Citation: Emlaei, Z.; Pourebrahim, S.; Heidari, H.; Lee, K.E. The Impact of Climate Change as Well as Land-Use and Land-Cover Changes on Water Yield Services in Haraz Basin. Sustainability 2022, 14, 7578. https:// doi.org/10.3390/su14137578 Academic Editor: Agnieszka Bieda Received: 6 April 2022 Accepted: 29 May 2022 Published: 21 June 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). sustainability Article The Impact of Climate Change as Well as Land-Use and Land-Cover Changes on Water Yield Services in Haraz Basin Zahra Emlaei 1 , Sharareh Pourebrahim 1, * , Hamidreza Heidari 2 and Khai Ern Lee 3, * 1 Department of Environmental Science, Faculty of Natural Resources, University of Tehran, Tehran 14179-35840, Iran; zahraemlaei@ut.ac.ir 2 Department of Environmental Science, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan 49189-43464, Iran; 23hamid.r.h@gmail.com 3 Institute for Environment and Development (LESTARI), Universiti Kebangsaan Malaysia, Bangi 43600, Selangor, Malaysia * Correspondence: sh_pourebrahim@ut.ac.ir (S.P.); khaiernlee@ukm.edu.my (K.E.L.) Abstract: Water-yield assessment is crucial to effectively achieve water supply management at the basin scale. It is affected by climate change, and Land Use/Land Cover Change (LULCC). This paper quantifies the combined impact of LULCC and climate change on water yield over short and long-term periods in the Haraz basin, Iran. This basin has experienced severe forest degradation, agricultural expansion, and urbanization. Most agricultural lands are within the plains and coastal areas, and 25% of the basin is covered by forest, which includes part of the Hyrcanian conservation forests. Four scenarios to distinguish the relative portion of Land Use/Land Cover (LULC) and climate for water supply variations are considered, including real conditions at the beginning of the period (Sn1), real conditions without changes in LULC (Sn2), real conditions without climate change (Sn3), and real conditions at the end of the period (Sn4). Four study periods include 1992–2007, 2007–2016, 2016–2026 as a short term, and 1992–2026 as a long-term period. The spatial patterns of annual precipitation showed decreasing amounts in the three studied years from the northwest to the south. Water yield also reduced during the study period 1992–2007 and 2007–2016, and climate change plays an essential role in this reduction. Forecasts show that rainfall will recover in 2026 and water yield will increase in the northern sub-basins. In the long run, from 1992 to 2026, the contribution of LULCC and climate change factors to water yield are equal. The results can provide references for land use management to enhance water yield considering global climate change. Keywords: climate change; land use/land cover change (LULCC); InVEST model; haraz basin; water yield 1. Introduction Regional water resource availability can be well described by water yield, which is one of the most important ecosystem services offered by basins and has a key role in the ecohydrological cycle [1,2]. Water yield not only determines the quantity of available water that ecosystems can provide humans but also refers to the conservation of water [3,4]. Water-yield service is known for its essential role in the ecohydrological cycle [5,6]. It is explained as the difference between actual evapotranspiration (ET) and precipitation (P), which is a function of many indicators such as LULC, and climate [7,8]. Based on the Intergovernmental Panel on Climate Change (IPCC) and other studies, hydrological changes that occur due to climate change and LULCC are expected to be different in time and location. LULCC alters basin hydrological functions by influencing soil infiltration, evapotranspiration, and surface runoff [9–13]. In contrast, climate change is inclined to affect that by changing the temperature, precipitation, distribution abundance, runoff, and production [14,15]. Perceiving the effects of LULCC and climate change on water resources has been essential for managing water resources [14–18]. Therefore, it is Sustainability 2022, 14, 7578. https://doi.org/10.3390/su14137578 https://www.mdpi.com/journal/sustainability