Santosh R. Ghimire

Sensitivity analysis of municipal drinking water distribution system energy use to system properties

Municipal Drinking Water Distribution Systems (MDWDSs) consume a significant quantity of energy to transport water, thereby exacerbating greenhouse gas emissions and global climate change. The current study is a sensitivity analysis that uses a network solver to quantify energy savings due to the alteration of three system properties—system-wide water demand, storage tank parameters (maximum water level, diameter, elevation), and pumping stations (horsepower, number of boosters, and their locations) of seven diverse MDWDSs. It was found that a 50% reduction in water demand, main pump horsepower, and booster horsepower resulted in an average energy savings of 47, 41, and 9.5% respectively, for the seven systems analyzed. Other properties examined showed insignificant savings. Even though an individual system analysis is more conclusive, this sensitivity analysis can guide optimization studies to focus on the most sensitive properties.

HEURISTIC METHOD FOR THE BATTLE OF THE WATER NETWORK SENSORS: DEMAND-BASED APPROACH

There is interest in optimally locating water quality sensors in a water distribution system due to possible terrorist injections of a contaminant. This paper is part of a contest for the 8 th Water Distribution System Analysis Symposium entitled “Battle of the Water Sensor Networks” (BWSN), which asks contestants to propose sensor designs for two networks and two numbers of sensors. The method of sensor location selection described here is a demand-based approach in which sensors are located at the junctions with the highest demands. The rationale behind this method is that an injection of a contaminant will be advected by the flow, which goes toward the high-demand locations. Therefore, demand is a surrogate for contaminant concentration. In addition, the mass of contaminant released from the system is a function of demand. The 5-sensor and 20-sensor designs are presented in the paper. Designs were identical for all of the contamination scenarios contained in the contest, thereby demonstrating the simplicity and uniformity of the sensor location designs.

ISSUES IN ENERGY CONSUMPTION BY MUNICIPAL DRINKING WATER DISTRIBUTION SYSTEMS

Energy consumption is a large cost for municipal water distribution system utilities. Approximately 80% of municipal water processing and distribution costs are for electricity. There are several components that contribute to the total cost of drinking water. In the US, 4% of the nation’s electricity use goes towards moving and treating water and wastewater. According to the EPA, drinking water and wastewater systems spend about

Effective-Power-Ranking Algorithm for Energy and Greenhouse Gas Reduction in Water Distribution Systems through Pipe Enhancement

4 billion a year on energy to pump, treat, deliver, collect, and clean drinking water. If drinking water and wastewater systems reduce energy use by just 10 percent through cost-effective investments in energy efficiency, collectively they would save about

Stormwater Low-Impact Development: A Call to Arms for Hydraulic Engineers

400 million and 5 billion kWh annually. The paper presented here will discuss the current issues in energy consumption, case studies of approaches to energy reduction, solution procedures for optimizing energy use, and the possible use of renewable energy to possibly reduce the life-cycle cost for municipal drinking water distribution system utilities. This paper will aid utility managers in making sustainable energy management decisions.

FLOW-SEQUENTIAL SECTOR-SPECIFIC LUMPED ALGORITHM FOR WATER NETWORK CALIBRATION

AbstractMany global municipal water distribution systems (WDS) are in need of repair. To save energy and greenhouse gas emissions due to pumping, pipes that need to be replaced can be enhanced by being enlarged and made of a smoother material. To choose which pipes to thus enhance first given a limited budget, an algorithm is introduced based on enhancing the pipe that requires the most effective power, which is defined as the product of discharge, specific weight, and headloss. The algorithm was verified with complete enumeration, life-cycle, and environmental-impact modeling on seven realistic WDSs. It was found that the additional cost and greenhouse gasses (GHG) emitted from purchasing and manufacturing a larger pipe are quickly recovered by the reduced cost and GHG emissions due to less pumping being required. The proposed pipe enhancement should be verified with modeling, however, since increased payback periods for both costs and GHG emissions can result if an increase in pipe size causes water to ...

Experiments Identifying Scour-Inducing Flow Patterns at a Gated Weir Stilling Basin

Conventional stormwater management teaches that the primary concern is to remove the water from the site being developed (Ahiablame et al. 2012). Therefore, in order to reduce the risk of flooding, impervious surfaces such as parking lots and buildings are fitted with drainage structures made of impervious materials (pipes or concrete). After the water is collected, it is discharged to the nearest stream or lake. This method prevents local flooding, but it can cause problems downstream such as increased erosion and flooding. Since the conventional stormwater facility on developed property is concerned with removing water as quickly as possible, it changes the hydrology of the site being developed (HolmanDodds et al. 2003). The increase in impervious surfaces reduces infiltration that would have occurred at a site, increasing the peak runoff that the receiving waters must handle, sometimes by multiple times as much over the natural runoff (Hood et al. 2007). Also, the stormwater runoff will carry suspended solids and pollutants from the site into the receiving water (Davis et al. 2009). For this reason, in recent years there has been significant study on establishing Low-Impact Development (LID) (Ahiablame et al. 2012; Davis and McCuen 2005), the goal of which is to mimic the natural hydrology of a site postdevelopment (Davis 2005) or to reduce pollutants entering waterbodies by altering the land use (Barfield et al. 2008). This is accomplished by promoting infiltration and detention, as well as removing pollutants when possible (Garrett 2007). Engineers and scientists are now collaborating to produce more-sustainable LID techniques such that the developed site will not affect runoff (Bedan and Clausen 2009) and watersheds are being restored using LID techniques (Guo 2010; Chang 2010). The purpose of the current work is to (1) briefly review issues involved in LID, (2) illuminate hydraulic issues that may lead to future modeling advances, and (3) encourage hydraulic engineers to lead in this rapidly developing field. Several LID techniques along with hydraulic issues that need addressed will be discussed next in an effort to encourage hydraulic engineers to participate in this rapidly-expanding field.

Network Modeling to Demonstrate Efficacy of Improved Water Quality Monitoring

As part of the Battle of the Water Calibration Networks (BWCN) an algorithm termed the Flowsequential Sector-specific Lumped Algorithm (FSL) is employed to determine a set of roughness values for each pipe and the user demands at every junction of the system used for the contest. The FSL algorithm for roughness determination lumps all pipes in each pressure zone (similar to given district metering areas) together and alters the roughness values proportionately as a whole. Fine tuning with the pipes adjacent to the known pressure nodes is the final step. This is done iteratively from the furthest upstream pressure zone to the furthest downstream pressure zone and repeated until a satisfactory agreement between predicted and measured value is attained. Age-dependent roughness values are initially assigned according to literature values. The network in the demand calibration phase of the study was handled as a whole. Demand values based on the monthly demands were provided, and a common residential diurnal pattern found in the literature was assigned as an initial value for the extended period simulation. The demand pattern was adjusted for select hours to calibrate the network to match the SCADA data. This was followed by the fine tuning of the demand pattern values. It was found that the calibration process resulted in mean absolute relative errors in pressure of approximately 0.1 when adjusting roughness values for calibration with fire flow tests and 0.21 for discharge and tank level values in the adjustment of demand values.

The Battle of the Water Sensor Networks (BWSN): A Design Challenge for Engineers and Algorithms

Excessive scour downstream of stilling basins poses significant risk of structural failure. This problem was experimentally investigated at Michigan Technological University in a Froude-scaled, physical model of one such structure operated by the South Florida Water Management District. Detailed flow measurements were taken on a flow scenario that resulted in high scour, namely that of a high flow rate and upstream headwater depth and a low tailwater depth. Equilibrium bed scour and velocity measurements were taken using an Acoustic Doppler Velocimeter. Velocity data was used to construct a vector plot in order to identify which flow components contribute to the scour hole. It was found that downward-plunging flow upon leaving the stilling basin induces the primary scour hole.

Battle of the water calibration networks

Water quality is a prime concern in the US and the world. In particular, the disinfection and security of water have become important for everyday health and terrorist risk reduction. To mitigate the effects of compromised water quality it is apparent that the quality and frequency of water quality data collection are of primary importance. In order to demonstrate the need for improved water quality data collection, a network solver (EPANET) has been used to model the response of the system to an inappropriate addition of chlorine at the water treatment plant. Simulations have been performed on a real municipal water distribution system (Baraga, MI) of approximately 100 nodes and a population of 9,000 and contaminant plume behavior simulated at select network locations. Concentration levels at selected nodes around the network were examined for time of exposure to unacceptable chlorine levels. It was found that having improved monitoring could reduce response time and human exposure to contamination by approximately 95%.