Assignment on the Global climate model

Introduction of Global climate model

Australian rainfall and runoff (ARR) guidelines are provided to incorporate information of climate changes in the regions. the approach uses different factors from the Global Climate Model (GCM) and it work for the future temperature and modify current IFD curves. In 2016, Intensity, Frequency Duration (IFD) design was used as a modified edition of Australian Rainfall and Runoff (ARR 2016). Our aim in present work is to analyze ARR model for Tasmania. The report identifies the modified IFD curve and design projections of future temperature from the IFD curves. It is an alternative approach that use hydrologic model and develop a long sequence for the flow of downscaled precipitation. The literature review will be conducted by using the hydrological model to analyze the changes in water, availability of river flows, and climate changes. The research is dedicated to the changes in runoff and flows of river due to climate changes. Besides the models, there are some flow simulations under the hydrologic models that derive the design of flood and estimates the future of climate. 

Hydrological model of Global climate model

Hydrological model work on the basis of river system models that are developed and used for the investigation of influence of changes in river basin. Hydrological modelling is used to improve the water policy and water resource for management and planning process. hydrological modelling has played an important role for the water resource management. in 2008, the council of Australian Government (COAG) endorsed a National Hydrological modelling strategy (NHMS) that ensure future water management and planning in Australia. The platform is developed and maintained well by the government to evaluate the water system in the selected regions. due to uncertainties of climate changes the planning and management of water resources is becoming challenging. The probability of floods increasing with the variation in precipitation, temperature, and changes in the frequency. The model uses hydrological processes, extreme events, tropical storms, and basin level information to identify the possible factors. The properly calibrated hydrological model provides information that help in management and planning of water resources. hydrological model combines the scenarios of general circulation models (GCMs). There are several hydrological models that are suitable for the estimation of current water availability such as Agriculture Management system (CREAMS), Hydrological Simulation Package FORTRAN (HSPF), Runoff, Chemicals and Erosion. The Hydrological modelling system use water resources, impact of climate changes, water balance, and other components.

Methods of Global climate model

Hydrological model work with the public domain can be used for the quality and quantity measurement of climate changes. The model is based on the general water balance equations which can be used to simulate different hydrological processes.

In the equation,  are the initial and final soil water contents in mm, t defines time in days,  is the amount of precipitation in mm,  is the amount of surface runoff in mm,  is the amount of evaporation in mm, is the amount of bypass flow exiting and percolation that exist in the bottom of soil profile in mm, and  describes the amount of return flow in mm.

The model uses graphical and statistical coefficient of determination , NSE, and percent bias (PBIAS) use hydrological calibration and validation. The value of  changes between 0 and 1 that indicate perfect fit. PBIAS use observations that indicate underestimation of the model. PBIAS measure the flows that are simulated by the model as follows,

Primary assumptions of Global climate model

The model simulation uses some conditions and assumptions according to which NSE > 0.5 and  for the stream flow. In the absolute PBIAS less water concentration from 20% is considered as good but satisfactory condition is between . NSE index is required to be greater than 0.75 and between 0.75 and 0.36.

Water availability of Global climate model

The 2016 IFDs is based on more extensive database with the increasing 30 years of additional rainfall data. the data is selected from the extra rainfall stations. 2016 IFDs are more accurate estimations that combine different techniques and contemporary statistical analysis. based on the analysis of 2016 IFDs there is an increased range from 12 exceedances per year to 1 in 2000 annual exceedance probability. Intensity frequency and duration design of rainfalls provide better estimates of 2% and 1% annual exceedance probability. The IFDs interim increased for 2013 IFDs.

Limitations of Global climate model