## 4 Results
Figure 10: Example of graphical output for Mixture 01 (contribution in mixtures and level of correlation between sources). The lines of different colors (light blue, orange, red and dark blue) represent the contour lines that group different levels of the data (10%, 20%, 30%, etc.). The results of the runs for all the mixing points are summarized in Table 6, where the contributions of the three (3) land uses identified in the mixtures and the levels of relevant correlations identified between the sources are shown in percentages. The contributions of the source **Sediment** (identified in Table 4) are predominant in most (82%) of the evaluated mixing points, changing this behavior only for samples M06 and M08. Correlations are significant (with negative sign) for **Sediment/Pasture** sources with index values greater than \(-0.80\), followed by **Pasture/Forest** with index values greater than \(-0.50\). When mixing points 5, 6, 9 and 10, the relationship for **Sediment/Forest** sources correlates significantly (with positive sign) with index values greater than \(0.50\). A spatial representation of the source contributions for each mixing point is presented in a map that graphically incorporates the contributions estimated by the MIXSIAR model (Figure 11). \({}^{*}\)SD, standard deviation. \end{table}
Table 6: Estimates of source contribution levels and correlations. According to the results obtained, the land use identified as **Sediment**, has a prominent contribution in most of the mixing points, following a similar pattern of proportions in the points located near the Chagres River (M02, M03 and M14) and the points downstream near the Indio Este River (M01 and M11). From a spatial point of view, the contributions of **Forest** land use are important in the mixing points located north of the study area in the Boqueron River (M05 and M10), in the upper and lower part of the Pequeni River (M06 and M08) and in the upper part of the In-dio Este River (M09 and M12). The contributions associated with **Pasture** land use are relevant in the points located in the proximity of this land use, represented in the upper and lower part of the Boqueron River (M05 and M10). The **Pasture** contributions also appear in the middle part of the Pe-queni River (M06), its mouth (M08) and in the upper part of the Indio Este River (M09 and M12). It is interesting to note the change in the pattern of sediment contributions in the Indio Este River, with a balanced presence of the three land uses evaluated (**Forest**, **Pasture** and **Sediment**) in its upper part and the preponderance of the **Sediment** class in the lower part and at the mouth of the river. This change is similar to that which occurs in the Pequeni River, with significant contributions of **Pasture** and **Forest** in its upper part and a majority presence of **Sediment** in its lower part and at the mouth of the Boqueron River. In the final part of the Pequeni River, after joining the Monocongo River, when it flows into the lake, the nature of the contributions changes to a majority presence of **Pasture** and **Forest**. The behavior of sediment contributions is different in the mixing points located near the Chagres River, where the use of **Sediment** soils always predominates in the upper and middle reaches and at the mouth of the river. From the studies carried out, it can be determined that the contributions to the sediment loads in Alhajuela Lake are measured at the mixing points located in its surroundings are of **Sediment** in the middle and southern part of the lake, while in its northern portion there is a more balanced presence of the three land uses studied. In the northern part of Alhajuela Lake, discharges from the mouth of the Pequeni River are mainly associated with the sources **Forest** and **Pasture**, while in the discharges from the  
Figure 11: Estimates of sediment contributions from evaluated sources (In sources the dots have the corresponding color of the legend, in mixtures the dots are black).