Iqbal Hossain

Estimation of build-up and wash-off models parameters for an east-Australian catchment

This paper presents calibration of a catchment water quality model for continuous simulation of the water quality parameters from a catchment to the catchment outlet. The model is an integration of two sub-models: the hydrologic model and the water quality model. The hydrologic model estimates the amount of surface water runoff generated from the catchment during the storm event/ events. The water quality model estimates the transportation of the pollutants (total nitrogen, total phosphorus and suspended solids) from a particular catchment. The water quality model integrates two sub-processes: pollutants build-up and pollutants wash-off. The model calculates separate build-up and wash-off from pervious and impervious catchment surfaces. Rainfall and water quality data were collected for the Hotham creek catchment in Gold Coast, Australia. Runoff calculations from hydrologic model were compared with calculated discharges through widely used Australian models WBNM and DRAINS. Finally, based on measured water quality data, model water quality parameters were calibrated for the above-mentioned catchment.

Continuous simulation of suspended sediment through a stream section

This paper presents the development of a one-dimensional stream water quality model for the continuous simulation of suspended sediment transport and deposition processes along a particular stream section. The model integrates stream hydraulics and suspended sediment transport and deposition processes. The stream hydraulic model was developed using the Muskingum-Cunge method of channel routing. The well-known suspended sediment processes have been modified and integrated with the developed hydraulic model. The developed model was applied and simulated for the Saltwater Creek, Gold Coast, Australia. Sensitivity analysis of the model showed that all the particles’ characteristics within the incoming stream flows are important for the better prediction of suspended sediment loads.

Long-term seasonal rainfall forecasting: efficiency of linear modelling technique

Using the lagged (past) climate indices, including El Nino–Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) as input parameters and long-term spring rainfall as outputs, calibration and validation of the linear multiple regression (MR) models have been performed. Since Australian rainfall varies both temporally and spatially, the analysis on the linear MR models was performed on regional scale. These models show the capability of linear MR technique for long-term predictions of Western Australian spring rainfall. The emphasis was given to assess the statistical correlations between Western Australian spring rainfall and dominating large-scale climate modes. The efficiency of linear modelling technique was evaluated to predict seasonal rainfall forecasting. At the same time, the Pearson correlation (R), mean absolute error, root-mean-square error and Willmott index agreement (d) were used to assess the capability of MR models. The models which fulfilled the limits of statistical significances were used for the prediction of future spring rainfall using independent data set. The results indicate that during calibration periods maximum achievable correlations varied from 0.47 to 0.53 for the selected stations. In regard to predict peaks and troughs of rainfall time series, it was found that correlations between predicted and actual peaks varied from 0.82 to 0.94 and between predicted and actual troughs varied from 0.53 to 0.91.

Advances in Landscape Runoff Water Quality Modelling: A Review

As the recognition of the concept ‘Sustainable Development’ is increasing throughout the world, understanding the adverse impact of water quality parameters is highly important for the protection and improvement of aquatic environments from the impact of pollution. Therefore, the measurement of water quality parameters is required to protect and improve aquatic environments from the impact of pollution. The estimation of water quality parameters from direct field measurement is costly, time-consuming and sometimes impossible. Therefore, mathematical approaches of water quality models have become prevalent in recent years for the purpose of watershed management strategies. However, water quality model parameters vary not only spatially (i.e. catchment to catchment), but also temporally (i.e. differ among different rainfall events). Because depending upon the catchment characteristics such as soil permeability and initial pollutant loads, the impact of the actual land-use and management changes. There exists a wide range of water quality models to be used in managing water quantity and quality with respect to a variety of environmental impacts. This chapter presents a rigorous literature review regarding available catchment water quality modelling techniques developed in recent years. The goal is to identify the most effective water quality modelling technique which will help in the analysis, improvement and update of best management practices (BMPs). The selected modelling technique will help watershed management authorities to enable them implement economically viable and effective management and mitigation strategies to protect aquatic environments from the impact of pollution.

Climatic and spatial variabilities of potential rainwater savings and economic benefits for Kathmandu Valley

This paper presented a detailed analysis of potential rainwater savings and economic benefits under different climatic conditions in three regions of Kathmandu Valley in Nepal. Analysis was performed using an earlier validated daily water balance model, eTank utilising historical daily rainfall data from the selected regions. It was found that significant climatic and spatial variations exist in potential water savings. Another important finding is that even for neighbouring regions potential water savings are not proportional to the mean annual rainfalls of the regions. Also, it is found that considering a mix of dry, average and wet years, average payback periods of initial investments will vary among the regions from 2.5-3.5 years if the residents use their existing tanks for rainwater harvesting and from approximately 8-11 years if residents need to construct new tanks.

Continuous simulations of nutrients and BOD through a stream section

This paper presents development of a one-dimensional stream water quality model for the continuous simulations of suspended sediments, biochemical oxygen demand (BOD), total phosphorus (TP) and total nitrogen (TN) along a particular stream section. The model first integrates stream hydraulics and suspended sediments transport and deposition processes. Then computations of degradation of water quality parameters (BOD, TP and TN) are incorporated with the hydraulic-sediment transport model. The stream hydraulic model was developed using Muskingum-Cunge method of channel routing. The well known suspended sediment transport/deposition processes have been modified and integrated with the developed hydraulic model. The developed water quality model was applied and simulated for the Saltwater Creek, Gold Coast, Australia. Sensitivity analysis of the model showed that all the particles characteristics within incoming stream flows are important for the better prediction of suspended sediment loads.