A fundamental characteristic of all river and stream ecosystems is that of discharge water from the landscape. The volume of water flowing in a channel is measured as a function of volume through a cross section of a stream per unit time. This measurement is key to understanding the physical forces that shape streams and alter the distribution of biota within the stream. This chapter details the various techniques used to measure discharge, and ranges from volumetric analysis (the most accurate but least used) to the most commonly applied velocity–area method to more advanced slope–area methods, which require estimates of channel resistance. In addition, flood frequency analysis and the applications of flood recurrence estimates are detailed. The utilization of newer acoustic Doppler methods are described, as well as the emerging field of geographic flow pattern analysis tied to large-scale temporal change in meteorological patterns (Atlantic Multidecadal Oscillation, Pacific Decadal Oscillation, and El Nino–Southern Oscillation) that affect hydrographs on decadal or multidecadal intervals.

Discharge Measurements and Streamflow Analysis

A multiscale and multivariate analysis of precipitation and streamflow variability in relation to ENSO, NAO and PDO

Droughts and tropical cyclones (TCs) are climatologically common events in the southeastern United States, yet little research has examined the potential for TCs to ameliorate drought impacts. Here, we identify the frequency of TCs that abruptly end drought conditions (i.e., drought busters, or DB) and determine possible influences of coupled ocean‐atmosphere teleconnections on the likelihood of a TC-induced DB (TCDB). Using the HURDAT database and Palmer Drought Severity Indexes from 1950 through 2008, we identified every TCDB for thirty-one climate divisions in the southeastern Atlantic United States. We present the spatial patterns of the total number of TCDBs and the percentage of all droughts ended by TCs using choropleth maps. To determine what teleconnections influenced TCDBs, we used logistic regression analysis and included multiple synoptic-scale circulation indexes as predictor variables. In addition, we used a Fisher’s exact test to examine the association between the North Atlantic Oscillation (NAO) and TCDBs. We found that up to 41 percent of all droughts and at least 20 percent of droughts in three fourths of the climate divisions were ended by TCDBs. NAO was a significant predictor (p = 0.005) in the logistic regression model (χ 2 = 10.91, p = 0.001), and the Fisher’s exact test showed a significant association between NAO and TCDBs (p = 0.003). An odds-ratio calculation showed that TCDBs are 5.8 times more likely to occur during a negative NAO phase than a positive

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Drought-Busting Tropical Cyclones in the Southeastern Atlantic United States: 1950-2008

Increased requirements for public involvement in water resources management (WRM) over the past century have stimulated the development of more collaborative decision-making methods. Participatory modeling (PM) uses computer models to inform and engage stakeholders in the planning process in order to influence collaborative decisions in WRM. Past evaluations of participatory models focused on process and final outcomes, yet, were hindered by diversity of purpose and inconsistent documentation. This paper presents a two-stage framework for evaluating PM based on mechanisms for improving model effectiveness as participatory tools. The five dimensions characterize the ‘who, when, how, and why' of each participatory effort (stage 1). Models are evaluated as “boundary objects,” a concept used to describe tools that bridge understanding and translate different bodies of knowledge to improve credibility, salience, and legitimacy (stage 2). This evaluation framework is applied to five existing case studies from the literature. Though the goals of participation can be diverse, the novel contribution of the two-stage proposed framework is the flexibility it has to evaluate a wide range of cases that differ in scope, modeling approach, and participatory context. Also, the evaluation criteria provide a structured vocabulary based on clear mechanisms that extend beyond previous process- and outcome-based evaluations. Effective models are those that take advantage of mechanisms that facilitate dialogue and resolution and improve the accessibility and applicability of technical knowledge. Furthermore, the framework can help build more complete records and systematic documentation of evidence to help standardize the field of PM. This article is protected by copyright. All rights reserved.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2016WR019373

An interdisciplinary framework for participatory modeling design and evaluation—What makes models effective participatory decision tools?

Baseflow response to climate variability induced droughts in the Apalachicola-Chattahoochee-Flint River Basin, U.S.A.

Pacific and Atlantic sea surface temperature influences on streamflow in the Apalachicola–Chattahoochee–Flint river basin

This paper serves as an example of transboundary water negotiations – what worked and what failed – in the three state conflict in the southeastern United States The states of Alabama, Florida, and Georgia have been involved in water negotiations since about the early 1970s leading to some successes and some failures This paper summarizes these experiences with the intention of providing generic “lessons learned” on multi-jurisdictional negotiation

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Steve Leitman

Papers

Pacific and Atlantic sea surface temperature influences on streamflow in the Apalachicola–Chattahoochee–Flint river basin

Lessons Learned from Transboundary Management Efforts in the Apalachicola—Chattahoochee—Flint Basin, USA