Hydro-dynamic modelling of malaria environmental suitability

疟疾是一种对气候敏感的病媒传播疾病，2016年全球2.16亿疟疾病例中，估计有44.5万人死亡；其中91%的疟疾死亡发生在非洲（世卫组织，2017年）。目前疟疾传播的详细地图对于卫生资源的分配和控制措施的确定至关重要。此外，了解疟疾传播所需的环境条件对于预测未来可能爆发疫情的地区是必要的。未来的气候变化可能会改变疟疾传播的分布和强度，尽管这种影响的确切性质和程度一直是最近争论的主题（Caminade et al., 2014）。提供适合蚊子繁殖的水是控制疟疾传播的一个关键因素，特别是在主要蚊子媒介适应利用季节性降雨和洪水产生的新水的情况下。如果我们要将其与气候联系起来，并估计预计的气候变化的影响，这种理解是至关重要的。此外，这种知识有助于疟疾适应/缓解，即确定疟疾控制规划中可能针对的蚊子幼虫“热点”。环境空气温度控制着疟疾传播周期中若干组成部分的速率，包括孢子生和淋养发育速率、咬伤速率和个体寿命。因此，疟疾气候适宜性是基于成熟的热响应曲线建模的（例如Mordecai等人，2012年）；然而，水体可利用性没有提供这样详细的处理。相反，使用简单的降雨阈值来表示水的可用性（见Smith et al., 2013）。该项目小组目前的研究是将一个大陆尺度的水文模型与疟疾热响应曲线结合起来，以提供一个更加基于物理的疟疾水文气候适宜性估计。同时，在景观尺度上，以前和正在进行的工作主要集中在景观尺度上对生境适宜性的水文和地貌影响有更深入的了解（例如Hardy et al., 2013）。这包括将详细的水力模型与基于agent的蚊子空间生态模型联系起来，以确定幼虫热点，并以高分辨率模拟每年洪水的动态。这个项目的主要目的是弥合大陆尺度和景观尺度在疟疾水文气候适宜性建模方面的差距。全球尺度水文模型的日径流输出可用于驱动全球水动力河流路径模型（如CaMa-Flood； Yamakazi等人，2011；Trigg等人，2016），这些模型能够在1公里以下的空间尺度上代表非洲的洪水扩张和收缩。这样的发展将允许在大陆尺度模型中明确表示矢量生态位。在这个项目中，你将与利兹大学、林肯大学和一个国际合作网络的科学家团队合作，将水文和地貌的理解嵌入到疟疾水文气候适宜性的大陆尺度模型中。特别是，根据他们的研究兴趣，成功的学生可以：(1)将每天的径流数据输入到全球水动力河流路径模型中，然后评估当前和2100年前非洲各地疟疾的水文气候适宜性；(2)将这种建模方法扩大到覆盖各大洲，并评估水文气候疟疾适宜性的潜在变化；(3)比较上述不同排放途径的预测结果；(4)评估全球水动力模型的输出，对个别油田（特别是赞比西河的巴罗茨洪泛平原）进行更详细的建模，并收集潜在的地面真实数据集。

Malaria is a climate sensitive vector-borne disease that was responsible for an estimated 445,000 deaths from 216 million malaria cases worldwide in 2016; 91% of these malaria deaths were in Africa (WHO, 2017). Detailed mapping of current malaria transmission is vital for distribution of health resources and targeting of control measures. Moreover, an understanding of environmental conditions required for malaria transmission is necessary for predicting areas subject to future outbreaks. Future climate change is likely to alter the distribution and intensity of malaria transmission, though the exact nature and extent of this influence has been the subject of recent debate (Caminade et al., 2014).The availability of water suitable for mosquito breeding is a critical control on malaria transmission, particularly where predominant mosquito vectors are adapted to exploit new water arising from seasonal rains and flooding. Such understanding is crucial if we are to make the link to climate and estimate the impact of projected climate change. Moreover, this knowledge can contribute to malaria adaptation/mitigation, namely the identification of mosquito larval 'hotspots' that could be targeted in malaria control programmes.Ambient air temperature controls the rate of several components of the malaria transmission cycle including sporogonic and gonotrophic development rates, biting rate and individual longevity. Malaria climatic suitability is thus modelled based on well-established thermal response curves (e.g. Mordecai et al., 2012); however, water body availability is afforded no such detailed treatment. Instead, simple rainfall thresholds are used to represent water availability (see the review in Smith et al., 2013). Current research by the project team is coupling a continental-scale hydrological model with malaria thermal response curves to provide a more physically-based estimate of malaria hydro-climatic suitability.Meanwhile, at the landscape scale, previous and ongoing work is focused on establishing a greater understanding of the hydrological and geomorphological impact of habitat suitability at the landscape scale (e.g. Hardy et al., 2013). This includes linking detailed hydraulic models with agent-based mosquito spatial ecology modelling to identify larval hotspots and model the dynamics with the passing of annual flood waves at high resolution.The major aim of this project will be to bridge the scale gap between continental-scale and landscape-scale efforts of modelling malaria hydro-climatic suitability. The daily runoff output of global scale hydrological models can be used to drive global hydro-dynamic river routing models (e.g. CaMa-Flood; Yamakazi et al., 2011; Trigg et al., 2016) capable of representing flood expansion and contraction across Africa at spatial scales below 1 km. Such a development will allow for vector niches to be represented explicitly in a continental-scale model. ObjectivesIn this project, you will work with a team of scientists at the University of Leeds, the University of Lincoln and a network of international collaborators to embed hydrological and geomorphological understanding into continental-scale models of malaria hydro-climatic suitability. In particular, according to their research interests, the successful student could:(1) Input daily runoff data into global hydro-dynamic river routing models to then evaluate hydro-climatic suitability for malaria across Africa both for the present day and up until 2100;(2) Expand this modelling approach to cover each continent and evaluate potential changes in hydro-climatic malaria suitability;(3) Compare predictions of the above for different emissions pathways;(4) Evaluate the global hydro-dynamic modelling output with more detailed modelling of individual field sites (particularly the Barotse floodplain of the Zambezi) along with potentially collecting ground truth data sets.