Comparing spatial and temporal transferability of hydrological model parameters

Operational use of hydrological models requires the transfer of calibrated parameters either in time (for streamflow forecasting) or space (for prediction at ungauged catchments) or both. Although the effects of spatial and temporal parameter transfer on catchment streamflow predictions have been well studied individually, a direct comparison of these approaches is much less documented. Here, we compare three different schemes of parameter transfer, viz., temporal, spatial, and spatiotemporal, using a spatially lumped hydrological model called EXP-HYDRO at 294 catchments across the continental United States. Results show that the temporal parameter transfer scheme performs best, with lowest decline in prediction performance (median decline of 4.2%) as measured using the Kling�Gupta efficiency metric. More interestingly, negligible difference in prediction performance is observed between the spatial and spatiotemporal parameter transfer schemes (median decline of 12.4% and 13.9% respectively). We further demonstrate that the superiority of temporal parameter transfer scheme is preserved even when: (1) spatial distance between donor and receiver catchments is reduced, or (2) temporal lag between calibration and validation periods is increased. Nonetheless, increase in the temporal lag between calibration and validation periods reduces the overall performance gap between the three parameter transfer schemes. Results suggest that spatiotemporal transfer of hydrological model parameters has the potential to be a viable option for climate change related hydrological studies, as envisioned in the �trading space for time� framework. However, further research is still needed to explore the relationship between spatial and temporal aspects of catchment hydrological variability

Hydrologic similarity among catchments under variable flow conditions

An assessment of regional similarity in catchment stream response is often needed for accurate predictions in ungauged catchments. However, it is not clear whether similarity among catchments is preserved at all flow conditions. We address this question through the analysis of flow duration curves for 25 gauged catchments located across four river basins in the northeast United States. The coefficient of variation of streamflow percentiles is used as a measure of variability among catchments across flow conditions. Results show that similarity in catchment stream response is dynamic and highly dependent on flow conditions. Specifically, within each of the four basins, the coefficient of variation is high at low flow percentiles and gradually reduces for higher flow percentiles. Analysis of the inter-annual variation in streamflow percentiles shows a similar reduction in variability from low flow to high flow percentiles. Greater similarity in streamflows is observed during the winter and spring (wet) seasons compared to the summer and fall (dry) seasons. Results suggest that the spatial variability in streamflow at low flows is primarily controlled by the dominance of high evaporative demand during the warm period. On the other hand, spatial variability at high flows during the cold period is controlled by the increased dominance of precipitation input over evapotranspiration. By evaluating variability over the entire range of streamflow percentiles, this work explores the nature of hydrologic similarity from a seasonal perspective

Controls on hydrologic similarity: role of nearby gauged catchments for prediction at an ungauged catchment

Prediction of streamflow at ungauged catchments requires transfer of hydrologic information (e.g., model parameters, hydrologic indices, streamflow values) from gauged (donor) to ungauged (receiver) catchments. A common metric used for the selection of ideal donor catchments is the spatial proximity between donor and receiver catchments. However, it is not clear whether information transfer among nearby catchments is suitable across a wide range of climatic and geographic regions. We examine this issue using the data from 756 catchments within the continental United States. Each catchment is considered ungauged in turn and daily streamflow is simulated through distance-based interpolation of streamflows from neighboring catchments. Results show that distinct geographic regions exist in US where transfer of streamflow values from nearby catchments is useful for retrospective prediction of daily streamflow at ungauged catchments. Specifically, the high predictability catchments (Nash-Sutcliffe efficiency NS > 0.7) are confined to the Appalachian Mountains in eastern US, the Rocky Mountains, and the Cascade Mountains in the Pacific Northwest. Low predictability catchments (NS < 0.3) are located mostly in the drier regions west of Mississippi river, which demonstrates the limited utility of gauged catchments in those regions for predicting at ungauged basins. The results suggest that high streamflow similarity among nearby catchments (and therefore, good predictability at ungauged catchments) is more likely in humid runoff-dominated regions than in dry evapotranspiration-dominated regions. We further find that higher density and/or closer distance of gauged catchments near an ungauged catchment does not necessarily guarantee good predictability at an ungauged catchment

A groundwater-fed coastal inlet as habitat for the Caribbean queen conch Lobatus gigas—an acoustic telemetry and space use analysis

The queen conch Lobatus (Strombus) gigas, a marine snail, is among the most important fisheries resources of the Caribbean region. To provide effective protection in marine reserves, a good understanding of its habitat usage is essential. Queen conches commonly inhabit marine habitats. In this study, its activity space in a marginal estuarine-like habitat, the groundwater-fed inlet of Xel-Há (Mexico) was determined using high-resolution acoustic telemetry (VEMCO Positioning System). Thirty-eight animals with syphonal lengths ranging from 80 to 200 mm were tagged, 1 of them with an accelerometer tag. Their trajectories were recorded for 20 mo at 5 m resolution in a closely spaced array of 12 receivers. Space–time kernel home ranges ranged from 1000 to 18500 m2 with an ontogenetically increasing trend. Juveniles, subadults and most adults displayed continuous, non-patchy home ranges consistent with the typical intensive feeding activity by this fast-growing gastropod. In some adults, Lévy flight-like fragmentation of home ranges was observed that may be related to feeding range expansion or other ecological drivers such as the breeding cycle. The observed small home ranges indicate that the space use of queen conch in this estuarine-like habitat is not conditioned by food availability, and despite environmental stress due to daily low-oxygen conditions, space use is comparable to that observed in more typical marine habitats. In a marine reserve context, the groundwater-fed inlet provides adequate protection of this inshore queen conch population. Such marginal habitats may play an increasingly important role in conservation management as pressure on populations increase

Impact of Reddit Discussions on Use or Abandonment of Wearables

Discussion platform, Reddit, is the third most visited website in the US. People can post their questions on this platform to get varying opinions from fellow users, which in turn might also influence their behavior and choices. Wearables are becoming widely adopted, yet challenges persist in their effective long term use because of technical and device related, or personal issues. Therefore, by employing sentiment analysis, this paper aims to analyze how decisions of use or abandonment of wearables are influenced by discussions on Reddit. The results are based on the analysis of 6680 posts and their associated 50,867 comments posted between December 2015 - December 2017 on the subreddit (user created groups) on android wear. Our results show that sentiment of the discussion is majorly dictated by the sentiment of the post itself, and people decide to continue using their devices when fellow Redditors offer them workarounds, or the discussion receives majority of positive or fact-driven neutral comments