FROM AUTHOR]

Most studies on the impact of climate change on regional water resources focus on long-term average flows or mean water availability, and they rarely take the effects of altered human water use into account. When analyzing extreme events such as floods and droughts, the assessments are typically confined to smaller areas and case studies. At the same time it is acknowledged that climate change may severely alter the risk of hydrological extremes over large regional scales, and that human water use will put additional pressure on future water resources. In an attempt to bridge these various aspects, this paper presents a first-time continental, integrated analysis of possible impacts of global change (here defined as climate and water use change) on future flood and drought frequencies for the selected study area of Europe. The global integrated water model WaterGAP is evaluated regarding its capability to simulate high and low-flow regimes and is then applied to calculate relative changes in flood and drought frequencies. The results indicate large `critical regions' for which significant changes in flood or drought risks are expected under the proposed global change scenarios. The regions most prone to a rise in flood frequencies are northern to northeastern Europe, while southern and southeastern Europe show significant increases in drought frequencies. In the critical regions, events with an intensity of today's 100-year floods and droughts may recur every 10-50 years by the 2070s. Though interim and preliminary, and despite the inherent uncertainties in the presented approach, the results underpin the importance of developing mitigation and adaptation strategies for global change impacts on a continental scale. [ABSTRACT FROM AUTHOR]

Adaptation strategies are essential to manage water demand and ensure optimal use of available water resources under climate change. Identification and prioritization of adaptation options would greatly support decision-making in drought-prone Northwest Bangladesh. This study identified climate adaptation options by literature review and stakeholder consultation, then used multi-criteria analysis to evaluate and prioritize the options. The complexity of the options was also evaluated, specifically social, institutional, and technical obstacles to their local uptake. Seventy-two adaptation options were identified, spanning six sector categories. The options were further classified as in-system dependent, i.e., options that could be implemented by local actors, or as out-system dependent, i.e., options reliant on actions by external actors. Finally, they were defined as on-farm or off-farm strategies. Transboundary cooperation to increase surface water flows was ranked as the overall top-priority option, though this option is very complex and out-system dependent. Integrated water resources management and integrated crop management were the top-ranked options in the water management and crop production management sectors, respectively. Clustering scattered households and offering training programs in on-farm water management were the most and least complex measures, respectively. Stakeholders exhibited a clear preference for higher scale out-system dependent strategies, rather than in-system dependent options focused on changing the agricultural system itself to cope with climate change. Nonetheless, it is recommended that short-term and medium-term planning focus on opportunities to implement achievable adaptation measures within the local agricultural system. Investment in complex, externally dependent strategies is important for long-term planning. [ABSTRACT FROM AUTHOR]

Groundwater plays a critical supporting role in agricultural production in the California Central Valley (CV). Recent prolonged droughts (notably 2007–2009 and 2012–2016) caused dramatic depletion of groundwater, indicating the susceptibility of the CV's water supply to climate change. To assess the impact of climate change on groundwater storage in the CV, we combined integrated surface water and groundwater models with climate projections from 20 global climate models and thereby explore the vulnerability of CV groundwater under two climate scenarios RCP4.5 and RCP8.5. We found that groundwater has been declining over the past decades (3 km3/year on average during 1950–2009). In the absence of future mitigating measures, this decline will continue, but at a higher rate due to climate change (31% and 39% increase in loss rate under RCP4.5 and RCP8.5). The greatest loss (more than 80% of the total) will occur in the semi-arid southern Tulare region. We performed computational experiments to quantify the relative contribution of future crop water use and headwater inflows to total groundwater storage change. Our results show that, without management changes, continuing declines in future groundwater storage will mainly be attributable to ongoing overuse of groundwater. However, future changes in the seasonality of streamflow into the CV, (small) changes in annual inflows, and increased crop water use in a warmer climate will lead to 40–70% more annual groundwater losses than the current annual average, up to approximately 5 km3/year. [ABSTRACT FROM AUTHOR]

Various frameworks related to climate change and adaptations that have been developed to date have notable benefits as well as significant limitations. It is not always practical to implement advanced climate change frameworks in situations with limited data availability. Social aspects, such as people's experience and perception, are often under-prioritized. Therefore, this study introduces an integrated framework linking social and physical aspects of climate change to assess its impacts on water resources and to evaluate differing adaptation options in poorly gauged basins. A case study of the Kali Gandaki River Basin (KGRB) in western Nepal is presented to demonstrate the applicability of this framework. Results of the study show that people of the mountainous Mustang district in the KGRB have perceived climate change or climate variability, its impacts on water resources, as well as other water-related issues and potential adaptations or responses. Furthermore, evaluation of people's perception using available physical data confirms the increase in temperature and average annual discharge in the Kali Gandaki River as well as poor water use, as a major problem at all levels in the basin. Despite increasing water availability, a concurrent increase in water use is difficult due to topographic constraints on irrigation development. However, the impacts of climate change are particularly severe in Mustang, owing to the fact that a large proportion of the population depends on a climate-sensitive livelihood like agriculture. Therefore, various adaptation options are identified in the agricultural sector, and one relevant option is further evaluated. The framework developed in this study has the potential to be further applied to other poorly gauged basins. [ABSTRACT FROM AUTHOR]