Stable Isotope Analysis

In order to quantify the impact of a mountain range on the incoming atmospheric water vapor we examined the stable isotope ratios of hydrogen and oxygen in streams and twigs an the lee side of a mountain range. When compared with the isotopic ratios of the incoming airmass it is possible to calculate the proportion of water vapor rained out as it passes the range, or the "Drying ratio".

Regional climate of the Middle East

As part of the South-West Asia Project (SWAP) I have been attempting to model the present day climate of the region. Various investigations into the effects of changes in land-use, drought - vegetation feedacks, and the transport and sources of water vapor etc have been conducted. Experiments looking into the future (ie. global warming scenarios), quantifying the predicted impact on precipitation and temperature, changes in precipitation processes and water vapor transport.

Regional climate modelling

I have been investigating the ability of several regional climate models to reproduce the current energy and water balances over multi-annual time scales. The models (RegCM2, MM5/BATS, MM5/SHEELS, MM5/OSU) have been applied over central USA. The domain is centered over the FIFE region in Kansas where an intensive field experiment was conducted and extensive data is available for evaluation of the models. While no model consistently performed better then the other models it was found that during 'normal' conditions the various land-surface schemes performed similarly but under stressed conditions (eg. unusually dry) they behaved quite differently. While the atmospheric radiation and precipitation parameterizations were important in determining the driving forces at the surface, differences in the transfer of momentum (eg. surface winds and drag coefficients) played a major role in determining the split between latent and sensible heat.

Orographic precipitation

Using numerical weather models we investigate the influence of topography on the initiation and continuation of precipitation events. This was done over the European Alps in cooperation with the Mesoscale Alpine Project (MAP).

Water quality research

I have been involved in studies looking at identifying relationships between catchment characteristics and in-stream phosphorus. These studies used reasonably large in-stream phosphorus data sets collected in the Goulburn-Broken basin in South East Australia. Slope and intensive agriculture within 500m of the stream seem to be the two most important catchment characteristics observed to date.

Hydrological Modelling

Much of the work I have done involves hydrological modelling of some sort. The rainfall-runoff model I have used most is IHACRES. It is a lumped conceptual model which has minimum data requirements (rainfall, streamflow and temperature) and only a small number of parameters (~7). This model has been applied in many places around the world, under many different climatic conditions often performing better than more complex models. I have applied it successfully to many catchments, from temperate, humid catchments in South East Australia to semi-arid catchments in inland New South Wales (NSW), Australia to tropical monsoonal catchments of northern Thailand.

Land surface/atmosphere Interaction modelling

Much of the hydrological modelling has been concerned with the climates effect on the surface hydrology, of particular interest here is the feedback to the climate from the land surface hydrology. This interaction is given by the exchange of energy and water fluxes at the surface. Both of these fluxes are embodied (to a large extent) in the evaporative flux. In order to investigate this interaction a new version of IHACRES was developed which explicitly calculated the evaporation each time step without requiring extra data and keeping the number of parameters to a minimum. The model is based on the catchment moisture deficit (CMD) which is a measure of how far from saturation a catchment is. CMD-IHACRES has been extensively tested and shown to provide streamflow results as good as IHACRES while still providing the evaporation estimates. The model structure also allows evaporation and streamflow to be dealt with using different time steps.

Climate Change Impacts

The impacts of climate change on streamflows has been investigated using different techniques. Around Perth, Australia results from a Global Climate Model (GCM) were spatially downscaled and temporally extended using a stochastic weather generator. This created climatic time series was then used in conjunction with CMD-IHACRES to provide estimates of the streamflow response to the climate change. Also in the Middle East, GCM results were downscaled using a regional climate model enabling investigation into changing precipitation processes and water vapor transport.

Land Use Change Impacts

A study into the effects of increasing numbers of farm dams on the streamflow was conducted in the Namoi basin, NSW, Australia. This study used CMD-IHACRES to estimate the streamflow response to these changes. I was involved in the creation of the methodology used to examine this response. This study found that rarely in an active agricultural catchment will only one land use change occur at a time, usually there are many catchment users and hence many changes occurring at once. This makes interpretation of results difficult at times, though in several cases we found significant trends in the streamflow response.

Integrated Water Resource Assessment and Management

With the Integrated Catchment Assessment and Management (iCAM) centre I have been involved in an integrated water resource assessment and management project in northern Thailand. The aim of this ongoing project is to incorporate bio-physical and socio-economical knowledge into a decision support system for use by the stakeholders involved especially those responsible for catchment management issues.

UNSW    This page is maintaind by Jason Evans | Last updated 31st January 2008