The quantification of uncertainty in the ensemble-based predictions of climate change and the corresponding hydrological impact is necessary for the development of robust climate adaptation plans. Although the equifinality of hydrological modeling has been discussed for a long time, its influence on the hydrological analysis of climate change has not been studied enough to provide a definite idea about the relative contributions of uncertainty contained in both multiple general circulation models (GCMs) and multi-parameter ensembles to hydrological projections. This study demonstrated that the impact of multi-GCM ensemble uncertainty on direct runoff projections for headwater watersheds could be an order of magnitude larger than that of multi-parameter ensemble uncertainty. The finding suggests that the selection of appropriate GCMs should be much more emphasized than that of a parameter set among behavioral ones. When projecting soil moisture and groundwater, on the other hand, the hydrological modeling equifinality was more influential than the multi-GCM ensemble uncertainty. Overall, the uncertainty of GCM projections was dominant for relatively rapid hydrological components while the uncertainty of hydrological model parameterization was more significant for slow components. In addition, uncertainty in hydrological projections was much more closely associated with uncertainty in the ensemble projections of precipitation than temperature, indicating a need to pay closer attention to precipitation data for improved modeling reliability. Uncertainty in hydrological component ensemble projections showed unique responses to uncertainty in the precipitation and temperature ensembles.

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The microclimatic requirements for successful seedling establishment are much more restrictive than those required for adult plant survival. The purpose of the current study was to use hydrothermal germination models and a soil energy and water flux model to evaluate intra-and interannual variability in seedbed microclimate relative to potential germination response of six perennial grasses and cheatgrass. We used a 44-yr weather record to parameterize a seedbed microclimate model for estimation of hourly temperature and moisture at seeding depth for a sandy loam soil type at the Orchard Field Test Site in southwestern Ada County, Idaho. Hydrothermal germination response was measured in the laboratory for two seed lots of cheatgrass (Bromus tectorum L.), four seed lots of bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] Löve), three seed lots of bottlebrush squirreltail (Elymus elymoides [Raf] Swezey), and one seed lot each of Sandberg bluegrass (Poa secunda J. Presl.), big squirreltail (Elymus multisetus [J.G. Smith] M.E. Jones), thickspike wheatgrass (Elymus lanceolatus [Scribn. And J.G. Smith] Gould) and Idaho fescue (Festuca idahoensis Elmer). Germination response models were developed to estimate potential germination rate for 13 subpopulations of each seed lot for every hour of the 44-yr simulation. Seedbed microclimate was assessed seasonally and for each day, month, and year, and germination rate-sum estimates integrated for a numerical index of relative site favorability for germination for each time period. The rate-sum favorability index showed a consistent pattern among seed lots for different years, and provides a relatively sensitive indicator of annual and seasonal variability in seedbed microclimate. This index could be used with field data to define minimum weather thresholds for successful establishment of alternative plant materials, in conjunction with weather forecast models for making restoration and fire-rehabilitation management decisions in the fall season, for evaluation of potential climate-change impacts on plant community trajectories, and in optimization schemes for selecting among alternative restoration/rehabilitation management scenarios.

This study aims to assess the spatiotemporal characteristics of agricultural droughts in Bangladesh during 1981–2015 using the Effective Drought Index (EDI). Monthly precipitation data for 36 years (1980–2015) obtained from 27 metrological stations, were used in this study. The EDI performance was evaluated for four sub-regions over the country through comparisons with historical drought records identified by regional analysis. Analysis at a regional level showed that EDI could reasonably detect the drought years/events during the study period. The study also presented that the overall drought severity had increased during the past 35 years. The characteristics (severity and duration) of drought were also analyzed in terms of the spatiotemporal evolution of the frequency of drought events. It was found that the western and central regions of the country are comparatively more vulnerable to drought. Moreover, the southwestern region is more prone to extreme drought, whereas the central region is more prone to severe droughts. Besides, the central region was more prone to extra-long-term droughts, while the coastal areas in the southwestern as well as in the central and north-western regions were more prone to long-term droughts. The frequency of droughts in all categories significantly increased during the last quinquennial period (2011 to 2015). The seasonal analysis showed that the north-western areas were prone to extreme droughts during the Kharif (wet) and Rabi (dry) seasons. The central and northern regions were affected by recurring severe droughts in all cropping seasons. Further, the most significant increasing trend of the drought-affected area was observed within the central region, especially during the pre-monsoon (March–May) season. The results of this study can aid policymakers in the development of drought mitigation strategies in the future.

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