{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,25]],"date-time":"2026-06-25T19:58:44Z","timestamp":1782417524705,"version":"3.54.5"},"reference-count":10,"publisher":"STEF92 Technology","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2022,11,15]]},"abstract":"<jats:p>The development of indicator systems for drought identification is part of the Drought Management Plans. The analysis of the correlation between the different indices is an essential part of the indicator systems. That research is part of a task related to the developed at NIMH system (http:\/\/hydro.bg) of drought indicators and the development of recommendations for their simultaneous use. For this purpose, the influence of climatic factors on the hydrological cycle components and the role of the characteristics of river basins has been studied. It is observed that a phase lag of the hydrological drought from the occurrence of meteorological drought is characteristic, because for the lack of precipitation is necessary more time to show itself in the hydrological system components. The lag depends on the river basin specifics - the size of the catchment, regulating volumes, aquifers, etc. As a first step, a transition from a regional assessment of meteorological drought to an assessment at basin level was made. As the Standardized Precipitation Index (SPI) is calculated within the different catchments for a different number of points, the Zonal Statistics tool of QGIS was used and the SPI average values for each catchment for all months in the period 2014-2020 were derived. Based on this, the correlation between the Standardized Runoff Index (SRI) and SPI indices at different time steps (SRI3, SPI3; SRI6, SPI6, etc.) for the period 2014-2020 was estimated. The regularities of the drought process are studied, identifying both the correlation and the transition from meteorological to hydrological drought, as well as the expected phase shift of the hydrological drought over time. The results confirm the drought process relations and clearly identify: 1) the transition from meteorological to hydrological drought and 2) the expected phase lag of the hydrological drought over time. In general, short time steps, such as monthly and quarterly, are suitable for small catchments and unregulated watersheds, while longer time steps are more suitable for larger river basins with a complex hydrological cycle or regulated watersheds. The analysis of the correlation between the indices, taking into account the influence and the relationship between the various factors of the hydrological cycle, is a long process and the time scale should be chosen depending on the characteristics of the basin and the purpose for which the indicator is used.<\/jats:p>","DOI":"10.5593\/sgem2022\/3.1\/s12.05","type":"proceedings-article","created":{"date-parts":[[2023,2,13]],"date-time":"2023-02-13T20:34:51Z","timestamp":1676320491000},"page":"41-48","source":"Crossref","is-referenced-by-count":3,"title":["ANALYSIS OF HYDROLOGICAL DROUGHT INDICES AND THEIR RELATIONSHIP WITH METEOROLOGICAL FACTORS AND RIVER BASIN SPECIFICS"],"prefix":"10.5593","volume":"22","author":[{"given":"Anna","family":"Yordanova","sequence":"first","affiliation":[{"name":"National Institute of Meteorology and Hydrology, Bulgarian Academy of Sciences","place":["Bulgaria"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Irena","family":"Ilcheva","sequence":"additional","affiliation":[{"name":"National Institute of Meteorology and Hydrology, Bulgarian Academy of Sciences","place":["Bulgaria"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lilia","family":"Bocheva","sequence":"additional","affiliation":[{"name":"National Institute of Meteorology and Hydrology, Bulgarian Academy of Sciences","place":["Bulgaria"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Krastina","family":"Malcheva","sequence":"additional","affiliation":[{"name":"National Institute of Meteorology and Hydrology, Bulgarian Academy of Sciences","place":["Bulgaria"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Krasimira","family":"Lubenova","sequence":"additional","affiliation":[{"name":"National Institute of Meteorology and Hydrology, Bulgarian Academy of Sciences","place":["Bulgaria"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"3602","reference":[{"key":"ref=1","unstructured":"[1] Dimitrov, Y., Management of river water resources in Northwest Bulgaria in drought conditions, Dissertation, Abstract, 2018"},{"key":"ref=2","unstructured":"[2] Drought Management Plan Report Including Agricultural, Drought Indicators and Climate Change Aspects, Water Scarcity and Droughts Expert Network, EC, 2007"},{"key":"ref=3","unstructured":"[3] Georgieva B., Kazandzhiev V., Soil drought \ufffd degrees and conditions for occurrence. Collection Reports from international conference dedicated to the International Year of Soils and the 140th anniversary of the birth of Nikola Pushkarov \"Soil and agrotechnologies in a changing world\", Sofia, Bulgaria, 2015"},{"key":"ref=4","doi-asserted-by":"crossref","unstructured":"[4] Hayes, M., Svoboda, M., Wall, N., Widhalm, M., The Lincoln Declaration on Drought Indices: Universal Meteorological Drought Index Recommended. Bulletin of the American Meteorological Society, 92(4): 485\ufffd488, 2011","DOI":"10.1175\/2010BAMS3103.1"},{"key":"ref=5","unstructured":"[5] Ilcheva, I., Yordanova, A., Rainova, V., Application of Standardized Status Index for prolonged drought identification and river basin management, International scientific refereed online journal with impact factor, SocioBrains, ISSN 2367-5721, ISSUE 54, ISSN 2367-5721, \ufffd\ufffd.114-122, 2019"},{"key":"ref=6","unstructured":"[6] Ninov, Pl., Tz. Karagiozova, E. Bojilova, N. Todorova, K. Krumova, R. Dobreva, A. Boeva, R. Ivanova, M. Rankova, Update of the technological scheme for assessment of surface water resources on the territory of Bulgaria, XXVII Conference of the Danubian countries on Hydrological Forecasting and Hydrological bases of water management, Golden Sands, Bulgaria, 2017"},{"key":"ref=7","unstructured":"[7] Guidelines for the use of SRI, SPI3 and SMI indices synchronously and analysis of the larger drought periods, reflected by the three indexes; Development of recommendations of an applied nature for the interpretation of the indicators for the assessment of meteorological drought (SPI indices) and hydrological drought (SRI indices) published on the NIMH website each month. Task of the Agreement with the MoEW, 2021"},{"key":"ref=8","unstructured":"[8] McKee, T.B., Doesken, N.J., Kleist, J., The Relationship of Drought Frequency and Duration to Time Scales. Proceedings of the 8th Conference on Applied Climatology, 17\ufffd22 January 1993, Anaheim, CA. Boston, MA, American Meteorological Society."},{"key":"ref=9","unstructured":"[9] Prolonged drought towards a common understanding of the phenomenon and of its impacts, Document produced by the expert network on water scarcity and drought, , WS&D Expert Network, Current state of play in august 2007"},{"key":"ref=10","unstructured":"[10] Update on Water Scarcity and Droughts indicator development, Document produced by the Expert Network Water Scarcity&Drought, 2012"}],"event":{"name":"22nd SGEM International Multidisciplinary Scientific GeoConference 2022","theme":"Earth and Planetary Sciences","location":"Albena, BG","acronym":"SGEM2022","number":"22","sponsor":["SGEM WORLD SCIENCE (SWS) Scholarly Society, Austria"],"start":{"date-parts":[[2022,7,4]]},"end":{"date-parts":[[2022,7,10]]}},"container-title":["SGEM International Multidisciplinary Scientific GeoConference\ufffd EXPO Proceedings","22nd SGEM International Multidisciplinary Scientific GeoConference Proceedings 2022, Water Resources. Forest, Marine and Ocean Ecosystems"],"original-title":[],"deposited":{"date-parts":[[2026,6,25]],"date-time":"2026-06-25T19:25:37Z","timestamp":1782415537000},"score":1,"resource":{"primary":{"URL":"https:\/\/epslibrary.at\/items\/33ade470-b02c-4c1e-a33e-434221a5bf27\/analysis-of-hydrological-drought-indices-and-their-relationship-with-meteorological-factor"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,11,15]]},"references-count":10,"URL":"https:\/\/doi.org\/10.5593\/sgem2022\/3.1\/s12.05","relation":{},"ISSN":["1314-2704"],"issn-type":[{"value":"1314-2704","type":"print"}],"subject":[],"published":{"date-parts":[[2022,11,15]]}}}