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Research Article
Comparative Performance of Non-Stationary Intensity-Duration-Frequency (NS-IDF) Models for Selected Gauge Stations in the Niger Delta
Masi Gabriel Sam
,
Ify Lawrence Nwaogazie*
Issue:
Volume 12, Issue 2, June 2024
Pages:
17-31
Received:
27 April 2024
Accepted:
20 May 2024
Published:
6 June 2024
Abstract: This study focused on a comparative analysis of developed Non-stationary rainfall intensity-duration-frequency (NS-IDF) models with existing IDF models for the Niger Delta with Uyo, Benin, Port Harcourt, and Warri as selected stations. Applied was 24-hourly (daily) annual maximum series (AMS) data with downscaling models also used to downscale the time series data. Uyo and Benin had statistically significant trends with Port Harcourt and Warri showing mild trends. The best linear behavioural parameter extremes model integrating time as co-variate was selected for each station for computation of the General extreme value (GEV) distribution fitted NS-IDF models with the open-access R-studio software. The Non-stationary intensity values were higher than computed stationary ones, with significant differences at a 5% significance level for a given return period. For example, for 2 and 10-year return periods for 1-hour storms the differences of 22.71% & 17.0%, 15.24% & 9.40%, 5.09% & 4.04%, and 6.15% & 4.43% for Uyo, Benin, Port Harcourt and Warri, respectively were recorded. While, the percentage difference in intensities was very high between the Non-stationary and existing, Stationary IDF models. For a return period of 2 years at 15 and 60 min durations, the differences were 97.9 & 3.2%, 240.6 & 67.2%, 78.2 & 0%, and 121.6 & 50.1% for Uyo, Benin, Port Harcourt and Warri, respectively. Such extreme value difference in intensity underestimates the peak flood and exagerate the flood risk. The general NS-IDF calibrated models showed very good match and fit with R2 = 0.977, 0.999, 0.999 & 0.999, and MSE accuracy = 193.5, 1.011, 4.1552 & 1.011 for Uyo, Benin, Port Harcourt, and Warri, respectively. Erosion and flood control facilities in the Niger Delta require upgrading using the calibrated general NS-IDF models to accommodate extra-value rainfall intensities due to climate change.
Abstract: This study focused on a comparative analysis of developed Non-stationary rainfall intensity-duration-frequency (NS-IDF) models with existing IDF models for the Niger Delta with Uyo, Benin, Port Harcourt, and Warri as selected stations. Applied was 24-hourly (daily) annual maximum series (AMS) data with downscaling models also used to downscale the ...
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Research Article
Opinion: Differentiating Natural Threats and Hazards for Water and Wastewater Structures and Operations - Energetic Threats and Hazards for the Water Industry
Lee Presley Gary Jr*,
Scott Richmond,
Daryl Spiewak
Issue:
Volume 12, Issue 2, June 2024
Pages:
32-35
Received:
6 April 2024
Accepted:
22 May 2024
Published:
26 June 2024
Abstract: A novel approach is presented to view, discern, and to redefine dangerous threats and hazards from natural events that can impact water and wastewater systems. The intent of this approach is to minimize ambiguity while enhancing preparedness and operational awareness of water and wastewater facilities, each vital for sustainable public health. This new approach recognizes potential and kinetic energy sources to differentiate between the threats and hazards generated by natural events, such as hurricanes, tornadoes or landslides, which can impact the steady-state operations of essential water and wastewater recovery facilities, associated infrastructure, plus endanger workers and exposed personnel. To support thisrethinking, absent in current literature searches, “energetic models” for anticipating latent, partial or total disruption of water and wastewater facilities and related management operations from naturally occurring events, such as a hurricane, tornado, or landslide, are presented. The proposed “energetic models” are atypical, yet they have practical value and encourage the rethinking and reimagining of threats and hazards used by water professionals and related fields and professions. The proposed models can be applied clearly to multiple and complex natural, human-caused, technological and equally disruptive events for water enterprises, expanding to similar challenges in public health responses to disease outbreaks.
Abstract: A novel approach is presented to view, discern, and to redefine dangerous threats and hazards from natural events that can impact water and wastewater systems. The intent of this approach is to minimize ambiguity while enhancing preparedness and operational awareness of water and wastewater facilities, each vital for sustainable public health. This...
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Research Article
Validating the Skills of Satellite Rainfall Products and Spatiotemporal Rainfall Variability Analysis over Omo River Basin in Ethiopia
Elsabet Temesgen Asefw*,
Getachew Tesfaye Ayehu
Issue:
Volume 12, Issue 2, June 2024
Pages:
36-51
Received:
26 March 2024
Accepted:
17 June 2024
Published:
29 June 2024
Abstract: Recently created long-term and regionally dispersed satellite-based rainfall estimates have emerged as crucial sources of rainfall data to assess rainfall's spatial and temporal variability, particularly for data-scarce locations. Objective (the general): The purpose of this paper is to assess the skills of nine selected satellite rainfall estimates i.e., (ARC 2.0, TRMM 3B42, CHIRPS v. 2.0, TAMSAT 3.1, CMORPH v. 1.0 adj., PERSIANN CDR and DNRT, and MSWEP v. 2.2) and understand Spatio-temporal variability of rainfall over the Omo River basin using the best performing product. Method: The validation analysis was done by using a point-to-grid-based comparison test at different temporal accumulations. MSWEP was selected as the best product to analyze the long-term trend and variability of rainfall over the Omo-River basin from 1990-2017. The coefficients of variation (CV) and the standardization rainfall anomalies index (SRAI) were used to examine rainfall variability, while the Mann-Kendall (MK) and Sen slope estimators were used to examine the trend and magnitude of rainfall patterns. Results: The overall statistical, categorical, and volumetric validation index results show that the MSWEP is the best performing rainfall product followed by CHRIPS, 3B42, and TAMSAT according to their order of appearance than the remaining products (i.e., ARC, RFE, PER CDR, PER DNRT, and CMORPH). The CV result with the relatively highest monthly variability (CV > 30%) was observed in some southern, northern, southeastern, and central parts of the study area. In general, the overall annual CV shows almost no variation in the entire basin except in the lower part because of the region's prevalent topographic variances, which ranged from 3455 to 352 m.a.s.l. In addition, the highest seasonal positive and negative anomalies are observed in each season in the entire basin. These abnormalities can result in significant floods and droughts that unquestionably influence the basin and its resources. Conclusion: In general, the basin has an increasing trend in the southern portions and a declining trend in the central to northern tip parts of the basin, as can be observed from the annual average MK trend tests. The basin has experienced a greeter variation but is not significant except in some parts of the basin.
Abstract: Recently created long-term and regionally dispersed satellite-based rainfall estimates have emerged as crucial sources of rainfall data to assess rainfall's spatial and temporal variability, particularly for data-scarce locations. Objective (the general): The purpose of this paper is to assess the skills of nine selected satellite rainfall estimate...
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