{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,19]],"date-time":"2026-10-19T03:13:15Z","timestamp":1792379595198,"version":"4.4.0"},"reference-count":14,"publisher":"Geological Institute, Bulgarian Academy of Sciences","issue":"3","funder":[{"DOI":"10.13039\/501100003336","name":"Bulgarian National Science Fund","doi-asserted-by":"publisher","award":["\u201cDFNI-E02\/4 (2015\u2013 2016)"],"award-info":[{"award-number":["\u201cDFNI-E02\/4 (2015\u2013 2016)"]}],"id":[{"id":"10.13039\/501100003336","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2019,12]]},"abstract":"<jats:p>Loess and loess-like sediments cover approximately 13% of the Bulgarian territory, mainly within the Danubian plain. From the Danube River to the Fore-Balkan, the loess soils form a loess complex where its depth varies from 50\u201360 meters in the north to few meters in the south, respectively. Widespread loess sediments possess a specific feature: they typically form deep unsaturated zones. Quantification of the near surface water balance is extremely important for evaluating land-atmosphere interactions, and the impact of land-use change on the subsurface flow and the evapotranspiration rate is an essential term in this quantification. In the frames of a scientific project, an automatic weather station was installed in a typical plain terrain of the loess complex in Northeast Bulgaria, recording meteorological data from September 2015 to February 2017.\nThis study provides a mathematical description of processes (i.e., Penman-Monteith and Hargreaves Methods) used to estimate daily evapotranspiration rates implemented into the numerical model HYDRUS-1D, as well as a respective rate investigation of months with and without intensive rainfalls. Overall results indicate that using the Hargreaves formula for evaluation of the potential evapotranspiration leads to overestimation between 10% and 20%, respectively for a \u201cwet\u201d and \u201cdry\u201d month.<\/jats:p>","DOI":"10.52321\/geolbalc.48.3.3","type":"journal-article","created":{"date-parts":[[2021,3,24]],"date-time":"2021-03-24T19:52:13Z","timestamp":1616615533000},"page":"3-9","source":"Crossref","is-referenced-by-count":4,"title":["Estimation of evapotranspiration rate by using the Penman\u2013Monteith and Hargreaves formulas for the loess in Northeast Bulgaria complex with HYDRUS-1D"],"prefix":"10.52321","volume":"48","author":[{"given":"Peter","family":"Gerginov","sequence":"first","affiliation":[{"name":"Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dimitar","family":"Antonov","sequence":"additional","affiliation":[{"name":"Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"29796","reference":[{"key":"ref0","unstructured":"Alexandris, S., Stricevic, R., Petkovic, S. 2008. Comparative analysis of reference evapotranspiration from the surface of rainfed grass in central Serbia, calculated by six empirical methods against the Penman-Monteith formula. European Water 21\/22, 17\u201328."},{"key":"ref1","unstructured":"Allen, R.G., Pereira, L.S., Raes, D., Smith, M. 1998. Crop evapotranspiration \u2013 guidelines for computing crop water requirements. FAO Irrigation and Drainage Paper 56, Food and Agriculture Organization, Rome, 300 pp. (http:\/\/www.fao.org\/docrep\/x0490e\/x0490e00.htm)."},{"key":"ref2","unstructured":"Antonov, D., Orehova, T., Gerginov, P., Kolev, S. 2018. Seasonal changes of the soil-water potential in loess deposits, Northeastern Bulgaria case. Review of the Bulgarian Geological Society 79 (3), 133\u2013134."},{"key":"ref3","unstructured":"Evlogiev, Y. 2006. The Pleistocene and the Holocene in the Danubian Plain. DSc Thesis, Geological Institute, Bulgarian Academy of Sciences, Sofia, 263 pp. (in Bulgarian; unpublished)."},{"key":"ref4","doi-asserted-by":"publisher","unstructured":"Hargreaves, G.H. 1994. Defining and using reference evapotranspiration. Journal of Irrigation and Drainage Engineering 120 (6), 1132\u20131139.","DOI":"10.1061\/(asce)0733-9437(1994)120:6(1132)"},{"key":"ref5","doi-asserted-by":"publisher","unstructured":"Leterme, B., Mallants, D., Jacques, D. 2012. Sensitivity of groundwater recharge using climatic analogues and HYDRUS-1Dd. Hydrological Earth System Science 16, 2485\u20132497.","DOI":"10.5194\/hess-16-2485-2012"},{"key":"ref6","unstructured":"Minkov, M. 1968. The Loess in North Bulgaria. A Complex Study. Publishing House of the Bulgarian Academy of Sciences, Sofia, 202 pp. (in Bulgarian, with French, Russian and English abstracts)."},{"key":"ref7","doi-asserted-by":"publisher","unstructured":"Mualem, Y. 1976. A new model for predicting the hydraulic conductivity of unsaturated porous media. Water Resources Research 12, 513\u2013522.","DOI":"10.1029\/wr012i003p00513"},{"key":"ref8","doi-asserted-by":"publisher","unstructured":"Schaap, M.G., Leij, F.J. 1998. Using Neural Networks to predict soil water retention and soil hydraulic conductivity. Soil and Tillage Research 47, 37\u201342.","DOI":"10.1016\/s0167-1987(98)00070-1"},{"key":"ref9","doi-asserted-by":"publisher","unstructured":"Schaap, M.G., Leij, F.J., van Genuchten, M.T. 2001. ROSETTA: a computer program for estimating soil hydraulic parameters with hierarchical pedotransfer functions. Journal of Hydrology 251, 163\u2013176.","DOI":"10.1016\/s0022-1694(01)00466-8"},{"key":"ref10","unstructured":"\u0160im\u016fnek, J. 2015. Estimating groundwater recharge using HYDRUS-1D. Engineering Geology and Hydrogeology 29, 25\u201336."},{"key":"ref11","unstructured":"\u0160im\u016fnek, J., \u0160ejna, M., Saito, H., Sakai, M., van Genuchten, M.T. 2008. The Hydrus-1D Software Package for Simulating the Movement of Water, Heat, and Multiple Solutes in Variably Saturated Media. Version 4.0. HYDRUS Software Series 3, Riverside California, Department of Environmental Sciences, University of California Riverside, 315 pp."},{"key":"ref12","unstructured":"Stoyanov, N.T. 2009. Prognostication of mass-transport of radionuclides in the loess complex in the region of NPS \u201cKozloduy\u201d. Annual of the University of Mining and Geology 52 (1), 159\u2013164 (in Bulgarian, with English abstract)."},{"key":"ref13","doi-asserted-by":"publisher","unstructured":"van Genuchten, M.T. 1980. A closed-form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Science Society of America Journal 44, 892\u2013898.","DOI":"10.2136\/sssaj1980.03615995004400050002x"}],"container-title":["Geologica Balcanica"],"original-title":[],"language":"en","deposited":{"date-parts":[[2021,3,24]],"date-time":"2021-03-24T19:52:35Z","timestamp":1616615555000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.geologica-balcanica.eu\/journal\/48\/3\/pp.-3-9"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,12]]},"references-count":14,"journal-issue":{"issue":"3","published-print":{"date-parts":[[2019,12]]}},"URL":"https:\/\/doi.org\/10.52321\/geolbalc.48.3.3","relation":{},"ISSN":["2535-1060","0324-0894"],"issn-type":[{"value":"2535-1060","type":"electronic"},{"value":"0324-0894","type":"print"}],"subject":[],"published":{"date-parts":[[2019,12]]}}}