Browsing by Author "Cisneros, Felipe"

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Comment on "Human impacts on headwater fluvial systems in the northern and central Andes" (Carol P. Harden, Geomorfología 79, 249 263)
(2008-04-01) Célleri, Rolando; Buytaert, Wouter; De Bièvre, Bert; Cisneros, Felipe; Wyseure, Guido; Deckers, Seppe
The high altitude grasslands of the tropical Andes, known as páramo, are a very fragile and unique ecosystem. Despite increasing human activities, many of its geomorphological and hydrological processes are still very poorly understood. We therefore welcome the paper of Harden [Harden, C.P., 2006. Human impacts on headwater fluvial systems in the northern and central Andes. Geomorphology 79, 249-263.] about "Human impacts on headwater fluvial systems in the northern and central Andes" as a valuable contribution to a better understanding of this complex ecosystem. However, in view of the available literature, we would like to complement the interpretation of the presented results and discuss some of the claims made in the paper.
Experimental assessment of the sprinkler application rate for steep sloping fields
(2007-06) Cisneros, Felipe; Torres, P.; Feyen, Jan
The Programa para el Manejo del Agua y del Suelo (PROMAS) assists the local farming community in introducing new types of locally available irrigation equipment that are both inexpensive and water efficient. Field experiments enabled determining the maximum application rates that cause zero runoff for slopes above 16% for low-cost sprinkler systems.
Forest impact on floods due to extreme rainfall and snowmelt in four Latin American environments 1: Field data analysis
(2011-01-22) Bathurst, James C.; Iroumé, Andrés; Cisneros, Felipe; Fallas, Jorge; Iturraspe, Rodolfo; Gaviño Novillo, Marcelo; Urciuolo, Adriana; De Bièvre, Bert; Guerrero Borges, V.; Gayoso, Jorge; Coello, Cristian; Miranda, Miriam; Ramírez, Marco
Flood peak data for focus catchments in Costa Rica, Ecuador, Chile and Argentina are analyzed to test the hypothesis that, as the size of the hydrological event increases, the effect of forest cover on the peak discharge becomes less important. Previous research suggests that this hypothesis may hold for small catchments (less than 1 km2) but the pattern is less clear for large catchments. The principal study results are for small paired catchments (0.6-10 km2) with different forest covers (forest/pasture) in highland Ecuador and a small (0.35 km2) plantation catchment in southern Chile subjected to logging. The former were analyzed by comparing the corresponding peak discharges for given rainfall events, the latter by comparing the relationships between peak discharge and rainfall event size for the pre- and post-logging periods. In all cases there is relative or absolute convergence of the responses as discharge increases, with convergence likely for flood return periods of around 10 years. More limited data for larger catchments which have undergone either deforestation or afforestation (131 km2 in Costa Rica and 94-1545 km2 in Chile) suggest that the percentage change in forest cover must exceed 20-30% to provoke a measurable response in peak discharge; convergence of peak discharge response at high flows (return periods of around 5 years) for the different forest covers may then be observed. For a 12.9-km2 snowmelt-affected catchment in Tierra del Fuego, Argentina, extreme floods require rain-on-snow events but the data are not sufficient to quantify the complex relationship between forest cover, event return period and peak discharge. In general, forest cover is unlikely to reduce, significantly, peak discharges generated by extreme rainfall but may still offer substantial mitigation benefits for moderate (i.e. more frequent) rainfall events.
Forest impact on floods due to extreme rainfall and snowmelt in four Latin American environments 2: Model analysis
(2011-04-11) Bathurst, James C.; Iroumé, Andrés; Cisneros, Felipe; Fallas, Jorge; Iturraspe, Rodolfo; Gaviño Novillo, Marcelo; Urciuolo, Adriana; Birkinshaw, Steve J.; Coello, Cristian; Alvarado, Andrés; Miranda, Miriam; Ramírez, Marco; Sarandón, Ramiro; Huber, Anton
Through a systematic modelling analysis for focus catchments in Costa Rica (131 km2), Ecuador (10 km2), Chile (0.35 km2) and Argentina (12.9 km2), the hypothesis is tested that, as the size of the hydrological event increases, the effect of forest cover on the peak discharge becomes less important. For each focus catchment, a 1000-year synthetic rainfall time series was generated, representative of the current climate. This time series was used to run SHETRAN hydrological models for each catchment with two contrasting land use scenarios (generally with and without a forest cover). The corresponding maximum daily discharges for the contrasting scenarios were then compared to show the extent to which the two responses converged as the size of the peak discharge increased. For a given forest catchment discharge there could be a range of larger non-forest catchment discharges, depending on antecedent soil moisture content. The simulations show consistently for the rainfall dominated sites that the width of this range either remains constant or narrows as discharge increases, indicating either relative or absolute convergence of the responses. The pattern is more difficult to distinguish for a snowmelt regime but a relative convergence of response still appears possible. The results therefore support the test hypothesis. However, the pattern is complicated by factors such as catchment scale, soil depth, antecedent moisture content and land management. Forests may also still offer significant flood mitigation benefits for moderate (and more frequent) rainfall events and they protect against soil erosion and sediment transport for a wide range of events.
Forests and floods in Latin America: science, management, policy and the EPIC FORCE project
(2010) Bathurst, James C.; Iroumé, Andrés; Cisneros, Felipe; Gaviño Novillo, Marcelo; Urciuolo, Adriana; Mintegui Aguirre, Juan Ángel; Miranda, Miriam; Amezaga, Jaime M.; Aristide Lenzi, Mario
The EPIC FORCE project aimed to develop science-based policy recommendations for integrated forest and water resources management, relevant to extreme events for Costa Rica, Ecuador, Chile and Argentina. Data analysis and model application support the hypothesis that, as the size of the flood peak increases, the effect of forest cover becomes less important. Guidelines for integrated water and forest resources management are developed which recognize this effect but emphasize the role that forests play in reducing the flood levels of more moderate events. The research findings are transferred to policy-making for the four focus countries via a set of policy briefs, taking into account the institutional frameworks, achievable policy objectives and key stakeholders. Forests and floods in Latin America: science, management, policy and the EPIC FORCE
Human impact on the hydrology of the Andean páramos
(2006) Buytaert, Wouter; Célleri, Rolando; De Bièvre, Bert; Cisneros, Felipe; Wyseure, Guido; Deckers, Jozef; Hofstede, Robert
This paper analyses the problems involved in the conservation and management of the hydrological system of the South American páramo. The páramo consists of a collection of neotropical alpine grassland ecosystems covering the upper region of the northern Andes. They play a key role in the hydrology of the continent. Many of the largest tributaries of the Amazon basin have their headwaters in the páramo. It is also the major water source for the Andean highlands and a vast area ofarid and semi-arid lowlands, where páramo water is used for domestic, agricultural and industrial consumption, and the generation of hydropower. Recently, the páramo is increasingly used for intensive cattle grazing, cultivation, and pine planting, among others. These activities, as well as global phenomena such as climate change, severely alter the hydrological regime. A review on the state of knowledge of its hydrology is given in a first part. In a second part, the impact of human activities and climate change on the hydrology of the páramo is discussed.
Identifying controls on water chemistry of tropical cloud forest catchments: Combining descriptive approaches and multivariate analysis
(2010) Bücker, Amelie; Crespo, Patricio; Frede, Hans Georg; Vaché, Kellie B.; Cisneros, Felipe; Breuer, Lutz
We investigated controls on the water chemistry of a South Ecuadorian cloud forest catchment which is partly pristine, and partly converted to extensive pasture. From April 2007 to May 2008 water samples were taken weekly to biweekly at nine different subcatchments, and were screened for differences in electric conductivity, pH, anion, as well as element composition. A principal component analysis was conducted to reduce dimensionality of the data set and define major factors explaining variation in the data. Three main factors were isolated by a subset of 10 elements (Ca2?, Ce, Gd, K?, Mg2?, Na?, Nd, Rb, Sr, Y), explaining around 90% of the data variation. Land-use was the major factor controlling and changing water chemistry of the subcatchments. A second factor was associated with the concentration of rare earth elements in water, presumably highlighting other anthropogenic influences such as gravel excavation or road construction. Around 12% of the variation was explained by the third component, which was defined by the occurrence of Rb and K and represents the influence of vegetation dynamics on element accumulation and wash-out. Comparison of base- and fast flow concentrations led to the assumption that a significant portion of soil water from around 30 cm depth contributes to storm flow, as revealed by increased rare earth element concentrations in fast flow samples. Our findings demonstrate the utility of multi-tracer principal component analysis to study tropical headwater streams, and emphasize the need for effective land management in cloud forest catchments.
Integrating hydraulic, physicochemical and ecological models to assess the effectiveness of water quality management strategies for the river Cuenca in Ecuador
(2013-04-10) Holguin Gonzalez, Javier E.; Boets, Pieter; Alvarado, Andrés; Cisneros, Felipe; Carrasco, María C.; Wyseure, Guido; Nopens, Ingmar; Goethals, Peter L. M.
During the past decades, the development and use of ecological models to predict the presence or absence of macroinvertebrates as water quality indicators for decision support in river management has gained a lot of interest. However, these models rarely integrate hydromorphological, physicochemical, and biological components in the submodels. We developed a generic framework for decision support in water management that can be applied to any river basin based on an integrated modelling approach. This approach integrates a mechanistic hydraulic and physicochemical water quality model with aquatic ecological models. Two types of ecological models were developed, habitat suitability models to predict the occurrence of macroinvertebrates and ecological assessment models to predict a biotic index score. Our main purpose was to assess the effectiveness of different wastewater treatment/disposal strategies considering receiving water's ecological aspects and to determine water quality requirements. This paper presents the testing and validation of this integrated framework on a case study of a mountain river (River Cuenca) in the Andes of Ecuador. Three wastewater management scenarios were tested. The different scenarios indicated that the foreseen investments in sanitation infrastructure will lead to modest improvements of the ecological water quality. This improvement (i.e. increase of the biotic index) was only identified in 6 of the 21 monitoring stations considered in the River Cuenca and its tributaries. Therefore, it is necessary to control the impact of the industrial wastewaters discharges and the diffuse pollution at the upper catchment of the tributaries to achieve a good ecological status. With these results, we proved that integrated models, like the one presented here, have an added value for decision support in water management by coupling ecological water quality to a set of hydraulic and chemical water quality measures based on a water quality model. In order to improve these models, it is necessary to change the river monitoring strategy towards collection of data which include simultaneous measurements of physicochemical, hydromorphological and biological data.
Modelación física del flujo a través de las compuertas radiales de la derivadora Cañar
(Universidad de Cuenca, 2014) Tinoco, Vicente; Cisneros, Felipe; Pacheco, Esteban; Carrillo, Verónica; Calle, Edison; Domínguez, Juan; Garate, Johana; Solís, Katty; Universidad de Cuenca; Dirección de Investigación de la Universidad de Cuenca; DIUC
The Cañar River lower basin is a coastal flat area with a high hydro-economic potential, however this zone is vulnerable to flooding. The Ecuadorian Government invests in a flood control project. The project design alternatives need testing in a physical model for supporting the final design. The variables related to the flow through the radial gates of the diversion works are investigated in a physical model. A discharge curve was calibrated for the gate operation. In addition, the best gate location was determined, as well as the optimum still basin depth. Unusual osculation with negative flow directions were found for specific tests. This phenomenon has a scour effect. In order to solve this problem, changes in the geometry of the still basin entrance are recommended by adjusting it to the flow profile.
Modelamiento de operación de embalses para el proyecto integral de riego en la cuenca del río Macul
(Universidad de Cuenca, 2014) Tinoco, Vicente; Willems, Patrick; Wyseure, Guido; Cisneros, Felipe; Universidad de Cuenca; Dirección de Investigación de la Universidad de Cuenca; DIUC
An irrigation project is planned in the Macul Basin Ecuador for developing the agriculture as the main income in the region. The proposed water system comprises three large reservoirs damming the rivers Macul and Maculillo. The river basin planning and operation was investigated by modelling alternative reservoir operation strategies aiming at a sustainable balance between irrigation and river ecology by integrated reservoir/river management. The model simulates the integrated water system for long term periods of data, covering also several historical extreme events. Results indicate that the planned irrigation volumes are higher than the available water for a sustainable irrigation. Two lines of action are suggested for reaching the target irrigation demands: one is to design a deficit irrigation schedule, and the second implies modification in the reservoir’s spillway height.
Modelling the effect of forest cover on shallow landslides at the river basin scale
(2010) Bathurst, James C.; Bovolo, C. Isabel; Cisneros, Felipe
The potential for reducing the occurrence of shallow landslides through targeted reforestation of critical parts of a river basin is explored through mathematical modelling. Through the systematic investigation of land management options, modelling allows the optimum strategies to be selected ahead of any real intervention in the basin. Physically based models, for which the parameters can be evaluated using physical reasoning, offer particular advantages for predicting the effects of possible future changes in land use and climate. Typically a physically based landslide model consists of a coupled hydrological model (for soil moisture) and a geotechnical slope stability model, along with an impact model, such as basin sediment yield. An application of the SHETRAN model to the 65.8-km2 Guabalcón basin in central Ecuador demonstrates a technique for identifying the areas of a basin most susceptible to shallow landsliding and for quantifying the effects of different vegetation covers on landslide incidence. Thus, for the modelled scenario, increasing root cohesion from 300 to 1500 Pa causes a two-thirds reduction in the number of landslides. Useful information can be obtained even on the basis of imperfect data availability but model output should be interpreted carefully in the light of parameter uncertainty.
Runoff generation in a degraded Andean ecosystem: Interaction of vegetation cover and land use
(2007-10-15) Molina, Armando; Govers, Gerard; Vanacker, Veerle; Poesen, Jean; Zeelmaekers, Edwin; Cisneros, Felipe
Tropical mountain regions are affected by rapid land use/-cover change, which may threaten their (eco-) hydrological functions. Although there is a growing interest in evaluating the effect of land use/-cover change on mountain hydrology, quantitative assessments of the impact of land use/- cover on hydrological processes are hampered by the lack of field measurements characterizing runoff generation processes. In this paper, we present results from field experiments of rainfall runoff mechanisms in the southern Ecuadorian Andes. A rainfall simulator was used to quantify the hydrological response of distinct land use/-cover types to intense rainfall (about 40 mm/h). The rainfall runoff experiments indicate that degraded and abandoned land generate surface runoff within a few minutes after the start of the rainfall event. These lands have a very rapid and sharp hillslope hydrological response, as Hortonian overland flow is the dominant runoff generation mechanism. In contrast, surface runoff on arable and rangelands is rare, as their soils are characterized by a high infiltration capacity (i.e. N29 mm/h). Our experiments provide evidence that runoff generation in degraded Andean ecosystems is mainly controlled by the surface vegetation cover and land management. When reducing the surface vegetation cover, the soil is increasingly affected by rapid hillslope runoff as the presence of large amounts of smectites in the outcropping soft rocks makes the material very prone to sealing and crusting, thereby enhancing runoff generation.
Vegetation and topographic controls on sediment deposition and storage on gully beds in a degraded mountain area
(2009-05) Molina, Armando; Govers, Gerard; Cisneros, Felipe; Vanacker, Veerle
Active gully systems developed on highly weathered or loose parent material are an important source of runoff and sediment production in degraded areas. However, a decrease of land pressure may lead to a return of a partial vegetation cover, whereby gully beds are preferred recolonization spots. Although the current knowledge on the role of vegetation on reducing sediment production on slopes is well developed, few studies exist on the significance of restoring sediment transport pathways on the total sediment budget of degraded mountainous catchments. This study in the Ecuadorian Andes evaluates the potential of vegetation to stabilize active gully systems by trapping and retaining eroded sediment in the gully bed, and analyses the significance of vegetation restoration in the gully bed in reducing sediment export from degraded catchments. Field measurements on 138 gully segments located in 13 ephemeral steep gullies with different ground vegetation cover indicate that gully bed vegetation is the most important factor in promoting short-term (1–15 years) sediment deposition and gully stabilization. In well-vegetated gully systems ( ≥ 30% of ground vegetation cover), 0.035 m3 m–1 of sediment is deposited yearly in the gully bed. Almost 50 per cent of the observed variance in sediment deposition volumes can be explained by the mean ground vegetation cover of the gully bed. The presence of vegetation in gully beds gives rise to the formation of vegetated buffer zones, which enhance short-term sediment trapping even in active gully systems in mountainous environments. Vegetation buffer zones are shown to modify the connectivity of sediment fluxes, as they reduce the transport efficiency of gully systems. First calculations on data on sediment deposition patterns in our study area show that gully bed deposition in response to gully bed revegetation can represent more than 25 per cent of the volume of sediment generated within the catchment. Our findings indicate that relatively small changes in landscape connectivity have the potential to create strong (positive) feedback loops between erosion and vegetation dynamics. Copyright © 2009 John Wiley & Sons, Ltd.