ORCID Profile
0000-0003-3763-1204
Current Organisation
University of Maryland at College Park
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Publisher: Elsevier BV
Date: 11-2020
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.22499/3.6602.008
Publisher: American Society of Civil Engineers (ASCE)
Date: 10-2020
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.22499/3.6602.007
Publisher: Copernicus GmbH
Date: 02-2023
Publisher: Research Square Platform LLC
Date: 19-09-2023
Publisher: Springer Science and Business Media LLC
Date: 31-10-2022
Publisher: Copernicus GmbH
Date: 22-12-2017
DOI: 10.5194/HESS-21-6541-2017
Abstract: Abstract. The primary objective of this study is to develop a stochastic rainfall generation model that can match not only the short resolution (daily) variability but also the longer resolution (monthly to multiyear) variability of observed rainfall. This study has developed a Markov chain (MC) model, which uses a two-state MC process with two parameters (wet-to-wet and dry-to-dry transition probabilities) to simulate rainfall occurrence and a gamma distribution with two parameters (mean and standard deviation of wet day rainfall) to simulate wet day rainfall depths. Starting with the traditional MC-gamma model with deterministic parameters, this study has developed and assessed four other variants of the MC-gamma model with different parameterisations. The key finding is that if the parameters of the gamma distribution are randomly s led each year from fitted distributions rather than fixed parameters with time, the variability of rainfall depths at both short and longer temporal resolutions can be preserved, while the variability of wet periods (i.e. number of wet days and mean length of wet spell) can be preserved by decadally varied MC parameters. This is a straightforward enhancement to the traditional simplest MC model and is both objective and parsimonious.
Publisher: Copernicus GmbH
Date: 24-01-2020
Abstract: Abstract. During the past decades, the increased impact of anthropogenic interventions on river basins has prompted hydrologists to develop various approaches for representing human–water interactions in large-scale hydrological and land surface models. The simulation of water reservoir storage and operations has received particular attention, owing to the ubiquitous presence of dams. Yet, little is known about (1) the effect of the representation of water reservoirs on the parameterization of hydrological models, and, therefore, (2) the risks associated with potential flaws in the calibration process. To fill in this gap, we contribute a computational framework based on the Variable Infiltration Capacity (VIC) model and a multi-objective evolutionary algorithm, which we use to calibrate VIC's parameters. An important feature of our framework is a novel variant of VIC's routing model that allows us to simulate the storage dynamics of water reservoirs. Using the upper Mekong river basin as a case study, we calibrate two instances of VIC – with and without reservoirs. We show that both model instances have the same accuracy in reproducing daily discharges (over the period 1996–2005), a result attained by the model without reservoirs by adopting a parameterization that compensates for the absence of these infrastructures. The first implication of this flawed parameter estimation stands in a poor representation of key hydrological processes, such as surface runoff, infiltration, and baseflow. To further demonstrate the risks associated with the use of such a model, we carry out a climate change impact assessment (for the period 2050–2060), for which we use precipitation and temperature data retrieved from five global circulation models (GCMs) and two Representative Concentration Pathways (RCPs 4.5 and 8.5). Results show that the two model instances (with and without reservoirs) provide different projections of the minimum, maximum, and average monthly discharges. These results are consistent across both RCPs. Overall, our study reinforces the message about the correct representation of human–water interactions in large-scale hydrological models.
Publisher: Copernicus GmbH
Date: 22-09-2023
Publisher: Elsevier BV
Date: 08-2022
Publisher: Elsevier BV
Date: 09-2023
Publisher: Research Square Platform LLC
Date: 06-07-2023
DOI: 10.21203/RS.3.RS-3089500/V1
Abstract: Vast hydropower resources remain untapped globally, the deployment of which could provide energy-economic benefits but impact riverine ecosystems. Across eco-sensitive river basins, it is unclear how drivers of hydropower expansion, such as rapid economic growth and a low-carbon energy transition, could interact with countervailing forces, such as increasingly cost-competitive variable renewable energy (VRE). Using an integrated energy-water-economy model, we explore the effects of these forces on long-term hydropower expansion in the world's 20 most eco-sensitive basins, which have high ecological richness and untapped hydropower potential. We find that a low-carbon transition exerts the strongest development pressure, causing deployment exceeding 80% of exploitable potential in more than 72% of eco-sensitive basins by 2050, most of which have limited deployment today. Rapid economic growth induces such extensive deployment in only 44% of eco-sensitive basins. Enhanced integration of VRE reduces deployment, alleviating the impacts of rapid economic growth but not the low-carbon transition.
Publisher: Wiley
Date: 04-2019
DOI: 10.1002/JOC.6071
Publisher: American Geophysical Union (AGU)
Date: 03-2021
DOI: 10.1029/2020EF001814
Abstract: The Greater Mekong Subregion is a transnational area bound together by the Mekong River basin and its immense hydropower resources, historically seen as the backbone of regional economic development. The basin is now punctuated by several dams, successful in attracting both international investors and fierce criticisms for their environmental and societal impacts. Surprisingly, no attention has been paid so far to the actual performance of these infrastructures: is hydropower supply robust with respect to the hydroclimatic variability characterizing Southeast Asia? When water availability is altered, what are the implications for power production costs and CO 2 emissions? To answer these questions, we focus on the Laotian–Thai grid—the first international power‐trade infrastructure developed in the region—and use a power system model driven by a spatially distributed hydrological‐water management model. Simulation results over a 30‐year period show that production costs and carbon footprint are significantly affected by droughts, which reduce hydropower availability and increase reliance on thermoelectric resources. Regional droughts across the Mekong basin are of particular concern, as they reduce the export of cheap hydropower from Laos to Thailand. To put the analysis into a broader climate‐water‐energy context, we show that the El Niño Southern Oscillation modulates not only the summer monsoon, but also the power system behavior, shaping the relationship between hydroclimatological conditions, power production costs, and CO 2 emissions. Overall, our results and models provide a knowledge basis for informing robust management strategies at the water‐energy scale and designing more sustainable power plans in the Greater Mekong Subregion.
Publisher: Elsevier BV
Date: 04-2020
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.22499/3.6602.006
Publisher: Research Square Platform LLC
Date: 30-03-2021
DOI: 10.21203/RS.3.RS-337017/V1
Abstract: Strategic dam planning and the deployment of decentralized renewable technologies are two elements of the same problem, yet they are normally addressed in isolation. Here, we show that an integrated view of the power system capacity expansion problem could have transformative effects for the 'Battery of Asia' plan. We demonstrate that Thailand, Laos, and Cambodia have tangible opportunities for meeting projected electricity demand and CO2 emission targets with less hydropower than currently planned--options range from halting the construction of all dams in the Lower Mekong to building 82% of the planned ones. The key enabling strategies for these options to succeed are solar PV and regional coordination, expressed in the form of centralized planning and cross-border power trading. The alternative expansion plans would slightly increase the cumulative costs, but limit the fragmentation of additional river reaches, thereby offering more sustainable pathways for the Mekong’s ecosystems and riparian people.
Publisher: Copernicus GmbH
Date: 02-2023
DOI: 10.5194/GMD-2023-12
Abstract: Abstract. This study enhances an existing global hydrological model (GHM), Xanthos, by adding a new water management module that distinguishes between the operational characteristics of irrigation, hydropower, and flood control reservoirs. We remapped reservoirs in the GranD database to Xanthos' 0.5-degree spatial resolution so that a single lumped reservoir exists per grid cell, which yielded 3790 large reservoirs. We implemented unique operation rules for each reservoir type based on their primary purposes. In particular, hydropower reservoirs have been treated as flood control reservoirs in previous GHM studies, while here, we determined the operation rules for hydropower reservoirs via optimization that maximizes long-term hydropower production. We conducted global simulations using the enhanced Xanthos and validated monthly streamflow for 91 large river basins where high-quality observed streamflow data were available. A total of 1878 (296 hydropower, 486 irrigation, and 1096 flood control and others) out of the 3790 reservoirs are located in the 91 basins and are part of our reported results. The Kling-Gupta Efficient (KGE) value (after adding the new water management) is ≥ 0.5 and ≥ 0.0 in 39 and 81 basins, respectively. After adding the new water management module, model performance improved for 75 out of 91 basins and worsened for only seven. To measure the relative difference between explicitly representing hydropower reservoirs and representing hydropower reservoirs as flood control reservoirs (as is commonly done in other GHMs), we use normalized-root-mean-square-error (NRMSE) and the coefficient of determination (R2). Out of the 296 hydropower reservoirs, NRMSE is 0.25 (i.e., considering 0.25 to represent a moderate difference) for over 44 % of the 296 reservoirs when comparing both the simulated reservoir releases and storage time series between the two simulations. We suggest that correctly representing hydropower reservoirs in GHMs could have important implications for our understanding and management of freshwater resource challenges at regional-to-global scales. This enhanced global water management modeling framework will allow for the analysis of future global reservoir development and management from a coupled human-earth system perspective.
Publisher: Ubiquity Press, Ltd.
Date: 12-03-2020
DOI: 10.5334/JORS.302
Publisher: Springer Science and Business Media LLC
Date: 06-07-2021
DOI: 10.1038/S41467-021-24437-6
Abstract: Strategic dam planning and the deployment of decentralized renewable technologies are two elements of the same problem, yet normally addressed in isolation. Here, we show that an integrated view of the power system capacity expansion problem could have transformative effects for Southeast Asia’s hydropower plans. We demonstrate that Thailand, Laos, and Cambodia have tangible opportunities for meeting projected electricity demand and CO 2 emission targets with less hydropower than currently planned—options range from halting the construction of all dams in the Lower Mekong to building 82% of the planned ones. The key enabling strategies for these options to succeed are solar PV and regional coordination, expressed in the form of centralized planning and cross-border power trading. The alternative expansion plans would slightly increase the cumulative costs (up to 2.4%), but substantially limit the fragmentation of additional river reaches, thereby offering more sustainable pathways for the Mekong’s ecosystems and riparian people.
Location: Bangladesh
Location: United States of America
Location: United States of America
No related grants have been discovered for AFM Kamal Chowdhury.