The aim of this paper is to explore how classic upstream-downstream conflicts of water resources management can be interpreted more broadly in terms of spatial misfits and disparities between the river basin, territorial jurisdictions, degrees of political influence and socio-economic conditions. It applies the analytical concept of spatial fit in order to explore issues of governance in managing water in the Dongjiang River basin, selected by virtue of the huge political and economic asymmetries existing between the upstream Jiangxi Province and the downstream Pearl River delta region. Using the concept of spatial fit, the paper explores the complex environmental, socio-economic and political geographies which frame the interdependencies of water use and management within the river basin. It analyses attempts by stakeholders at different levels and locations in the basin to advance their own water-related interests and the initiatives some are developing to share benefits and costs more equitably across the basin.

High-gradient headwater streams are major participants in the carbon (C) cycle because of their capabilities of emitting a significant amount of carbon dioxide (CO2). Notwithstanding, their CO2 emissions have been largely overlooked in previous studies owing to their small water surface area and are sometimes strenuous to be measured because of their narrow channel widths and strong turbulence. This study examined the spatial and seasonal variabilities of CO2 dynamics of a subtropical steep headwater stream fed by groundwater. Our study found that the pH and dissolved oxygen exhibited a general increasing trend away from the source of the headwater whereas the partial pressure of carbon dioxide (pCO2) showed a downward trend. The stream water pCO2 in the upper reach was found to be higher than the ambient level by 19–114 times, with an average drop of >70% at just 9.2 m from the groundwater source, demonstrating the potentially large emission of CO2 into the atmosphere within this short distance. Additionally, the sampling works conducted further downstream revealed that the CO2 derived from groundwater could almost completely dissipate within approximately half a kilometer downstream of the source. The concentrations of dissolved organic carbon and pCO2 were also lower during the period with lower air temperatures in the headwater stream, indicating temperature-dependent metabolism and decomposition of organic matter in soil might modulate the C dynamics in the headwater stream, although the rapid gas exchange along the stream remained the determinative factor. Our findings reassert that headwater streams are an essential source of CO2 and disregarding them from the studies of greenhouse gas emissions of inland waters would underestimate their potency to influence the global C cycle.