Dharma Hagare

Quantification of Water Savings due to Drought Restrictions in Water Demand Forecasting Models

AbstractThis paper presents a technique to quantify water savings due to implementation of water restrictions by adopting water restriction indexes as a continuous numerical predictor variable in regression analysis. The adopted modeling technique compares four methods: yearly base difference method, weighted average method, before and after method, and expected use method. These methods are applied to single and multiple dwelling residential sectors in the Blue Mountains region, Australia. In the study, three forms of multiple regression techniques are adopted: raw data, semi-log, and log-log. The model performances are evaluated by a number of statistics such as relative error, Nash-Sutcliffe coefficient, and percentage bias. Moreover, the potential of using the water restriction savings and water conservation savings as continuous predictor variables in the water demand forecasting model is investigated. The performances of different modeling techniques are evaluated using split-sample and leave-one-ou...

A comparison of linear and nonlinear regression modelling for forecasting long term urban water demand : a case study for Blue Mountains Water Supply System in Australia

Prediction of long term water demand is necessary to assess the future adequacy of water resources, to attain an efficient allocation of water supplies among competing water users and to ensure long-term water sustainability. In order to predict future water demand and assess the effects of future climate and other factors on water demand, suitable mathematical models are needed. The study compares a multiple linear and nonlinear regression model to forecast monthly water demand in the Blue Mountains Water Supply System, Australia. The performance of the developed models are assessed through the relative error (RE), the coefficient of determination (R2), the percent bias (PBIAS) and the accuracy factor (Af), computed from the observed and model predicted water demand values. The RE, R2, PBIAS, Af , values are found to be 0.46%, 0.88, 2.07% and 1.04, respectively for multiple linear regression model and 2.49%, 0.30, -20.79% and 1.21, respectively for multiple nonlinear regression model. The results of the study show that the developed multiple linear regression model is capable of predicting water demand more accurately than multiple nonlinear regression model.

Use of recycled water for irrigation of open spaces : benefits and risks

The supply and sustainable use of recycled water may play an important role in enhancing urban water supplies in many water-scarce parts of industrialised countries like Australia because of the reduced treatment cost relative to seawater desalination and imported surface water. One such reuse option includes application of recycled water in the irrigation of urban open spaces. In 2009–2010, in Australia, the state-wide average of recycled water use in urban irrigation was 27.2 % and the nation-wide average was 14 % of the total recycled water produced. In Sydney, New South Wales (NSW) approximately 3.8 GL of recycled water is used for irrigating sports fields, golf courses, parks, landscapes and racecourses and, by 2015, it is expected that the recycled water will meet 12 % of the total water demand in greater Sydney. Despite significant benefits of recycled water, there are several concerns related to environmental and health risks. If not properly managed, recycled water could deteriorate soil health in terms of increased salinity and sodicity, heavy metal accumulation and decreased hydraulic conductivity of soil. However, there are tools to reduce risks due to urban irrigation using recycled water; such as, national and state-wide standards of recycled water quality for urban irrigation, sustainable urban water management strategy and the pollutant control framework. In this chapter, recycled water usage for urban open space irrigation was discussed in the international and national contexts. Also, benefits and risks associated with recycled water usage in open space irrigation were examined and possible control measures were discussed.