Developing a conceptual model for water accounting in peri-urban catchments

R. Singh, B. Maheshwari, H. M. Malano

    Research output: Chapter in Book / Conference PaperConference Paper

    10 Citations (Scopus)

    Abstract

    ![CDATA[Water accounting, i.e. identifying, quantifying and reporting information of water flow in a system, is the first step towards formulating productive and sustainable water management strategies in a region. This requires a significant effort of monitoring, collecting and modelling hydro-meteorological information over both spatial and temporal scales. A number of catchment water balance models developed in Australia and overseas are capable of estimating runoff, evapotranspiration, and streamflow generated from rainfall received in a catchment. However, most existing catchment water balance models do not account for potable water supply, wastewater discharges and surface and groundwater extractions, and yet these components of surface water cycle significantly modify streamflow in peri-urban catchments such as the South Creek catchment in Western Sydney. The South Creek catchment, the main focus of this study, covers an area of around 625 km2 in gently undulating plains and low hills of Western Sydney. It is a typical example of a peri-urban catchment with urban development over nearly 20% of the land area, and agriculture activities over nearly 17% of the land area. The urban areas in the catchment are serviced with potable water supply from dams outside the catchment, and there are five sewage treatment plants which discharge treated effluent into the South Creek and its tributaries. There are also annual access entitlements to extract water from surface water and groundwater sources mainly for irrigation purposes. In this paper, we describe the development of a simple conceptual water balance model to account for rainfall, runoff, evapotranspiration, potable water supply, wastewater discharges and surface water and groundwater extractions in a peri-urban catchment. The rainfall-runoff (from infiltration excess, saturation excess and baseflow) and evapotranspiration are simulated using a daily time step rainfall-runoff model, i.e. SIMHYD, for both pervious and impervious surfaces in the catchment. The developed model further combines the modelling of daily rainfall-runoff with monthly potable water supply, wastewater flows, and surface and groundwater extractions to simulate complete surface water cycle of a peri-urban catchment. The input data for the model include daily rainfall, daily potential evapotranspiration, monthly potable water supply, and annual surface water and groundwater access entitlements. Using the annual surface water and groundwater access entitlements as input, the model estimates monthly surface and groundwater extraction amounts depending on water requirement and water availability in the catchment. The model outputs, on a monthly time-step, includes runoff from infiltration excess, saturation excess and baseflow over pervious areas; stormwater from impervious areas, evapotranspiration from both pervious and impervious areas; residential, non-residential and primary production water use, and monthly surface water and groundwater extractions. The estimated monthly residential and non-residential water uses are further separated into the indoor and outdoor components, and finally estimated are the monthly wastewater discharges and streamflow in a catchment. The developed conceptual water balance model has been tested to estimate monthly water balance components of surface water cycle in the South Creek and its subcatchments over 15 years period (1992 to 2006). The calculated statistical measures such as the coefficient of efficiency (E), the coefficient of determination (R2), the ratio of mean simulated and observed (Y) and the coefficient of mass residual (CRM) between monthly observed and simulated wastewater discharges, and between monthly observed and simulated streamflow suggest that the model satisfactorily reproduced monthly wastewater discharges and streamflow in the South Creek and its tributaries. The developed conceptual water balance model could be very useful for water accounting or hydrological characterisation, and for simulating the impact of increased impervious surface and potable water supply due to urbanization, and projected climate change on surface water cycle of a peri-urban catchment.]]
    Original languageEnglish
    Title of host publication18th World IMACS / MODSIM Congress, Cairns, Australia 13-17 July 2009
    Pages3654-3660
    Number of pages7
    Publication statusPublished - 2009
    EventWorld IMACS Congress and MODSIM09 International Congress on Modelling and Simulation -
    Duration: 1 Jan 2009 → …

    Conference

    ConferenceWorld IMACS Congress and MODSIM09 International Congress on Modelling and Simulation
    Period1/01/09 → …

    Keywords

    • Australia
    • Centre for Western Sydney
    • New South Wales
    • South Creek (N.S.W.)
    • Western Sydney (N.S.W.)
    • ecology
    • environment and sustainability
    • infrastructure (economics)
    • runoff
    • water supply

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