Journal of Water Resources Planning and Management

The management of large river basins, such as the Yellow River Basin (YRB) in China, is complicated by distributed, localized decision processes and by mechanisms that coordinate local decisions and manage basin-level issues. Since 1998, the Yellow River Conservancy Commission (YRCC) has launched the Unified Water Flow Regulation (UWFR) as a centralized controlling mechanism that enforces an upper limit on water withdrawals (water use permits) for eight provinces located in the basin. The implementation of UWFR has maintained a prescribed minimum flow in the downstream channel and avoided the flow cutoff events that occurred every year between 1972 and 1998. This study attempts to explore the socioeconomic and environmental consequences of the regulation and test plans to improve water allocation management in the YRB. A decentralized optimization is combined with a multipleagent system (MAS) framework for the YRB, in which water users, reservoirs, and downstream ecological zones are defined as agents. This method iteratively determines water prices for each water use agent in the context of water market. The proposed water market scenario shows possible improvements of UWFR with respect to social, economic, and environmental objectives.

Spring Valley, Nevada, is one of several areas proposed for the pumping and export of ground-water to Las Vegas by the Southern Nevada Water Authority. Long-term annual-to-decadal variability of water supply in the region is not well understood, so tree-ring records were used to develop a longer baseline of variability in streamflow and drought episodes. Long-lived (up to about 600 years), climatically sensitive single-leaf pinyon pine (Pinus monophylla) trees within the Cleve Creek watershed provided a 550-year (1458–2007) tree-ring chronology that was compared to water-year mean monthly runoff from USGS gauge 10243700. Using a proxy record from within the watershed under study increased confidence in the statistical relationships used for streamflow reconstruction. Linear correlation between the tree-ring chronology and the streamflow record over 34 years of overlap was 0.73, explaining 53% of the instrumental variance. After comparison with multiple linear regression and linear regression with transformed data, the line of organic correlation (LOC) method was used to develop a streamflow reconstruction with water-year resolution from 1458 to 2007. During these 550 years, a total of 257 wet and dry episodes were quantified according to their duration, magnitude, and peak. The longest episode was 1848–1855 (an 8-year wet spell); the greatest magnitude belonged to the drought of the mid-1600s (1652–1655); the three highest peaks all corresponded to dry episodes, 1506–1508, 1590, and 1933–1936. Using a numerical scoring rule, the 1930s drought (1933–1936) was in eighth position, making it one of the most remarkable episodes in the past half millennium. This result is not entirely consistent with recent dendroclimatic reconstructions for the eastern Sierra, suggesting that regional drought severity varies by locality within the Great Basin. Evaluating the responses of trees at multiple elevations to various local climate and hydrological parameters through in situ monitoring will help refine tree-ring reconstructions of past ecohydrological conditions.

A geographical information system (GIS)-based decision support system has been developed for dam-break flood management based on realistic two-dimensional flood simulations. With the ability of interacting with and using classified remote sensing (RS) image layers and other GIS feature layers like zoning layer, survey database, and census block boundaries, it can be used for flood damage calculations and loss-of-life estimations. It also provides a user-friendly interface that allows construction of user-defined criteria, such as stage-damage curves, running computations, and visualization of the results. The Monte Carlo Simulation method is used to take into account uncertainties in various variables and parameters, and event tree analysis is used to estimate the population dynamics. The analysis of a dam-break flood management strategy for Sinclair Dam in Milledgeville, Georgia is chosen as a case study to demonstrate the capabilities of the decision support system. The test results validated by HEC-RAS and HEC-FDA software indicate that this new system provides a very versatile and reliable environment for estimating various flood damage and may greatly enhance decision-making processes for future design of flood proofing facilities.

The flow regime of rivers is a complex but important measure of environmental quality and one that can be significantly impacted by conventional hydropower generation. While traditional hydropower scheduling creates a periodicity in downstream flows corresponding to seasonal and daily electricity demand patterns, deregulated electricity markets may provide financial incentives to further alter flows, as utilities respond to hourly market dynamics. This study investigates the potential for deregulated markets to impact both a hydropower utility’s revenue stream and downstream flow regimes. Six operating scenarios are explored: (1–2) full-market participation (including real-time energy), with and without flow reregulation; (3) day-ahead market only; and (4–6) run-of-river operations (ROR), with and without flood control and flow reregulation. Results suggest that, relative to a day-ahead-only scenario, the scale of any differences in flow regime resulting from full-market participation is relatively small compared to the additional revenue-generating potential of such a strategy. Implementing a run-of-river policy frequently yields “more natural” flow regimes than the day-ahead only scenario; but, in some cases these improvements are modest, and in others the ROR scenarios exacerbate deviation from unregulated flows. Regardless, the effects of implementing an ROR strategy come at a substantial cost in terms of foregone hydropower revenue.

Solving water distribution network hydraulics depends to a great extent on demand representation in the related simulation models. The classical approach of simulation models for water distribution networks (WDNs) is described as demand-driven. The demands are fixed a priori in the model as an assumption or from field observations. Recently a more realist approach to predict the hydraulic system behavior, described as head/pressure-driven, better accounts for the fact that the demands depend in some ways on head status of the network. Thus, this paper presents a comprehensive view of demands in the enhanced WDN simulation models, including considerations of human-based, volume-based, uncontrolled orifice-based, and leakage-based demands as distinct types of network outflows. The paper proposes and discusses the representation of each type of demand in a comprehensive framework that is consistent with the hydraulic principles and the specific working condition.

This work describes a simple procedure for the analysis of water distribution system (WDS) performance. It is based on the reliability assessment of a WDS during failure states resulting from the unavailability of a pipe (maintenance or repair), taking into account the probability of the failure events. The procedure may consider changes in daily demand by using patterns defined to represent seasonal trends. Applying this method to a network with around 200 pipes demonstrates its usefulness, especially when the aim is to objectively compare different design solutions. The procedure takes also into account variations in design parameters such as an increase in water demand and/or a drop in hydraulic conductance resulting from pipe lining degradations (corrosion or deposits).

Pressure control is a key issue for the reduction of water loss through leakage in municipal water distribution networks (WDNs). The paper presents a general method to calibrate the proportional controllers for the real time control (RTC) of motorized pressure valves in WDNs to reduce leakage during ordinary operation. The method is based on the comprehensive dimensionless analysis of the behavior of simplified hydraulic systems under RTC scenarios. A numerical approach was used to derive a simple regressive relationship to tune the controller on the basis of the system dimensionless variables involved in the control process. The method was validated by application to a well-known bench-test water distribution network and compared with an existing literature calibration procedure. Results show that the proposed method allows for effective controller tuning and leads to performing leakage reduction-oriented real time control of pressures.