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The mining industry of the Democratic Republic of the Congo (DRC) represents the most important sector of the country's economy, and the DRC belongs to the world top five diamond producers. Artisanal small-scale mining (ASM) of alluvial diamonds represents an important source of alternative income for subsistence farmers, but it also leads to several socio-environmental impacts: deforestation, river pollution, water resources exploitation, unhealthy, unregulated and sometimes dangerous work environments. We perform a data-driven comprehensive analysis of the impact of the diamond mining industry on natural resources and assess the potential relevance of these resources to the DRC food system. To this end, we evaluate land and water resources consumption associated with diamond mining from 2001 to 2018, cross-referencing high-resolution data on mines, land use and tree cover, and using a dynamic and spatially distributed agro-hydrological model. We leverage disaggregated agrological data to provide alternative resources allocation scenarios, and use subnational development indicators and spatially explicit conflict data to frame our analysis within the socio-economic context. We find that, despite the richness in natural resources of the DRC, the impact of diamond mining is relevant because of its effects on ecology, economy, and society. Resources and efforts currently put into the mining industry may have the potential to alleviate the malnourishment crisis in DRC if diverted towards the construction of a more structured and resilient food system. Phenomena such as the illicit trafficking of diamonds and their use to finance wars contribute to nullify the potential of mining as an alternative source of income for subsistence farmers.

The inner connections between floods and food security are extremely relevant, especially in developing countries where food availability can be highly jeopardized by extreme events that damage the primary access to food, i.e. agriculture. A method for the evaluation of the effects of floods on food supply, consisting of the integration of remote sensing data, agricultural statistics and water footprint databases, is proposed and applied to two different case studies. Based on the existing literature related to extreme floods, the events in Bangladesh (2007) and in Pakistan (2010) have been selected as exemplary case studies. Results show that the use of remote sensing data combined with other sources of onsite information is particularly useful to assess the effects of flood events on food availability. The damages caused by floods on agricultural areas are estimated in terms of crop losses and then converted into lost calories and water footprint as complementary indicators. Method results are fully repeatable; whereas, for remote sensed data the sources of data are valid worldwide and the data regarding land use and crops characteristics are strongly site specific, which need to be carefully evaluated. A sensitivity analysis has been carried out for the water depth critical on the crops in Bangladesh, varying the assumed level by ±20%. The results show a difference in the energy content losses estimation of 12% underlying the importance of an accurate data choice.

© 2017 The Authors Since small-scale farmers manage most of the cultivated land worldwide, the ongoing shift in systems of production associated with large-scale land acquisitions (LSLAs) may dramatically reshape the world's agrarian landscape, significantly impacting rural populations and their livelihoods. The societal, hydrological and environmental implications resulting from the expansion of large-scale agricultural production, through LSLAs, make their ultimate sustainability questionable. This study, through a literature review, analyses the negative impacts of LSLAs, their hydrological dimension and how they may affect the Sustainable Development Goals (SDGs). The core literature on land and water grabbing is reviewed and systematized using the 17 SDGs as a framework, in order to highlight the relationship between LSLAs and the sustainable development agenda. The magnitude of the global land rush phenomenon and the criticism raised in scholarly research highlight the controversial role that transnational land acquisitions may be playing in the global development agenda.

Rainforests ensure fundamental water-related ecosystem services that are currently threatened by land-use change, in particular deforestation. Quantitative assessments of water-related ecosystem services have traditionally focused on the benefits linked to direct water availability for humans. Under this perspective, forests have been considered as water consumers, due to high interception and transpiration rates that reduce water flows available to downstream human activities. In contrast, their role as water suppliers through transpiration from tree canopies has often been neglected. Integrating this second perspective into assessments of water-related ecosystem services from forests and other land covers is key to providing a comprehensive support to decision-making processes on land-use change. In addition, specific indicators are necessary to incorporate the contribution of the different water balance components into ecosystem service assessment. In this paper, we investigate the use of water balance partitioning for the assessment of water-related ecosystem services. We use three water balance models (two existing ones and one developed in this study) and compare, via model simulations, water balance partitioning and water-related ecosystem services of a forested and a deforested area of the Brazilian State of Rondonia. Then, we propose a set of indicators that, based on the outputs of the models, provide a multidimensional characterization of different land-use types. Regardless of the model used, the values of these indicators for the selected case study consistently point out the key role of vegetation in regulating the water cycle. Forests act as effective indirect water suppliers for human activities and are key players in moisture recycling, thanks to high evapotranspiration rates (about 68% of total precipitation). Deforested areas, instead, act as direct suppliers of water flows for human activities due to higher drainage rates (about 50% of total precipitation). The proposed methodology helps highlight the importance of comprehensive water-related ecosystem services assessments. Moreover, the indicators quantitatively support the impact assessment of land-use change on the different processes involved in the water cycle and on human activities relying, directly or indirectly, on these processes.

Summary This study addresses the problem of modelling sediment erosion at the catchment scale, in order to predict the possible impact of reservoirs and land use changes on sediment load in South East Asia. The investigated basin is the Lo river basin, (38,165 km 2 in Viet Tri), a left tributary of the Red River, where the Thac Ba and the recently built Tuyen Quang reservoirs have already been changing downstream sediment load since 1971 and 2005 when they were, respectively, in operations. The RUSLE equation is adopted in a distributed GIS framework to assess catchment erosion, and is coupled with a sediment accumulation and routing scheme to model suspended sediment load in the Lo basin at a monthly scale. Monthly precipitation were collected and used as input to the model. Suspended sediment load data, measured at eight gauging stations in Vietnam, from 1959 to 2007, were compared with the model’s simulated sediment yield. Resulting average Nash–Sutcliffe efficiency is 0.45, ranging from 0.33 to 0.62 and bias is 5% at Vu Quang, close to the basin outlet, and results 1.4% by averaging biases at the eight stations, thus confirming that the model is adequate. Effects of reservoirs were analysed by modelling erosion and sediment yield passing from natural to impounded conditions and resulted in a suspended sediment load reduction of about 95% and 75% downstream, respectively, the Thac Ba reservoir in the Chay river and the Tuyen Quang reservoir in the Gam river . Land use change scenarios, parameterized on the basis of observed land use changes in the impounded basin and assuming that 20% of forest area is converted into rice and agricultural crops and 15% into bushes, shrubs and meadows, are expected to induce a 28% increase of suspended sediment load which can compensate, at least in part, sedimentation in reservoirs. Also agricultural and hillslope maintenance practices can modify sediment erosion in the basin.

To which extent do wildfires affect runoff production, soil erosion and sediment transport in upland catchments? This transient effect is investigated here by combining data of long term precipitation, sediment yield and wildfire records with a fine resolution spatially distributed modeling approach to flow generation and surface erosion. The model accounts for changes in the structure and properties of soil and vegetation cover by combining the tube-flux approach to topographic watershed partition with a parsimonious parametrization of hydrologic processes. This model is used to predict hydrologic and sediment fluxes for nine small catchments in Saint Gabriel mountains of southern California under control (pre-fire) and altered (post-fire) conditions. Simulation runs using a 45 years record of hourly precipitation show the passage of fire to significantly modify catchment response to storms with a major effect on erosion and flood flows. The probability of occurrence of major floods in the post-fire season is shown to increase up to an order of magnitude under same precipitation conditions. Also, the expected anomaly of sediment yield can increase dramatically the desertification hazard in upland wildfire prone areas. One should further consider the role of firefloods produced by the combined occurrence of wildfires and storms as a fundamental source of non-stationarity in the assessment of hydrologic hazard.

Summary Rainfall simulator experiments were carried out in the Liguria region, Italy, immediately after a forest fire in early August, 2003, to evaluate the effects of forest fire on soil hydraulic properties, runoff and erosion. Two adjacent 30 m 2 plots were set up with common physiographic features, and the same fire history, except for the fire of August 2003, which burned only one of them. Since both plots were previously subject to the passage of fire in March 1997, one compares the hydrologic and sedimentologic response of an area burned in year 2003 (B03) with that of an area burnt 6 years before (B97). Each rainfall simulation consisted of a single 60 min application of rainfall with constant intensity of about 76 mm h −1 . The results show runoff ratio, evaluated for different pre-event soil moisture conditions, ranging from 0% to 2% for B97 plot, and from 21% to 41% for B03. Runoff ratio for the recently burned plot was 60 times higher than for the plot burned six years before, under wet conditions, and 20 times higher, under very wet conditions. A large increase in sediment production also was measured in B03 plot, as compared with that in B97 plot. Suspended sediment yield from B03 plot was more than two orders of magnitude higher than that from B97 plot in all the simulated events. The high soil losses measured immediately after burning indicate that effective post-fire rehabilitation programs must be carried out to reduce soil erosion in recently burned areas. However, the results for the plot burned six year prior show that recovery of the hydrological properties of the soil occurs after the transient post-fire modification.

Flume experiments were carried out to investigate the motion of large woody debris (LWD) in rivers as influenced by the presence of obstacles. Non-rooted, defoliated LWD was modelled by placing properly scaled wooden dowels placed into controlled water flow. Obstacles were represented by wooden rods randomly placed into the flume with a specified probability distribution. The results provide the probability of lodging of the dowels and statistics of the distance travelled. Their relationships with flow rate and depth, dowel length and spatial density of the obstacles is explored. This yields a general theoretical framework to approach LWD transport in rivers by combining random factors with deterministic dimensionless variables.