During recent decades, the use of high-resolution light detection and ranging altimetry (LiDAR) data in fluvial studies has rapidly increased. Airborne laser scanning (ALS) can be used to extensively map riverine topography. Although airborne blue/green LiDAR can also be utilized for the mapping of river bathymetry, the accuracy levels achieved are not as good as those of terrain elevation measurements. Moreover, airborne bathymetric LiDAR is not yet suitable for mapping shallow water areas. More detailed topographical data may be obtained by fixed-position terrestrial laser scanning (TLS) or mobile terrestrial laser scanning (MLS). One of the newest applications of MLS approaches involves a boat/cart-based mobile mapping system (BoMMS/CartMMS). This set-up includes laser scanning and imaging from a boat moving along a river course and may be used to expand the spatial extent of terrestrial scanning. Detailed digital terrain models (DTMs) derived from LiDAR data can be used to improve the recognition of fluvial landforms, the geometric data of hydraulic modelling, and the estimation of flood inundation extents and fluvial processes.

Fresh water provisioning is a crucial ecosystem service (ES) in the agrarian societies of East Africa. Water resources are highly dependent on several other ES such as the water retention capacity of vegetation and the purification properties of soil. However, ES are constantly challenged by dynamic changes within water-land-vegetation-human relations. Environmental policies usually address immediate anthropic pressures but overlook multiple historical stressors, or 'drivers'. This article presents a local assessment of changes in the water-related ES in the Taita Hills, Kenya, applying the Drivers, Pressures, Actions, State, Ecosystem services, Responses (DPASER) model, adapted from the Drivers, Pressures, State, Impacts, Responses (DPSIR) framework, boosted with ecosystem services and human actions and combined into a historical perspective. A review of the legislation, interviews, participatory mapping, timelines and focus group discussions were used in data gathering. The results indicate that land demarcation in the 1960s and consequent land privatization have been the main drivers of change in water-related ES, since these determined the prioritization of agricultural production over conservation of forests, wetlands and rivers. This case study shows that the degradation of water-related ES is strongly linked to historical development of land ownership and loss of commonality, and suggests enhancement of inter-sectoral management.

Participation of local people is often neglected in natural resource management, which leads to failure to understand the social aspects and historical construction of environmental problems. Participatory mapping can enhance the communication of local spatial knowledge for management processes and challenge the official maps and other spatial representations produced by state authorities and scientists. In this study, we analyze what kind of social meanings can be revealed through a multimethod participatory mapping process focusing on water resources in Taita Hills, Kenya. The participatory mapping clearly complicates the simplified image of the physical science mappings, typically depicting natural water supply, by addressing the impacts of contamination, inadequate infrastructure, poverty, distance to the sources, and restrictions in their uses on people's access to water. Moreover, this shared exercise is able to trigger discussion on issues that cannot always be localized but still contribute to place making. Local historical accounts reveal the social and political drivers of the current water-related problems, making explicit the political ecology dynamics in the area. Key Words: environmental histories, participatory mapping, spatial meaning, Taita Hills, water resource management. 自然资源的管理经常忽略在地人的参与, 并导致无法理解环境问题的社会面向及历史建构。参与式製图能够为管理过程增进在地空间知识的沟通, 并挑战国家机构和科学家所绘製的官方地图及其他空间再现。我们于本研究中聚焦肯亚台达山丘 中的水资源管理, 分析透过多重方法参与式製图过程, 能够揭露何种社会意涵。参与式製图透过指出污染、基础建设不 足、贫穷、获得资源的距离, 以及使用他人的水资源管道的限制之影响, 明确地复杂化描绘出自然资源供给的一般物理科 学製图。再者, 此一共享的活动, 能够引发对无法总是在地化、但却仍对地方打造有所影响的议题进行讨论。地方历史的 说明, 揭露了当前与水资源有关的问题的社会及政治驱力, 明确呈现出该地的政治生态动态。 关键词: 环境历史, 参与式製 图, 空间意涵, 台达山丘, 水资源管理。 La participaci on de la gente de la localidad a menudo no es atendida en el manejo de los recursos naturales, lo cual lleva al fracaso de entender los aspectos sociales y la construcci on hist orica de los problemas ambientales. El mapeo participativo puede robustecer la comunicaci on de conocimiento local para los procesos del manejo y reta los mapas oficiales y otras representaciones espaciales producidas por autoridades estatales y científicos. En este estudio analizamos los tipos de significados sociales que pueden revelarse a trav es un proceso de mapeo participativo de m etodo m ultiple enfocado en los recursos hídricos de Taita Hills, Kenia. El mapeo participativo claramente complica la imagen simplificada de los mapeos de ciencia física, que típicamente representa el suministro de agua, abocando los impactos por contaminaci on, infraestructura inadecuada, distancia a las fuentes y restricciones en sus usos de los accesos de la gente al agua. A un m as, este ejercicio compartido sirve tambi en para instigar la discusi on sobre asuntos que no siempre pueden localizarse, pero que a un así contribuyen a la construcci on de lugar. Los registros hist oricos locales revelan los controles sociales y políticos de los problemas actuales relacionados con agua, haciendo explícita la din amica de la ecología política en el area. Palabras clave: historias ambientales, mapeo partici...

Her PhD research focuses on Development Geography, human-environment interactions, local ecological knowledge, participatory methods, migration and political ecology of water.

Environmental resource management policies worldwide have long insisted on the need to involve local communities and their diverse ecological knowledges in management planning and decision-making. In SubSaharan post-colonial countries, however, formal resource management is still largely dominated by bureaucratic governance regimes that date back to colonial power structures and that rely mainly on professional or formal knowledge. In this study, we use a political ecology approach to analyze disputes over eucalyptus plantations in the Taita Hills, Kenya. The approach recognizes the plurality of socially constructed and powerladen perceptions of environmental resources. We found that local people regard eucalyptus plantations not only as a threat to local water resources but they also highlight historical injustices and the loss of control over, and cultural relationships to their land. Bureaucratic resource management institutions, however, support the planting of eucalyptus to meet national demands for commercial forestry. Management officials also plead a lack of "valid" evidence for the negative impacts of eucalyptus on local water resources, diverting attention away from the formal environmental governance system which has unequal sharing of benefits, unclear policies, and internal incoherence. Recognition of historically rooted asymmetries of knowledge and power provides a step towards social transformation, ending a long-standing reproduction of subalternity, and promoting environmental justice and pluralism in decision-making. Keywords: bureaucratic knowledge; environmental justice; eucalyptus; Kenya; knowledge asymmetries; local ecological knowledge; political ecology; resource management RésuméLes politiques de gestion des ressources environnementales dans le monde insistent depuis longtemps sur la nécessité d'impliquer les communautés locales et leurs diverses connaissances écologiques dans la planification, l'aménagement et la prise de décisions. Dans les pays post-coloniaux subsahariens, cependant, la gestion formelle des ressources est encore largement dominée par des régimes de gouvernance bureaucratique qui remontent aux structures de pouvoir coloniales et qui reposent principalement sur des connaissances professionnelles ou formelles. Dans cette étude, on propose une approche d'écologie politique pour l'analyse des disputes sur les plantations d'eucalyptus dans les collines de Taita au Kenya. L'approche reconnaît la pluralité des perceptions sur les ressources environnementales en tant que socialement construites et chargées des relations de pouvoir. On a constaté que pas seulement les populations locales considèrent les plantations 1 Johanna Hohenthal, PhD student, Department of Geosciences and Geography, University of Helsinki, Finland. Email: johanna.hohenthal "at" helsinki.fi. Marinka Räsänen, MSc. Email: marinka.rasa "at" gmail.com. Dr. Paola Minoia, Adjunct Professor, Development Studies, Department of Political and Economic Studies, University of Helsinki, Finland. Email: paola.mi...

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