An extension of the logistic function to account for nonstationary drought losses
<p>While the stationary intensity loss function is fundamental to drought impact assessment, the relationship between drought loss and intensity can change as time progresses owing to socio-economic developments. This paper addresses this critical gap by modelling nonstationary drought losses....
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2025-06-01
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| Series: | Hydrology and Earth System Sciences |
| Online Access: | https://hess.copernicus.org/articles/29/2429/2025/hess-29-2429-2025.pdf |
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| author | T. Zhao Z. Chen Y. Zhang B. Zhang Y. Li |
| author_facet | T. Zhao Z. Chen Y. Zhang B. Zhang Y. Li |
| author_sort | T. Zhao |
| collection | DOAJ |
| description | <p>While the stationary intensity loss function is fundamental to drought impact assessment, the relationship between drought loss and intensity can change as time progresses owing to socio-economic developments. This paper addresses this critical gap by modelling nonstationary drought losses. Specifically, time is explicitly formulated by linear and quadratic functions and then incorporated into the magnitude, shape and location parameters of the logistic function to derive six nonstationary intensity loss functions in total. To examine the effectiveness of this approach, a case study is designed for drought-affected populations by province in mainland China during the period from 2006 to 2023. The results highlight the existence of nonstationarity in that the drought-affected population exhibits significant correlation not only with the standard precipitation index but also with time. The proposed nonstationary intensity loss functions are shown to outperform not only the classic logistic function but also the linear regression. They present effective characterizations of observed drought loss in different ways: (1) the nonstationary function with the flexible magnitude parameter fits the data by adjusting the maximum drought loss by year; (2) the nonstationary function with the flexible shape parameter works by modifying the growth rate of drought loss with intensity; and (3) the nonstationary function with the flexible location parameter acts by shifting the response curves along the axis by year. Among the nonstationary logistic functions, the function incorporating the linear function of time into the magnitude parameter generally outperforms the others in terms of having a high coefficient of determination, a low Bayesian information criterion and an explicit physical meaning. Taken together, the nonstationary intensity loss functions developed in this paper can serve as an effective tool for drought management.</p> |
| format | Article |
| id | doaj-art-43dde193bbbc40ea9bed56ef03d67666 |
| institution | Kabale University |
| issn | 1027-5606 1607-7938 |
| language | English |
| publishDate | 2025-06-01 |
| publisher | Copernicus Publications |
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| series | Hydrology and Earth System Sciences |
| spelling | doaj-art-43dde193bbbc40ea9bed56ef03d676662025-08-20T03:25:42ZengCopernicus PublicationsHydrology and Earth System Sciences1027-56061607-79382025-06-01292429244310.5194/hess-29-2429-2025An extension of the logistic function to account for nonstationary drought lossesT. Zhao0Z. Chen1Y. Zhang2B. Zhang3Y. Li4Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Civil Engineering, Sun Yat-sen University, Guangzhou 510275, ChinaSouthern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Civil Engineering, Sun Yat-sen University, Guangzhou 510275, ChinaKey Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, ChinaSchool of Hydraulic Engineering, Dalian University of Technology, Dalian 116024, ChinaSchool of Hydraulic Engineering, Dalian University of Technology, Dalian 116024, China<p>While the stationary intensity loss function is fundamental to drought impact assessment, the relationship between drought loss and intensity can change as time progresses owing to socio-economic developments. This paper addresses this critical gap by modelling nonstationary drought losses. Specifically, time is explicitly formulated by linear and quadratic functions and then incorporated into the magnitude, shape and location parameters of the logistic function to derive six nonstationary intensity loss functions in total. To examine the effectiveness of this approach, a case study is designed for drought-affected populations by province in mainland China during the period from 2006 to 2023. The results highlight the existence of nonstationarity in that the drought-affected population exhibits significant correlation not only with the standard precipitation index but also with time. The proposed nonstationary intensity loss functions are shown to outperform not only the classic logistic function but also the linear regression. They present effective characterizations of observed drought loss in different ways: (1) the nonstationary function with the flexible magnitude parameter fits the data by adjusting the maximum drought loss by year; (2) the nonstationary function with the flexible shape parameter works by modifying the growth rate of drought loss with intensity; and (3) the nonstationary function with the flexible location parameter acts by shifting the response curves along the axis by year. Among the nonstationary logistic functions, the function incorporating the linear function of time into the magnitude parameter generally outperforms the others in terms of having a high coefficient of determination, a low Bayesian information criterion and an explicit physical meaning. Taken together, the nonstationary intensity loss functions developed in this paper can serve as an effective tool for drought management.</p>https://hess.copernicus.org/articles/29/2429/2025/hess-29-2429-2025.pdf |
| spellingShingle | T. Zhao Z. Chen Y. Zhang B. Zhang Y. Li An extension of the logistic function to account for nonstationary drought losses Hydrology and Earth System Sciences |
| title | An extension of the logistic function to account for nonstationary drought losses |
| title_full | An extension of the logistic function to account for nonstationary drought losses |
| title_fullStr | An extension of the logistic function to account for nonstationary drought losses |
| title_full_unstemmed | An extension of the logistic function to account for nonstationary drought losses |
| title_short | An extension of the logistic function to account for nonstationary drought losses |
| title_sort | extension of the logistic function to account for nonstationary drought losses |
| url | https://hess.copernicus.org/articles/29/2429/2025/hess-29-2429-2025.pdf |
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