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Many rivers in Chilean Patagonia are difficult to access, experience high flow variability and frequent sudden floods, which make traditional grain size distribution sampling and analysis extremely challenging. There are several diverse methods and software that attempt to determine grain size using analysis of photographs. Manual methods, although of high precision, are extremely labour and time intensive as they process particle by particle by hand. On the other hand, automated methods although fast, still produce low precision in particle identification and size determination, This motivated us on developing a field and desktop method that is fast, precise and requires light equipment. It includes good natural light management with a light and inexpensive kit, considering a good representative selection of the study site. Preliminary to the automated method, the photographic sample is calibrated regarding tones, colours and brightness, with the aim of generating high contrast between clasts and therefore an easier recognition by the software ImageJ. We tested the method with 50 photographs analysed with manual and other (semi)automated methods, characterizing the surface depoosits of río Simpson between the towns of El Blanco and Coyhaique, in Chilean Patagonia. We identified and mapped sediment patches using an UAV. Results show that our method has a lower error and processing time. Ongoing challenges include the underestimation in size and number of some clasts, and overestimation of sand, with respect to the manual method, but it still outperforms other (semi)automatic methods.

Debris flows and flash floods occur frequently in Chile due to geology, geomorphology and weather, costing human lives and impacting settlements, infrastructure and economic activities. One of the problems relates to the lack of adequate monitoring technology in remote areas with limited connectivity. We have developed a low cost system that processes acquired lidar and image data in-situ with a Raspberry Pi obtaining flow level and velocity and transmits near real time via satellite (or cellular network if available). The low implementation cost allows to replicate the system in the many hazardous sites, as well as advance towards early warning systems in locations with limited communication networks. The velocimetry method consists of two steps: first obtaining the images, and then a brightness filter and normalized cross correlation. To eliminate outliers a flow direction filter is used, and velocities are obtained by tracking of flow surface elements. Also the flow level is measured with a lidar also connected to the R-Pi. We will present both laboratory and field test results.

Glacier outburstfloods are a major hazard in glacierized catchments. Global analyses have shownreduced frequency of glacierfloods over recent decades but there is limited longer-term data on eventmagnitude and frequency. Here, we present a Holocene palaeoflood record from the Río Baker (ChileanPatagonia), quantifying the discharge and timing of glacierfloods over millennial timescales. A cata-strophicflood of 110,000 m3/s (0.11 Sv) occurred at 9.6±0.8 ka, duringfinal stages of the Late GlacialInterglacial Transition, followed byfiveflood-phases coeval or post-dating Holocene neoglacials. Highestflood frequencies occurred at 4.3e4.4 ka, with 26floods of minimum discharges of 10,000e11,000 m3/s,and 0.6 ka with 10floods exceeding 4600e5700 m3/s. The largest modern outburstflood recordedsurpassed ~3810 m3/s. Thus glacierflood magnitude declines from the order of 0.1 to 0.01 Sv over theEarly to Mid Holocene, and to 0.001 Sv in the instrumental record., GB was supported by the Spanish Ministry of Science, Innovation and Universities. VT would like to thank the Natural Resources Defence Council and Royal Holloway University of London Research Strategy Fund (RHUL-RSF) for funding initialfield visits that led tothis research. AD thanks equipment and field support from CIEP, B.Reid, DGA-Aysen, J. Tureo, C. Meier, C. Olivares, H. Soto, M. Williams(U Greenwich) and NERC-GEF. Xavier Rodriguez-Lloveras providedfield assistance duringfield work in April 2014.

With the substantial glacier mass reduction projected by the end of the century, the formation and rise of periglacial lakes has to be expected. Even though these changes often occur in remote areas, they can nevertheless have catastrophic impacts on populations and infrastructure through processes such as glacial lake outburst floods (GLOF). GLOFs are the result of complex geomorphic changes and subject to various timescales, thus urging the need for a multidimensional approach. The present study combines two approaches to analyze natural hazards in the secluded San Rafael National Park in Chilean Patagonia (North Patagonian Icefield). The Grosse glacier outlet was chosen after interpreting satellite imagery and historical pictures showing a historical emptying of a lateral lake, which was also supported by local testimonies. Dendrogeomorphology was primarily used with an automatic detection approach to identify possible dates of occurrence of past GLOFs at the Grosse outlet. A total of 105 disturbed Nothofagus trees were sampled highlighting 6 event years between 1958 and 2011. The second method aimed at complementing the tree-ring-based findings with UAV imagery acquired during fieldwork and the mapping of geomorphic evidence of past GLOFs. Huge boulders and deposits are one of the signs recognized as remnants of past lake outbursts and were thus used to differentiate small, rainfall-induced floods from high magnitude events. More precisely, through an object-based strategy, we mapped deposits and extrapolated a theoretical flow orientation. Whereas the first method allowed to select dates of potential events, the second facilitated identification and mapping of the spatial extent of past high-energy events. Analysis of imagery also allowed detection of the occurrence of a 200-m wide breach in the frontal moraine as well as the vanishing of a lateral lake estimated to be 1.8 × 106 m2 in the 1950s, which we date to 1958 using tree-ring records. When used together the two approaches can represent a valuable contribution to historical records and help future assessments of natural hazard at Grosse glacier, but also in other high-mountain environments.

Landslides and mass flows are dynamic processes that involve the movement of rock, debris and earth down a slope. As a result of the 2017 catastrophic mass flow, these processes have been further established as a significant risk to the population of Chile, and further afield. Through field site investigations, it is possible to develop a greater insight into the mechanisms and conditions that influence the dynamics of these phenomena.On Saturday 16 December 2017, a catastrophic debris flow (aluvión) partially destroyed the village of Villa Santa Lucía and a 5 km long reach of the Panamerican Highway resulting in 22 fatalities. The apparent trigger was an intense rainfall event of 124 mm in 24h associated with an elevated 0˚C isotherm (1600 m.a.s.l.) that led to the failure of 5.5 - 6.8x106m3 mountainside in the uppermost catchment of Rio Burritos near the SE end of the Cordón Yelcho Glacier. The landslide transformed rapidly into a highly mobile debris flow as it entrained water from the Rio Burritos river and glacier ice from the Cordón Yelcho.This study characterises the geomorphological impacts and dynamics of the 2017 mass flow. Post-event DEMs, aerial photos and satellite imagery provided the basis for geomorphological mapping and terrain analysis. Fieldwork in January 2019 allowed sampling of mass flow deposits, logging of sedimentary sections and dGPS surveys.Both erosion and deposition occurred over the Villa Santa Lucía flow path. Erosion occurred more frequently in the first 7.9km of the flow path due to high slope angles and presence of the Rio Burritos that channelised flow. A high proportion of coarse particles in the flow enhanced basal scouring and erosion of the valley sides, resulting in significant flow bulking. A total of 7.6x106m3 – 7.7x106m3 of material was deposited across the latter 6.3km of the flow path.Sediment sample analysis showed that the flow began as cohesive and viscous in nature in spite of a lack of clay particles and high proportions of sands and gravels. The addition of water from the Rio Burritos reduced the viscosity of the flow as the flow propagated downstream. This resulted in enhanced lobe spreading and particle interactions in the depositional zone. In spite of this water entrainment, the flow remained both sediment and debris rich over its duration.Catastrophic mass flows like the event at Villa Santa Lucía are likely to become more common around the world in the future as intense rainfall events become more frequent due to the dominance of El Nino Southern Oscillation (ENSO) events. By studying recent catastrophic mass flow events, an insight into the relationship between mass flow triggers and flow composition will be developed. This will allow for greater understanding of how these influence mass flow behaviours. As a result, it may then be possible to predict the rheology and routes of future flows. These predictions have the ability to be used to protect communities from such events in the future.

Glacier dynamics are sensitive to the formation and expansion of proglacial lakes. Proglacial lakes development can accelerate glacier retreat rate by flotation of the terminus, formation of a calving front, and increased ice flow. Understanding the impacts of proglacial lakes formation and development, which are reported to be growing in number in Patagonia and other regions, is relevant to improve the understanding and prediction of glacier response to climate change.This study aims to characterize and monitor recent spatial and temporal changes in the lower section of the Exploradores Glacier (15 km2), located at the northeast section of the Northern Patagonian Icefield. A proglacial lake located at the east margin has been expanding by calving since the early 2000s, and supraglacial ponds located at the front of the glacier could coalesce to form a larger proglacial lake.We performed repeated unmanned aerial vehicle (UAV) surveys to obtain a series of high-resolution orthoimages (10cm/pixel) and digital elevation models (DEM) of the lower section of Exploradores Glacier. The series consists in 7 orthoimages and DEMs across one year (March 2019 to March 2020), forming in a dataset that is the first of its kind for a Patagonian glacier. The images are processed by photogrammetric technique structure from motion using Pix4D software, and are co-registered using stable off glacier tie-points. Next, the orthoimages are correlated using a feature tracking algorithm (IMCORR) to derive glacier flow velocities. Surface lowering and morphological changes is obtained by DEM differencing analysis. In addition, an aerial photographic archive (Aniya et al. 2017) providing a 20-year observation record is incorporated in the analysis. The results of the imagery analysis are compared with in-situ ablation stakes measurement during the summer season 2019-2020, which indicates downwasting rates up to 100mm/day. This allows estimating rates of proglacial lake expansion at the east margin, supraglacial lakes coalescence, and increase in debris-covered area.This study contributes to a better understanding of the processes that occur during a relatively short period in a highly transient glacier. Future work will include modelling ice dynamics to better characterize and predict the response of the glacier to the development of proglacial lakes.

Acquisition of real-time hydraulic data is an essential component for flood forecasting. However, we frequently face difficulties in obtaining discharge data using classical contact methods during high magnitude floods and for systems experiencing rapid hydro-geomorphological adjustment. Therefore, we developed low-cost, non-contact sensors and platforms that are designed to overcome these difficulties. These advances enable flood flow properties to be monitored at multiple locations across a river catchment, at low-cost, and communicated in near real-time by using an image velocimetry method. This is an optics-based approach for stream flow measurement using commercially available near-infrared digital cameras to acquire video footage in full HD (30fps). Video footage is then subjected to optical flow tracking techniques based on cross-correlation, and feature-based tracking, enabling the displacement rates of detected features (for example natural foam, seeds, woody debris, and turbulent structures) to be computed. This manual provides step by step guidance to install an image-based gauging station. It contains the list of necessary components, the calibration process of a new camera and the assembly procedure of the system.

The El Yali lagoon is a wetland of great importance in the central zone of Chile, especially due to its relation with the native and foreign avifauna that arrives there periodically, and being a habitat for about 25% of the birds’ biodiversity in Chile. This study aims to identify and quantify the main variables of the hydrological cycle of the lagoon and to characterize the main physicochemical variables of surface and groundwater, in order to estimate a hydrological balance of the wetland that will allow, in the future, to evaluate the vulnerability of this body of water. The data still do not allow to identify the hydrological cycle of the lagoon, but even though, the records collected will be presented, including the “behavior” on the coastal and interior sides of the lagoon. A significant concentration of phosphates from the aquifer has been detected, whose magnitude (above 2 mg (PO) 43-L-1) triples in the body of water (about 1 mg (PO) 43-L-1).

A major problem of increased urbanization is the rise in pollution caused by runoff. A solution to this problem can be found through the use of Sustainable Urban Drainage Systems (SUDS) such as rain gardens. Previous research has focused primarily on hydrologic design including the degree to which groundwater is replenished by these systems and models have been developed to quantify the extent of that recharge. However these models do not simulate the transport or fate of pollutants. In this paper, a preliminary heavy metal retention computer model is proposed that consists of two parts: a water flow module and pollutant retention module. To describe flow behaviour a dual-permeability approach is implemented which facilitates the prediction of both matrix and macropore flow. This subroutine is then combined with the retention module, which utilizes and couples the linear, Langmuir and Freundlich isotherms with the advection-diffusion equation. Both submodels are validated using existing literature data. This validation was assessed using efficiency indexes and showed good results with an R2 > 0.93 for the matrix region, an R2 > 0.89 for the macropore region and an R2 = 0.99 for the pollutant retention module. This results in a valuable tool for the design and implementation of bioretention facilities.

A major problem of increased urbanization is the rise in pollution caused by run-off. Among alternative management strategies, the use of sustainable drainage systems (SuDS) such as rain gardens and other bioretention facilities is becoming an increasingly attractive option to reduce these problems. However, there are few tools if any available for their design considering pollutant retention. In this paper, a dual-permeability based model that predicts the fate of heavy metals in SuDS is presented, and applied to the design of a rain garden system for a planned roundabout in Kent, UK. Preliminary design considered an upper root zone layer with organic soil and a sandy storage sub-layer, each 30 cm thick, for a bioretention area of 5 and 10% the size of the contributing impervious surface. Two scenarios are examined: the accumulation and movement of metals without macropores and the possibility of groundwater contamination due to preferential flow. It is shown that levels of lead can build up in the upper layers of the system, but only constitute a health hazard (surpass UK standard of 750 mg/kg) after 10 years. Simulations show that copper was successfully retained (no significant concentrations below 50 cm of rain garden soil depth). Finally, given concerns of preferential flow bypassing bioretention facilities, macropore flow was examined. Results indicated that due to site conditions it was not a threat to groundwater in the timeframe considered.

Five similar glacial-lake outburst floods (GLOFs) occurred in April, October, December 2008, March and September 2009 in the Northern Patagonia Icefield. On each occasion, Cachet 2 Lake, dammed by the Colonia Glacier, released circa 200-million m3 water into the Colonia River. Refilling has occurred rapidly, such that further outbreak floods can be expected. Pipeflow calculations of the subglacial tunnel drainage and 1D hydraulic models of the river flood give consistent results, with an estimated peak discharge surpassing 3,000 m3 s−1. These floods were larger in magnitude than any flood on record, according to gauged data since 1963. However, geomorphological analysis of the Colonia valley shows physical evidence of former catastrophic outburst floods from a larger glacial-lake, with flood discharges possibly as high as 16,000 m3 s−1. Due to potential impacts of climate change on glacier dynamics in the area, jökulhlaups may increase future flood risks for infrastructure and population. This is particularly relevant in view of the current development of hydropower projects in Chilean Patagonia.

Traditional stormwater management does not mitigate groundwater depletion resulting from groundwater pumping and reduction in recharge. Infiltration practices, such as rain gardens, offer a potentially effective approach for addressing groundwater depletion. A rain garden is a landscaped garden in a shallow depression that receives the stormwater from nearby impervious surfaces, focusing recharge. We have developed a numerical model that can be applied in rain garden design and evaluation. Water flow through the rain garden soil is modeled over three layers: a root zone, a middle storage layer of high conductivity, and a subsoil lower layer. To continuously simulate recharge, runoff, and evapotranspiration, the model couples the Richards Equation with a surface water balance. The model was applied to the climate of southern Wisconsin. Simulation results show that very high recharge rates are possible during the non-snowfall season. (The model does not handle snowmelt.) A rain garden with an area of about ...

The Baker basin (27 000 km2) is located in one of the most pristine and remote areas of the planet. Its hydrological regime is poised to undergo dramatic changes in the near future due to hydropower development and climate change. The basin contains the second-largest lake in South America, and part of a major icefield. This study documents the natural baseline of the Baker River basin, discusses the main hydrological modes and analyses the potential for sustainable management. Annual precipitation varies several-fold from the eastern Patagonian steppes to the North Patagonian Icefield. The westernmost sub-basins are strongly governed by glacier melt with a peak discharge in the austral summer (January–March). The easternmost sub-basins have a much more seasonal response governed by quicker snowmelt in spring (November–December), while they exhibit low flows typical for semi-arid regions during summer and autumn. Topography, vegetation and wetlands may also influence streamflow. The strong spatio-temporal gradients and variability highlight the need for further monitoring, particularly in the headwaters, especially given the severe changes these basins are expected to undergo. The great diversity of hydrological controls and climate change pose significant challenges for hydrological prediction and management.

Hillslope erosion causes important soil loss, contributes significantly to contaminant transport, and causes stream and lake embankment. Recent studies estimate that worldwide, the existing 45,000 dams (dams over 15 m [49 ft] high) trap more than 25% of global sediment flux and that these dams would be losing between 0.5% and 1% of their capacity annually (Syvitski et al. 2005). Additionally, the increase in soil erosion due to human mismanagement causes advancing desertification of the landscape. The aim of this work is to provide an alternative tool for decision making regarding erosion management in the Chilean “Secano” (dryland) area. Specifically, a numerical erosion model with a physical base was developed and tested. Although the model is based on previous developments, it considers rainfall splash together with sheet and rill flow in a novel way and can be easily incorporated in distributed hydrological models and/or geographical information systems. It is an event model, which divides the hillslope length into elements. Water and sediment can enter each element from upslope, while Manning's equation is used to estimate mean velocities. New data gathered in the area, the first to be obtained in a systematic manner, was available from field plots in the Secano and was used to test the model. Soil loss had been monitored for a year in standard erosion plots with three different treatments: traditional rotation (wheat/fallow), no-till rotation (wheat/legume), and natural prairie (plus one bare soil control per slope). The total event sediment loss for the treatments was predicted rather well without using parameter calibration, obtaining estimations within 35% to 165% of field measurements and reasonable root-mean square errors, given the range expected when models were applied to data from plots installed in agricultural fields. Two-way analysis of variance results suggest the model considers factors of slope and treatment well, and the results show an overall r2 of 0.46 considering all pairs of estimated values to measurements. Predictions were better for the case of milder slopes and native vegetation (prairie). Sensitivity analysis showed that for sheet flow, the most sensitive parameters were vegetation cover and soil cohesion; while for rill flow, these were cohesion and slope. In both cases, the rill network information provided as input to the model had little effect on simulation results.

Rain gardens are infiltration systems that provide volume and water quality control, recharge enhancement, as well as landscape, ecological, and economic benefits. A model for application to rain gardens based on Richards equation coupled to a surface water balance was developed, using a two-dimensional finite-volume code. It allows for alternating upper boundary conditions, including ponding and overflow, and can simulate heterogeneous soil-layering or more complex geometries to estimate infiltration and recharge. The algorithm is conservative, and exhibits good performance compared to standard models for several test cases (less than 0.1% absolute mass balance error); simulations were also performed for an experimental rain garden and comparisons to collected data are presented. The model accurately simulated the matrix flow, soil water distribution, as well as deep percolation (potential recharge) for a natural rainfall event in the controlled experimental setup. \ud Read More: http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29HY.1943-7900.0000111?prevSearch=authors%3A%28Dussaillant%2C%29&searchHistoryKey=

Traditional stormwater management does not mitigate groundwater depletion resulting from pumping and loss of recharge. There has been an increasing interest in the use of alternative practices, such as raingardens, that enhance infiltration of stormwater. We develop a simple numerical model for their design and evaluation. Water flow through the soil is modelled over three layers: a root zone; a middle storage layer; and the site subsoil. To continuously simulate recharge, runoff and evapotranspiration, a Green-Ampt equation coupled with a surface water balance is used. For the humid climate of Madison, Wisconsin, USA, results show very high recharge rates in the rainy season, where a raingarden with an area of 10–20% of the contributing impervious area maximizes recharge. For the semiarid climate of Santiago, Chile, the optimum ratio was 10–20%, and for the arid climate of Reno, Nevada, USA, it was closer to 5%.