Large-area hydrologic modelling can play an important role in policy planning related to water and land management issues. Models are often required to assess the impacts and risks of management alternatives on the availability and quality of water in large and complex river systems. This paper describes the Hydrologic Unit Model for the United States (HUMUS): a decision support system designed...

Soil moisture is an important state variable in the hydrologic cycle, and its spatiotemporal distribution depends on many geophysical processes operating at different spatial and temporal scales. To achieve a better accounting of the water and energy budgets at the land-atmosphere boundary, it is necessary to better understand the spatiotemporal variability of soil moisture under different hydr...

The importance of hydrologic variability in sustaining natural riverine ecosystems is now well accepted. Over the last 15 years or so, many typologies and assessment tools have been developed to assist ecologists and managers in describing natural flow regimes in quantitative terms. In the course of this recent progress, however, some critical questions have arisen concerning the degree to whic...

Simulations conducted using a coupled lake-catchment, hydrologic and isotope mass-balance model indicate that small, closed-basin lakes in north-central Washington are isotopically sensitive to changes in precipitation, relative humidity, and temperature. Most notably, model simulations predicted inconsistent lake responses to precipitation changes due to differences in lake outseepage rates an...

Distributed, physics-based hydrologic models require spatially explicit specification of parameters related to climate, geology, land-cover, soil, and topography. Extracting these parameters from national geodatabases requires intensive data processing. Furthermore, mapping these parameters to model mesh elements necessitates development of data access tools that can handle both spatial and tem...

The co-occurrence of closely related species is challenging to explain because biotic filters are expected to limit the ecological similarity of species within communities. To investigate the mechanisms important in facilitating species’ co-occurrence in diverse willow and poplar communities, we examined functional diversity and community phylogenetic structure along a hydrologic gradient. We f...

With extraordinary resolution and accuracy, Light Detection and Ranging (LiDAR)-derived digital elevation models (DEMs) have been increasingly used for watershed analyses and modeling by hydrologists, planners and engineers. Such high-accuracy DEMs have demonstrated their effectiveness in delineating watershed and drainage patterns at fine scales in low-relief terrains. However, these high-reso...

The usefulness of a hydrologic model is directly related to its application and how well it is calibrated. Calibration is a subjective exercise where model parameters are adjusted to reduce discrepancies between measured data and modeled predictions. Automated calibration can be used to accelerate the model calibration process, minimize modeler bias, and increase the goodness of fit between mea...

The potential expansion of freeze-tolerant (FT) Eucalyptus plantations in the United States has raised concerns about the implications for water resources. Modeling was used to examine the potential effects of expanding the distribution of FT Eucalyptus plantations in US Department of Agriculture Plant Hardiness Zones 8b and greater on water yield (Q). Analyses focused on two scales: the stand ...

Variability of groundwater quality parameters is linked to various processes such as weathering, organic matter degradation, aerobic respiration, iron reduction, mineral dissolution and precipitation, cation exchange and mixing of salt water with fresh water. Multivariate statistical analyses such as principal component analysis (PCA) and hierarchical cluster analysis (HCA) were applied to the ...