The over-exploitation of non-renewable resources for energy demands is a serious issue. Convergence towards renewable resources such as solar energy is need of the day. Solar energy is the cleanest form of energy available on Earth. The objective of this research is to extract the building rooftop from the satellite images using a k-means clustering algorithm to identify the usable area for solar potential assessment. The scenes of WorldView-3 and Google Earth are segmented into nine parts and the algorithm implemented in Matlab is applied to the individual parts for better utilization of computing resources. This approach has been applied to the parts of northern states of India for solar potential assessment in a fast and accurate manner. The Global Horizontal Irradiance (GHI) data obtained from the database of National Renewable Energy Laboratory (NREL), United States have been used in the solar potential assessment. For the validation purpose, the above-mentioned algorithm has been compared with the digitization in QGIS software. The results obtained from the above-mentioned algorithm developed have extracted 85% to 90% of the features in the satellite image. The developed algorithm has given best results with the WorldView-3 (high-resolution image) than the other coarser resolution scenes. The developed approach is helpful in evaluating the feasibility of the large areas for solar potential assessment. This methodology is useful for the implementation of different government’s solar energy generation schemes for rural and hilly areas. It helped in estimating the solar potential of the large hilly area for electricity generation. This approach is useful for a larger area as it computes the usable area by dividing the scenes into smaller parts and applies the algorithm individually to each part of the scene. Keywords: k-means clustering, GHI, rooftop, solar potential, Google Earth, WorldView-3

Informal education can be a vital part of a person’s learning experience, thus it is important to continue studying its effectiveness and consider improvements. To that end, we studied participants who built their own AM radio at three School of Earth and Space Exploration open house events at Arizona State University. For this qualitative research study, we audio recorded and transcribed interviews of 41 adults after they completed the activity. Median duration of interviews was 3 minutes. Based on their responses, we categorized participants as either a parent who brought their children (Np = 23) or an individual (Ni = 18). This is consistent with previous studies since over 50% of participants are typically parents. We further grouped each category based on their Science, Technology, Engineering & Math (STEM) background: No STEM Background (NSB), Some STEM Background (SSB) and Expert Electronics Background (EEB). STEM backgrounds of parents were evenly distributed, with each group (i.e., NSB, SSB & EEB) accounting for about 30%. In contrast, about 60% of individuals were in the SSB group. Regardless of STEM background, the vast majority of parents stated that they came to the activity because of their children. Additionally, a majority of participants stated that they learned something from the activity, with only 4 of 41 participants saying they did not learn anything. Thus, this activity provides learning opportunities for people of all STEM backgrounds. As an example, one individual in the EEB group stated, “The design of the transmitter and the receiver itself is completely complicated based on me studying for 10 years trying to understand what a transmitter and receiver is. But just in five minutes I found that I could really built [sic] it by myself.” Yet, individuals who are either in the NSB or the EEB group may be overlooking certain informal education opportunities, since together they accounted for only 40% of individuals. To improve public understanding of science, informal learning centers should continue to consider ways to make events more accessible and more enticing for people who may not be experiencing these valuable learning opportunities.

Many resource management studies focus on one resource. Humans, however, rely on multiple resources in a complicated way. A person may derive more well-being from one unit of a resource than from another; one resource may be substituted by another to some degree. How should one manage such coupled natural-human systems? In this work, we build on recent research that focuses on developing conceptual frameworks and mathematical models to understand such interactions. The multiple resource condition injects the concept of substitutability into models of coupled human-natural systems and affects how such systems should be governed. Substitutability has been mostly mentioned in the field of economics for a substitution of natural and human capitals. Similarly, one resource may substitute for other scarce resources in coupled human-natural systems since some of these resources are not completely independent. In this study, we revise and expand an existing conceptual framework to include two natural resources, resource users, governing agency and public infrastructure in a centralized governance structure, i.e., all the natural resources are managed by the same governing entity. We then devise a set of dynamical equations and relationships from different fields, such as a replicator equation, a population equation, and a CES production equation, to capture the dynamics of this coupled system. This analysis can provide a decision-support tool to design policies to sustainably govern the built environment where human, natural resources, and infrastructure are interconnected. Model analysis takes a multi-faceted perspective of both resource users and governing entities to assess policies against different levels of disturbance. The results reveal how substitutability and asymmetry in resource use affect the viable policies needed to maintain the system.

Sap flux probes have been used to study sap velocity since the early 20th century and have progressively improved in accuracy and usability. Advances are also being made in making these devices cheaper via open-sourced projects; however, these solutions require extensive time and skill to construct a reliable device. When our lab tried to replicate Miner’s results, only two of the first ten probes built passed rudimentary testing. We therefore redesigned the system in a PCB-based design that simplifies construction, and presents opportunity for automated mass manufacturability at a scale not possible with existing designs. New designs for both the Thermal Dissipation Method (TDM) and the Heat Ratio Method (HRM) techniques were tested. We present our open-source designs for wireless sap flux probes that communicate over 2km using the LoRa protocol through canopy to an internet hub, where data is logged in near-real-time and accessible online.

In the semi-arid Andes Cordillera of central Chile (31–36°S), mountain glaciers are important reservoirs of freshwater, especially during droughts, contributing between 70 and 80% of the total runoff. In this work, we use the physically-oriented and spatially-distributed TOPKAPI-ETH glacio-hydrological model to simulate the response of glaciers to severe droughts in the Olivares River catchment. The glacierized area of this catchment is equivalent to 26% of the total glacier area in the Maipo River basin, the main source of surface water for Santiago de Chile – where more than 40% of the population in the country lives. To this end, we force TOPKAPI-ETH with synthetic droughts under several scenarios of glacier retreat, defined by two climate scenarios: i) current climate, preserving the mean and standard deviation of precipitation and temperature observed during the period 1990-2009, and ii) considering the Paris Agreement and constraining the global temperature rise – relative to preindustrial levels – to 1.5°C, projected by a small number of climate models under the RCP2.6 long-term scenario. We also use outputs from regional climate model simulations generated by the Center for Climate and Resilience Research (CR2) to represent what would be an increase of mean temperature in our domain. To assess the hydrological response of glaciers, and the contribution to total runoff under these scenarios, we compare our results with those obtained for droughts observed in this region during 1967-1969 and 2010-2015, considered as the most important events to date in Chile. Ongoing efforts are oriented to quantify ice loss under current climatic conditions, elevation line altitude variations during the long-term simulation, variations in glacier area and volume, and basin response to future drought under glacier retreat scenarios. Preliminary results show that glacier relative contribution to runoff at the end of the summer season increases up to 25% during the reference droughts, but decreases about 40% to 75% in comparison to the reference period considering climate scenarios.

Ground Penetrating Radar (GPR) is shown to be a successful tool in detecting tunnels and voids. Lava tubes are tunnel-like features in volcanic terrains that can be potential safe places for human crews and equipment on the Moon and Mars. We utilize GPR to detect and map lava tubes (Valentines cave, Skull cave and Hercules Leg cave) in Lava Beds National Monument, CA. Our preliminary results show that the ceiling of the lava tubes are readily detectable by GPR. However, due to the strong radar velocity contrast between lava and the air-filled tubes, accurate recovery of the position of the lava tube floor is much more challenging. Careful migration of the GPR data is required to resolve the floor signature and create an image with the tube floor restored to its correct depth. We are developing an optimal workflow for recovering complete lava tube geometries. We can do this because we have collected centimeter-scale LiDAR data from the interior of tubes as well as on the surface along GPR transect lines. Thus we can test the accuracy of GPR migration methods against the LiDAR-measured tube geometry. We are testing conventional 2D migration techniques as well as topographic migration. At selected field sites we have limited 3D ‘grids’ of data. We expect to compare the results of different migration techniques to identify optimal methods for this problem. As a part of this project, we also seek to develop a library of different lava tube geometries and their corresponding GPR image from their migrated sections. The GPR image library will encompass a range lava tube geometries, including tubes of different heights, widths, shapes, and structures (e.g., pillars), plus a variety of floor textures (e.g., smooth, ropey, rubble) and overhead thickness. This library will be an asset for determining the utility of deploying GPR technology in mapping a tube-rich environment.

Earthen dam failures of high hazard dams are expected to cause downstream human life loss and economic and environment loss. Of the three most prevalent failure modes for earthen dams, seepage (or piping) failures account for approximately 40 percent. All earthen dams seep and it is not uncommon to observe some seepage on the downstream toe, but the flow rate of uncontrolled seepage should be negligible. In general, seepage occurs through the dam and/or its foundation. The cross section of the dam is designed to force the waterside head (pressure) to drop as the water flows through the cross section to the downstream toe. Uncontrolled or unexpected seepage can promote soil movement (i.e. piping) and cause a pipe or a cavity to develop within the earthen structure which can lead to a complete failure of the embankment. At present there are over 84,000 earthen dams throughout the United States many of which depend on the US Army Corps of Engineers for inspection, monitoring, maintenance, and repair. Recently a multi-method geophysical investigation, was performed at a site where a suspected seep outflow had increased ten-fold, warranting further investigation. Because the seep presented in a historically dry stream channel in the karst bedrock adjacent to the dam abutment there was some question as to whether the origin of the seep was indeed a result of piping or due to a naturally occurring seasonal spring. Electromagnetic induction measurements of terrain conductivity, as well as electrical resistivity tomography and mise-a-la-masse surveys were performed in an attempt to delineate the source water of the seep. The geophysical methods identified potential flow paths from the impoundment to the seep; however, a geochemical analysis of the seep outflow was compared to the same analysis of the impoundment water on the upstream side of the dam and found to be statistically different.

Deep convective storms assume many intensities, sizes and morphologies in Earth’s atmosphere, reflecting varying balances of the competing forces that arise in the diverse atmospheric conditions that promote and support such storms. The understanding of how these forces compete with each other lends itself only with great difficulty to observational study, but much more easily to idealized parameter space studies using numerical models. A parameter space study was recently designed and executed using an eight-dimensional framework, with 2-h experiments run using all possible combinations of reasonably chosen high and low values of the eight independent parameters. The basic parameters are those needed to build an idealized vertical profile of temperature, moisture and wind: bulk convective available potential energy (CAPE), radius of an assumed semicircular hodograph, shape of the buoyancy profile, shape of the shear profile, lifting condensation level, level of free convection, cloud-base temperature (roughly equivalent to total precipitable water), and free tropospheric relative humidity. Each of the parameters is found to exert noteworthy independent impacts on the intensity and morphology of the convection, with drastic differences in updraft overturning efficiency (the ratio of simulated peak updraft speed to that predicted from pseudoadiabatic parcel theory), updraft rotation, updraft steadiness and precipitation efficiency. Storm rotational efficiency relative to ambient vertical shear, and its steadiness, may also be examined. Results will be shown that demonstrate the strongly patterned convective response within this large parameter space, for both updraft overturning and rotational efficiency and their temporal steadiness. For example, in experiments having CAPE = 2000 J/kg, peak updraft efficiency reaches 94% in some cases, while in others with unfavorable combinations of parameters, that peak is less than 20%. While the eight basic parameters used in this study cover most of the variability of the vertical meteorological structure of the convective atmosphere, the framework can easily be expanded by adding new dimensions to deal with other physical effects, such as varying types and distributions of aerosols and other tracers that influence atmospheric chemistry.

Federal agencies in the US must evaluate the environmental justice implications of regulatory actions. Environmental justice analyses frequently use demographic tests to determine whether regulated projects will disproportionately impact vulnerable communities, including American Indian communities. Demographic tests typically yield negative results, which are often cited as evidence of no environmental justice implications. However, susceptibility of demographic tests to false negative errors is unknown. In these cases, false negative errors occur when a test cannot identify a vulnerable population concentrated disproportionately within a project study area. We developed a technique to evaluate the susceptibility of demographic tests to false negative errors. We used the technique to assess a test commonly used by regulators to permit fossil fuel pipelines. The Atlantic Coast Pipeline served as a case study. The demographic test did not identify disproportionately large American Indian populations under any realistic scenario, a false negative error rate of 100%. In our case study, the test did not detect a disproportionately large American Indian population until the study area contained a four times greater fraction of American Indians than the reference area. We extend the results to study the test’s performance throughout the US. The test’s inability to detect disproportionately large American Indian populations calls into question the validity of negative results and the general ability of the test to inform conclusions about environmental justice or sustainability. We recommend abandoning the test in favor of more rigorous methods.

Low seasonal precipitation and high demand for water use for agriculture, mining, industry, power generation and human consumption have made water resources management a concern in the Arequipa Region of Peru, which may be worse under future climate projections. In this study, the hydrologic response to climate change is evaluated within the Quilca-Vitor-Chili River Basin in the Arequipa Region of Peru. The Soil and Water Assessment Tool (SWAT) is used to develop a watershed model based on topographical, land cover, soil, and climatic (precipitation and temperature) data, while taking into account anthropogenic inter-basin transfers. The model is calibrated and validated for current conditions. Three climate scenarios derived from Atmosphere-Ocean General Circulation Model (AOGCM) simulations for both Representative Concentration Pathways (RCPs) 4.5 and 8.5 are obtained from the NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP) dataset. Surface runoff and water yield associated with future climate scenarios are calculated for two near (2010-2039) and far (2040-2069) futures. Results of this study will provide a guideline for developing water policy in the region in order to mitigate negative impacts of climate variations in the region.

Water-Energy-Food Nexus assessments at river basin scale make sense in particular if hydropower is an important source of energy in a given region. The Blue Nile Basin is a major source for Water in the Nile river basin. It provides around 65 % of the flow of the Nile entering Egypt, and occupies a mere 10% of the total basin area. The Blue Nile water is primarily used for irrigation, hydropower, and domestic supply in Ethiopia, Sudan, and Egypt. Climate variability and long-term climate and socio-economic changes pose a growing challenge to the provision of water, energy, and food security within the Blue Nile Basin as well as downstream. Thus, the scientifically sound quantification of available natural resources sustaining water, energy, and food security, and the development of different future scenarios can be helpful for decision-makers in the region. We suggest a new method of WEF Nexus accounting based on quantification of Nexus indicators derived mainly from public domain data. As observed data on water and land resources in the Blue Nile Basin are scarce, this study uses diverse remote sensing-based data sources to derive essential environmental information validated by using ground data, where possible. This includes land cover data, different precipitation products, actual evapotranspiration, net primary productivity (NPP), among others. Furthermore, several data analysis and modeling tools, such as WA+, various hydrological models, RiverWare, CropWat, etc., are employed to quantify the natural resources availability, variability, and productivity as a basis for a comprehensive WEF accounting based on selected indicators which were developed by a team of experts and scientists. The currently constructed Grand Ethiopian Renaissance Dam (GERD) as well as other planned hydropower and irrigation schemes are also considered for the future scenarios. The result is a comprehensive WEF Nexus accounting estimating water availability and uses with a focus on irrigation as the dominant water user, productivities (based on NPP and derived yield estimates), water use efficiency, energy production from hydropower and estimation of security levels compared to the required current and future demands. Finally, the derived nexus indicators are put into context of selected SDG target indicators.

Droughts are a recurrent phenomenon in water abundant tropical countries worldwide and are expected to become more frequent in the future. However, drought risk in tropical catchments is poorly understood and usually not adequately incorporated in water management strategies. Thus, methodologies to evaluate spatial and seasonal drought risk in data scarce tropical catchments are urgently needed. We combined hazard and vulnerability related information to assess drought risk in the test basin, the rural Muriaé basin in southeast tropical Brazil. Hazard indicates the cumulative frequency of drought anomalies, while vulnerability represents the potential of a drought to cause damages in the socioeconomic system. We simulated subcatchment discharges with a hydrological model (SWAT) to evaluate spatially distributed hydrological drought hazard and combined this information with precipitation and vegetation based indices to define the cumulative frequency of drought occurrence for each grid cell (0.1°). We tested the sensitivity of different climate and catchment related model input variables against low flow events and simulated artificial drought risk scenarios. To assess vulnerability, we reclassified and weighted globally and regionally available gridded socioeconomic data. Vulnerability in the downstream area was found to be stronger which coincided with a higher hydrological and vegetation based hazard. The drought risk map clearly identified the downstream area of the Muriaé basin as being exposed to a stronger drought risk compared to the upstream areas. Only limited hydrological drought sensitivity of the system against changes in land cover type and temperature was shown in the model results while geology and soils turned out to play a larger role for low flows. The drought scenarios showed that low flows were more severely affected than high flows by climatic changes such as decreased precipitation. In can be concluded that our risk assessment methodology offers a holistic, science based and innovative solution to inform regional planning and water management institutions dealing with the control of drought disasters in tropical rural areas. Such drought risk evaluation frameworks and spatial information are urgently needed in tropical regions worldwide.

Glaciers act as hydrologic reservoirs in mountain environments around the world. In regions that are particularly water-stressed, such as the Andes, glaciers contribute significantly to water resources in downstream communities. As these glaciers recede rapidly throughout the Andes under climatic changes, the surface composition of their ablation zones appears to be shifting from predominantly clean-ice to debris-covered ice. Determining what climatological and topographical factors control debris-coverage in the ablation zones of glaciers throughout the Andes will assist in understanding why these glaciers are becoming increasingly covered by debris and how this debris coverage will continue in the future. By exploring multiple drainage basins across the Andes, this study will discover which regions are most impacted by this transition. Debris-coverage is known to have varying impacts on the ablation rates of glaciers and likely alters the sub-glacial and pro-glacial hydrology of the drainage basin they reside in. With debris-covered glaciers becoming more prevalent across the Andes, it is imperative to gain a better understanding of the hydrology of these complex cryospheric features. Through the use of terrestrial photogrammetry and hydrological techniques, this study will investigate the controls of debris coverage and assess the hydrological impacts of this debris on glaciers throughout the Andes.

The NASA InSight mission, landing in late November 2018, promises to revolutionize our understanding of Martian interior structure via analysis of seismic data returned by the SEIS instrument. The extent to which the mission’s potential is realized will depend on the number of detectable seismic events that occur during the period of operation. Here I estimate the rate of detectable events generated by volcano-tectonic activity on Mars based on extrapolation of Hawai’i’s seismic record. I use a catalog of 5603 earthquakes spanning 48 years [IRIS, 2018], with moment magnitudes MW ranging from 3.0 to 6.9, to derive the Gutenberg-Richter (G-R) frequency-magnitude relation for the Island of Hawai’i, expressed as log(N) = a – b MW, where N is the number of earthquakes with magnitudes greater than or equal to MW, and a and b are constants. By this analysis, one earthquake with MW 5.1 or greater can be expected every year at Hawai’i. Under the assumption that the mechanisms of seismicity associated with edifice building are similar at Hawai’i and Olympus Mons (supported by observation of decollement-based volcanic spreading at both), I use the same b for both settings and scale a according to estimates of magmatic volume flux rates dV/dt at both settings. Over the 80 Myr history of the Hawaiian-Emperor volcanic chain, dV/dt ≈ 1.7 x 10-2 km3/yr. An estimate of dV/dt for the Olympus Mons volcano on Mars was derived from paleotopographic analysis of a set of lava flows south of Olympus Mons with discordant topography. Given the mean flow age from crater counts (210 Ma), an estimate of the amount of volcanic material needed to cause deflections of flow orientations of the required magnitudes yields estimates of dV/dt over this timespan ranging from 6.33 x 10-4 to 6.43 x 10-3 km3/s. Taking the mean of these values and scaling a by the ratio of dV/dt values for Mars and Hawai’i yields a rate of at least 1 quake of MW = 4.4 or greater per year (Figure 1). Thus, under several assumptions (including a steady recent magma supply rate for Olympus Mons), we can expect ≈ 2 volcano-tectonically driven quakes of magnitude MW > 4.4 from the vicinity of Olympus Mons during the nominal 2 Earth-year InSight prime mission. This is a conservative lower bound that does not consider contributions from numerous potential volcano-tectonic sources in Tharsis and elsewhere on Mars.

Large life, as currently present on Earth, diversified during a late and seemingly non-trivial historic event. Although other biological revolutions – such as the advent of photosynthesis or the eukaryotic cell – are attributed to innovations within life itself, the dramatic diversification of animals tends to associated with a change in the environment. The environmental change that remains most thoroughly explored and debated is that of a synchronous increase of free oxygen. Paradoxically, studies of multicellularity from the perspective of tissue and of successful tumor growth highlight how oxic settings are incompatible with the core mechanism of tissue renewal (Ivanovic, 2009). Tumor biology also demonstrates biological mechanisms that, through the hypoxia inducible transcription factors (HIFs), overcome this paradox (Pietras et al., 2008) and, thus, allow tissue renewal despite oxic settings. We have explored how HIFs may serve as an adaption within multicellularity that allow viable large life forms in the oxic setting, by offering improved control of the cellular hypoxia-response machinery that sustain oxygen-insensitive growth of complex tissue. We found that this control is animal-specific and is at its highest refinement within vertebrate animals; in which the innovation of high-oxygen carrying capacity through red blood cells followed first subsequently (Hammarlund et al., 2018). We hypothesize that such a refinement within biology itself, during the Neoproterozoic, allowed metazoans to fully access and exploit the primordial oxic niche on Earth. Testable predictions of this perspective, such as that invertebrate animals and other large multicellular organisms still require phases or settings of truly hypoxic conditions to manage tissue renewal, have implications that reach from geology and medicine to astrobiology. Indeed, a perspective based in the prerequisites of tissue maintenance suggests that being large is a biological achievement of cosmic proportions.

Cloud water interception (CWI) is not captured by conventional rain gauges and not well characterized, but could have ecohydrological significance in systems such as tropical montane cloud forests. Quantifying CWI is necessary to assess the impacts of climate and land cover changes in places such as Hawai‘i. CWI can be estimated from wind speed, cloud liquid water content (LWC), and vegetation characteristics with an empirical model. Cloud microphysics sensors measure LWC accurately, but are expensive and often designed only for use on aircraft. LWC can be estimated by fog gauges, but poorly constrained catch efficiency and spurious rain catch can cause large errors. Visibility is related to LWC, but the relationship is non-linear and depends on the (usually unknown) drop size distribution. This study is part of a project aimed at mapping CWI across the Hawaiian Islands. Earlier analyses found disagreement between LWC estimated from fog gauge and visibility observations at the project field sites. In this study, we experimented with a novel in situ observation platform and cross disciplinary collaboration to compare cloud microphysics observations with those commonly used in cloud forest studies. Field missions took place from April to July 2018 at the summit of Mt. Ka‘ala (1,200 m) on O‘ahu Island. We built a pickup truck-mounted mobile weather station that can be assembled in the field, with weather-sensitive processing modules inside the cab. A total of 10 instruments were deployed: Phase Doppler Interferometer, Cloud Droplet Probe, fog gauge, visibility sensor, rain gauge, wind monitor, camera, water isotope sampler, UAV atmospheric sensor, and Aerosol Spectrometer. A nearby long-term station provides climate and canopy water balance data. Analyses found a strong relationship between visibility and LWC in dense fog. The fog gauge showed weak correlations due to coarse resolution and false rain catch, but had a reasonable catch efficiency. The start of fog catch lagged compared to the nearby station possibly due to screen surface wetting. Concurrent with other analyses, one goal is to calibrate the fog gauge and visibility sensor for long-term LWC monitoring. The mobile platform was effective for short-term deployment of airborne sensors. We hope to repeat the experiment in the future on O‘ahu and other islands.

Coral reefs are one of the most diverse ecosystems on Earth and provide significant ecological, economic, and societal benefits valued at approximately $9.8 trillion U.S. dollars per year. While there are multiple ways humans threaten coral reefs, climate change has become the single most important of these threats. NOAA’s Coral Reef Watch is the only program that operationally issues coral bleaching forecasts, using near real-time satellite monitoring to provide ecological nowcasting of the ocean heat stress that can cause mass coral bleaching and using climate models to forecast the potential for bleaching months into the future. Ocean temperatures began to rise in mid-2014, starting what turned out to be three full years of marine heatwaves that caused corals to bleach — expelling their symbiotic algae. When the film team at Exposure Labs started exploring how to film coral bleaching as it happened, Coral Reef Watch was an obvious partner. Exposure Labs worked with numerous scientists, including me as a Co-Chief Scientific Advisor, to get the science behind the Sundance-Award Winning film Chasing Coral correct. The film team went to great extremes to ensure every statistic, graph, scientific principle, and animation was clear and accurate – using science to explain and support the adventure of trying to capture the first on-reef time-lapse imagery of this important phenomenon. The result is a visually compelling film that tells the story of climate change and its impacts on an important ecosystem in a way that appeals to audiences, including viewers who usually would not sit down to watch a climate change documentary. Chasing Coralis an extremely effective combination of science and art that opens opportunities for dialogue on climate change in ways no scientific paper ever could.

Studies of the dissolved and sediment composition of global rivers provide crucial insights into the relationship between climate, weathering, and landscape dynamics. The chemical composition of suspended riverine sediment constrains contemporary erosion and chemical weathering, and is critical to the interpretation of sedimentary records, such as continental shelf deposits. Here we present suspended sediment flux and chemical composition data from the Irrawaddy (Ayeyarwady) and Salween (Thanlwin) rivers in Myanmar, from samples collected in the wet and dry seasons in 2017-2018. Analyses of major element, 87/86Sr, and εNd composition are combined with a multi-step leaching protocol to determine the ccompositions of silicate, carbonate, and iron oxide components in the bulk sediment. Sources of the organic matter are determined by analyses of carbon and nitrogen isotopes. We show that, as in other large rivers, suspended sediment concentration and composition in the river channel is depth-dependent due to hydrodynamic sorting. Depth profile sampling is therefore required for the complete characterization of the sediment flux and composition in these rivers. Having accounted for hydrodynamic sorting, we demonstrate that there are key differences in the composition of the Irrawaddy and the Salween rivers at the mouth. We further show how the composition of the Irrawaddy sediments evolves along a downstream transect from the northern headwaters to the delta, due to inputs from tributaries draining distinct lithologies and the continued weathering of sediments transported through the floodplain. Finally, we discuss the implications of our findings for the interpretation of offshore sedimentary deposits and for quantifying the regional chemical weathering and carbon budgets.