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Cycle 8 (2019 Deadline)

Impacts of alluvial mining in the Madre de Dios Basin: physical effects and mitigation planning

PI: Mónica Moreno Brush (, Universidad de Ingeniería y Tecnología (original PI through February 4, 2021: Jorge D. Abad Cueva)
U.S. Partner: Eddy Langendoen, United States Department of Agriculture/ Agricultural Research Service
Project Dates: January 2020 - October 2021

Project Website:

Project Overview:
Despite many efforts in the Madre de Dios Basin to estimate the impacts of alluvial gold mining with regard to mercury concentration, deforestation, and socioeconomic implications (e.g., human trafficking, tax evasion), very few investigations have been conducted to understand the effects of extensive alluvial mining operations on the rates of sediment supply and morphodynamics of the rivers in southeastern Peru and on the spatiotemporal distribution of mercury concentrations. This is a time-sensitive project because mining activities advancing rapidly, producing drastic physical alterations to river systems, and the Peruvian National Government lacks adequate impact assessment methodologies of alluvial mining concessions, many of them already operating. Currently, basic analyses with satellite imagery feature these assessments, rather than analyses with multi-temporal and historical data to elaborate predictive models to determine principal sources and sinks of mercury across the watershed and gold deposits that indicate potential areas to be targeted for mining. The location and topography of the Madre de Dios headwaters, where alluvial gold mining occurs, create a high potential for escalating this environmental and public health problem, putting large portions of the basin at risk. There is a critical need to provide both a baseline of river morphodynamics and linkages between aquatic ecosystems and landscapes to develop not only decision-relevant indicators for environmental quality but also methods for identifying trends to determine environmental quality in the future.

This PEER-supported project will involve an integrated assessment of a coupled natural-human system in southeastern Peru where there is an urgent need to develop science-based sustainable practices and conservation of natural resources. By combining state-of-the-art techniques in field measurement, remote sensing, and mathematical modeling of riverine processes, this project will explore the interactions between flow, sediment transport, and channel change in rivers in association with the distribution of mercury along the food chain. The outcomes will provide useful insights for land managers and decision makers on river morphodynamics and function, a crucial gap in the understanding of rivers, currently a critical national priority for Peru. Local authorities and partners working in the region will be encouraged to share their knowledge about sediments in rivers in the area, as well as gaps that can be fulfilled with this research. They will also be encouraged to incorporate best practices and environmental standards in their management efforts and to include river morphodynamics as a component of natural resource management. Developing a more sustainable approach for the use and monitoring of the environment will promote and support responsible economic activity in the Amazon region through viable economic alternatives to illegal exploitation of natural resources and the development of alternative processes for extracting gold with the least possible negative impact on the surrounding ecosystems.

Summary of Recent Activities:

In early February 2021, new PI Dr. Monica Moreno Brush assumed responsibility for this project after the departure of the previous PI. That same month, the situation was further complicated because the Lima area was under increased public health restrictions due to the COVID pandemic. By March, however, thanks to intensive efforts by the PI and colleagues and with the addition of several new team members, the project was moving forward smoothly. Following are updates on recent and upcoming activities on each of the work packages involved:

Hydrobiology: Team members completed the processing of hydrobiological data (taxonomic diversity, richness, abundance, biodiversity indices) and environmental data (water physicochemical parameters and sampling location description) collected along the Madre de Dios River basin in late 2020. They passed along 76 fish tissue samples from 24 different species to the Mercury Pollution work package group for analysis. In the next few months, they will interpret all the processed data and parameters related to gold mining activities along with the characteristics of the sampling area. Results of total mercury concentrations in fish will also be interpreted according to the species feeding guild (herbivore, omnivore, and carnivore). This information, along with the biodiversity indices, will be published in a research brief. Overall, this work package aims to complement the work of the others to establish a connection between abiotic effects and biological data.

Mercury Pollution: The samples were sorted and codified in January and began to be freeze-dried in February after the previously malfunctioning freeze-dryer started working again. The total mercury analyzer also had technical issues during the first quarter of the year but was repaired. This group plans to conclude the total mercury analysis of fish and sediment samples by early May and continue with the data interpretation to produce a research brief summarizing their preliminary and most relevant results. Once the total mercury sediment data are available and revised, suitable sediment samples will be shipped to academic labs abroad for isotopic mercury signature and speciation analyses. From August 2021 onwards, they expect to focus on data interpretation and write a scientific paper on identifying the source of mercury in the study area.

8-235 Puerto Maldonado8-235 Site Visit 2020
Dr. Abad (at right) speaks to participants in the February 2-4 meeting with CINCIA and UTEC staff in Puerto Maldonado. (photo courtesy of Dr. Abad)PEER PI Dr. Jorge Abad (center) and colleagues welcome USAID Research Advisor Dr. Lily Sweikert and NAS Program Officer Ms. Lina Stankute-Alexander during their January 2020 visit to UTEC. (photo courtesy of Lina Stankute-Alexander)

Hydrogeomorphology: Members of this group worked on processing acoustic Doppler current profiler, river morphological, and sediment data, including 159 suspended sediments and 55 bottom sediments processed for concentration and grain-size distribution. This work package has been the most time-consuming during the reporting period.

Communications: The PI and communications specialists began started designing the project’s communication and influence plan. They updated the stakeholders’ map and brainstormed ideas for communication and advocacy products, including outlining plans for a webinar session to disseminate their research results and preparing a one-pager presenting the project status and some initial results. Later on this year, plans call for further dissemination activities via web postings, social media, and workshops, with the goal being to involve decision-makers in achieving collaborative agreements to improve public policies and monitoring protocols for mining-affected Amazonian rivers.

Modelling: In the second and third quarters of 2021, a two-dimensional hydraulic model for the Puquiri River will be developed using the Telemac 2D Software to analyze the bedload transport and predict the dynamics of the river before the occurrence of alluvial gold mining activities. This will be done using information from the hydrological model that will provide water flows and a sediment hydrograph. Data on total mercury in suspended sediments will also be considered in an effort to predict the environmental fate of waterborne mercury.

Remote Sensing: The planimetric morphodynamics of the Madre de Dios River and its tributaries the Colorado and Inambari will be characterized using satellite images from different years by determining the principal river metrics. The results will be interpreted and the processed products will be published in a data map on the PEER team’s interactive web portal

A no-cost extension has been issued through October 31, 2021, to provide extra time for completing all planned activities.

Previous Presentations:

On August 5, 2020, UTEC and CINCIA organized the webinar “Impactos ambientales de la minería ilegal e informal en la Cuenca del río Madre de Dios,” which was focused on the environmental impacts generated by artisanal and small-scale gold mining in the Madre de Dios region. The event was open to the public, with English-Spanish interpretation provided, and approximately 300 people were in attendance. Claudia Vega opened and moderated the event, and local keynote speakers were Luis Fernandez and Jorge Abad. Additional invited keynote speakers were Liset Rodriguez (Amazonian National University of Madre de Dios, UNAMAD), Monica Moreno-Brush (University of Freiburg), Heileen Hsu-Kim (Duke University), and Bridget Bergquist (University of Toronto). For more information, please visit the recording link:

At the V National Water Congress held at UTEC March 12-14, 2020, CINCIA and UTEC personnel presented the project in both oral lectures and scientific posters. UTEC presented the general outline of the project, preliminary measurements in the region, and future steps, which CINCIA covered data on mercury concentrations found in sediment and fishes along the Madre de Dios river, current changes in land cover (from forests into contaminated wetlands), and the loss of biodiversity. Abstracts can be downloaded from

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