Research On Sediments And Nutrient Export Modules In George Catchment

Sources of Nutrient and Sediment Loads

This assignment is setup as a review article and from the title “Water quality improvement by good system design: A review of modelling approaches”. From the title, it has several key elements, Water Quality, System and Modelling. By the way you need to think about what is a System, for example, Catchment is a system. When you look at an assignment or task, first, you may need to think about alternative interpretation, such as we can convert it into how to apply modelling to improve water quality – a catchment case study. Of course you can have more alternatives, thinking of alternative can ensure you don’t go to the wrong direction. This is an important step.
 
The term catchment can be referred to natural catchment or urban catchment which can capture / collect water. Wastewater which we are not covering in the lecture series is collected from the catchment (network of sewer pipes). I made it very flexible in terms of marking and I basically accept any interpretations of the title. It is designed to allow you to explore in this modelling area.
 
In our lecture slides and discussion during the lecture in relation to explain what is required for assignment 1, I mentioned combination of two processes. If catchment is viewed as a treatment device, water quality can be improved by the process. In addition, I like you to think about nowadays, modern society is working toward optimising energy use or optimising the use of resources, it is very common that we need to look at the most effective way to treat water, it is often by combining two processes together and get the best for each process. This is the reason I like you to think about combining two processes, as they are linking to each other, we need to have an open mind about this. Later when you are in the workforce, in case you were asked to design a system, you may consider the option of combining two processes to provide the most cost effective solution.
 
I believe when you first see the title, you were lost, the reason we made it open is because we like to provide you the option to select a topic that you are interested or you see it will help to enrich your knowledge in a particular area which can be useful for your future career. From your assignments, I believe we have achieved this, we have a very good range of case studies. When you can learn and understand more during this assignment, that's the purpose.
 
As it is a review article which uses source information as evidence for an argument, we like to look at how you put information together and illustrate your points, particularly we have been talking about data to decision. How you use your collected information and convert it into use information that can be used to inform decision. Even you have all the elements, a good review article is required to have a logical sequence and clear structure. Similar to what you have learnt in your research project that we need to highlight the knowledge gap from the current literature, what else you need to do to find the answer you need. In the workforce, I believe you will be involved in some forms of research, research may not be at the level of your research project, it may be just collecting information and prepare a recommendation. I believe this assignment can provide some trainings to cover this area.
 
One point I like to mention, are you just describe something or provide recommendation of something? To describe a process, an approach is not too hard, just collect the info and write it. To review / recommend a process, you need to fully understand the situation before you can make strong argument of what should be done.
 
Several times, I was asked by students about word count / word limit, if it is called word limit, then you cannot go more than the limit, when we submitting an article to the journal, usually we have word limit, even tables and figures are counted as words, some journals stated, each table is counted as 300 words. In this assignment, we used 2000 words (should be limited), in this case, you are OK to go a bit more to take the advantage of scoring more marks. Figures are not counted, therefore it would be good to put some figures to make the overall more presentable. I am sure you will be facing more situations later when you were asked to prepare progress reports, business cases, be sure, you follow the instructions and take the maximum allowed words / space to impress your employer.
 
I cannot provide you a model answer for this assignment. I hope you have gained some knowledge during the time that you worked on it. I have been mentioning job, workforce and work environment a lot, from my experience, it is not whether you have the knowledge or not, it is how you apply what you have learnt, both knowledge and methodology.

In the research work the concentration of the sediments and nutrients is considered the main problem to be solved. This report has extensively covered the sediments, hydrolytic and nutrient export modules that are included in the model of George catchment (Abbaspour et al 2015).

The report also included the sources that were used for data generation. In this modeling there was a suggestion that South and North George sub-catchment in the west regions were the potential sources of the nutrients and also sediments to the river George. This process of sedimentation has been through the hill erosion in the slopes. The potential sources of the nutrients were taken as Lower and Upper Sub catchment.Consequently,management actions that lower or reduce the erosions at the stream banks in the center of the catchment were fronted as the possible strategies to reduce the loadings of nutrients and sediments.

• To highlight water catchment areas
• To identify system that function to improve water quality

Scientific and very accurate information is required by the management to maintain and also improve the productivity of the natural resources .This improvement extend to the health status of these catchment areas. The Tasmanian Department of Primary industries is committed to use of detailed and very comprehensive information on the conditions of the resources of land and water. The research seeks to dig in the understanding of how the resources are linked and later becoming the basis of management decision on the catchment.

 The establishment of the effective water catchment policies and practices are normally based on the information regarding the catchment impacts on the river. The available information will provide the indicators for assessing the  performance effectiveness of the programs of the environment. In order to help in the making of the informed decisions, the project aims at developing a tool that is evidence- based. This tool will assist in the assessment of the relationship between the river health conditions and management action.

The presented report is considered part of the larger project that  demonstrates the existing processes related to the catchment management. The relevant actions can be integrated in the framework of decision making. The outcome of the project will help those making decisions to analyze the best options in terms of the cost and benefits that are associated with the improvements in the management of the catchment.

The report entails the research of the two years that predict  the changes in the loading of the nutrients and the sediments. The earlier sections have outlined the various approaches to the modeling of water quality. In the description is the representation of the physical and temporal variability of the models.

Hydrological models are biophysical models that function to predict the effects of the changes of the environment and also influence of human on the properties of water. These properties are chemical in the terms of quality and also physical in the terms of the quantity. The classification of the model can focus on the ground water or surface water. The classification however will depend on the way they tackle both temporal and spatial variability(Broekhuizen et al 2012).

Importance of Comprehensive Information for Management

System of classification that that is based on the way models represent spatial scales will provide a distinction between the distributed model and lumped models. In the lumped models, the catchment is considered as a single operational unit with its parameter and variables representing average values for the whole catchment. On the other hand, distributed models take into account variables as multiples when considering process of the catchment. The impacts are considered within the chosen geographical areas. In the semi distributed models, partial units with similar characteristics like land use are lumped with the other sub units that are large enough. Such units may include hydrological response units.

 This practice does not take into account the exact location of  each unit. The operations of the models are usually taking place at different temporal sacles.This implies that the models can either be event-based or just continous.They may focus on the longer changes or just daily changes. Australia possesses  a hydrological setting that is unique on its own and provides room for the development of the model of water quality. These models are built for the Australian water catchment areas.

Some of these unique features include high temporal and spatial variability in rainfall, with the regions that get very long months of drought as well as flooding events that are also common. There is concentration of the resources of water in the coastal areas that are actually populated. The present demand is actually exceeding the available water or just supply. The effects of the present large  dams on the water table are very much evident. These particular impacts extend to the ground water usage that leads to lowering of the water tables. The drying salinity on the ecosystem provides the contrast of this incidence that in turn reduces river flows. There is relatively little information on the process of biophysical in the Australia database. The information that is available regarding the properties of the soil, soil erosion and other relevant tools is very scarce(Chen et al 2012).

Water cast is also known as Water Contaminant Analysis and Simulation Tool. This is an empirical model that has been developed as part of the bigger Cooperative Research center for the  Catchment Hydrology. It is therefore considered as a catchment tool kit. Water CAST is part of that whole modeling of the catchment framework. This section incorporates a range of frame work of other sub models. This approach is very flexible and allows the model to change with the changes in the objectives of the modeling(Deus et al 2013).

 The spatial unit in this tool is called Functional Units,FUs.These functional units are identified as the regions of the catchment that possess similar process of the water quality. Different models can be assigned within each FU form examples there may be different models on the nutrient generation, rainfall runoff and filtering within a particular FU. The representation of the spatial variability is through definition of the sub catchments. These catchment may contain a number of FUs.The FU load from every FU that exist in a sub- catchment are lumped to form loads of sub- catchment that are later directed downstream through a structure of node-link. These nodes normally represent outlets of sub-catchment that may be places of interest like dam walls.

Using Evidence-Based Tools in Catchment Management

A lot of models have been developed to help in the prediction of the changes of the water quality in the catchments of Australia. It is interesting to note that only few models have been used to eliminate the sediments and nutrients loadings in Tasmania. The catchment water quality must be built on the knowledge that is already available from the records of Australia. The study has focused on very comprehensive and physically based- model that aims at solving problems on sub catchment scale. The model was also to be used in the identification of the potential sources of pollution. The selected model was Catch MODS to assist in the provision of the solution to the challenges at the George catchment (Dietzel  and Reichert 2012).

This particular model is designated and designed to simulate the present situation and also effects of that alternative actions of the management on the quality of receiving water at the scales of the catchment. This model is based on a structure of the node link in which the loading is from the upstream. These upstream sources  act as the feeder to the downstream. This framework can have a lot of hydrologic erosion and economic sub-models.

 The operation of the hydrological is on daily basis. The output is normally presented as constant state annual averages. The stream reaches and what follows is a record of catchment data in a coded form. The spatial disaggregation into the stream reaches and the record on the sub- catchment unit is taken. The catchment unit is based on the threshold that is set by the user. The definition of the modeled reach extent is done through use of this area threshold. It is also used to check on the topology of the networks of the river or the stream. Finally it is used in the determination of the associated areas of sub catchment.

This model is used in the prediction of the surface and sub-surface discharge that originate from the surface runoff. This technique is commonly referred to as HACRES.HACRES is considered a conceptual model with specific parameters. These parameters helps in the reflection of the lumped properties that are integral  with other factors.HACRES models always give very many different response. Some of these responses received have been classified into two (Fonseca et al.2015).

 On-linear loss module and linear module. In the non-linear module there is conversion of the  of the effective rainfall that come from the precipitation and also temperature time series information into recharge,rainfall,evaportation and effective rainfall.HACRES is utilized at the step of daily temperature and rainfall. The increase in such parameters increase lineally according to the selected sub-catchnment.The model daily discharge is used in the estimation of the steady state, characteristics of the flow that may include the quick flow, medium over bank  and the mean annual flow.

 These statistics provide  the basis of investigation of the quality of water using modeling of catchMODS.In order to estimate the mean flow for a subcatchment,sum of all the available records were divided by the number of days of the study. The cases of the impacts or effects of the changes in the climate can be achieved using by use of proper framework of the models(Ma et al 2012).

Water Quality Modelling in Australia

CatchMODs operates on two different platforms of modeling. The GIS software is used in the spatial processing of data. The data set from the GIS are used in the identification of  the topology of the catchment, data about the physical streams, distribution of the rainfall ,soil properties and finally the land use. The use of the GIS software allows for the spatial disaggregation of the catchment in accordance to the topology and mapping of the land use (Fan et al 2015).

 The application of the model to other sections or catchment is made possible is facilitated by the presence of the public data. The CatchMODs is built in a system that is object oriented and which utilizes Interactive Component Modeling System. This is a PC-based product that is used to support the intergration,rapid building and also deployment of the models. The system can as well incorporate the combination of the data and the models(Fonseca et al 2014).

 The ICMS retain the structure of the model that is underlying using simple interface of graphs. The graphical method is normally preferred since it assists in the simplification of the results presentation. In order to extract those information or data that is considered relevant for those different model users, several user-customized views are normally incorporated within the ICMS (Martin and McCutcheon 2018).

In the traditional evaluation, model simulation was used on the data sets. However comprehensive testing of the catchment of George water quality model was actually not feasible since there was limitation in the monitoring of the available data. The evaluation involved calibration and testing of the model of the hydrological component.The best test for validating nutrient model and sediment model was by the use of this technique.

Nutrient accumulation.

Table 1.Nutrient accumulation.

Conclusion

Many approaches of modeling are available to help in the estimation of the water quality challenges in the catchments of Australia. In this particular study, the framework of the modeling called Catch MODS was utilized to develop a model of nutrient and sediment for the catchment of George in Tasmania.CatchMODS includes stream sediment, hydrologic and nutrient export models that allows for the assessment of the variations in the sediment and nutrient loading to the Georges Bay especially under different alternatives of the management. The advantage of the model is relying on its flexibility structure that can readily be incorporated into other systems that are required in the study( Yao et ai.2015).

Spatial scales are represented by systems of classification in the form of models. These representations provide a clear distinction between the lumped models and the distributed model. In the lumped models, the catchment is considered as a single operational unit with its parameter and variables representing average values for the whole catchment. On the other hand, distributed models take into account variables as multiples when considering process of the catchment. They should therefore be given much attention.

References

Abbaspour, K.C., Rouholahnejad, E., Vaghefi, S., Srinivasan, R., Yang, H. and Kløve, B., 2015. A continental-scale hydrology and water quality model for Europe: Calibration and uncertainty of a high-resolution large-scale SWAT model. Journal of Hydrology, 524, pp.733-752.

Broekhuizen, N., Park, J.B., McBride, G.B. and Craggs, R.J., 2012. Modification, calibration and verification of the IWA River Water Quality Model to simulate a pilot-scale high rate algal pond. Water research, 46(9), pp.2911-2926.

Chen, Q., Wu, W., Blanckaert, K., Ma, J. and Huang, G., 2012. Optimization of water quality monitoring network in a large river by combining measurements, a numerical model and matter-element analyses. Journal of environmental management, 110, pp.116-124.

Deus, R., Brito, D., Mateus, M., Kenov, I., Fornaro, A., Neves, R. and Alves, C.N., 2013. Impact evaluation of a pisciculture in the Tucuruí reservoir (Pará, Brazil) using a two-dimensional water quality model. Journal of hydrology, 487, pp.1-12.

Dietzel, A. and Reichert, P., 2012. Calibration of computationally demanding and structurally uncertain models with an application to a lake water quality model. Environmental modelling & software, 38, pp.129-146.

Fan, F.M., Fleischmann, A.S., Collischonn, W., Ames, D.P. and Rigo, D., 2015. Large-scale analytical water quality model coupled with GIS for simulation of point sourced pollutant discharges. Environmental Modelling & Software, 64, pp.58-71.

Fonseca, A., Botelho, C., Boaventura, R.A. and Vilar, V.J., 2014. Integrated hydrological and water quality model for river management: a case study on Lena River. Science of the Total Environment, 485, pp.474-489.

Ma, L., Ahuja, L.R., Nolan, B.T., Malone, R.W., Trout, T.J. and Qi, Z., 2012. Root zone water quality model (RZWQM2): model use, calibration, and validation. Transactions of the ASABE, 55(4), pp.1425-1446.

Martin, J.L. and McCutcheon, S.C., 2018. Hydrodynamics and transport for water quality modeling. CRC Press.

Yao, H., Qian, X., Yin, H., Gao, H. and Wang, Y., 2015. Regional risk assessment for point source pollution based on a water quality model of the Taipu River, China. Risk Analysis, 35(2), pp.265-277.