Your search found 4 records
1 Satish, M. G.; Zhu, J.. 1992. Stochastic approach for groundwater flow in a semiconfined aquifer subject to random boundary conditions. Advances in Water Resources, 15(6):329-339.
(Location: IWMI-HQ Call no: PER Record No: H012769)
A methodology is presented for analyzing the ground water flow through a shallow semiconfined aquifer with random parameters, governed by the Helmholtz equation and subject to stochastic boundary conditions. Stochasticity in an aquifer parameter is considered along with the stochasticity in the Dirichlet and Neumann boundary conditions. The hierarchical equations based on the expansion of the potential into the perturbation series are derived and the regular boundary element procedure is applied for obtaining the solutions of these equations. The standard deviation in the potential is observed to increase with an increase in either the standard deviation in the random quantities or the strength of the correlation between the random quantities. The boundary element method based on perturbation does not require specification of the probability density function of the parameters but only their expectations, variances and the covariance of the random quantities. The applicability of the method is demonstrated by presenting a groundwater flow example as well as by comparing the numerical results with analytical solutions for a special case without the Neumann boundary condition uncertainty.
2 Liu, D.; Wang, X.; Aminjafari, S.; Yang, W.; Cui, B.; Yan, S.; Zhang, Y.; Zhu, J.; Jaramillo, F. 2020. Using InSAR [Interferometric Synthetic Aperture Radar] to identify hydrological connectivity and barriers in a highly fragmented wetland. Hydrological Processes, 14p. (Online first) [doi: https://doi.org/10.1002/hyp.13899]
Wetlands ; Hydrological factors ; SAR (radar) ; Radar imagery ; Water levels ; Satellites ; Remote sensing ; Interferometry ; Barriers ; Ecosystems ; Grasslands ; Vegetation / China / Baiyangdian Wetland
(Location: IWMI HQ Call no: e-copy only Record No: H049975)
https://onlinelibrary.wiley.com/doi/epdf/10.1002/hyp.13899
https://vlibrary.iwmi.org/pdf/H049975.pdf
https://vlibrary.iwmi.org/pdf/H049975.pdf
(3.71 MB) (3.71 MB)
Hydrological connectivity is a critical determinant of wetland functions and health, especially in wetlands that have been heavily fragmented and regulated by human activities. However, investigating hydrological connectivity in these wetlands is challenging due to the costs of high-resolution and large-scale monitoring required in order to identify hydrological barriers within the wetlands. To overcome this challenge, we here propose an interferometric synthetic aperture radar (InSAR)-based methodology to map hydrologic connectivity and identify hydrological barriers in fragmented wetlands. This methodology was applied along 70 transects across the Baiyangdian, the largest freshwater wetland in northern China, using Sentinel 1A and 1B data, covering the period 2016–2019. We generated 58 interferograms providing information on relative water level changes across the transects that showed the high coherence needed for the assessment of hydrological connectivity. We mapped the permanent and conditional (temporary) barriers affecting connectivity. In total, 11% of all transects are permanently disconnected by hydrological barriers across all interferograms and 58% of the transects are conditionally disconnected. Areas covered by reed grasslands show the most undisturbed hydrological connectivity while some of these barriers are the result of ditches and channels within the wetland and low water levels during different periods of the year. This study highlights the potential of the application of Wetland InSAR to determine hydrological connectivity and location of hydrological barriers in highly fragmented wetlands, and facilitates the study of hydrological processes from large spatial scales and long-time scales using remote sensing technique.
3 Zhang, J.; Zhu, J.; Liu, Y.; Lu, N.; Fang, W. 2022. The economic impact of payments for water-related ecosystem services on protected areas: a synthetic control analysis. Water Resources Management, 36(5):1535-1551. [doi: https://doi.org/10.1007/s11269-022-03099-z]
Payment for Ecosystem Services ; Water resources ; Economic impact ; Economic development ; Economic growth ; Gross national product ; Policies ; Towns ; Case studies / China / Shaanxi / Hubei / Henan / Gansu / Sichuan / Hanzhong / Ankang / Shangluo / Danjiangkou Reservoir
(Location: IWMI HQ Call no: e-copy only Record No: H051072)
(3.30 MB)
Payments for Water-Related Ecosystem Services (PWES) are increasingly popular for promoting water ecological conservation, and their impact on development is of considerable interest. This study estimates the economic impact of PWES on protected areas using the synthetic control method. Taking the Middle Route of the South to North Water Diversion Project in China as a case study, we find that the per capita GDP in protected areas increased markedly relative to synthetic control regions, and PWES had a positive economic impact. Additionally, we conducted many placebo tests to verify the validity and robustness of the results. We believe that the main factor responsible for the positive effect lies in developing the ecological-economic industrial system. This study provides a baseline for synthetic control analysis of PWES to compare regions of interest with their counterfactuals. The case study findings provide reference for the economic development of protected areas.
4 Zhu, J.; Dang, P.; Cao, Y.; Lai, J.; Guo, Y.; Wang, P.; Li, W. 2024. A flood knowledge-constrained large language model interactable with GIS: enhancing public risk perception of floods. International Journal of Geographical Information Science, 24p. (Online first) [doi: https://doi.org/10.1080/13658816.2024.2306167]
(Location: IWMI HQ Call no: e-copy only Record No: H052627)
https://www.tandfonline.com/doi/pdf/10.1080/13658816.2024.2306167?download=true
https://vlibrary.iwmi.org/pdf/H052627.pdf
https://vlibrary.iwmi.org/pdf/H052627.pdf
(3.07 MB) (3.07 MB)
Public’s rational flood mitigation behaviors depend on accurate perception of flood risks. The use of natural language for flood risk perception is an effective approach, and it is critical to ensure the accuracy and comprehensibility of the flood information provided by the system in natural language dialogues. This study presents a framework for large language model (LLM) that is constrained by flood knowledge and can interact with geographic information system (GIS), aimed at enhancing the public’s perception of flood risks. We tested the performance of LLM within this framework and the results demonstrate that LLM can generate accurate information about floods under the constraints of entities and relationships in the knowledge graph, and interact with GIS to produce personalized knowledge through real-time coding. Furthermore, we conducted flood risk perception experiments on users with different cognitive levels. The results indicate that using natural language dialogue can narrow the differences brought about by cognitive levels, allowing the public to equally access knowledge related to flood events.
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