Regional impacts of re-vegetation on water resources of the Loess Plateau, China, and the Middle and Upper Murrumbidgee Catchment, Australia

China

Dr Tim McVicar
Phone: 02-6246 5741
Fax: 02-6246 5800
Email: tim.mcvicar@csiro.au

• Chinese Academy of Sciences and Ministry of Water Resources, China

$872,795

01/01/2003 - 31/12/2005

01/01/2006 - 30/06/2007

Dr Ian Willett

Western China's Loess Plateau is a unique combination of soil type, slope and rainfall intensity. Much of the land is too steep for farming. Average farm sizes are small, often as little as 1.5 hectares. The distant and remoteness from potential markets, mainly on the eastern seaboard, eat up any profits in expensive transport costs. Low levels of productivity mean smallholders relying on farming are amongst the poorest in China. The most far-reaching problem for these farmers is soil erosion. Traditional tillage practices have served to further, rather than limit, erosion. Low levels of perennial vegetation and intense monsoonal summer rains, which dump more than half of the annual fall, also exacerbate the problems.

The large level of rainfall, low vegetation and high erosion all contribute to excessive water runoff. This transports both water and soil sediment into groundwater systems. The most important of these is the Yellow River, its name taken from the colour of the river once the sediment enters it. Revegetation of the Plateau should alleviate many of the erosion and water/soil losses, but the impacts on hydrology are not clear. Hydrology and erosion interactions are also elements found in the Murrumbidgee catchment in Australia. Understanding these interactions and their impacts at the system level requires complex data interpretation, is best handled by computer modelling.

The project is working to optimise the impact of large-scale revegetation on the water resources of the Coarse Sandy Hilly Region of the Loess Plateau of western China, and in the Middle and Upper Murrumbidgee Catchment of southeast Australia by developing software tools to predict the impact of revegetation strategies on the two regions.

assemble the regional databases of climate, river flow, land use and DEMs
annual rainfall and runoff data from 1980 to 2005, and topography and land cover databases assembled for the catchments
map suitability assessments for trees, shrubs and perennial grasses, taking into account changes to equilibrium soil moisture
for the catchments show suitability and longevity of the proposed re-vegetation schemes, taking into account rainfall, potential ET, landscape position and changes to the soil moisture
soil moisture data collected and analysed for sites
suitability rules developed from knowledge gained
develop a GIS tool to predict the impact of re-vegetation schemes on annual flow and seasonal stream flow distribution curves
develop a Web-based interactive scenario modelling tool
perform ongoing communications of project developments with potential users and other scientists

The key output from our successful project has been the development of a bilingual computer based simulation tool called ReVegIH (Re-Vegetation Impacts on Hydrology) that allows managers of terrestrial land use (forestry and agricultural) to understand the regional impacts of current and proposed plans to re-vegetate large areas of the Loess Plateau. While re-vegetation activities will assist controlling soil erosion, in the water limited Yellow River basin, off-sites impacts of reducing water yields need to be acknowledged and planned for. Additionally, to promote use of the tool by the land use managers, ReVegIH provides suitability assessments of 38 perennial tree and shrub species, and identifies priority and target areas where re-vegetation activities should occur. Thus land use managers are advised about the "what and where" concerning re-vegetation activities, and are also provided an assessment of the reduction in water yield these actions will generate.

Extensive consultation with stakeholders from the Middle and Upper Reaches of the Yellow River Conservation Commission, and selected leaders of the county-level heads from Bureau of Forestry, Bureau of Agriculture, and Bureau of Hydrology meant that their functional requirements were taken into account during the design and implementation of ReVegIH. For example, initially a web-based tool was proposed, however, following consultation and feedback from these stakeholders we modified our design to be a CD-based tool (that can also be downloaded from our project web-site - see http://www.clw.csiro.au/ReVegIH). By listening to stakeholders and refining our project plan accordingly, this has greatly increased its uptake by regional and county level managers (the so called "target audience") since release. To facilitate the widespread use of ReVegIH, user training was a major focus of the project extension - two training courses have been run with users being introduced to the underpinning data sets and scientific concepts prior to being trained in how to use ReVegIH to assist in operational re-vegetation planning. An adaptive educational model was implemented, where feedback from participants of the training courses has been sought ultimately improving subsequent training activities by addressing the issues identified.