Political Ecologies of Dynamic Wetlands: Hydrosocial Waterscapes in the Okavango Delta

Research within geography and related disciplines has directed much attention to the coupled interactions between social and ecological systems. These studies have usefully analyzed the multifaceted, temporal, and scalar dimensions of human–environment interactions and how future environmental change will continue to challenge human resource needs. Political ecology research has also made contributions in this regard, particularly by emphasizing livelihood systems, impacts of conservation and development, agricultural production, and environmental governance. Yet although political ecology research has contributed to socioecological systems scholarship, much of this work has been situated within dryland environments or marine ecosystems that have particular biophysical features. Comparatively, wetland environments that experience dynamic flooding regimes warrant further attention from political ecology. This article engages with the findings from an ongoing research project that is evaluating the impacts of flooding variability for rural livelihoods in the Okavango Delta of Botswana. We outline some of the main findings from this work by concentrating on two themes central to political ecology: access and governance. We conclude by arguing that the Okavango Delta should be understood as a hydrosocial waterscape that encompasses a variety of socioecological relationships within the region, as well as the power relations operating at a variety of scales that both produce and govern them.     

Environmental Perception,Sense of Place,and Residence Time in the Okavango Delta,Botswana

Integral to the geographic discipline are cross-cultural analyses, many of which use languages outside of the researcher’s own. There are few analyses, however, that address issues of translation that are inherently geographic; namely, that language is understood as a manifestation of place and culture. This article argues that the results of environmental interviews must be interpreted through a lens that evaluates how the translation of a word, or even a concept, is understood differentially based on one’s sense of place. Interviews were conducted in three of the Etsha villages situated in the Okavango Delta, Botswana, comparing perceptions of changes in both the local area and the flooding regime. Findings show qualitatively and quantitatively how residents perceive environmental change in light of their residential histories and their production of place. These results highlight that environmental change in an area is perceived in the context of previous residences, including the length of time spent in residence and the environmental characterization of that place. The process of interviewing regarding such change, especially when translation is necessary, should therefore proceed by incorporating inquiries about previous residences and the environments of those areas to correctly contextualize environmental change in a particular area.     

Contending with unequal and privileged access to natural resources and land in the Okavango Delta, Botswana

This paper reviews how state policy and regulatory instruments, including protected area alienations and concessions, have altered or denied the access to land and natural livelihood resources of the indigenous Basarwa and minority subsistence-oriented communities in the Okavango Delta (OD) in Botswana. Drawing on field research and guided by a sustainable rural livelihoods framework, the paper provides an overview of key institutional interventions – in particular the setting up of the Moremi Game Reserve, Wildlife Conservation Policy, Tourism Policy, Agricultural Development Policy and the erection of veterinary fences – that have served to privilege a foreign-owned and dominated commercialized wildlife and nature tourism sector and the export-oriented beef industry in the OD. The officially sanctioned barriers to customary and usufructory rights and access, and the non-recognition of historically embedded traditional land uses have decimated already marginalized resource-based subsistence livelihoods, and precipitated intergroup conflicts over preferential rights and access to resources and opportunities, notably wildlife, non-timber veld products, agriculture and community-based tourism schemes. Such outcomes, moreover, will have consequences for the longer-term sustainability of the OD both as a socioeconomic resource base and as a natural ecosystem.     

Late Quaternary palaeosols in the Yangtze Delta, China, and their palaeoenvironmental implications

The stiff clays beneath Holocene strata in the Yangtze Delta are interpreted as palaeosols, based on pedogenic features including illuvial argillans, voids, cracks, iron–manganese concretions and nodules, and carbonate materials. Variations in clay content with depth, the occurrence of foraminifera, and the environmental magnetism characteristics of the palaeosols suggest that their parent materials are floodplain deposits. Anisotropy of magnetic susceptibility (AMS) parameters of the sediments correlate well both with sedimentary dynamics and depositional processes in different sedimentary environments, and AMS analysis may be a useful tool for inferring sedimentary environments. Based on their considerable thickness (> 3.0 m), vertical changes of palaeosol maturity, and occurrence of ageing argillans throughout the palaeosols, the palaeosols are inferred to be compound ones (pedocomplexes) resulting from alternating deposition and pedogenesis on the palaeointerfluve of the Yangtze River. Phytoliths in the palaeosols indicate that climates turned generally from warm and wet to cold and dry with marked fluctuations during development of the palaeosols. This suggests that the palaeosols developed mainly during the marine regression prior to the last glacial maximum. The vertical distribution of manganese materials (e.g., concretions, nodules, speckles and mottles) in the palaeosols suggests that the groundwater tables were about 2.0–3.0 m beneath the upper boundary of the palaeosols during their development. Yellow–brown streaks and speckles are abundant from the middle to lower parts of the palaeosols, and layers with high CaCO₃ content occur in the strata just beneath the palaeosols, but which lack caliche, suggesting that the groundwater table fluctuated markedly during their development. Voids and cracks filled with clays, and carbonate nodules (less than 0.1 mm in diameter) with thin iron–manganese rims are abundant in the palaeosols, indicating that wet and dry seasons were marked during the palaeosol development. It is suggested that the monsoonal influence was marked in the Yangtze Delta, with both winter and summer monsoons strongly developed during the development of the late Quaternary palaeosols.     

Drivers of water pollutant discharge in urban agglomerations and their scale effects: Empirical analysis of 305 counties in the Yangtze River Delta

Revealing the drivers and scale effects of water pollutant discharges is an important issue in the study of the environmental consequences during urban agglomeration evolution. It is also a prerequisite for realizing collaborative water pollutant reduction and environmental governance in urban agglomerations. This paper takes 305 counties in the Yangtze River Delta (YRD) as an example and selects chemical oxygen demand (COD) and ammonia nitrogen (NH₃-N) as two distinctive pollutant indicators, using the Spatial Lag Model (SLM) and Spatial Error Model (SEM) to estimate the drivers of water pollutant discharges in 2011 and 2016. Then the Multiscale Geographically Weighted Regression (MGWR) model is constructed to diagnose the scale effect and spatial heterogeneity of the drivers. The findings show that the size of population, the level of urbanization, and the economic development level show global-level increase impacts on water pollutant discharges, while the level of industrialization, social fixed assets investment, foreign direct investment, and local fiscal decentralization are local-level impacts. The spatial heterogeneity of local drivers presents the following characteristics: Social fixed assets investment has a strong promoting effect on both COD and NH₃-N discharges in the Hangzhou-Jiaxing-Huzhou region and the coastal area of the YRD; industrialization has a promoting effect on COD discharges in the Taihu Lake basin and Zhejiang province; foreign direct investment has a local inhibitory effect on NH₃-N discharge, and the pollution halo effect is more prominent in the marginal areas of the YRD such as northern Jiangsu, northern Anhui, and southern Zhejiang; local fiscal decentralization has a noticeable inhibitory effect on COD discharge in the central areas of the YRD, reflecting the positive impacts on improved local environmental awareness and stronger constraints of multilevel environmental regulations in the urban agglomeration. Therefore, it is recommended to guide greener development to reduce the water pollutant discharge; to embed an environmental push-back mechanism in the fields of industrial production, capital investment, and financial income and expenditure; and to establish a high-quality development pattern of urban agglomerations systematically compatible with the carrying capacity of the water environment.     

黄河三角洲湿地保护与恢复的现状、问题与建议

黄河三角洲湿地是中国暖温带保存最完整、最广阔和最年轻的湿地生态系统,其原始性、脆弱性和作为珍稀濒危鸟类重要栖息地的作用在国际上备受关注。着眼于当前黄河三角洲湿地的生态问题及变化趋势,分析了黄河三角洲湿地保护与恢复的现状、问题和发展趋势,阐明了黄河三角洲湿地保护与恢复的基本框架和关键技术,明确了下一步黄河三角洲湿地保护与恢复的主要任务,并从区域可持续发展角度提出了黄河三角洲湿地保护与恢复的措施与建议。     

珠三角县域城市潜力的空间集聚演化及影响因素

运用因子分析、扩展的潜力模型、ESDA和空间计量经济学模型,基于五个时间断面的数据,探讨了1990-2009年珠三角县域潜力的空间集聚格局演变特征及其影响因素。研究发现：总体上珠三角县域潜力具正空间集聚特征,但集聚程度不高且趋于减弱;大多数县域潜力的局部空间集聚特征保持相对稳定且规律性明显,高潜力县域集中在广-佛都市区并呈向深-莞-惠都市区发展态势,低潜力县域进一步向研究区西部集聚,并在西部形成面状连续分布区;局部空间集聚格局也发生了一些变化：HH和LL集聚区位有所变化,局部集聚类型间有一定的转化,县域潜力的空间集聚的不均衡性在西部与中东部地带间有进一步扩大倾向。从县域潜力集聚演化的影响因素上看,县域间相互作用、地理区位、消费者购买力、人力资本、劳动力成本、信息化水平有显著正向影响;企业数量、城市化水平有显著负向影响;交通运输条件、固定资本投入和两个经济政策因素的影响不显著。     

Relationships between hydrological and limnological conditions in lakes of the Slave River Delta (NWT,Canada) and quantification of their roles on sedimentary diatom assemblages

Water chemistry and surface sediments were analyzed from 41 shallow lakes representing three previously-defined hydrological categories in the Slave River Delta, Northwest Territories, Canada, in order to identify relationships between hydrological and limnological conditions and their associations with recently deposited diatom assemblages. Evaporation-dominated lakes are physically removed from the influence of the Slave River, and are characterized by high alkalinity and high concentrations of nutrients and ions. In contrast, flood-dominated lakes tend to receive a pulse of floodwater from the Slave River during the spring thaw and have low alkalinity and low concentrations of most nutrients and ions. Exchange-dominated lakes are variably influenced by floodwaters from the Slave River and seiche events from Great Slave Lake throughout the spring thaw and open-water season, and are characterized by a broad array of limnological conditions that are largely dependent on the strength of the connection to these sources of floodwater. Specific diatom ‘indicator’ taxa have been identified that can discriminate these three hydrological lake categories. Evaporation-dominated lakes are associated with high relative abundance of common epiphytic diatom taxa, while diatoms indicative of flood- and exchange-dominated lakes span a wide range of habitat types (epiphytic, benthic) but also include unique planktonic diatoms (Stephanodiscus and Cyclostephanos taxa) that were not found in surface sediments of evaporation-dominated lakes. The planktonic diatom taxa originate from the Slave River, and thus are indicative of river influence. In complex, remote, freshwater ecosystems like the Slave River Delta, integration of results from hydrological and limnological approaches provides a necessary foundation to assess present, past and future hydroecological responses to changes in river discharge and climate.     

长江三角洲人口迁移空间格局、模式及启示

本文运用修正后的重力模型和城市之间最短通行时间的O-D矩阵,模拟长江三角洲人口迁移节点联系状态,判断吸引中心的从属结构,划分人口迁移引力体系的等级结构。结果表明:至2005年,长三角共形成上海、南京、杭州、宁波、温州5个一级人口吸引中心,无锡、徐州2个二级吸引中心,连云港、淮安、扬州等9个三级吸引中心;这些吸引中心共同构成5个Ⅰ级引力体系,7个Ⅱ级引力体系和14个Ⅲ级引力体系。在此基础上,归纳出人口迁移空间结构演变的一般模式:即"单核集聚"—"多核结构"—"单中心体系"—"多中心网络"。通过吸引中心等时圈分析,认为区域快速交通体系布局对人口流动空间格局的形成起着重要的引导和支撑作用。最后从城市轨道交通、地方行政壁垒和中心城市发展角度对长江三角洲不同层次的规划提出了相应的建议。     

Self-weight consolidation and compaction of sediment in the Yellow River Delta,China

Extensive studies of land subsidence in the Yellow River Delta (YRD) have identified sediment consolidation and compaction as important contributors to geologic processes. Although previous studies were informed by detailed knowledge of subsurface getechnical properties and depositional history, geotechnical data that are sufficient for detailed modeling are still unavailable for much of the delta. To overcome this limitation, we use a modified Monte Carlo method to model the incremental sedimentation and compaction in the delta and identify the stratigraphic characteristics of all abandoned lobes in the delta on a short-term scale of decades. A Digital Elevation Model (DEM) of the thickness of the delta plain is generated based on a contour map of the delta using Geographic Information Systems technology. Combining our simulation results and the DEM creates an overall view of the delta’s temporal and spatial land subsidence characteristics. Most data from the 152 boreholes show properties of soft soil, which is saturated and compressible. Our data confirm that the most rapidly compacting strata contain 100% soft soil. Research on settlement from soft soil compaction is particularly important because of the widespread distribution of soft soil in the YRD.     

Role of hydrological regime and floodplain sediments in channel instability of the Bhagirathi River,Ganga-Brahmaputra Delta,India

Abstract

This research deals with the surface dynamics and key factors – hydrological regime, sediment load, and erodibility of floodplain facies – of frequent channel shifting, intensive meandering, and lateral instability of the Bhagirathi River in the western part of the Ganga-Brahmaputra Delta (GBD). At present, the floodplain of the Bhagirathi is categorized as a medium energy (specific stream power of 10–300 W m^?2), non-cohesive floodplain, which exhibits a mixed-load and a meandering channel, an entrenchment ratio >2.2, width–depth ratio >12, sinuosity >1.4, and channel slope <0.02. In the study area, since 1975, four meander cutoffs have been shaped at an average rate of one in every 9–10 years. In the active meander belt and sand-silt dominated floodplains of GBD, frequent shifting of the channel and meander migration escalate severe bank erosion (e.g. 2.5 × 10⁶ m³ of land lost between 1999 and 2004) throughout the year. Remote sensing based spatio-temporal analysis and stratigraphic analysis reveal that the impact of the Farakka barrage, completed in 1975, is not the sole factor of downstream channel oscillation; rather, hydrogeomorphic instability induced by the Ajay–Mayurakshi fluvial system and the erodibility of floodplain sediments control the channel dynamics of the study area.     

长江三角洲区域开放开发政策的内涵与演变

以改革开放以来长江三角洲实施的区域开放开发政策为样本,将开放开发政策分为宏观开放开发政策、经济特区与综合配套改革试验区政策、开发区政策3个能级,从政策内容、工具、作用强度3个维度分析了区域开放开发政策演变的过程。长江三角洲国家级/省级宏观区域开放开发政策的目标从对外开放转为综合开发,对外开放在空间演化上呈从点到面、从沿海到内地、从中心城区到农村的梯度开放特征,政策工具从财税政策和行政控制转为发展社会资本与改善发展环境,前期的财税优惠政策和开放政策逐渐削弱甚至消亡,一些区域规划上升为国家战略而得到增强。上海浦东经历了从经济特区向综合配套改革试验区的转变,政策工具从优惠政策转向全方位的优先探试权。开发区政策集中在经济领域,省级开发区政策效应较国家级开发区弱,不同开发区间的政策逐渐趋同,强度在不断弱化。     

Sediment variability and transport in the littoral area of the abandoned Yellow River Delta,northern Jiangsu

The delta evolution and erosion process of the abandoned Yellow River Delta (AYRD) have been extensively studied. However, the variation of sediment at a large littoral scale along the north coast of Jiangsu is less understood. In this study, the data of surface sediment samples obtained in the littoral area of the Yellow River Delta in 2006 and 2012 is used to study the sediment variability and sediment transport trends by using the geostatistics analysis tool and the grain size trend analysis model. In order to ensure the applicability of the model, the geostatistics method is used to determine the characteristic distance (Dc) with the average range value (Ao) of grain size parameter. Filtering method (removing data that not at a sampling station) is used to improve accuracy of data selection. The results show that sedimentary spatial correlation in Lianyun Port area and southern part of the abandoned Yellow River Delta (AS) is better than that in the northern part of the abandoned Yellow River Delta (AN). Sediment in the area is found to be anisotropy at the northeast-southeast direction. The grain size trend analysis reveals that the sediment trend is towards bayhead and southerly in the Haizhou Bay, southeasterly along the shoreline in the south Lianyun Port, northwesterly in AN and easterly-southeasterly in AS respectively. The investigation of possible relationships between Dc, Ao, sediment transport and delta evolution shows a close link between Dc and Ao of one sediment combination. It is also found that sediment transport trends could reasonably represent the delta evolution to a certain degree.     

State-Sponsored and Spontaneous Urbanization in the Pearl River Delta of South China, 1980-1998

State-sponsored urbanization prevailed in the prereform China. A new track of spontaneous urbanization has emerged since 1978. However, state-sponsored urbanization has continued to be an important process of urbanization in the reform period. The Chinese pattern of urbanization since 1978 is distinguished by dual-track urbanization. This paper uses the dualtrack urbanization approach to examine the urbanization process in Pearl River Delta in the reform period. Whether urbanization takes place in main cities or low-order settlements has been a lasting theme of the urbanization inquiry. This issue is assessed by an analysis of the relative concentration and deconcentration of urban population among four groups of settlements: the primate city, cities with special economic zones, prefecture-level cities and county-level cities/counties. Contrary to previous research, it is found that both state-sponsored and spontaneous urbanization are driving a dispersed pattern of urbanization in the region.     

Sediment variability and transport in the littoral area of the abandoned Yellow River Delta,northern Jiangsu

The delta evolution and erosion process of the abandoned Yellow River Delta (AYRD) have been extensively studied. However, the variation of sediment at a large littoral scale along the north coast of Jiangsu is less understood. In this study, the data of surface sediment samples obtained in the littoral area of the Yellow River Delta in 2006 and 2012 is used to study the sediment variability and sediment transport trends by using the geostatistics analysis tool and the grain size trend analysis model. In order to ensure the applicability of the model, the geostatistics method is used to determine the characteristic distance (D _c) with the average range value (Ao) of grain size parameter. Filtering method (removing data that not at a sampling station) is used to improve accuracy of data selection. The results show that sedimentary spatial correlation in Lianyun Port area and southern part of the abandoned Yellow River Delta (AS) is better than that in the northern part of the abandoned Yellow River Delta (AN). Sediment in the area is found to be anisotropy at the northeast-southeast direction. The grain size trend analysis reveals that the sediment trend is towards bayhead and southerly in the Haizhou Bay, southeasterly along the shoreline in the south Lianyun Port, northwesterly in AN and easterly-southeasterly in AS respectively. The investigation of possible relationships between D _c, Ao, sediment transport and delta evolution shows a close link between D _c and Ao of one sediment combination. It is also found that sediment transport trends could reasonably represent the delta evolution to a certain degree.     

Diagenesis in Okavango fan and adjacent dune deposits with implications for the record of palaeo-environmental change in Makgadikgadi–Okavango–Zambezi basin, northern Botswana

This work considers the spatial distribution and ages of western MOZ basin siliclastic sediments prior to providing insights into the diagenesis of degraded dune and alluvial fan sands. Previously published and new TL/OSL ages imply that extensive over-washing of dune sands took place at least 100 ka ago while ages on Okavango floodplains imply that the fan was formed ca. 40 ka and has since undergone periods of higher and lower flood regimes. Sediment analyses indicate that both dune and fan sands contain a diagenetic matrix of clay-enhanced amorphous silica (CEAS) which bonds weakly formed aggregates. The time of formation of diagenetic matrix products is inconclusive but may have been accelerated during or shortly after events dated using OSL/TL techniques. Hence earlier dune over-washing may have led to greater porewater of an acidic to near neutral nature which in turn promoted smectite formation and silicic acid precipitation > 100 000 years ago. The relatively abundant CEAS matrix in floodplain sands implies more recent semi-continuous flood events again of an acidic-near neutral nature leading to the formation of smectite. In this case the floodplain sediments are dated as having been deposited around 40 and 11 ka, when porewater content may have accelerated clay formation and silica dissolution. The dual nature of the CEAS in the islands reflects a changing environment from smectite-dominated flooding events to sepiolite-dominated desiccation events. Flooding may also correspond to TL/OSL ages over the past 40 000 years which contributed to accelerated CEAS formation. The sepiolite is associated with a Ca-rich matrix implying desiccation which may relate to drying events over the 40 000 year period or to riparian tree root pumping and selective salt accumulation. This work shows that sedimentation in incipient rifts is complex and rarely explained totally in terms of primary depositional events. The implications of different stages of sand diagenesis may be significant in enhancing palaeo-environmental interpretations in semi-arid fluvial environments.     

1990-2014年泛长三角地区能源利用碳排放时空格局及影响因素

区域碳排放时空格局及其关键影响因素是近年来学者们关注的热点。本文以中国经济发达、经济关联密切、产业格局变化剧烈的泛长三角地区为案例,分析1990年以来典型年份碳排放的空间分异、时间演变,解析碳排放空间分异的关键影响因素。结果表明：①区域碳排放总量快速增长,总体格局稳中有变,核心区16个城市排放量占比大都超过50%。②以2005年为拐点,之前外围城市增长幅度较低,之后外围城市碳排放量快速增长;外围地区碳排放量占比从2005年的33%快速增加至2014年的47%,区域碳排放量的空间集聚度呈现先增后减的态势。③碳排放格局变化受多种因素影响,不同变量对碳排放的影响各异。其中,工业生产、城镇化建设及人口集聚仍是现阶段泛长三角地区最主要的碳排放来源;固定资产与外商投资对区域碳排放的作用呈增强趋势,但其作用强度较工业生产、城镇化建设、人口集聚要小。地区生产总值对碳排放影响存在倒U型关系,随着经济发展水平的提高,碳排放与经济发展呈现脱钩趋势。研究结果可为揭示经济发展格局变化的环境效应、制定节能减排政策提供参考。     

转型视阈下珠三角地区乡村发展过程及地域模式梳理

在乡村振兴战略背景下,系统梳理珠三角地区的乡村发展演变历程及其主要地域模式,对中国乡村发展和振兴的科学路径选择具有重要参考价值。珠三角地区的乡村发展演变历经了4个阶段。① 1978年以前,传统乡村发展阶段。在国际市场需求刺激下出现“弃田筑塘,废稻树桑”,逐渐形成桑基鱼塘的有机循环农业生产模式,呈现出传统农业景观。② 1978—2000年,工业化驱动发展阶段。以乡镇企业嫁接外资形式推动了自下而上的工业化和城镇化,乡村空间逐渐形成了“生活居住+农业生产+工业生产”三位一体的功能结构,空间分化与混杂性特征显著。③ 2000—2008年,城市化与都市化双轨并行阶段。政府主导的城市土地开发和基础设施投资建设,促使珠三角地区逐渐演变为“大集聚,小分散”的城乡发展转型空间格局。④ 2008年至今,都市化驱动乡村急剧转型阶段。珠三角都市圈建设进程加快,城乡体系逐步向一体化和网络化发展,乡村地区的产业发展趋向多元分化,乡村破碎化的非正规空间促使形成全球城市区域下马赛克式分布的空间格局。基于不同区位的外部性和内生性因素的差异性,珠三角地区的乡村发展模式可归纳为城市区域型、近郊型、远郊型等不同地域类型。在乡村发展转型过程中,外部性的环境变化、内部要素分化与重构机制直接影响到乡村振兴的科学路径和模式选择。     

国际码头企业的珠江三角洲进入路径与空间网络

长期以来,港口竞争主要发生在不同港口之间,随着港口管制的放松,许多港口陆续引入私营资本,促进了港口竞争的发展变化,并在理论上形成了新的空间模式。珠江三角洲是中国港口建设最早引入外资和码头市场竞争最激烈的地区,也是中国港口管制放松和外向经济最活跃的地区。在阐述国内外研究现状的基础上,以珠江三角洲集装箱港口群为研究对象,分析国际码头企业进入珠江三角洲的时间路径,包括企业结构、企业数量与股权变化、港口数量等,总结其时间进入规律;基于空间视角,刻画国际码头企业的码头网络,重点包括参股港口分布、装卸能力演化、各企业投资差异等,考察国际码头企业的码头网络特征和扩张规律,并从港口建设经营、港口竞争码头化两方面分析国际码头企业进入对珠江三角洲港口发展的影响。研究表明,国际码头企业的进入路径受改革开放及政策的影响较大,目前已在珠三角码头市场中占据主导地位,集中投资大型港口,呈现先投资枢纽港再进入中小型港口的市场模式;国际码头企业的进入加剧了港口内部码头或泊位利益主体分化而形成港口内部竞争,促使港口竞争形成码头化态势,和记黄埔、招商国际、珠江船务等分别形成了规模庞大的码头网络,相互之间形成竞争和合作格局。研究丰富了港口地理学的研究视角,充实了港口研究的理论范畴。