Juan Valdes - Academia.edu (original) (raw)
Papers by Juan Valdes
Stochastic Hydrology and its Use in Water Resources Systems Simulation and Optimization, 1993
In this part of the panel presentations I shall attempt to summarize the recent developments in t... more In this part of the panel presentations I shall attempt to summarize the recent developments in the modelling of precipitation, both at a point and in space, and to discuss the major strengths and weaknesses of these models. In doing so and following Dennis Lettenmaier’s path, I shall report on what I have read about and what are my own thoughts in this matter.
Journal of Hydroinformatics, 2017
The task of real-time streamflow monitoring and forecasting is particularly challenging for ungau... more The task of real-time streamflow monitoring and forecasting is particularly challenging for ungauged or sparsely gauged river basins, and largely relies upon satellite-based estimates of precipitation. We present the design and implementation of a state-of-the-art real-time streamflow monitoring and forecasting platform that integrates information provided by cutting-edge satellite precipitation products (SPPs), numerical precipitation forecasts, and multiple hydrologic models, to generate probabilistic streamflow forecasts that have an effective lead time of 9 days. The modular design of the platform enables adding/removing any model/product as may be appropriate. The SPPs are bias-corrected in real-time, and the model-generated streamflow forecasts are further bias-corrected and merged, to produce probabilistic forecasts that are computed via several model averaging techniques. The platform is currently operational in multiple river basins in Africa, and can also be adapted to any...
Water Resources Research, 2017
We develop and test a probabilistic real-time streamflow-forecasting platform, Multimodel and Mul... more We develop and test a probabilistic real-time streamflow-forecasting platform, Multimodel and Multiproduct Streamflow Forecasting (MMSF), that uses information provided by a suite of hydrologic models and satellite precipitation products (SPPs). The SPPs are bias-corrected before being used as inputs to the hydrologic models, and model calibration is carried out independently for each of the model-product combinations (MPCs). Forecasts generated from the calibrated models are further bias-corrected to compensate for the deficiencies within the models, and then probabilistically merged using a variety of model averaging techniques. Use of bias-corrected SPPs in streamflow forecasting applications can overcome several issues associated with sparsely gauged basins and enable robust forecasting capabilities. Bias correction of streamflow significantly improves the forecasts in terms of accuracy and precision for all different cases considered. Results show that the merging of individual forecasts from different MPCs provides additional improvements. All the merging techniques applied in this study produce similar results, however, the Inverse Weighted Averaging (IVA) proves to be slightly superior in most cases. We demonstrate the implementation of the MMSF platform for real-time streamflow monitoring and forecasting in the Mara River basin of Africa (Kenya & Tanzania) in order to provide improved monitoring and forecasting tools to inform water management decisions.
Ecology and Society, 2009
We have analyzed how the collaborative development process of a decision-support system (DSS) mod... more We have analyzed how the collaborative development process of a decision-support system (DSS) model can effectively contribute to increasing the resilience of regional social-ecological systems. In particular, we have focused on the case study of the transboundary San Pedro Basin, in the Arizona-Sonora desert region. This is a semi-arid watershed where water is a scarce resource used to cover competing human and environmental needs. We have outlined the essential traits in the development of the decisionsupport process that contributed to an improvement of water-resources management capabilities while increasing the potential for consensual problem solving. Comments and feedback from the stakeholders benefiting from the DSS in the San Pedro Basin are presented and analyzed within the regional (United States-Mexico boundary), social, and institutional context. We have indicated how multidisciplinary collaboration between academia and stakeholders can be an effective step toward collaborative management. Such technology transfer and capacity building provides a common arena for testing watermanagement policies and evaluating future scenarios. Putting science at the service of a participatory decision-making process can provide adaptive capacity to accommodate future change (i.e., building resilience in the management system).
Remote Sensing, 2016
We present an evaluation of daily estimates from three near real-time quasi-global Satellite Prec... more We present an evaluation of daily estimates from three near real-time quasi-global Satellite Precipitation Products-Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA), Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN), and Climate Prediction Center (CPC) Morphing Technique (CMORPH)-over the African continent, using the Global Precipitation Climatology Project one Degree Day (GPCP-1dd) as a reference dataset for years 2001 to 2013. Different types of errors are characterized for each season as a function of spatial classifications (latitudinal bands, climatic zones and topography) and in relationship with the main rain-producing mechanisms in the continent: the Intertropical Convergence Zone (ITCZ) and the East African Monsoon. A bias correction of the satellite estimates is applied using a probability density function (pdf) matching approach, with a bias analysis as a function of rain intensity, season and latitude. The effects of bias correction on different error terms are analyzed, showing an almost elimination of the mean and variance terms in most of the cases. While raw estimates of TMPA show higher efficiency, all products have similar efficiencies after bias correction. PERSIANN consistently shows the smallest median errors when it correctly detects precipitation events. The areas with smallest relative errors and other performance measures follow the position of the ITCZ oscillating seasonally over the equator, illustrating the close relationship between satellite estimates and rainfall regime.
Abstract : The Han River Basin is the major river in South Korea, with a basin area of more than ... more Abstract : The Han River Basin is the major river in South Korea, with a basin area of more than 26,000 square kilometers. Seven major dams are located in the North Han River Basin. These dams are operated primarily for hydropower generation, although flood control and water supply are also important objectives. The Han River Control System (HRCS) is a decision support computer software system developed by the U.S. Army Engineer Waterways Experiment Station to provide near real-time information on flooding conditions resulting from river operations. The system also provides reservoir operations necessary to meet downstream constraints. An overview describing the Han River Basin will be presented to highlight the importance of reservoir operations within the basin and the significance of a system that assists the user in determining how to operate the different reservoirs to best meet the different objectives. The HRCS components will than be described. These components include the following: TAMU, the rainfall-runoff module; CARIMA, the hydrodynamics module; OHIMA, the reservoir optimization module; DAMBRK, the dam breach forecasting module; and the inundation mapping module, which uses the graphical information system, GRASS. (AN)
Using rain-gauge station records for the statistical characterization and simulation of spatio-te... more Using rain-gauge station records for the statistical characterization and simulation of spatio-temporal precipitation fields involves many issues and simplifying assumptions. One major issue is related to dealing with uncertainty at-site sample statistical inference, because of the limited length of records. Regional frequency analysis uses substituting space for time in order to reduce uncertainty by assuming equal shapes of the precipitation statistical distributions in a region. However, this assumption limits the area of the analyzed region where this assumption is valid. The extension is dependent on terrain complexity. This work presents a new approach for the statistical regionalization of a large precipitation fields, replacing the constant shape assumption by using a smooth spatial variation. The approach accounts for every uncertainty on site information, using an L-moment method for inference analysis. Additionally, the orographic effect is introduced in the regionalization, which substantially improves the interpolation performance and estimation of areal precipitation. The approach is used for modelling the monthly precipitation field in the Júcar River Basin Authority Demarcation (Spain), incorporating its stochastic structure, and spatial dependency from a geostatistical analysis. Issues related to the estimation of regional precipitation, and mean areal precipitation are also discussed.
Tecnologia Y Ciencias Del Agua, 2010
Irrigation District No. 041, Río Yaqui, in Northwestern Mexico, has been affected by an unsustain... more Irrigation District No. 041, Río Yaqui, in Northwestern Mexico, has been affected by an unsustainable agricultural development due to intensive agricultural practices that combined, with an extreme drought, collapsed the system in 2003. The objective of this research is to develop a multiyear simulation-optimization model that allows for the creation of a quantitative and transferable methodology that promotes and impulses better and sustainable practices in the activities of the irrigation district. Furthermore, it attempts to define indices that explain the most important sustainable attributes of the system, and as a result of this study it is determined at each decision level, how these sustainable practices will be performed and by whom. In this research, the annual hydrologic-agronomic-economic simulation-optimization model developed by Minjares et al. (2008) was used and extended to a multiyear model connecting the annual models. In the long-term model, sustainable criteria like productivity, reliability, resilience, vulnerability and equity, to control the relationship between the decisions taken in the present and their long term consequences are included. The results indicate that the model can be used for developing the annual irrigation plan for the irrigation district, under different management scenarios in the long-term framework, and to identify possible practices or decisions that can put the sustainability of the system at risk. In addition, the model can be used to evaluate water management practices and decisions that have been taken in the past and possible conflicts for water in the future.
UNESCO-IHE Delft Lecture Note Series, 2016
This is chapter 21 of the book, Water Bankruptcy in the Land of Plenty (edited by Poupeau et al. ... more This is chapter 21 of the book, Water Bankruptcy in the Land of Plenty (edited by Poupeau et al. 2016) in which the research consortia discuss the body of work, some aspects of the process and the values of such a collective project in international environmental studies
Tecnologia Y Ciencias Del Agua, Apr 1, 2014
UNESCO-IHE Delft Lecture Note Series, 2016
Tecnologia Y Ciencias Del Agua, Apr 1, 2014
This study evaluates the usefulness and applicability of the discrete Kalman lter algorithm for ... more This study evaluates the usefulness and applicability of the discrete Kalman lter algorithm for predicting short-term oods. The algorithm is applied to the basin of the Ángel Albino Corzo (Peñitas) dam, which is part of the Grijalva Hydroelectric System, as well as to the Sayula Hydrometric Station. It is used to determine the response function for the basin and thus forecast ows into the reservoir. To that end, both ow data and precipitation recorded at weather stations located in the study area are used, as well as calculated inows to the basin. This analysis evaluates multiple time increments and dierent response functions, as well as their associated parameters, using the Nash-Sutclie coecient. Highly acceptable values were obtained, such that the lter is found to be useful for short-term ow forecasting, highlighting its usefulness as a tool to support policy development and the operational control of reservoirs.
Ingenieria Hidraulica En Mexico, 2004
VELASCO, l., APARlClO, J., VALDES, J. B., VELAZQUEZ, J. KlM, T.W. Drought index assessment in the... more VELASCO, l., APARlClO, J., VALDES, J. B., VELAZQUEZ, J. KlM, T.W. Drought index assessment in the watersheds of affluents from the Rio Bravo/Rio Grande River. Hydraulic engineering in Mexico (in Spanish). Vol. XlX, no. July-September, pp. There are several methods and indices to characterize drought, but none of them is superior to the others in all circumstances. The most frequently used indices in North America are the Standardized Precipitation lndex (SPl) and the Palmer Drought Severity lndex (PDSl). Each one has characteristics which can be advantageously used to characterize drought and trigger actions established in Drought Mitigation Plans. The Mexico-US Treaty on conjunctive management of the Colorado, Tijuana and Bravo/Grande Rivers, for example, foresees ways to modify the mutual water allocations between the two countries in case of extreme drought. However, it does not define precisely such concept. Therefore, it is important to examine in detail the applicability and characteristics of both methods to characterize droughts. This paper shows the application of the SPl, which is based only on precipitation data and reflects the temporary rain efficiency, considered as the hydrological component that determines, to a great extent, the occurrence and characteristics of a drought. The PDSl method is also studied. This index is based on soil moisture balance for the soil layer where crops grow, and, therefore, not only precipitation and temperature have influence in water availability, but also soil characteristics are decisive. Both indices are applied to the Conchos and Pecos watersheds, in order to evaluate theirbehaviol: When time scales are appropriate for both methods, the results obtained are similar, and they show that droughts have been persistent and recurrent over the region during the last few years. Besides, a sensitivity analysis of PDSl to some parameters is presented.
Egs Agu Eug Joint Assembly, Apr 1, 2003
Stochastic Hydrology and its Use in Water Resources Systems Simulation and Optimization, 1993
In this part of the panel presentations I shall attempt to summarize the recent developments in t... more In this part of the panel presentations I shall attempt to summarize the recent developments in the modelling of precipitation, both at a point and in space, and to discuss the major strengths and weaknesses of these models. In doing so and following Dennis Lettenmaier’s path, I shall report on what I have read about and what are my own thoughts in this matter.
Journal of Hydroinformatics, 2017
The task of real-time streamflow monitoring and forecasting is particularly challenging for ungau... more The task of real-time streamflow monitoring and forecasting is particularly challenging for ungauged or sparsely gauged river basins, and largely relies upon satellite-based estimates of precipitation. We present the design and implementation of a state-of-the-art real-time streamflow monitoring and forecasting platform that integrates information provided by cutting-edge satellite precipitation products (SPPs), numerical precipitation forecasts, and multiple hydrologic models, to generate probabilistic streamflow forecasts that have an effective lead time of 9 days. The modular design of the platform enables adding/removing any model/product as may be appropriate. The SPPs are bias-corrected in real-time, and the model-generated streamflow forecasts are further bias-corrected and merged, to produce probabilistic forecasts that are computed via several model averaging techniques. The platform is currently operational in multiple river basins in Africa, and can also be adapted to any...
Water Resources Research, 2017
We develop and test a probabilistic real-time streamflow-forecasting platform, Multimodel and Mul... more We develop and test a probabilistic real-time streamflow-forecasting platform, Multimodel and Multiproduct Streamflow Forecasting (MMSF), that uses information provided by a suite of hydrologic models and satellite precipitation products (SPPs). The SPPs are bias-corrected before being used as inputs to the hydrologic models, and model calibration is carried out independently for each of the model-product combinations (MPCs). Forecasts generated from the calibrated models are further bias-corrected to compensate for the deficiencies within the models, and then probabilistically merged using a variety of model averaging techniques. Use of bias-corrected SPPs in streamflow forecasting applications can overcome several issues associated with sparsely gauged basins and enable robust forecasting capabilities. Bias correction of streamflow significantly improves the forecasts in terms of accuracy and precision for all different cases considered. Results show that the merging of individual forecasts from different MPCs provides additional improvements. All the merging techniques applied in this study produce similar results, however, the Inverse Weighted Averaging (IVA) proves to be slightly superior in most cases. We demonstrate the implementation of the MMSF platform for real-time streamflow monitoring and forecasting in the Mara River basin of Africa (Kenya & Tanzania) in order to provide improved monitoring and forecasting tools to inform water management decisions.
Ecology and Society, 2009
We have analyzed how the collaborative development process of a decision-support system (DSS) mod... more We have analyzed how the collaborative development process of a decision-support system (DSS) model can effectively contribute to increasing the resilience of regional social-ecological systems. In particular, we have focused on the case study of the transboundary San Pedro Basin, in the Arizona-Sonora desert region. This is a semi-arid watershed where water is a scarce resource used to cover competing human and environmental needs. We have outlined the essential traits in the development of the decisionsupport process that contributed to an improvement of water-resources management capabilities while increasing the potential for consensual problem solving. Comments and feedback from the stakeholders benefiting from the DSS in the San Pedro Basin are presented and analyzed within the regional (United States-Mexico boundary), social, and institutional context. We have indicated how multidisciplinary collaboration between academia and stakeholders can be an effective step toward collaborative management. Such technology transfer and capacity building provides a common arena for testing watermanagement policies and evaluating future scenarios. Putting science at the service of a participatory decision-making process can provide adaptive capacity to accommodate future change (i.e., building resilience in the management system).
Remote Sensing, 2016
We present an evaluation of daily estimates from three near real-time quasi-global Satellite Prec... more We present an evaluation of daily estimates from three near real-time quasi-global Satellite Precipitation Products-Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA), Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN), and Climate Prediction Center (CPC) Morphing Technique (CMORPH)-over the African continent, using the Global Precipitation Climatology Project one Degree Day (GPCP-1dd) as a reference dataset for years 2001 to 2013. Different types of errors are characterized for each season as a function of spatial classifications (latitudinal bands, climatic zones and topography) and in relationship with the main rain-producing mechanisms in the continent: the Intertropical Convergence Zone (ITCZ) and the East African Monsoon. A bias correction of the satellite estimates is applied using a probability density function (pdf) matching approach, with a bias analysis as a function of rain intensity, season and latitude. The effects of bias correction on different error terms are analyzed, showing an almost elimination of the mean and variance terms in most of the cases. While raw estimates of TMPA show higher efficiency, all products have similar efficiencies after bias correction. PERSIANN consistently shows the smallest median errors when it correctly detects precipitation events. The areas with smallest relative errors and other performance measures follow the position of the ITCZ oscillating seasonally over the equator, illustrating the close relationship between satellite estimates and rainfall regime.
Abstract : The Han River Basin is the major river in South Korea, with a basin area of more than ... more Abstract : The Han River Basin is the major river in South Korea, with a basin area of more than 26,000 square kilometers. Seven major dams are located in the North Han River Basin. These dams are operated primarily for hydropower generation, although flood control and water supply are also important objectives. The Han River Control System (HRCS) is a decision support computer software system developed by the U.S. Army Engineer Waterways Experiment Station to provide near real-time information on flooding conditions resulting from river operations. The system also provides reservoir operations necessary to meet downstream constraints. An overview describing the Han River Basin will be presented to highlight the importance of reservoir operations within the basin and the significance of a system that assists the user in determining how to operate the different reservoirs to best meet the different objectives. The HRCS components will than be described. These components include the following: TAMU, the rainfall-runoff module; CARIMA, the hydrodynamics module; OHIMA, the reservoir optimization module; DAMBRK, the dam breach forecasting module; and the inundation mapping module, which uses the graphical information system, GRASS. (AN)
Using rain-gauge station records for the statistical characterization and simulation of spatio-te... more Using rain-gauge station records for the statistical characterization and simulation of spatio-temporal precipitation fields involves many issues and simplifying assumptions. One major issue is related to dealing with uncertainty at-site sample statistical inference, because of the limited length of records. Regional frequency analysis uses substituting space for time in order to reduce uncertainty by assuming equal shapes of the precipitation statistical distributions in a region. However, this assumption limits the area of the analyzed region where this assumption is valid. The extension is dependent on terrain complexity. This work presents a new approach for the statistical regionalization of a large precipitation fields, replacing the constant shape assumption by using a smooth spatial variation. The approach accounts for every uncertainty on site information, using an L-moment method for inference analysis. Additionally, the orographic effect is introduced in the regionalization, which substantially improves the interpolation performance and estimation of areal precipitation. The approach is used for modelling the monthly precipitation field in the Júcar River Basin Authority Demarcation (Spain), incorporating its stochastic structure, and spatial dependency from a geostatistical analysis. Issues related to the estimation of regional precipitation, and mean areal precipitation are also discussed.
Tecnologia Y Ciencias Del Agua, 2010
Irrigation District No. 041, Río Yaqui, in Northwestern Mexico, has been affected by an unsustain... more Irrigation District No. 041, Río Yaqui, in Northwestern Mexico, has been affected by an unsustainable agricultural development due to intensive agricultural practices that combined, with an extreme drought, collapsed the system in 2003. The objective of this research is to develop a multiyear simulation-optimization model that allows for the creation of a quantitative and transferable methodology that promotes and impulses better and sustainable practices in the activities of the irrigation district. Furthermore, it attempts to define indices that explain the most important sustainable attributes of the system, and as a result of this study it is determined at each decision level, how these sustainable practices will be performed and by whom. In this research, the annual hydrologic-agronomic-economic simulation-optimization model developed by Minjares et al. (2008) was used and extended to a multiyear model connecting the annual models. In the long-term model, sustainable criteria like productivity, reliability, resilience, vulnerability and equity, to control the relationship between the decisions taken in the present and their long term consequences are included. The results indicate that the model can be used for developing the annual irrigation plan for the irrigation district, under different management scenarios in the long-term framework, and to identify possible practices or decisions that can put the sustainability of the system at risk. In addition, the model can be used to evaluate water management practices and decisions that have been taken in the past and possible conflicts for water in the future.
UNESCO-IHE Delft Lecture Note Series, 2016
This is chapter 21 of the book, Water Bankruptcy in the Land of Plenty (edited by Poupeau et al. ... more This is chapter 21 of the book, Water Bankruptcy in the Land of Plenty (edited by Poupeau et al. 2016) in which the research consortia discuss the body of work, some aspects of the process and the values of such a collective project in international environmental studies
Tecnologia Y Ciencias Del Agua, Apr 1, 2014
UNESCO-IHE Delft Lecture Note Series, 2016
Tecnologia Y Ciencias Del Agua, Apr 1, 2014
This study evaluates the usefulness and applicability of the discrete Kalman lter algorithm for ... more This study evaluates the usefulness and applicability of the discrete Kalman lter algorithm for predicting short-term oods. The algorithm is applied to the basin of the Ángel Albino Corzo (Peñitas) dam, which is part of the Grijalva Hydroelectric System, as well as to the Sayula Hydrometric Station. It is used to determine the response function for the basin and thus forecast ows into the reservoir. To that end, both ow data and precipitation recorded at weather stations located in the study area are used, as well as calculated inows to the basin. This analysis evaluates multiple time increments and dierent response functions, as well as their associated parameters, using the Nash-Sutclie coecient. Highly acceptable values were obtained, such that the lter is found to be useful for short-term ow forecasting, highlighting its usefulness as a tool to support policy development and the operational control of reservoirs.
Ingenieria Hidraulica En Mexico, 2004
VELASCO, l., APARlClO, J., VALDES, J. B., VELAZQUEZ, J. KlM, T.W. Drought index assessment in the... more VELASCO, l., APARlClO, J., VALDES, J. B., VELAZQUEZ, J. KlM, T.W. Drought index assessment in the watersheds of affluents from the Rio Bravo/Rio Grande River. Hydraulic engineering in Mexico (in Spanish). Vol. XlX, no. July-September, pp. There are several methods and indices to characterize drought, but none of them is superior to the others in all circumstances. The most frequently used indices in North America are the Standardized Precipitation lndex (SPl) and the Palmer Drought Severity lndex (PDSl). Each one has characteristics which can be advantageously used to characterize drought and trigger actions established in Drought Mitigation Plans. The Mexico-US Treaty on conjunctive management of the Colorado, Tijuana and Bravo/Grande Rivers, for example, foresees ways to modify the mutual water allocations between the two countries in case of extreme drought. However, it does not define precisely such concept. Therefore, it is important to examine in detail the applicability and characteristics of both methods to characterize droughts. This paper shows the application of the SPl, which is based only on precipitation data and reflects the temporary rain efficiency, considered as the hydrological component that determines, to a great extent, the occurrence and characteristics of a drought. The PDSl method is also studied. This index is based on soil moisture balance for the soil layer where crops grow, and, therefore, not only precipitation and temperature have influence in water availability, but also soil characteristics are decisive. Both indices are applied to the Conchos and Pecos watersheds, in order to evaluate theirbehaviol: When time scales are appropriate for both methods, the results obtained are similar, and they show that droughts have been persistent and recurrent over the region during the last few years. Besides, a sensitivity analysis of PDSl to some parameters is presented.
Egs Agu Eug Joint Assembly, Apr 1, 2003