The Use of chloramines to eradicate quagga mussel larvae

Quagga Mussels, Dressenia bugensis, are a growing problem in the western United States, particularly in their ability to infest underwater infrastructures and clog water intake pipes and screens of power and treatment plants. Chlorine has been found to be the most effective chemical to get rid of veligers (planktonic larval form of quagga mussels) in the pipes. However, chlorine leaves a residue called trihalomethane, which is a carcinogen at higher concentrations. The purpose of this project is to test the effectiveness of an alternate chemical, chloramines (chlorine and ammonia), which leaves behind little to no residual trihalomethane. Upon experimentation with various dosages of chloramines, it was found that 1.0 mg/l effectively kills approximately 97% of the veligers after an exposure time of approximately 4 hours. Our results provide critical information needed to replace the use of harmful chlorines in drinking water systems

Assessment of coliform bacteria from point and nonpoint sources in the Las Vegas Wash

This project focuses on an assessment of coliform bacteria from point and non point sources in Las Vegas Wash. Correlations between land use related runoffs, nutrients and organic matter loading and total coliform will be studied. Data will be collected for both daily low and high flow events. Sampling locations will cover all major land use types such as golf course, hotels, hospitals, residential areas, etc., at both the main Wash and its tributaries

Climate Change in the Nepal Himalayas: What we know and what we need to know

This study reports synthesis of a systematic literature review on climate change observations, projections, impacts, and research gaps and needs in the Nepal Himalayas. The major findings on climate change observations are rising temperature trends across all geographical regions in Nepal, increasing occurrences of temperature and precipitation extremes, increasing loss of glacier mass, and increase in glacier lake formations. Literature on nationwide trend analysis report lack of consistent long-term trend in precipitation, contrary to others at watershed scale, which show trend in both directions. A study on stream-flow trend in Nepal suggests absence of stream-flow trend in most of the stations and general lack of spatial trend

Point and nonpoint source analysis of nutrients, metals, and pathogens in the sediment and water column in Las Vegas Wash

Formerly an ephemeral watercourse, Las Vegas Wash is now a perennial system due to urban runoff and wastewater treatment plant (WWP) effluent. Las Vegas Wash flows into Lake Mead, where the discharge point is only a few miles upstream of Las Vegas’ main water intake. This small water cycle establishes the necessity to evaluate water quality especially due to non point sources pollution, wherein my research lies. Several points along Las Vegas Wash upstream and downstream of WWP have been chosen to represent different landuse types such as commercial, residential, wastewater treatment plants, etc. At each location, parameters including arsenic, selenium, nitrogen, phosphorus, total organic carbon, bacteria, and fecal coliforms are to be analyzed and compared for the influence of landuse change on both sediments and water

Diverse responses of hydrodynamics, nutrients and algal biomass to water diversion in a eutrophic shallow lake

Water diversion has been increasingly applied to accelerate lake water exchange and alleviate urgent water crisis. However, effects of water diversion on water exchange and water quality for eutrophic lakes remain controversial. In this study, a three-dimensional hydrodynamic-water quality-sediment diagenesis model has been developed to assess effects of water diversion on hydrodynamics and water quality in eutrophic shallow Lake Wanghu. Results suggested that water diversion could dramatically promote water exchange and reduce residence time in most lake regions but its influence on water quality was diverse. A water transferring flow rate of 20–30 m3/s could reduce water age to 40–58 days during regular water diversion operation, whereas a high transferring flow rate of 100 m3/s was the best for emergency operation in late spring before the wet season. Moreover, nutrients and Chlorophyll-a exhibited notable spatial heterogeneity in improvement efficiency. Nutrients level in the donating system was a prerequisite to the relationship among water transport time scales, nutrients, and algal biomass in this eutrophic lake. During a clean water diversion, nutrients and algal biomass were positively associated with water age. However, when the donating system contained high level of nutrients, accumulated nutrients in the lake may still trigger algal bloom after a temporary relief due to flushing effect. Therefore, these water diversion strategies could be applied to guide a sustainable management of eutrophic Lake Wanghu in terms of transferring flow rate, wind fields, water quality in the donating system, transferring operation, and water diversion route.acceptedVersionPeer reviewe

Climate Change in the Himalayas: Current State of Knowledge

This paper reviews the literature on the potential biophysical and economic impacts of climate change in the Himalayas. Existing observations indicate that the temperature is rising at a higher rate in Nepal and Chinese regions of the Himalayas compared with rest of the Himalayas. A declining trend of monsoon in the western Indian Himalayas and an increasing trend in the eastern Indian Himalayas have been observed, whereas increasing precipitation and stream flow in many parts of Tibetan Plateau are noted. Glaciers in both the eastern and western Himalayas are mostly retreating, but the majority of the glaciers in Karakorum are either stable or advancing slowly. Expansion of glacier lakes is reported, with the highest rate in Nepal and Bhutan. Most literature predicts increases in temperature and monsoon precipitations and decreases in winter precipitations in the future thereby leading to monsoon flooding and increased sediments in stream flow. Available hydrological simulations indicate reduced rainfall and shrinkage of glacier thereby leading to shortage of water supply for power generation and irrigation in winter particularly in highly glaciated basins. Projected economic impacts of glacial lake outburst floods can be substantial on the developed river basin with infrastructures and population centers. However, there is a clear gap in knowledge of economic impacts of climate change in the Himalayas

Detention basins as best management practices for water quality control in an arid region

Flood control detention basins (DBs) can act as water quality control structures or best management practices (BMPs). A key pollutant that DBs serve to settle out is particulate phosphorus, which adsorbs onto sediment. This study examines the sediment phosphorus concentration and its relationship with the particle size of sediment microcosms from pre- and post-rain event samples obtained from six DBs located in Clark County, Nevada. DBs were allotted a land use classification to determine if there was a correlation between the sediment phosphorus concentration and surrounding land use. The curve number method was used to calculate the runoff and subsequent phosphorus carried into the DB by the runoff. Our data show sediment phosphorus concentrations to be highest in soils from undeveloped areas. Runoff amount also plays a substantial role in determining the amount of phosphorus brought into the DB by sediment. This research has implications for improvement of water quality in arid regions

Characterization of first flush phenomenon in an urban stormwater runoff: A case study of Flamingo Tropicana watershed in Las Vegas valley

This case study deals with the characterization of pollutants in runoff for major storm events in an urban watershed in Las Vegas, NV. The occurrence of first flush was checked based on several first flush definitions. Grab samples were collected from 6 major storm events at the Flamingo Tropicana Wash during a period from January 2008 to December 2009. Correlation of non point pollutants such as total phosphorous (TP), total nitrogen (TN) and total suspended solids (TSS) with runoff was derived through the use of hydrographs and pollutographs. The concentration of grab samples at different stages of the same storm event varied considerably. Based on concentration, the higher strength of first flush was seen in case of TSS and lower in TN and TP. The analysis of cumulative runoff volume vs. pollutant load showed that the first 30% of the intercepted runoff volume transported 44% of TN, 34% of TP and 35% of TSS respectively. The first 20%, 30%, 50% and 80% of runoff volume transported 28%, 38%, 58% and 85% mass of the pollutants respectively. Based on first flush definitions, the storm events showed the presence of moderate first flush. The ADD was found to have a direct impact on build up and wash up of TSS. The rainfall events with higher water depths were more polluted for TSS than the less intense events. The findings will be helpful in retrofitting or designing BMPs, developing other treatment works and control strategies to enhance the water quality standards, and reducing the pollutant loads in surface water bodies

Drought in the Western United States: Its Connections with Large-Scale Oceanic Oscillations

In this paper, we applied the Empirical Orthogonal Function (EOF) analysis on a drought index expressed as consecutive dry days (CDD) to identify the drought variability in western United States. Based on the EOF analysis, correlation maps were generated between the leading principle component (PC) of seasonal CDD and sea surface temperature (SST) anomalies to explore the dynamic context of the leading modes in CDD. The EOF analysis indicates that the spatiotemporal pattern of winter CDD is related to an integrated impact from El Niño⁻Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and Atlantic Multi-decadal Oscillation (AMO), while summer CDD is mainly controlled by PDO phases. We also calculated seasonal CDD anomalies during selected climatic phases to further evaluate the impacts of large-scale oceanic oscillation on the spatial pattern of droughts. We found that AMO+/PDO− will contribute to a consistent drought condition during the winter in the western United States. El Niño will bring a dry winter to the northern part of western United States while La Niña will bring a dry winter to the southern part. During El Niño years, the drought center changes with the type of El Niño events. Considering the future states of the examined ocean oscillations, we suggest possible drier than normal conditions in the western United States for upcoming decades, and moreover, an intensified drought for the coast areas of the north Pacific region and upper Mississippi River Basin