Recent satellite mapping and coring of the peatland complex of the Congo Basin’s Couvette Centrale region underscores the global significance of this area. Freshwater tropical peatlands in the Congo Basin make up one of Earth’s largest terrestrial carbon sinks which forms an important nexus between global climate, biogeochemical cycling, and biodiversity. These peatlands are also a unique record of past climates, containing microfossil and geochemical proxies documenting past climatic and hydrological conditions in the region, yet there are no published studies of these peatland deposits south of the Congo River in the Democratic Republic of Congo (DRC). Recent coring and radiocarbon dating of peatland core sequences collected from the Couvette Centrale and Mai Ndombe regions of DRC provides new data on the timing of peatland establishment in the Congo Basin. Furthermore, preliminary results of palynological and isotope geochemical analysis shed light on the spatial and temporal variability in regional rainfall regimes for these regions.

The Congo Basin stands out as a convective hotspot and plays a crucial role in the Earth’s climate system by modulating the atmospheric circulation and carbon emissions caused by biomass burning in its southern and northern bands. Climate variability in this region is a result of interactions among various features acting on different time-scales. This presentation provides an overview of our current understanding of such features that operate at regional (e.g., Walker-like cells) and global (e.g., ENSO) scales. The distinct spatial heterogeneity of the region with respect to interannual variability will be presented and compared with the spatial variability of annual and diurnal cycles. Differences in driving factors of these variabilities will be discussed. Some challenges, such as the lack of in-situ observations, that limit the climate analysis over the region will be addressed. Finally, several aspects of future research opportunities will be highlighted. This includes interactions between local atmospheric jets, waves, precipitation-producing systems, deforestation and biomass burning, as well as potential improvements in collecting ground-based meteorological data in the region.

River transport, with more than 17,000 km of navigable channels in the Congo, is a crucial part of the economy for many of the countries sharing the river basin and allows the transport of many goods (timber, charcoal, minerals etc.) and enables access to many areas where roads do not exist. However, river transport falls short of the role it could play in development of the region and has actually declined since the Congo basin countries became independent in the 1960s. This is in part due to years of civil unrest, aging equipment, a lack of infrastructure maintenance, and the poor support and operation of public waterway agencies. River navigation maps are a specialist form of map specifically designed to allow safe navigation of river traffic such as for barges carrying cargo. Boat captains use them as they travel along the river to follow the advised navigation route and avoid hazards such as submerged rocks and shallow channels. The navigation maps for the 1,700 km of river between Kinshasa and Kisangani are issued by RVF (Régie de Voie Fluvial), the state river navigation authority, and are therefore used by all boat captains. These maps originate from the early 1900s and have not been updated since colonial times. As part of the CRuHM project we are exploring the possibility of updating these maps using modern remote sensing methods, together with RVFs experienced input. As part of the update process, RVF have provided us with detailed digital scans of the original navigation maps and we are geo-referencing these to modern geospatial projections, in line with the remote sensing data. This provides us with a unique opportunity to compare snapshots of the river system geomorphology separated by nearly 100 years. We will show the current state of the project and some of the river secrets we have discovered so far.

Land use change due to population growth and an increase in anthropogenic activities such as logging and mining (mostly illegal) have led to an increase in the sediment load of the Kasai River in the Congo River Basin. However, even with recent developments in technologies such as remote sensing and improvements in erosion prediction models to study sediment transport in water bodies; this phenomenon has been little studied in this poorly gauged catchment and the wider Congo River Basin due to lack of field-based sediment concentration measurements required to calibrate the results of such studies. The present study describes recently concluded field excursions to set up a high frequent sediment sampling station on one of the major tributaries of Congo River, the Kasai River. The station is fitted with an ISCO 6712 automatic pumping sampler to enable high frequency sampling. The ISCO is coupled with an OBS 501 turbidity sensor to collect even higher frequent sediment concentration data. The site is also fitted with other instruments to measure other hydrologic and climatic variables such as a manual staff gauge and an automatic water levels logger. The preliminary sampling efforts have been designed to guide a comprehensive sediment sampling programme which is part of a wider study to build a sediment yield model for the Congo River Basin in order to study the impacts of sedimentation on hydropower planning.

A reach-scale high resolution digital elevation model (DEM) of the Congo’s main stem bathymetry is presented. The Bathymetry DEM covers a multichannel reach of the main stem situated in the Cuvette Centrale, and is developed from a series of in-situ measurements of bathymetry, water surface elevation and discharge that were obtained during a CRuHM fieldtrip in summer 2017. The main stem’s complex network of channel threads requires a bathymetry modelling methodology that is capable of intelligently interpolating the raw bathymetry measurements. The methodology must also estimate a significant portion of the bathymetry, since it is not feasible to measure the entire extent of the massive and complex channel network that this study reach is comprised of. This methodology is also presented. Remote sensing from satellites is increasingly being used to resolve the scarcity of contemporary hydrological and hydrographic measurements in the Congo Basin. However, river channel bathymetry information cannot yet be reliably obtained from remote sensing methods. This is problematic since river channel representation has been shown to be an essential input into a hydraulic model. Analyses of satellite observations suggest that, relative to other global rivers, in-channel flows on the Congo’s main stem represent a relatively large proportion of total flows through the river-floodplain system. This implies the Congo’s in-channel bathymetry may play a relatively large role in controlling Congo main stem hydrodynamics. When used in a hydraulic model, the bathymetry DEM presented here will provide new information on Congo in-channel hydraulics and the extent to which bathymetry controls the Congo’s middle reach hydrodynamics. It will help better quantify the capacity of the Congo main stem channels through the Cuvette Centrale, and thus provide further insights into the extent to which the main stem channel floods in this region. It is also intended to be used for testing simplified methods of Congo bathymetry representation that are necessary for larger scale hydraulic models.

A great deal of paleoenvironmental research on tropical alluvia and slope sediments assumed the long-term persistence of stable climates and associated rainforest vegetation in the Congo basin during the Quaternary. Geomorphological, paleo-hydrological and ecosystem history research in the eastern Congo basin (Kivu, DR Congo) has provided evidence of the frequent occurrence of multi-layered alluvia and fans in river valleys and plains as well as stratified slope deposits (hill-wash, stone-lines, pedo-sediments) that reflect former modifications of the environment. Numerous radiocarbon data indicate that ecosystems within the Congo basin are highly sensitive to climate change through modification of surfaces and run-off dynamics. A stratigraphic record characterized by variable sediment layers of 2.0–5.5 meters thick spans the Holocene and the Pleistocene back to 50 ka BP (completed by finds from Cameroon and Central African Republic). Buried stone-lines and paleo-soils indicate once drier, more open landscapes under alternating wet and dry climates in currently humid and semi-humid regions. A conceptual morpho-dynamic model is presented and summarizes process related response to former environmental modifications.