Revitalizing Urban Population Projections: New Data, New Methods

随着发展中国家继续城市化，非洲和亚洲接近城市化程度超过农村的程度，需要对人口数据和研究方法进行新的投资，以了解和解决城市居民的公共卫生和社会经济需求。如果决策者要制定有效的发展战略，他们至少需要对城市人口规模、增长率和地理范围进行合理的估计。目前，人口研究界无法提供这种估计数（国家研究理事会，2003年），因为它依赖于过时的方法和数据来源。然而，在过去20年中，发展中国家获得了大量新数据，主要来自调查，这些数据在改进城市估计和预测方面具有相当大的潜力。此外，最近的方法学进展已经提出了新的方法，通过这些方法，卫星图像可以用于探测城市区域并测量其空间范围（Balk等人，2005年，Small 2005年，Elvidge等人，1997年）。与25年前相比，现在有更多的空间编码数据，其中包括卫星来源。此外，来自人口调查的城市数据大大加强了估计城市增长的人口组成部分的基础，并将继续这样做。在注意到这些积极的事态发展之后，我们现在不仅要大幅改善我们对城市增长的估计和预测，而且要为其城市估计和预测建立明确的空间基础。拟议中的研究小组的目标-包括科学家从哥伦比亚大学的中心国际地球科学信息网络（CIESIN）和拉蒙特-多尔蒂地球观测站（LDEO），人口理事会和联合国人口司-是生产和评估新的空间明确的人口统计方法估计和预测城市人口在发展中国家。这项工作将利用人口学、经济学和遥感方面的最新技术。在未来几十年，亚洲和非洲可能会跨越一个历史性的门槛，首次成为城市而不是农村。拟议的工作是系统地改进对未来城市世界的估计和预测，并将更清楚地说明这些转变可能发生的地点、时间和速度，以及由此产生的健康和福利影响。

DESCRIPTION (provided by applicant): As the developing world continues to urbanize, and Africa and Asia approach the point at which they will become more urban than rural, new investments in demographic data and research methods will be required to understand and address the public health and socioeconomic needs of urban residents. At a minimum, policy-makers will need defensible estimates of city population sizes, rates of growth, and geographic extents if they are to formulate effective development strategies. At present the demographic research community cannot supply such estimates (National Research Council, 2003) as it relies on out-of-date methods and sources of data. Yet over the two past decades, a wealth of new data, largely from surveys, has become available for developing countries, with considerable potential to improve city estimates and projections. Further, recent methodological advances have suggested new ways by which satellite imagery can be used to detect urban areas and measure their spatial extents (Balk et al, 2005, Small 2005, Elvidge et al., 1997). Far more spatially-coded data-such satellite sources among them-are available now than was the case 25 years ago. Moreover, urban data from demographic surveys have greatly strengthened the basis for estimating the demographic components of urban growth and will continue to do so. Having taken note of these positive developments, we are now posed to not only to substantially improve our estimates and projections of city growth, but also to establish an explicitly spatial basis for its city estimates and forecasts. The goal of the proposed research team-including scientists from the Columbia University's Center for International Earth Science Information Network (CIESIN) and Lamont-Doherty Earth Observatory (LDEO), the Population Council, and the UN Population Division-is to produce and evaluate new spatially-explicit demographic methods for estimating and projecting city populations in the developing world. The work will draw on recent techniques in demography, economics, and remote-sensing. Over the next few decades, Asia and Africa will likely cross an historic threshold, becoming, for the first time, more urban than rural. The proposed work is systematic improvement in the estimation and forecasting of the future urban world, and will offer much greater clarity on where, when, and the pace at which those transitions may occur and the health and welfare implications thereof.