Investigating the changes in agricultural land use and actual evapotranspiration of the Urmia Lake basin based on FAO’s WaPOR database

Rahman Barideh and Fereshteh Nasimi

Agricultural Water Management, 2022, vol. 264, issue C

Abstract: The Urmia Lake Basin (ULB) is a critical region in terms of water and environment in Iran. The purpose of this study was to investigate the relationship between agricultural land-use changes and the decrease of the Lake Urmia water level, calculating the actual evapotranspiration and interception (ETIa) in agricultural and non-agricultural lands, investigating the trend of temperature changes and its relationship with ETIa, determining the water balance, and estimating net and gross biomass water productivity in the ULB. So, Land Cover Classification (LCC) maps, ETIa and water productivity were prepared from FAO’s WaPOR product (FWP) from 2009 to 2020. Daily precipitation and temperature were collected from 24 meteorological stations in the ULB. To validate FWP land cover classification, 354 control points were collected and the error matrix and Kappa coefficient were used. Then, based on the ETIa and LCC estimated by FWP, the volume of water consumed in irrigated, rainfed, fallow and non-agricultural lands, as well as the water balance of the basin, was calculated. The overall accuracy (OA) and Kappa coefficient for LCC were 86% and 0.81, respectively. The results showed that until 2013, the area of irrigated and rainfed agricultural lands had been increased by 48%, which could be regarded as an influential factor in reducing the water level of Lake Urmia. The average annual precipitation and ETIa of the basin were 15.24 × 109 and 15.91 × 109 m3, respectively. Also, the average annual ETIa of agricultural lands, grasslands and evaporation from the surface of Lake Urmia were 4.88 × 109, 8.18 × 109 and 2.85 × 109 m3, respectively. Therefore, a negative balance of 0.67 × 109 m3 was observed. The results also showed that the average annual temperature had been increased by 1.1 °C from 2009 to 2020. Finally, the rise of the temperature and area of irrigated croplands, the decrease of precipitation and the negative water balance should be considered as warning signals calling for the proper management of water resources.

Keywords: Land Cover Classification; Precipitation; Remote Sensing; WaPOR Database; Water Balance (search for similar items in EconPapers)
Date: 2022
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Persistent link: https://EconPapers.repec.org/RePEc:eee:agiwat:v:264:y:2022:i:c:s0378377422000567

DOI: 10.1016/j.agwat.2022.107509

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