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In fields such as hydrology, meteorology, and civil engineering, the study of extreme precipitation events is useful to prevent rainfall related disasters. A widely-used practice to address such a problem is by using statistical inferences about precipitation intensity, duration and frequency (IDF). Despite of its great usefulness, the selection of the adequate data and methodology to characterize precipitation's IDF in the urban area of high-altitude Andean cities remains an open issue for practitioners and decision makers. In this sense, the present paper develops an approach to schematically build the IDF curves for a sub-basin of the study case Andean city, Quito–Ecuador. The here-used data holds information from 12 meteorological stations. Then, the IDF curves are obtained by using both a parametrization followed by a Gamma distribution and a 3-parameter cumulative distribution function, also called mnp. Finally, the curve-fitting process is estimated numerically by adjusting the Sherman equation. Results (average R 2 = 0.9 ) demonstrated that the framework is well-suited for the high-altitude regime. As a noticeable outcome, a novel spatial interpolation-based analysis is introduced, which enabled the identification of extreme rainfall events according to its duration. [ABSTRACT FROM AUTHOR]

This study addresses the financial sustainability challenge of integrated watershed management (IWM) in regions with inadequate water service tariffs. A novel water service tariff model is proposed, incorporating supply costs, water loss reduction investments, and IWM expenses informed by user perceptions. The model is applied to an intermediate Andean city in southern Ecuador, where the current tariff impedes the financial viability of the water utility, reflecting a regional trend. The results indicate a necessary tariff increase exceeding 100% to cover the costs and support IWM. The economic value of watershed environmental services (WES) were estimated at USD 1,505,530.64 per year. This value translates to an average water consumption of 20 m3/user/month, equivalent to a WES of USD 2.60 per month. Despite the users' willingness to pay falling below the estimated economic value of WES, there is a clear need for implementing incentive programs to promote water conservation and policy adjustments that favor the financial sustainability of water supply companies in developing countries. [ABSTRACT FROM AUTHOR]

Suspended and bedload transport dynamics on rivers draining glacierized basins depend on complex processes of runoff generation together with the degree of sediment connectivity and coupling at the basin scale. This paper presents a recent dataset of sediment transport in the Estero Morales, a 27 km2 glacier-fed basin in Chile where suspended sediment concentration (SSC) and bedload (BL) fluxes have been continuously monitored during two ablation seasons (2014–2015 and 2015–1016). The relationship between discharge and SSC depends on the origin of runoff, which is higher during glacier melting, although the hysteresis index reveals that sediment sources are closer to the outlet during snowmelt. As for suspended sediment transport, bedload availability and yield depend on the origin of runoff. Bedload yield and bedload transport efficiency are higher during the glacier melting period in the first ablations season due to a high coupling to the proglacial area after the snowmelt period. Instead, on the second ablation seasons the peak of bedload yield and bedload transport efficiency occur in the snowmelt period, due to a better coupling of the lower part of the basin caused by a longer permanency of snow. Differences in volumes of transported sediments between the two seasons reveal contrasting mechanisms in the coupling dynamic of the sediment cascade, due to progressive changes of type and location of the main sources of runoff and sediments in this glacierized basin. The paper highlights the importance of studying these trends, as with retreating glaciers basins are likely producing less sediments after the "peak flow", with long-term consequences on the ecology and geomorphology of rivers downstream. [ABSTRACT FROM AUTHOR]

The activity concentrations of 222Rn were measured in 53 public water supplies of underground (50) and surface (3) origin, and the relation of such with five geological units where these supplies are located, in the central Ecuadorian Andes, was also explored. These units supply drinking water to 10 cities, located between the 1500 and 3120 m.a.s.l. The experimental setup consisted of the RAD7 radon detector and the RAD H2O degassing system. The 222Rn levels measured in groundwater ranged from 0.53 to 14.78 Bq/L while surface waters did not indicate detectable radon levels. The radon concentrations were below the parametric value of 100 Bq/L for water intended for human consumption, recommended by the European Atomic Energy Community (EURATOM) in its Directive 2013/51, and the alternative maximum contamination level (AMCL) of 150 Bq/L, proposed by the Environmental Protection Agency (EPA). The Pisayambo Volcanic unit, mapped as intermediate volcaniclastic to felsic deposits, presented a mean radon concentration higher than the other geological units and lithologies (9.58 ± 3.04 Bq/L). The Cunupogyo well (11.36 ± 0.48 Bq/L) presented a radon concentration more than 70% higher than the neighboring springs, which may be explained by its proximity to the Pallatanga geological fault. The maximum annual effective doses, by cities, due to the ingestion and inhalation of radon, ranged from 0.010 to 0.108 mSv and from 0.008 to 0.091 mSv, respectively; therefore, these waters do not represent a risk to the health of the population. In addition, a correlation was observed between the activity concentration of 222Rn and the activity concentration of the parent 226Ra in samples collected from some springs. [ABSTRACT FROM AUTHOR]

The aim of this paper is to create a glacial lake inventory for the Cordillera Huayhuash in Peru and to evaluate the susceptibility of lakes to the generation of glacial lake outburst floods (GLOFs). Using high-resolution satellite images, we undertook qualitative and quantitative analysis of lake type, characteristics and distribution, and placed our findings within the context of existing Peru-wide lake inventories. We also mapped and analyzed past GLOFs, revealing a total of 10 GLOFs and 4 ambiguous events, most of which have not been reported before. We found that past GLOFs usually occurred as a result of moraine dam breach during the proglacial stage of lake evolution. Further, we used our lake inventory to evaluate GLOF susceptibility of all lakes larger than 20,000 m2. Of 46 evaluated lakes, only two lakes (Lake Tsacra and Lake W014) are currently susceptible to generating a GLOF, which would most likely be through dam overtopping resulting from a flood originating in smaller lakes located upstream. The future perspectives of lake evolution and implications for GLOF hazard management are discussed in light of the post-Little Ice Age glacier ice loss as well as in the context of extensive related research undertaken in the nearby Cordillera Blanca. [ABSTRACT FROM AUTHOR]

Solar disinfection (SODIS) of drinking water is a cost-effective household water treatment (HWT) method. Despite its simplicity of use, evidence suggest that SODIS water uptake remains lower than implementers planned. In this paper, we investigate socio-cultural factors associated with SODIS water uptake in rural Andean Bolivia. We conducted 28 semi-structured in-depth interviews and six focus group discussions within the framework of a community randomised trial to assess the uptake of SODIS water in the Bolivian Andes. Participants argued that SODIS does not produce an attractive type of drinking water despite acknowledging that SODIS represents a simple, safe, low-cost, and easy method of preparing safe drinking water. Attitudes towards SODIS water reflected local interpretations of water, health, and illness. The taste of SODIS water, the invisibility of water-borne pathogens, and habituation to untreated water represented the main barriers to SODIS water uptake. Alternative culturally adapted SODIS promotional campaigns (e.g., using herbs and additives to improve SODIS water taste) can increase its perceived desirability. [ABSTRACT FROM AUTHOR]

Nature-Based Solutions for Integrated Water Resources Management (NbS-IWRM) involve natural, or nature-mimicking, processes used to improve water availability in quantity and quality sustainably, reduce the risks of water-related disasters, enhance adaptation to climate change and increase both biodiversity and the social-ecological system's resilience. United Nations and the European Commission promote their research as a cornerstone in the changeover to the Ecological Transition. In the Sierra Nevada range (Spain) and the Andean Cordillera, there is a paradigmatic and ancestral example of NbS-IWRM known as "careo channels" and "amunas", respectively. They recharge slope aquifers in mountain areas and consist of an extensive network of channels that infiltrate the runoff water generated during the snow-thawing and rainy season into the upper parts of the slopes. The passage of water through the aquifers in the slope is used to regulate the water resources of the mountain areas and thus ensure the duration of water availability for the downstream local population and generate multiple ecosystem services. This form of water management is known as Water Sowing and Harvesting (WS&H). As shown in this work, it is a living example of a resilience and climate change adaptation tool that can be qualified as a nature-based solution. [ABSTRACT FROM AUTHOR]

The variability of the rainfall stable isotopic values (δ2Hp, δ18Op) in the Ecuadorian Amazon to the Andes presents a marked local "altitude" effect. At the same time, this complex orography creates diverse precipitation regimes (unimodal, bimodal, and three-modal) that make it difficult to establish a relationship with the local amount. Nevertheless, stations along these regions show a similar intra-annual isotopic variability, with lower values during MAM and ON. In contrast, higher values are found during DJF and JAS in a w-shaped pattern, suggesting a common regional controller. A monthly δ2Hp and δ18Op collection campaign was established in Central Ecuador (n = 30) to complement stations biased towards the northern and southern parts. Based on back trajectory analysis, the results demonstrated that moisture arrives from two primary sources: the Tropical North Atlantic (DJFM) and the Amazon Basin (JAS). Nevertheless, their convergence (AMJ and ON) is the crucial factor modulating the lowest isotopic values. Precisely, this convergence is stronger at the V-Index region (5° S–5° N, 65°–75° W), where the wind seasonality and reversal at low levels are enhanced, allowing the inter-hemispheric moisture flux transport (cross-equatorial flow). We propose that the amount of rainfall located at the V-Index region is a more robust approach for explaining the δ2Hp and δ18Op variability rather than the local amount. [ABSTRACT FROM AUTHOR]

The increase of human interventions and developments are modifying the land use/land cover (LULC) of the global landscape, thus severely affecting the water quality of rivers and lakes. Appropriate management and effective policy developments are required to deal with the problems of surface water contamination around the globe. However, spatiotemporal variations of water quality and its complex relation with land cover (LC) changes, challenge adequate water resources management. In this study, we explored the use of remote sensing to relate LC change in the Katari River Basin (KRB) located in the Bolivian Andes and water quality on the shores of Lake Titicaca, in order to support water management. An unsupervised classification of Landsat 7 satellite images and trajectory analysis was applied to understand the modifications of LC through time. In addition, water-quality indicators at the outlet of the basin were retrieved from remote-sensing images and its temporal behavior was analyzed. The results show that the expansion of urban areas is the predominant environmental driver in the KRB, which has great impact on the water quality of Lake Titicaca. We conclude that there is a strong link between the rapid growth of urban and industrial areas with the detriment of river and lake water quality. This case study shows how remote sensing can help understand driver–impact relations. [ABSTRACT FROM AUTHOR]

A laser-optical disdrometer served as reference to assess the absolute percent bias of calculated rainfall intensity using the data of different-resolution tipping-bucket rain gauges classically applied by climatologists and hydrologists in the Andean region. Additionally, the impact of the calculation method (tip counting versus cubic spline interpolation) was examined. The combined effect was assessed for different rainfall intensity classes (0-0.99, 1-1.99, 2-4.99, and 5-10 mm.h-1) and timescales (5, 10, 30, and 60 min). Additionally, the variation in percent absolute bias of the Davis rain gauge, the collector most widely used in the study region, was defined with respect to the Texas rain gauge along an elevation gradient between 3300 and 4000 m a.s.l. Results reveal that the value of the percent absolute bias is largest for small rainfall intensities (≼2 mm.h-1) and short timescales (≼10 min), and decreases when the cubic spline interpolation is used. No relation was found between the error, the elevation, and rainfall depth along the gradient. Based on the research findings, it is recommended to measure precipitation in the high Andean mountain region with a high-resolution sensor and to consider cubic spline for the computation of intensities. [ABSTRACT FROM AUTHOR]

The Andes are defined by human struggles to provide for, and control, water. Nowhere is this challenge more apparent than in the unglaciated western mountain range Cordillera Negra of the Andes where rain runoff provides the only natural source of water for herding and farming economies. Based on over 20 years of systematic field surveys and taking a political ecology and resilience theory focus, this article evaluates how the Prehispanic North-Central highlands Huaylas ethnic group transformed the landscape of the Andes through the largescale construction of complex hydraulic engineering works in the Cordillera Negra of the Ancash Province, North-Central Peru. It is likely that construction of these engineered landscapes commenced during the Middle Horizon (AD 600–1000), reaching their apogee under the Late Intermediate Period (Huaylas group, AD 1000–1450) and Inca (AD 1450–1532) period, before falling into disuse during the early Spanish colony (AD 1532–1615) through a combination of disease, depopulation, and disruption. Persistent water stress in the western Pacific-facing Andean cordillera was ameliorated through the construction of interlinked dams and reservoirs controlling the water, soil, and wetlands. The modern study of these systems provides useful case-studies for infrastructure rehabilitation potentially providing low-cost, though technologically complex, solutions to modern water security. [ABSTRACT FROM AUTHOR]

In the Andes, indigenous communities are being increasingly besieged because their páramos act as water providers for cities and irrigation systems downstream. This has led indigenous communities to protect their hydrosocial territories from external actors and re-create them to contest these threats. In this context, we analyse how the Kayambi community of La Chimba in the northern Sierra of Ecuador has managed to defend and secure its hydrosocial territory through the creation and re-creation of its indigenous identity and networks and related cultural politics that find expression in different forms of contractual reciprocity. As a result, the community hydrosocial territory (re)-creation itself is a weapon of resistance, a decolonising process where rural communities continuously can produce their own forms of development. This is particularly important in a context where governments in the region are relying on extractivism and in the explotation of indigenous territories. [ABSTRACT FROM AUTHOR]

Our study analyzes the distribution of fish communities related to the environmental variables of the Alto Madre de Dios River, an Andean-Amazon watershed of southern Peru, between 300 and 2811 m a.s.l. within the Manu Biosphere Reserve. We provide new ecological and diversity data on fishes for these poorly studied rivers and new data for palm swamp habitats. With electric fishing techniques, we collected a total of 1934 fish specimens belonging to 78 species, 42 genera and 15 families. To assess main patterns of diversity we combined SIMPER and ANOSIM with canonical correspondence analysis to obtain an overview of the community structure of fish and their distribution related to aquatic habitats. Our results show an important shift on fish diversity at 700 m a.s.l. separating headwater and middle-lowland communities. Electrofishing was a hindrance due to the depth, flow and low conductivity of the rivers, but also allowed us to capture fish not observed with other techniques. We also compared the use of elevation with slope as an alternative variable for statistical analysis. Our results show that slope offers a solid and equivalent explanation for fish distribution variability, avoids redundance, and instead of giving geographical data offers ecologically solid information. [ABSTRACT FROM AUTHOR]

In this study, the SWAT (Soil Water Assessment Tool) hydrological model is implemented to determine the effect of climate change on various hydrological components in two basins located in the foothills of the Andes: the Quino and Muco river basins. The water cycle is analyzed by comparing the model results to climatic data observed in the past (1982–2016) to understand its trend behaviors. Then, the variations and geographical distribution of the components of the hydrological cycle were analyzed using the Representative Concentration Pathway (RCP)8.5 climate scenario to model two periods considering the immediate future (2020–2049) and intermediate future (2050–2079). In this way, in the study area, it is predicted that yearly average temperatures will increase up to 1.7 °C and that annual average precipitation will decrease up to 210 mm for the intermediate future. Obtained results show that the analyzed parameters presented the same trend behavior for both periods of time; however, a greater impact can be expected in the intermediate future. According to the spatial distribution, the impact worsens for all the parameters as the elevation increases in both basins. The model depicted that yearly average evapotranspiration would increase around 5.26% and 5.81% for Quino and Muco basins, respectively, due to the large increase in temperature. This may cause, when combined with the precipitation lessening, a decrease around 9.52% and 9.73% of percolation, 2.38% and 1.76% of surface flow, and 7.44% and 8.14% of groundwater for Quino and Muco basins, respectively, with a consequent decrease of the water yield in 5.25% and 4.98% in the aforementioned watersheds, respectively. [ABSTRACT FROM AUTHOR]

Although complex hydrological models with detailed physics are becoming more common, lumped and semi-distributed models are still used for many applications and offer some advantages, such as reduced computational cost. Most of these semi-distributed models use the concept of the hydrological response unit or HRU. In the original conception, HRUs are defined as homogeneous structured elements with similar climate, land use, soil and/or pedotransfer properties, and hence a homogeneous hydrological response under equivalent meteorological forcing. This work presents a quantitative methodology, called hereafter the principal component analysis and hierarchical cluster analysis or PCA/HCPC method, to construct HRUs using gridded meteorological data and hydrological parameters. The PCA/HCPC method is tested using the water evaluation and planning system (WEAP) model for the Alicahue River Basin, a small and semi-arid catchment of the Andes, in Central Chile. The results show that with four HRUs, it is possible to reduce the relative within variance of the catchment up to about 10%, an indicator of the homogeneity of the HRUs. The evaluation of the simulations shows a good agreement with streamflow observations in the outlet of the catchment with an Nash–Sutcliffe efficiency (NSE) value of 0.79 and also shows the presence of small hydrological extreme areas that generally are neglected due to their relative size. [ABSTRACT FROM AUTHOR]

Water pollution by heavy metals is one of the leading environmental concerns as a result of intense anthropogenic pressure on the aquatic environment. This constitutes a significant limitation to the human right of access to drinking water. In this context, the risk to humans from exposure to heavy metals and arsenic in water from rivers subject to mining influence in the Central Andes of Peru was assessed. Water samples were collected from seven rivers at 63 sampling sites, and concentrations of Cu, Fe, Pb, Zn, and As were determined using flame atomic absorption spectrophotometry. Cluster analysis was used to group 21 sampling sites into four groups with similar chemical characteristics, and principal component analysis was used to simplify the complex relationship between the toxic elements by generating two main components with a total percentage of variation of 86%. Fe, Zn, and As had higher percentages of contribution in the Mantaro, Cunas, and Chia rivers. The hazard quotient was highest for children and adults. The hazard index for ingestion of all the studied heavy metals and As was higher than the threshold value (HIing > 1). HIing in 43% of the rivers indicated that the adult population is at risk of non-carcinogenic effects, and HIing in 14% of the rivers revealed a very high health risk. The risk of cancer by ingestion for children varied from medium to high risk and for adults from low to high risk. [ABSTRACT FROM AUTHOR]

Andean headwater catchments are key components of the hydrological cycle, given that they capture moisture, store water and release it for Chilean cities, industry, agriculture, and cities in Chile. However, knowledge about within-Andean catchment processes is far from clear. Most soils in the Andes derive from volcanic ash Andosols and Arenosols presenting high organic matter, high-water retention capacity and fine pores; and are very dry during summer. Despite their importance, there is little research on the hillslope hydrology of Andosols. Environmental isotopes such as Deuterium and 18-O are direct tracers for water and useful on analyzing water-soil interactions. This work explores, for the first time, the efficiency of cryogenic vacuum extraction to remove water from two contrasting soil types (Arenosols, Andosols) at five soil water retention energies (from −1500 to −33 kPa). Two experiments were carried out to analyse the impact of extraction time, and initial water content on the amount of extracted water, while a third experiment tested whether the cryogenic vacuum extraction changed the isotopic ratios after extraction. Minimum extraction times to recover over 90% of water initially in the soil samples were 40–50 min and varied with soil texture. Minimum volume for very dry soils were 0.2 mL (loamy sand) and 1 mL (loam). After extraction, the difference between the isotope standard and the isotopic values after extraction was acceptable. Thus, we recommend this procedure for soils derived from volcanic ashes. [ABSTRACT FROM AUTHOR]

The intensification of the hydrological cycle because of global warming raises concerns about future floods and their impact on large cities where exposure to these events has also increased. The development of adequate adaptation solutions such as early warning systems is crucial. Here, we used deep learning (DL) for weather-runoff forecasting in región Metropolitana of Chile, a large urban area in a valley at the foot of the Andes Mountains, with more than 7 million inhabitants. The final goal of this research is to develop an effective forecasting system to provide timely information and support in real-time decision making. For this purpose, we implemented a coupled model of a near-future global meteorological forecast with a short-range runoff forecasting system. Starting from a traditional hydrological conceptual model, we defined the hydro-meteorological and geomorphological variables that were used in the data-driven weather-runoff forecast models. The meteorological variables were obtained through statistical scaling of the Global Forecast System (GFS), thus enabling near-future prediction, and two data-driven approaches were implemented for predicting the entire hourly flow time-series in the near future (3 days), a simple Artificial Neural Networks (ANN) and a Deep Learning (DL) approach based on Long-Short Term Memory (LSTM) cells. We show that the coupling between meteorological forecasts and data-driven weather-runoff forecast models are able to satisfy two basic requirements that any early warning system should have: The forecast should be given in advance, and it should be accurate and reliable. In this context, DL significantly improves runoff forecast when compared with a traditional data-driven approach such as ANN, being accurate in predicting time-evolution of output variables, with an error of 5% for DL, measured in terms of the root mean square error (RMSE) for predicting the peak flow, compared to 15.5% error for ANN, which is adequate to warn communities at risk and initiate disaster response operations. [ABSTRACT FROM AUTHOR]