**4. Conclusions**

The RSS and the prediction error (SE and RMSE) results of spatial and geostatistical 2-dimensional modelling, mapping, and validation of Lithaios River water flows confirmed the validity and accuracy of the generated 2D digital GIS velocity maps of the river's

cross-sections. These outcomes have proven that the Kriging with power model had good performance and that it is regarded as very appropriate for 2-D streamflow modelling and digital mapping, as well as being suitable for other hydraulic parameters (n Manning's coefficient, Chow's composite n coefficient, Froude number, shear, Darcy–Weisbach f coefficient, hydraulic radius, etc.). The outcomes of the study are recommended to provide a hydrological toolkit for environmental water resources administration and irrigation programming. This toolkit could assist water supply principalities to rapidly and precisely calculate streamflow volumes and the river's features with a minimal cost rate and workload, and it could be engaged in water supply and agricultural watering administration, the calculation of environmental flows, flood protection, groundwater recharge, and other objectives.

**Author Contributions:** Conceptualization, A.F.; methodology, A.F., G.S. and G.P.; software, A.F.; validation, A.F., G.S. and G.P.; formal analysis, A.F., G.S. and G.P.; investigation, A.F., G.S. and G.P.; resources, A.F. and G.P.; data curation, A.F., G.S. and G.P.; writing—original draft preparation, A.F.; writing—review and editing, A.F.; visualization, A.F.; supervision, A.F.; project administration, A.F.; funding acquisition, A.F., G.S. and G.P. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** All the data of the study are presented in the paper.

**Conflicts of Interest:** The authors declare no conflict of interest.
