The Vulnerability of Groundwater Resources to Climate Change in Timor-Leste. Prepared for the Australian Government Department of Climate Change and Enerfy Efficiency by B. Mayers, R. Fisher, T. Paul P. Wurm. A. Campbell, Research Institute for the Enviro

This report is part of a two part study of the vulnerability of Timor-Leste’s ground water resources, and those who use them, to predicted climate change.In this part of the study by Charles Darwin University (CDU) we focus on potential impact and adaptive capacity to address the vulnerability of Districts to water availability, and provide recommendations for water management. The second part of the study, by Geosciences Australia and presented separately, investigates the biophysical vulnerability of Timor Leste (of the aquifers) to climate change.This report uses a mixed methods approach including:• Review of current climate change predictions• Review of information about aquifer characteristics, provided by the GA study• Assessment of exposure of aquifers to pressure by groundwater users, by reviewing population distribution and growth• Evaluation of adaptive capacity of groundwater users, using census data on indicators of wealth, and field interviews about use and management of water resources.Using these methods we identify priority areas for action in water management and current and potential adaptation options. These options link readily to the National Adaptation Programmes of Action for Timor-Leste (NAPA), and we have also ranked them broadly in terms of predicted cost of implementation.Timor-Leste is a small island developing state, located in the eastern part of the lesser Sunda Islands archipelago. Topography is rugged, with the central mountains of the island reaching altitudes of almost 3000m. The climate is monsoonal, and annual rainfall varies with elevation and aspect, from less than 1000mm in some coastal areas to over 2500mm in the wettest high altitude areas. Timor-Leste has a complex geology and much of the bedrock is sedimentary calcareous rock with shallow soils of low water holding capacity, high alkalinity and low nutrient content.According to the national census, in 2010 Timor-Leste had a population of 1.07 million. Population growth is high (2.4%), fertility rate is high (5.7 births for each fertile aged woman) and the population is relatively young (41% under 14 years, 54% between 15-66 years, and about 5% over 65 years).Already, water insecurity is widespread in Timor-Leste and is a major limitation of food security and livelihoods. Low-input agriculture is the main economic activity in Timor-Leste, with over 86% of households involved in subsistence farming. The main staple crops are rice, maize and cassava, with the limited rice production on the coastal plains fed by gravity irrigation and maize widely grown on the uplands.Geoscience Australia has classified aquifer types in Timor-Leste according to geology and “prospectivity”, i.e. potential flow rates or yields. The major aquifer types in Timor-Leste are:• Sedimentary aquifers with intergranular porosity, which have potential to hold large amounts of groundwater. Alluvial sedimentary aquifers have potential to be high yielding aquifers, with higher yield associated with greater porosity where sediments are more well-sorted (e.g. Dili).• Limestone karstic aquifers with fissured porosity are associated with many springs fed by groundwater and are sensitive to rainfall. In limestone areas, groundwater recharge, storage and yield are affected by the age of the system which determines whether fissures and channels have formed (e.g. in and around Baucau).• Fractured rock aquifers with localised porosity are low yielding and usually only sufficient for household use and animal watering. There is little or no porosity and groundwater is stored in existing fractures, with new channels not becoming larger with time (e.g. Lequidoe in Aileu District).A substantial proportion (about 33%) of the population live on high yielding sedimentary aquifers, particularly on the coast, such as in Dili District, however, most of the population (44%) live on localised aquifers in the highlands (approximately equally on high yielding karst and low yielding localised fractured rock aquifers aquifers).Uncertainty in climate change projections for Timor-Leste is relatively high because Timor-Leste is a similar in size to the grid cells of the models used for projections, has variable topography and little climatic data with which to test the validity of the models that underpin the projections.The most recent climate projections for Timor-Leste have been published by the Pacific Climate Change Science Program (www.pacificclimatechangescience.org). These projections include:• warming of average air and sea temperatures (by 0.4-1.0oC by 2030 under a high emissions scenario);• decrease in dry season and increase in wet season rainfall;• extreme rainfall events to occur more frequently;• decrease in frequency and increase in high intensity cyclones;• sea level rise will continue (by 6-15cm by 2030 under a high emissions scenario)• ocean acidification will continue.Impacts of climate change are discussed within the following framework:Exposure of groundwater resources to climate change were derived from prospectivity of aquifers as determined by Geoscience Australia. Sensitivity of groundwater resources was mapped by overlaying relative aquifer yield and modelled annual rainfall. Areas along the central northern coast and in Oecussi are expected to be particularly sensitive. Sensitivity was also considered in terms of population pressures, both density and rate of change.Potential impacts of climate change were a function of expected exposure to climate change and sensitivity to those changes. High potential impact was identified in several areas on low yielding, localised aquifers: Liquica District, with low rainfall west of Dili; the Districts of Ainaro, Aileu, Bobonaro, and Ermera, with high and rapidly growing populations; Oecussi District, with high population growth and low rainfall. The major towns of Dili and Baucau can also be considered sites of high potential impacts because of high population densities and high population growth rates. This is despite having relatively high yielding aquifers: high yielding sedimentary aquifer in the case of Dili and high yielding fissured aquifer in the case of Baucau. In addition, the surrounding hills are underlain by low yielding fractured rock aquifers.Vulnerability to climate change is a product of potential impacts and adaptive capacity.High adaptive capacity can minimise the vulnerability of a community or nation in the face of high potential impacts. Adaptive capacity is influenced by many factors, including poverty, education, health and social capital. We derived some possible indicators of adaptive capacity using data from the national census and Demographic and Health Survey, and from field surveys at sites representing the main aquifer types. This investigation indicated higher vulnerability due to potentially low adaptive capacity in some Districts. Dili is wealthy compared with other Districts and this may represent relatively high capacity for adaptation. Other factors, such as implementation of some health programs and evidence of community management bodies, suggest high adaptive capacity in other Districts. Current adaptation strategies in some sites included cooperative management of water resources, moving temporarily when water sources became unavailable, carrying water, and collecting rainwater.In summary, the following adaptation options are recommended:1. Documentation and monitoring of ground water resources – to improve understanding of water availability;2. Integrated water harvesting and storage, and irrigation maintenance – to build local resilience and adaptive capacity;3. Agricultural diversification - to build resilience and adaptive capacity;4. Improving governance (policy and regulation) – to reduce waste and over use, to secure availability and access, and to increase adaptive capacity.The people of Timor-Leste face substantial challenges in coping with the variability of the current climate, and further challenges regarding the expected changes to climate and water availability. Options for adaptations to climate change should be considered in the context of food security and sustainable agriculture and natural resource management practices at community, landscape and national scales. The need for this broader framework is stipulated in the National Adaptation Programmes of Action for Timor-Leste (NAPA)