Validating commonly used drought indicators in Kenya
Drought is a complex natural hazard that can occur in any climate and affect every aspect of society. To better prepare and mitigate the impacts of drought, various indicators can be applied to monitor and forecast its onset, intensity, and severity. Though widely used, little is known about the eff...
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2021-01-01
|
| Series: | Environmental Research Letters |
| Subjects: | |
| Online Access: | https://doi.org/10.1088/1748-9326/ac16a2 |
| _version_ | 1797747569847173120 |
|---|---|
| author | Andrew Bowell Edward E Salakpi Kiswendsida Guigma James M Muthoka John Mwangi Pedram Rowhani |
| author_facet | Andrew Bowell Edward E Salakpi Kiswendsida Guigma James M Muthoka John Mwangi Pedram Rowhani |
| author_sort | Andrew Bowell |
| collection | DOAJ |
| description | Drought is a complex natural hazard that can occur in any climate and affect every aspect of society. To better prepare and mitigate the impacts of drought, various indicators can be applied to monitor and forecast its onset, intensity, and severity. Though widely used, little is known about the efficacy of these indicators which restricts their role in important decisions. Here, we provide the first validation of 11 commonly-used drought indicators by comparing them to pasture and browse condition data collected on the ground in Kenya. These ground-based data provide an absolute and relative assessment of the conditions, similar to some of the drought indicators. Focusing on grass and shrublands of the arid and semi-arid lands, we demonstrate there are strong relationships between ground-based pasture and browse conditions, and satellite-based drought indicators. The soil adjusted vegetation index has the best relationship, achieving a mean r ^2 score of 0.70 when fitted against absolute pasture condition. Similarly, the 3-month vegetation health index reached a mean r ^2 score of 0.62 when fitted against a relative pasture condition. In addition, we investigated the Kenya-wide drought onset threshold for the 3-month average vegetation condition index (VCI3M; VCI3M $\lt$ 35), which is used by the country’s drought early warning system. Our results show large disparities in thresholds across different counties. Understanding these relationships and thresholds are integral to developing effective and efficient drought early warning systems. Our work offers evidence for the effectiveness of some of these indicators as well as practical thresholds for their use. |
| first_indexed | 2024-03-12T15:52:30Z |
| format | Article |
| id | doaj.art-19bc4ea9764c42aca1b1a63146f0438b |
| institution | Directory Open Access Journal |
| issn | 1748-9326 |
| language | English |
| last_indexed | 2024-03-12T15:52:30Z |
| publishDate | 2021-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | Environmental Research Letters |
| spelling | doaj.art-19bc4ea9764c42aca1b1a63146f0438b2023-08-09T15:03:48ZengIOP PublishingEnvironmental Research Letters1748-93262021-01-0116808406610.1088/1748-9326/ac16a2Validating commonly used drought indicators in KenyaAndrew Bowell0Edward E Salakpi1Kiswendsida Guigma2James M Muthoka3John Mwangi4Pedram Rowhani5https://orcid.org/0000-0002-0709-9168Department of Geography, School of Global Studies, University of Sussex , Brighton BN1 9QJ, United KingdomDISCUS, Department of Physics and Astronomy, University of Sussex , Brighton BN1 9QH, United KingdomDepartment of Geography, School of Global Studies, University of Sussex , Brighton BN1 9QJ, United KingdomDepartment of Geography, School of Global Studies, University of Sussex , Brighton BN1 9QJ, United KingdomThe National Drought Management Authority (NDMA) , Lonrho House, Nairobi, KenyaDepartment of Geography, School of Global Studies, University of Sussex , Brighton BN1 9QJ, United KingdomDrought is a complex natural hazard that can occur in any climate and affect every aspect of society. To better prepare and mitigate the impacts of drought, various indicators can be applied to monitor and forecast its onset, intensity, and severity. Though widely used, little is known about the efficacy of these indicators which restricts their role in important decisions. Here, we provide the first validation of 11 commonly-used drought indicators by comparing them to pasture and browse condition data collected on the ground in Kenya. These ground-based data provide an absolute and relative assessment of the conditions, similar to some of the drought indicators. Focusing on grass and shrublands of the arid and semi-arid lands, we demonstrate there are strong relationships between ground-based pasture and browse conditions, and satellite-based drought indicators. The soil adjusted vegetation index has the best relationship, achieving a mean r ^2 score of 0.70 when fitted against absolute pasture condition. Similarly, the 3-month vegetation health index reached a mean r ^2 score of 0.62 when fitted against a relative pasture condition. In addition, we investigated the Kenya-wide drought onset threshold for the 3-month average vegetation condition index (VCI3M; VCI3M $\lt$ 35), which is used by the country’s drought early warning system. Our results show large disparities in thresholds across different counties. Understanding these relationships and thresholds are integral to developing effective and efficient drought early warning systems. Our work offers evidence for the effectiveness of some of these indicators as well as practical thresholds for their use.https://doi.org/10.1088/1748-9326/ac16a2NDVIVCIEarth ObservationFood SecurityEarly Warning Systems |
| spellingShingle | Andrew Bowell Edward E Salakpi Kiswendsida Guigma James M Muthoka John Mwangi Pedram Rowhani Validating commonly used drought indicators in Kenya Environmental Research Letters NDVI VCI Earth Observation Food Security Early Warning Systems |
| title | Validating commonly used drought indicators in Kenya |
| title_full | Validating commonly used drought indicators in Kenya |
| title_fullStr | Validating commonly used drought indicators in Kenya |
| title_full_unstemmed | Validating commonly used drought indicators in Kenya |
| title_short | Validating commonly used drought indicators in Kenya |
| title_sort | validating commonly used drought indicators in kenya |
| topic | NDVI VCI Earth Observation Food Security Early Warning Systems |
| url | https://doi.org/10.1088/1748-9326/ac16a2 |
| work_keys_str_mv | AT andrewbowell validatingcommonlyuseddroughtindicatorsinkenya AT edwardesalakpi validatingcommonlyuseddroughtindicatorsinkenya AT kiswendsidaguigma validatingcommonlyuseddroughtindicatorsinkenya AT jamesmmuthoka validatingcommonlyuseddroughtindicatorsinkenya AT johnmwangi validatingcommonlyuseddroughtindicatorsinkenya AT pedramrowhani validatingcommonlyuseddroughtindicatorsinkenya |