WetSpass to model the components of hydrologic cycle in the big watershed of Khafr affected by land use.

In the present research, the hydrologic cycle in the big watershed of Khafr (1108.05 km2), Fars province, Iran, affected by land use in a 9-year period (2009–2017) was investigated. The flow of water and the trends of temperature (6.1–27.2 °C) and rainfall (300–600 mm) (1967–2018) were investigated using Mann–Kendall and Sen's tests. The hydrologic cycle was investigated using 22 observing wells and was subsequently simulated using the WetSpass (Water and Energy Transfer between Soil, Plants and Atmosphere under quasi Steady State) model in which the input variables including climate, potential evapotranspiration, soil layer, ground water level, topography, slope and land use were integrated in ArcView GIS maps. The land use in the region was illustrated by Landsat, and was processed by ENVI for the production of the final maps for use in the model. The output variables of the model were plant cover, land use, flooding pathways, rain-harvesting, rainfall-runoff, and charging and discharging of groundwater level. The maximum total yearly runoff of 724 mm, cold season of 632 mm and warm season of 250 mm were estimated by the model. The maximum of yearly groundwater charging of 91 mm, discharge (warm season) of 25 mm and yearly rain-harvesting of 145 mm were also estimated by the model. The WetSpass model simulated the hydrologic cycle in the region with a high accuracy. If land use is managed properly in the region, it would be possible to increase the efficiency of water sources. [ABSTRACT FROM AUTHOR]