Boris F Ochoa-Tocachi

An initial ground validation of the Integrated Multisatellite Retrievals for GPM (IMERG) Day-1 product from March 2014 to August 2015 is presented for the tropical Andes. IMERG was evaluated along with the Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA) against 302 quality-controlled rain gauges across Ecuador and Peru. Detection, quantitative estimation statistics, and probability distribution functions are calculated at different spatial (0.1°, 0.25°) and temporal (1 h, 3 h, daily) scales. Precipitation products are analyzed for hydrometeorologically distinct subregions. Results show that IMERG has a superior detection and quantitative rainfall intensity estimation ability than TMPA, particularly in the high Andes. Despite slightly weaker agreement of mean rainfall fields, IMERG shows better characterization of gauge observations when separating rainfall detection and rainfall rate estimation. At corresponding space–time scales, IMERG shows ...

<p>In the tropical Andes and adjacent lowlands, human and natural systems often rely on high-mountain water resources. Glaciated headwaters play an essential role in safeguarding water security for downstream water use. However, there is mounting concern particularly about long-term water supply as the timing and magnitude of glacier meltwater contribution to river streamflow become less reliable with rapid glacier shrinkage. This concern matches an increase in water demand from growing irrigation, population and hydropower capacity in combination with high social-ecological vulnerabilities threatening sustained water security. Despite important progress in assessing the impacts of glacier shrinkage and consequences for meltwater availability, little is known about the associated hydrological risks and how they propagate downstream. Therefore, integrated approaches are needed that combine a detailed picture of the meltwater propagation through the terrestrial water cycle with human vulnerabilities and exposure to water scarcity. However, the complex topographic and sociocultural setting including scarce data, limited local capacities and frequent water conflicts hamper a more thorough process understanding and water security assessment at a basin scale.</p><p>Under high complexity and uncertainty, we propose a coupled risk framework combining water scarcity hazards, exposed people and multiple human vulnerabilities to address these limitations. An important aspect of the framework is the recognition of knowledge from indigenous and rural communities that can potentially be integrated into current scientific baselines and innovative adaptation debates. Our framework interlinks a broad set of hydroclimatic, socioeconomic and water management variables at unprecedented detail. We put particular emphasis on the quantification and understanding of multidimensional vulnerabilities as a key element for evaluating the enabling effects of these impacts in social-environmental systems. However, the assessment of corresponding vulnerabilities might not be relevant if the degree of the systems’ exposure is not sufficiently addressed. Therefore, we further analyse the interplay of the diverse variables and critical system thresholds that determine the dimensions and spatiotemporal patterns which enable meaningful assessments of cascading processes and interconnected risks to water scarcity.</p><p>Our risk framework provides a thorough baseline to support assessments of future water availability for guiding climate change adaptation, water management, and governance in rapidly changing mountain basins. Nonetheless, remaining uncertainties and limited understanding relate to the availability of local data and highlight the need for additional data collection. Lastly, we identify specific opportunities to explore the use of nature-based solutions, such as source water and wetland protection, in combination with a strong engagement of local communities and policy makers as an efficient pathway to cope with emerging risks to water scarcity in glacier-fed river basins.</p>

<p>In the tropical Andes, mountain communities and coastal livelihoods downstream strongly depend on glaciers and Andean ecosystems for their water security. Year-round streamflow from glaciers, high-altitude peat bogs and hydraulic infrastructure buffer water scarcity and discharge variability in many areas. Nonetheless, climatic and non-climatic stressors are altering the hydrological regime and exacerbating human vulnerabilities. In the Vilcanota-Urubamba basin (VUB) in Southern Peru, the overall glacier area has substantially decreased by 37% between 1988 and 2016. At the same time, water demand from growing population, irrigated agriculture and hydropower is considerably increasing. This development bears threats to local water security and several challenges to long-term water management and governance in a context of data scarcity and social conflicts arising from socioenvironmental grievances, and highlights the need for interdisciplinary and interlinked water resource research and management.</p> <p>In this context, the two projects <em>Water security and climate change adaptation in Peruvian glacier-fed river basins</em> (RAHU) and <em>Natural Infrastructure for Water Security</em> (NIWS) are collaborating at developing adaptation strategies to increase long-term water security in deglaciating basins in Peru. In the face of global environmental change, natural infrastructure – including forests, wetlands, and nature-based solutions – has been promoted as a buffer to attenuate the loss of hydrological ecosystem services caused by accelerated glacier shrinkage. Furthermore, natural infrastructure can provide a complement to man-made ‘grey’ infrastructure enhancing its performance, lifespan, and adaptability and provide multiple defense lines against natural disasters and other climate risks.</p> <p>Here, we implemented hydrological data collection using participatory monitoring approaches and integrated ancestral and contemporary nature-based solutions. Conservation of natural grasslands can avoid streamflow variability and flashiness caused by common land-use activities such as cultivation and grazing. Flow duration curves show that median flows in cultivated catchments are approximately half those of natural catchments, whereas low flows are up to five times lower but high flows remain virtually the same. Despite being highly promoted, afforestation interventions reduce water yield significantly. High and mean daily flows in afforested catchments are approximately four times lower than in natural grasslands, whilst low flows are between seven to ten times lower. Most catchment management practices, however, are more complex, and involve a combination of interventions. An example of this are pre-Inca infiltration enhancement systems, which divert water from headwater streams onto mountain slopes to increase the yield and longevity of downslope natural springs. Tracer experiments in another study site reveal that water residence times range between 2 weeks and 8 months, with a mean of 45 days, which might be able to increase dry season flow downstream by up to 33%.</p> <p>Currently, a first Water Management Plan is being implemented in the VUB and part of its headwaters have just been declared a Regional Conservation Area. This progress in local policy and headwater conservation offers new opportunities for the project consortium to provide scientific evidence to stakeholders. Our first findings have particular implications for the implementation of robust adaptation measures for future water management planning embedded into local-national policies in close…

This article presents a hydrometeorological dataset from a network of paired instrumented catchments, obtained by participatory monitoring through a partnership of academic and non-governmental institutions. The network consists of 28 headwater catchments (<20 km) covering three major biomes in 9 locations of the tropical Andes. The data consist of precipitation event records at 0.254 mm resolution or finer, water level and streamflow time series at 5 min intervals, data aggregations at hourly and daily scale, a set of hydrological indices derived from the daily time series, and catchment physiographic descriptors. The catchment network is designed to characterise the impacts of land-use and watershed interventions on the catchment hydrological response, with each catchment representing a typical land use and land cover practice within its location. As such, it aims to support evidence-based decision making on land management, in particular evaluating the effectiveness of catchme...

This article presents a hydrometeorological dataset from a network of paired instrumented catchments, obtained by participatory monitoring through a partnership of academic and non-governmental institutions. The network consists of 28 headwater catchments (o 20 km 2) covering three major biomes in 9 locations of the tropical Andes. The data consist of precipitation event records at 0.254 mm resolution or finer, water level and streamflow time series at 5 min intervals, data aggregations at hourly and daily scale, a set of hydrological indices derived from the daily time series, and catchment physiographic descriptors. The catchment network is designed to characterise the impacts of land-use and watershed interventions on the catchment hydrological response, with each catchment representing a typical land use and land cover practice within its location. As such, it aims to support evidence-based decision making on land management, in particular evaluating the effectiveness of catchment interventions, for which hydrometeorological data scarcity is a major bottleneck. The data will also be useful for broader research on Andean ecosystems, and their hydrology and meteorology.