SRCLET (Soil wateR CircuLation and EvapoTranspiration model) ia a software tool for the calculation of evapotranspiration (ET), analysis of soil water balance (SWB), frequency (Us) and irrigation hydromodule (q24).

Within the MEET project it was planned to make SRCLET operational and available as open-source free software, on this site by the end of 2021.

SRCLET will be programmed to run in a Windows environment (Windows 7 and later) on a wizard basis. The graphical interface of the software has a simple form and offers the user the possibility to choose the work in Bosnian and English language.
SRCLET as the input uses tabbed, comma-separated, or space-separated values in text file (.txt). The results of the calculation are also displayed in text files that SRCLET places in the project folder where the user determines the path and method of saving.
It is a monthly model, so input and output are monthly data.

After selecting the type, the use can select the calculation method, after which the validity and sufficiency of the entered data is checked against the selected method. In case the data is insufficient or inadequate SRCLET returns the user to data entry.

In the case of evapotranspiration (ET) calculation, it is possible to select one of the following methods:
i. FAO-PM
ii. Thornthwaite (1948)
iii. Turc (1961)
iv. Hargreaves et al. (1985)
v. Trajkovic (2007)
Within the FAO-PM method, it is possible to perform a calculation in case of insufficient climate data following the procedure provided by Allen et al. (1998).

From the soil water balance (VBT) method, the software allows you to select one of the following:
i. Thornthwaite (1948)
ii. Palmer (1965)
iii. Alley (1984)
iv. Dingman (2002)
v. McCabe i Markstrom (2007)

Frequency analysis (Us) can be performed on the data obtained during SWB calculation, such as: D (deficit), S (surplus), DRO (direct runoff), RO (subsurface runoff), AET (actual evapotranspiration), ETc (crop evapotranspiration), SNOW, etc. Also, it is possible to enter the values of a certain climatic or hydrological parameter directly into SRCLET, without an earlier calculation in SRCLET, and to perform a frequency calculation on this data.
Finally, the obtained monthly values can be exported as a .txt file or further used within the same project.

SRCLET enables the analysis of several years at the same time, the adjustment of the available soil water capacity (AWC), as well as different coefficients within the ET and SWB methods.
Due to the limited input data on a monthly basis, this is a regional model, and can only be used at the regional level or for a wider area.

In the future, an upgrade of the SRCLET software tool is planned, which includes the addition of other ET and SWB calculation methods, as well as the possibility of drought index calculation (SPI, SPEI, PDSI, etc.), precipitation analysis and climatic conditions.

ET – Evapotranspiration; SWB – Soil water balance; Us – Frequency; q24 – Irrigation hydromodule; FAO-PM – Penman-Monteith (Allen et al., 1998); THOR – Thornthwaite (1948); HS – Hargreaves-Samani (1985); TRAJ – Trajkovic (2007); z – elevation; 0N – Northern latitude; uz – height of wind speed measurement (m); „as+bs“ – Ångström koeficijenti; kRs – Empirical coefficient for correction of solar radiation; „Tmean + 17,8“ – Trajković’s empirical coefficient; AWC – Awailabel water capacity; Ss, Su – water capacities, Aa – Direct runoff coefficient; Aλ – Coefficient of surplus (Qi).