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...

Deterministic rainfall-runoff models require parameter calibration with the aim of matching the modeled streamflow record to an observed record as closely as possible. Much attention has been focused on automated methods of model calibration using meta-heuristics, such as genetic algorithms. In this study, two meta-heuristic algorithms were compared: the shuffled complex evolution (SCE) algorit...

A catchment is a basic unit of landscape particularly for investigations of hydrologic processes. Typically, the topographic boundary of a catchment coincides with the hydrologic boundary causing any precipitation falling on to the catchment to be routed to a stream where it is transported out of the catchment. Fundamental components of the hydrologic cycle, such as precipitation, runoff and ev...

This paper examines Internal Vowel Alternation (IVA) in Noun Plurals (e.g. 'tooth/teeth') and Past Tense formation (e.g. 'sing/sang') according to the signoriented theory of the Columbia School (CS) in general and the theory of Phonology as Human Behavior (PHB) in particular. Today, these IVA forms are considered to be "irregular", and are vestiges of former prevalent and productive processes i...

Floodplain lakes are especially dynamic due to the irregular flow regime of the Paraná River and its location along the geomorphologic gradient between the lakes and the river. The response of Eichhornia crassipes (Mart.) Solms (one of the most frequent aquatic plant) was studied in two floodplain lakes with different flooding regimes. Samples were taken between March 1997 and December 2001 on ...

Computer applications to storm runoff prediction have revolutionized the watershed modeling techniques. In general, a watershed is modeled as a system with inputs and outputs (Chow 1964). A system can be lumped or distributed, depending upon the spatial and temporal characteristics of the design variables used in the model. A lumped parameter ignores the variability in space. On the other hand,...

For some time, ecologists have attempted to make generalizations concerning how disturbances influence natural ecosystems, especially river systems. The existing literature suggests that dams homogenize the hydrologic variability of rivers. However, this might insinuate that dams affect river systems similarly despite a large gradient in natural hydrologic character. In order to evaluate patter...

The systematic decline of in situ networks for hydrologic measurements has been recognized as a crucial limitation to advancing hydrologic monitoring in medium to large basins, especially those that are already sparsely instrumented. As a collective response, sections of the hydrologic community have recently forged partnerships for the development of space-borne missions for cost-effective, ye...

Using two versions of the GFDL coupled ocean-atmosphere model, one where water vapor anomalies are allowed to affect the longwave radiation calculation and one where they are not, we examine the role of water vapor feedback in internal precipitation variability and greenhouse-gas-forced intensification of the hydrologic cycle. Without external forcing, the experiment with water vapor feedback p...