Environmental Determinants of Malaria Transmission in Africa: Hydrology of Water Pools near Villages

非洲疟疾传播的环境决定因素：村庄附近水池的水文水文在形成非洲疟疾传播动态方面起着重要作用。导致非洲村庄附近形成水池的水文过程是自然环境变化与疟疾传播动态之间的关键联系。拟议研究的长期目标是开发可信的计算工具，可用于(1)设计基于当地水文环境管理的干预技术；以及(2)预测气候变率对水池水文和相关疟疾传播的影响。拟议的项目代表了实现这一目标的第一步。在拟议的研究过程中，两名研究生将被介绍到这一重要的研究领域。该项目将有助于正在进行的非洲季风多学科分析（AMMA）国际研究项目。拟议项目的目标是提高我们对确定非洲水池水文的因素的理解。Bomblies等人（2008）的水文学、昆虫学和疟疾传播模拟器（HYDREMATS）将进一步开发，以纳入当地含水层与水池形成之间的相互作用，并描述区域气候强迫和土地利用变化的影响。我们将厘定当地的环境条件如何导致这些天然水体的形成，从而为亚成虫提供适宜的生境；我们将尝试预测这些池对气候变率和气候变化的反应。尼日尔的一个实地场址将作为这项活动的重点。将特别注意联系实地测量和模式开发活动，例如选择代表地下水位变化范围的村庄。几个重要的问题将被解决：当地环境条件（降雨、土壤、地形和植被）和小气候条件（根据辐射、温度、风和湿度定义）在决定作为蚊子种群栖息地的水池的动态方面的作用是什么？当地的水文条件，如在流域内的位置和地下水位的深度，在形成水池中的相对作用是什么？我们能否预测这些水池对非洲季节性、年际和长期气候变化的反应？土地利用变化对这些水池的空间覆盖和持久性有何影响？将研究一组具体的假设，重点放在下列方面：(i)村庄之间蚊子丰度的很大一部分变化可以用地下水位相对于地表位置的变化来解释；萨赫勒地区土地利用的变化以及与之相关的植被和土壤退化将导致空间覆盖率的增加和蚊子繁殖生境的持续存在；（三）可以利用萨赫勒地区降雨的卫星观测来预测成蚊的丰度。本研究的预测将受到对模式假设和/或模式强迫规定范围可能产生的不确定性的系统分析的影响。

ENVIRONMENTAL DETERMINANTS OF MALARIA TRANSMISSION IN AFRICA: HYDROLOGY OF WATER POOLS NEAR VILLAGES Hydrology plays an important role in shaping the dynamics of malaria transmission in Africa. The hydrologic processes that lead to the formation of water pools near African villages represent a key link between variability in the natural environment and the dynamics of malaria transmission. The long-term goal of the proposed research is to develop credible computational tools that can be used to (1) design intervention technologies based on environmental management of the local hydrology; as well as to (2) predict the impact of climate variability on the hydrology of water pools and the associated malaria transmission. The proposed project represents the first steps toward this goal. In the course of the proposed research, two graduate students will be introduced to this important field of research. This project will contribute to the ongoing international research project on African Monsoon Multidisciplinary Analysis (AMMA).The objective of the proposed project is to improve our understanding of the factors that define the hydrology of water pools in Africa. The HYDRology, Entomology and, MAlaria Transmission Simulator (HYDREMATS) of Bomblies et al (2008) will be developed further to incorporate interaction between local aquifers and formation of water pools and to describe the impact of changes in regional climate forcing and in land use. We shall determine how local environmental conditions lead to the formation of these natural water bodies and hence provide habitats that are suitable for sub-adult mosquitoes; and we shall attempt to predict the response of these pools to climate variability and climate change. A field site in Niger will serve as the focus of this activity. Special attention will be devoted to link field measurements and model development activities, e.g. villages are selected to represent a range of variation of water table levels. Several important questions will be addressed: What is the role of local environmental conditions (rainfall, soil, topography, and vegetation) and microclimatic conditions (defined in terms of radiation, temperature, wind and humidity) in dictating the dynamics of the water pools that serve as habitat for mosquito populations? What is the relative role of local hydrologic conditions, such as location within a watershed and depth to the groundwater table, in shaping the water pools? Can we predict the response of these water pools to seasonal, inter-annual, and longer term climate variability in Africa? What is the impact of land use change on the spatial coverage and persistence of these water pools? A specific set of hypotheses will be studied with emphasis on the followings: (i) A significant fraction of the variation in mosquito abundance between villages can be explained by variation in the location of groundwater table relative to the surface; (ii) Land use change in the Sahel and the associated degradation of vegetation and soil will result in increasing the fractional spatial coverage and the persistence of mosquito breeding habitats; and (iii) Adult mosquito abundance can be predicted using satellite observations of rainfall over the Sahel. The predictions of this study will be subjected to a systematic analysis of the uncertainty that may arise from model assumptions and/or from prescribed range of model forcing.