University of Tehran Press Iranian Journal of Soil and Water Research 2008-479X 55 12 2025 02 19 Investigating Spatial Variability of the hydraulic characteristics of Sistan plain soils Investigating Spatial Variability of the hydraulic characteristics of Sistan plain soils 2409 2420 101056 10.22059/ijswr.2024.379744.669772 FA Rasoul Mirkhani Members of Scientific Board, Soil and Water Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran. 0000-0003-0119-9771 Leila Esmaeelnejad Members of Scientific Board, Soil and Water Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran. 0000-0001-8133-7833 Saeed Saadat Members of Scientific Board, Soil and Water Research Institute, Agricultural Research, Education and Extension Organization (AREEO)Karaj, Iran. 0000-0002-0398-619x Hamed Rezaei Members of Scientific Board, Soil and Water Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran. 0000-0002-1323-1524 Naser Davatgar Members of Scientific Board, Soil and Water Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran. 0000-0002-1872-9815 Mojtaba Hadizadeh Researcher, Zabol Agricultural and Natural Resources Research Center, Zabol, Iran. 0009-0003-1415-4318 Journal Article 2024 07 31  Saturated hydraulic conductivity (Ks) is one of the most important soil physical properties that plays a major role in its hydrological behaviour. In this study, the hydraulic characteristics of 312 soil samples, taken from the top layer (0-30 cm), were measured. Additionally, soil texture and bulk density were analyzed in 2080 top-soil (0-30 cm) samples. The results showed that the soil texture in the region varied from sandy to clayey, with most soils classified as medium-textured. The average bulk density in the region was found to be 1.43 g.cm-3. The mean field capacity moisture content across the counties of Sistan Plain was less than 35%, placing them in the low field capacity class. The highest and lowest plant-available moisture content was observed in Hirmand and Zabul, respectively. The coefficient of variation for plant-available moisture in all surface agricultural soils of Sistan Plain was 33.83%, indicating a very high variability. Regarding the mean values of saturated hydraulic conductivity, the lowest and highest values of surface soil saturated hydraulic conductivity (Ks) were observed in Zabul (0.15 m per day) and Hirmand (0.42 m per day), respectively.  Saturated hydraulic conductivity (Ks) is one of the most important soil physical properties that plays a major role in its hydrological behaviour. In this study, the hydraulic characteristics of 312 soil samples, taken from the top layer (0-30 cm), were measured. Additionally, soil texture and bulk density were analyzed in 2080 top-soil (0-30 cm) samples. The results showed that the soil texture in the region varied from sandy to clayey, with most soils classified as medium-textured. The average bulk density in the region was found to be 1.43 g.cm-3. The mean field capacity moisture content across the counties of Sistan Plain was less than 35%, placing them in the low field capacity class. The highest and lowest plant-available moisture content was observed in Hirmand and Zabul, respectively. The coefficient of variation for plant-available moisture in all surface agricultural soils of Sistan Plain was 33.83%, indicating a very high variability. Regarding the mean values of saturated hydraulic conductivity, the lowest and highest values of surface soil saturated hydraulic conductivity (Ks) were observed in Zabul (0.15 m per day) and Hirmand (0.42 m per day), respectively. https://ijswr.ut.ac.ir/article_101056_4dde0a3cc56d30dfaee04b74c9307860.pdf