An urban faecal pollution mapping tool for water quality protection and enhancement

近几十年来，全球水和卫生景观发生了重大变化，但安全管理排泄物的完整卫生服务链基础设施仍然是一项挑战，许多中低收入国家城市地区的地表水粪便污染是一个重大问题。因此，粪便污染的风险只是将其位置从家庭转移到排水沟和地表沃茨。这也是对人类健康和水生生物的关注。受污染水体的影响差异很大，往往影响环境健康，例如，在没有捕食者的情况下，病媒的繁殖地会产生难闻的气味，并成为温室气体排放源。联合国可持续发展目标6（具体目标3）旨在通过到2030年将排放到环境中的未经处理的废水比例减半来改善水质。此外，美国北卡罗来纳州大学最近进行的一项研究指出，由于在知识和处理能力方面存在差距，因此应将其列为优先研究领域，如果不加以处理，将影响到生活的各个方面，包括健康、农业产量，从而导致生产力低下，导致负担能力下降，最终形成恶性循环。一些国家正在制定卫生框架，但往往没有将水质纳入政策。城市当局管理各种环境卫生问题正成为一项挑战。因此，需要对粪便污染的来源、途径和受体进行综合的空间认识，并对环境水质进行评估。然而，在处理与水质改善和保护有关的粪便污染方面存在一些制约因素，特别是缺乏1）水质监测数据，2）用于评估与粪便污染相关的水质和绘制卫生服务链的经验证的地理空间技术，3）可以整合水质和粪便污染以促进必要的有针对性的干预措施的简单规划工具。该项目旨在通过回答以下研究问题来填补其中的一些空白：“城市集水区粪便污染的来源、途径和受体（SPR）的综合空间表示能否用于创建一种新的污染预防规划工具？”“该项目将使用广泛的数据，包括实地调查和卫星图像，以提取粪便SPR信息，并开发新的水质测绘方法，随后将建立两者之间的联系。这项工作将包括3个工作包（WP），每个工作包包含一些任务。WP1将把地理空间信息与现场实地调查相结合，进行空间尺度的粪便SPR分析，WP2将确定水透明度参数与粪便污染之间的关系，随后开发一种用于卫星图像分析的水质算法，WP3将开发一种基于层次的方法，将粪便SPR与水质退化相结合。整个项目将与孟加拉国的当地合作伙伴合作，通过计算机数据分析、实地调查、取样和实验室工作相结合的方式来实施，这一项目的成果将使人们更好地了解低收入和中等收入城市环境中的环境水质和卫生服务供应之间的联系。拟采用的绘图工具应尽可能简单易用，并依赖于随时可用和易于获取的数据，并将为城市规划者提供一个实用的指南，以恢复粪便污染造成的水质，减少环境健康风险。环境水质差往往是城市环境卫生差的一个指标，因此，该项目有可能对这两个部门产生影响，这是全球南方的一个共同问题。

The global water and sanitation landscape has changed significantly in recent decades, but the complete infrastructure of sanitation service chain for managing excreta safely remains a challenge and faecal contamination of surface water in urban areas of many low and middle-income countries is a vital problem. Therefore, the risk of faecal pollution just shifting its location away from households to drains and surface waters. This is a concern for human health and aquatic life as well. The impact of the polluted waterbodies varies widely and often affects environmental health, e.g., breeding grounds for disease vectors in the absence of their predator, produce unpleasant odour, and become greenhouse gas emission sources. The UN Sustainable Development Goal 6 (target 3) aims to improve water quality by halving the proportion of untreated wastewater discharged to the environment by 2030. Also, a recent study led by the University of North Carolina, USA identified as a priority research area because of gaps in knowledge and ability to deal with it. If it is not dealt with, there will be consequences affecting all sector of life including health, agricultural yield and thereby low productivity leading to reduced affordability ending in a vicious cycle. Some countries are developing sanitation framework but often that is not integrating water quality into the policy. It is becoming a challenge for city authorities to manage various environmental health issues. Therefore, an integrated and spatial understanding of the sources, pathways and receptors of faecal pollution and assessment of environmental water quality is needed. However, there are some constraints to deal with faecal pollution in relation to water quality enhancement and protection, notably, lack of 1) water quality monitoring data, 2) proven geospatial technique for assessing water quality associated with faecal pollution and to map sanitation service chain, 3) simple planning tools which can integrate water quality and faecal pollution to facilitate necessary targeted intervention. This project will aim to fill some of these gaps by answering the following research question 'can an integrated spatial representation of sources, pathways and receptors (SPR) of faecal pollution in urban catchments be used to create a new planning tool for pollution prevention?' The project will use a wide range of data including field survey and satellite images to extract faecal SPR information and develop new water quality mapping methods and subsequently will establish the association between the two. The work will include 3 work-packages (WPs) each containing a few tasks. The WP1 will integrate geospatial information with spot field survey for a spatial-scale faecal SPR analysis, WP2 will identify a relation between water clarity parameters and faecal pollution and subsequently develop a water quality algorithm for satellite image analysis, and WP3 will develop a tier-based approach to integrate the faecal SPR and water quality degradation. The overall project will be carried out by a combination of computer-based data analysis, field survey, sampling and laboratory work in collaboration with the local partners in Bangladesh.The outcome of this project will provide an improved understanding of the link between environmental water quality and sanitation service provisions in a low and middle-income urban setting. The intended mapping tool would be as simple to use as possible and rely on readily available and easily acquirable data and will provide a practical guideline to the city planner in restoring water quality from faecal pollution to reduce the environmental health risk. Poor environmental water quality often is an indicator of poor sanitation in urban setting therefore this project has the scope to have an impact in both sectors which is a common problem in the global south.