Browsing by Author "Labat, David"
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Item Restricted Basin-scale analysis of rainfall and runoff in Peru (1969–2004): Pacific, Titicaca and Amazonas drainages(Taylor & Francis, 2012-04-03) Lavado Casimiro, Waldo Sven; Ronchail, Josyane; Labat, David; Espinoza, Jhan Carlo; Guyot, Jean-LoupAccording to the Peruvian agricultural ministry, the Pacific watersheds where the great cities and intense farming are located only benefit from 1% of the available freshwater in Peru. Hence a thorough knowledge of the hydrology of this region is of particular importance. In the paper, analysis of this region and of the two other main Peruvian drainages, the Titicaca and Amazonas are reported. Rainfall and runoff data collected by the Peruvian National Service of Meteorology and Hydrology (SENAMHI) and controlled under the Hydrogeodynamics of the Amazon Basin (HyBAm) project is the basis of this basin-scale study that covers the 1969–2004 period. Beyond the strong contrasting rainfall conditions that differentiate the dry coastal basins and the wet eastern lowlands, details are given about in situ runoff and per basin rainfall distribution in these regions, and about their different altitude–rainfall relationships. Rainfall and runoff variability is strong in the coastal basins at seasonal and inter-annual time scales, and related to extreme El Niño events in the Pacific Ocean. However, rainfall and runoff are more regular in the Andes and Amazonas at the inter-annual time scale. Warm sea-surface temperatures in the northern tropical Atlantic tend to produce drought in the southern Andes basins. Moreover, significant trends and change-points are observed in the runoff data of Amazonas basins where rainfall and runoff decrease, especially after the mid-1980s and during the low-stage season. Almost all the coastal basins show some change in minimum runoff during the last 35 years while no change is observed in rainfall. This means that human activity may have changed runoff in this region of Peru, but this hypothesis deserves more study.Item Restricted Contrasting regional discharge evolutions in the Amazon basin (1974–2004)(Elsevier, 2009-09-15) Espinoza, Jhan Carlo; Guyot, Jean Loup; Ronchail, Josyane; Cochonneau, Gérard; Filizola, Naziano; Fraizy, Pascal; Labat, David; Oliveira, Eurides de; Ordoñez, Juan Julio; Vauchel, PhillippeFormer hydrological studies in the Amazon Basin generally describe annual discharge variability on the main stem. However, the downstream Amazon River only represents the mean state of the Amazonian hydrological system. This study therefore uses a new data set including daily discharge in 18 sub-basins to analyze the variability of regional extremes in the Amazon basin, after recalling the diversity of the hydrological annual cycles within the Amazon basin. Several statistical tests are applied in order to detect trends and breaks in the time series. We show that during the 1974–2004 period, the stability of the mean discharge on the main stem in Óbidos is explained by opposite regional features that principally involve Andean rivers: a decrease in the low stage runoff, particularly important in the southern regions, and an increase in the high stage runoff in the northwestern region. Both features are observed from the beginning of the nineties. These features are also observed in smaller meridian sub-basins in Peru and Bolivia. Moreover we show that the changes in discharge extremes are related to the regional pluriannual rainfall variability and the associated atmospheric circulation as well as to tropical large-scale climatic indicators.Item Open Access La distribución de las lluvias en la vertiente del Pacífico peruano y su relación con El Niño(Instituto Geofísico del Perú, 2017-01) Rau, Pedro; Bourrel, Luc; Dewitte, Boris; Labat, DavidEn 1892, se difundió la primera observación documentada de la corriente costera “El Niño”, denominada por aquel entonces: “Contracorriente marítima en Paita y Pacasmayo” (Carranza, 1892) y donde se intentaba explicar las lluvias torrenciales acaecidas en 1891. Un siglo y cuarto después, aun continúa el reto de poder comprender el efecto de este fenómeno sobre las lluvias a diferentes escalas de espacio y tiempo, especialmente en regiones del planeta como la Vertiente del Pacífico Peruano (VPP), donde sus efectos son experimentados frecuentemente. En el presente artículo se responde a preguntas comunes sobre la distribución de las lluvias en la VPP y el impacto del Fenómeno El Niño o ENSO (El Niño Oscilación del Sur en inglés), basándose en una revisión del estado del arte en la temática, las metodologías y los nuevos aportes.Item Open Access Global karst springs hydrograph dataset for research and management of the world’s fastest-flowing groundwater(Nature Research, 2020-02) Olarinoye, Tunde; Gleeson, Tom; Marx, Vera; Seeger, Stefan; Adinehvand, Rouhollah; Allocca, Vincenzo; Andreo, Bartolome; Apaéstegui Campos, James Emiliano; Apolit, Christophe; Arfib, Bruno; Auler, Augusto; Barberá, Juan Antonio; Batiot-Guilhe, Christelle; Bechtel, Timothy; Binet, Stephane; Bittner, Daniel; Blatnik, Matej; Bolger, Terry; Brunet, Pascal; Jean-Baptiste, Charlier; Chen, Zhao; Chiogna, Gabriele; Coxon, Gemma; De Vita, Pantaleone; Doummar, Joanna; Epting, Jannis; Fournier, Matthieu; Goldscheider, Nico; Gunn, John; Guo, Fang; Guyot, Jean Loup; Howden, Nicholas; Huggenberger, Peter; Hunt, Brian; Jeannin, Pierre-Yves; Jiang, Guanghui; Jones, Greg; Jourde, Herve; Karmann, Ivo; Koit, Oliver; Kordilla, Jannes; Labat, David; Ladouche, Bernard; Serena Liso, Isabella; Liu, Zaihua; Massei, Nicolas; Mazzilli, Naomi; Mudarra, Matías; Parise, Mario; Pu, Junbing; Ravbar, Nataša; Hidalgo Sanchez, Liz; Santo, Antonio; Sauter, Martin; Sivelle, Vianney; Skoglund, Rannveig Øvrevik; Stevanovic, Zoran; Wood, Cameron; Worthington, Stephen; Hartmann, AndreasKarst aquifers provide drinking water for 10% of the world’s population, support agriculture, groundwater-dependent activities, and ecosystems. These aquifers are characterised by complex groundwater-flow systems, hence, they are extremely vulnerable and protecting them requires an in-depth understanding of the systems. Poor data accessibility has limited advances in karst research and realistic representation of karst processes in large-scale hydrological studies. In this study, we present World Karst Spring hydrograph (WoKaS) database, a community-wide effort to improve data accessibility. WoKaS is the first global karst springs discharge database with over 400 spring observations collected from articles, hydrological databases and researchers. The dataset’s coverage compares to the global distribution of carbonate rocks with some bias towards the latitudes of more developed countries. WoKaS database will ensure easy access to a large-sample of good quality datasets suitable for a wide range of applications: comparative studies, trend analysis and model evaluation. This database will largely contribute to research advancement in karst hydrology, supports karst groundwater management, and promotes international and interdisciplinary collaborations.Item Restricted Trends in rainfall and temperature in the Peruvian Amazon–Andes basin over the last 40 years (1965–2007)(Wiley, 2013-09-30) Lavado Casimiro, Waldo Sven; Labat, David; Ronchail, Josyane; Espinoza, Jhan Carlo; Guyot, Jean LoupThe hydroclimatology of the Peruvian Amazon-Andes basin (PAB) which surface corresponds to 7 % of the Amazon basin is still poorly documented. We propose here an extended and original analysis of the temporal evolution of monthly rainfall, mean temperature (Tmean), maximum temperature (Tmax), and minimum temperature (Tmin) time series over two Peruvian Amazon-Andes basins (Huallaga and Ucayali) over the last forty years. This analysis is based on a new and more complete database that includes 77 weather stations over the 1965-2007 period and we focus our attention on both annual and seasonal meteorological time series. A positive significant trend in mean temperature of 0.09°C per decade is detected over the region with similar values in the Andes and Rainforest when considering average data. Though, a high percentage of stations with significant Tmean positive trends are located over the Andes region. Finally, changes in the mean values occurred earlier in Tmax (during the 1970s) than in Tmin (during the 1980s). In the PAB, there is neither trend nor mean-change in rainfall, during the 1965-2007 period. However, annual, summer and autumn rainfall in the southern Andes presents an important interannual variability that is associated with the sea surface temperature (SST) in the tropical Atlantic Ocean while there are limited relationships between rainfall and ENSO events. On the contrary, the interannual temperature variability is mainly related to ENSO events.