Category Archives: Urban Watersheds

Does watershed protection lower the cost of drinking water treatment?

Price JI, Heberling MT. The Effects of Source Water Quality on Drinking Water Treatment Costs: A Review and Synthesis of Empirical Literature. Ecological Economics 2018 Sep 3;151:195-209. doi: 10.1016/j.ecolecon.2018.04.014.

Watershed protection, and associated in situ water quality improvements, has received considerable attention as a means for mitigating health risks and avoiding expenditures at drinking water treatment plants (DWTPs). This study reviews the literature linking source water quality to DWTP expenditures. For each study, we report information on the modeling approach, data structure, definition of treatment costs and water quality, and statistical methods. We then extract elasticities indicating the percentage change in drinking water treatment costs resulting from a 1% change in water quality. Forty-six elasticities are obtained for various water quality parameters, such as turbidity, total organic carbon (TOC), nitrogen, sediment loading, and phosphorus loading. An additional 29 elasticities are obtained for land use classification (e.g., forest, agricultural, urban), which often proxy source water quality. Findings indicate relatively large ranges in the estimated elasticities of most parameters and land use classifications. However, average elasticities are smaller and ranges typically narrower for studies that incorporated control variables consistent with economic theory in their models. We discuss the implications of these findings for a DWTP’s incentive to engage in source water protection and highlight gaps in the literature.

Real-time Modeling and Visualized Monitoring of Urban Water Drinking Quality

Weiwu Yan, Jialong Li, Xiaohui Bai. Comprehensive assessment and visualized monitoring of urban drinking water quality. Chemometrics and Intelligent Laboratory Systems, Volume 155, 15 July 2016, Pages 26-35.

It is important to comprehensively assess and monitor drinking water quality to ensure a safe and clean drinking water supply. A real-time comprehensive assessment based on modeling and visualized monitoring of urban drinking water quality is discussed in this paper. A weighted aggregative index, a method for evaluating problems with multiple indexes, is used to evaluate the drinking water quality in Shanghai city. Considering the disadvantages of the subjective and objective weighted methods, a combined weighted index method called the geometric mean weighted method is proposed to assign weights to the indexes of drinking water in order to make the weight distribution more scientific, reasonable and robust. Then, the drinking water quality is displayed visually by a distribution map of drinking water quality based on a geographic information system (GIS). This real application shows that the proposed methods are effective and promising for the assessment and monitoring of water quality.

Urban Flood Forecasting under Rapid Urbanization, China

Chen Y, Zhou H, Zhang H, Du G, Zhou J. Urban flood risk warning under rapid urbanization. Environmental Research. 2015 Mar 10. pii: S0013-9351(15)00062-6. doi: 10.1016/j.envres.2015.02.028.

In the past decades, China has observed rapid urbanization, the nation’s urban population reached 50% in 2000, and is still in steady increase. Rapid urbanization in China has an adverse impact on urban hydrological processes, particularly in increasing the urban flood risks and causing serious urban flooding losses. Urban flooding also increases health risks such as causing epidemic disease break out, polluting drinking water and damaging the living environment. In the highly urbanized area, non-engineering measurement is the main way for managing urban flood risk, such as flood risk warning. There is no mature method and pilot study for urban flood risk warning, the purpose of this study is to propose the urban flood risk warning method for the rapidly urbanized Chinese cities. This paper first presented an urban flood forecasting model, which produces urban flood inundation index for urban flood risk warning. The model has 5 modules. The drainage system and grid dividing module divides the whole city terrain into drainage systems according to its first-order river system, and delineates the drainage system into grids based on the spatial structure with irregular gridding technique; the precipitation assimilation module assimilates precipitation for every grids which is used as the model input, which could either be the radar based precipitation estimation or interpolated one from rain gauges; runoff production module classifies the surface into pervious and impervious surface, and employs different methods to calculate the runoff respectively; surface runoff routing module routes the surface runoff and determines the inundation index. The routing on surface grid is calculated according to the two dimensional shallow water unsteady flow algorithm, the routing on land channel and special channel is calculated according to the one dimensional unsteady flow algorithm. This paper then proposed the urban flood risk warning method that is called DPSIR model based multiple index fuzzy evaluation warning method, and referred to as DMFEW method. DMFEW first selects 5 evaluation indexes based on the DPSIR model for flood risk warning evaluation, including driving force index, pressure index, state index, impact index and response index. Based on the values of all evaluation indexes, one evaluation index for the whole system evaluation result is determined by using the fuzzy comprehensive evaluation method. The flood risk level is divided into 4 levels, having Level 1 the most serious. Every evaluation index is also categorized as 4 levels, and a linear fuzzy subjection function is proposed to do the fuzzy comprehensive evaluation. Dongguan City is used as the study case to validate the proposed method. The urban flood forecasting model is set up with the topographic data, the city map, the underground pipelines and land cover types, and two flood events are simulated with observed precipitation, one is interpolated from the rain gauges data, and another is estimated by digital weather radar. The simulated results are compared with the investigated water depth, and the results show the model has very good performances. The results are further used for the flood risk warning simulation, and are very reasonable.

Paper is here (fee).

Emerging Contaminants in the Urban Water Cycle

Pal A, He Y, Jekel M, Reinhard M, Gin KY. Emerging contaminants of public health significance as water quality indicator compounds in the urban water cycle. Environment international. 2014 Oct;71:46-62. doi: 10.1016/j.envint.2014.05.025.

The contamination of the urban water cycle (UWC) with a wide array of emerging organic compounds (EOCs) increases with urbanization and population density. To produce drinking water from the UWC requires close examination of their sources, occurrence, pathways, and health effects and the efficacy of wastewater treatment and natural attenuation processes that may occur in surface water bodies and groundwater. This paper researches in details the structure of the UWC and investigates the routes by which the water cycle is increasingly contaminated with compounds generated from various anthropogenic activities. Along with a thorough survey of chemicals representing compound classes such as hormones, antibiotics, surfactants, endocrine disruptors, human and veterinary pharmaceuticals, X-ray contrast media, pesticides and metabolites, disinfection-by-products, algal toxins and taste-and-odor compounds, this paper provides a comprehensive and holistic review of the occurrence, fate, transport and potential health impact of the emerging organic contaminants of the UWC. This study also illustrates the widespread distribution of the emerging organic contaminants in the different aortas of the ecosystem and focuses on future research needs.

Surface water quality models

Wang Q, Li S, Jia P, Qi C, Ding F.  A review of surface water quality models. ScientificWorldJournal. 2013 Jun 17;2013:231768. doi: 10.1155/2013/231768.

231768.fig.001

Surface water quality models can be useful tools to simulate and predict the levels, distributions, and risks of chemical pollutants in a given waterbody. The modeling results from these models under different pollution scenarios are very important components of environmental impact assessment and can provide a basis and technique support for environmental management agencies to make right decisions. Whether the model results are rightor not can impact the reasonability and scientificity of the authorized construct projects and the availability of pollution control measures. We reviewed the development of surface water quality models at three stages and analyzed the suitability, precisions, and methods among different models. Standardization of water quality models can help environmental management agencies guarantee the consistency in application of water quality models for regulatory purposes. We concluded the status of standardization of these models in developed countries and put forward available measures for the standardization of these surface water quality models, especially in developing countries.

Click here for full paper (Open Source).

USGS publishes fictional projections of climate hydrologic effects

The US Geological Survey (USGS), a primary driver of “climate change” dogma, is publishing basin studies based on downscaled General Circulation Models (GCMs). USGS’s Precipitation Runoff Modeling System (PRMS) applies information from the downscaled GCM projections to local watersheds, where impacts of climate change on water availability will depend on local conditions. Prior posts on this blog and other blogs have discussed ad nauseum the scientific limitations of GCM downscaling and the research-nature of these efforts. Planners can believe these projections, but there is no scientific data supporting them.

So far, USGS has applied these models to fourteen basins, including (click on basin for the report):

The quote below from the press release is revealing….we knew there is “not just one response” without having to spend money on fictionalized hydrologic projections….. 

“The advantage of these studies is that they demonstrate that there is not just one hydrological response to climate change: the predictions account for essential local factors that will govern the timing, severity, and type of impact, whether it be water shortage, drought, or flood,” said USGS Director Marcia McNutt.

The USGS claims to be able to project hydrological reponses that should be observable….without having demonstrated the ability of such models to do so on existing data with any degree of confidence.

As typical of USGS reports, they are professionally published and are impressive. But this does not change the limitations of the analyses described. Modeling efforts like this are useful for advancing research…..but not for responsible science-based water supply planning.

Click here for more…..

Marin Municipal Water District (CA) celebrates 100 years

The Marin Municipal Water District (MMWD) serves 185,000 customers from Sausalito to San Rafael in California. Drinking water is provided from seven reservoirs, with a 19,000 acre of watershed on Mount Tamalpais. Click here for a news report on MMWD’s 100 year anniversary.