*Soil Erosion Risk Analysis of a Small Watershed DOI: http://dx.doi.org/10.5772/intechopen.111424*

frequency values remained positively skewed throughout the analysis (**Figure 12**). A slight increase in TSM can be seen for January 7th, implying that TSM concentrations had increased, likely due to sediment runoff from Ramla valley system (**Figure 13**).

Climatological analysis for the Ramla coastal waters shows that rainstorm events are highly likely to increase the water levels of CHLA and TSM levels since these two parameters were observed to peak during the wetter months. The near real-time high-resolution imagery confirmed this observation (**Table 4**) in a way that CHLA and TSM levels have increased after the rainfall event and decreased after a few days. This also links to the impact of rainfall on the sedimentation process within the Ramla watershed. According to **Table 4**, during the January rainstorm event, the sedimentation and associated nutrients ending up in adjacent coastal waters found next to the mouth of the watershed resulted in a 120% and 133% increase in CHLA and TSM levels, respectively, against background levels.


#### **Table 3.**

*Rainfall (mm) during the rainstorm of January 2021.*

#### **Figure 7.**

*CHLA concentration (mg.m*�*<sup>3</sup> ) during the period January 2–12, 2021 detected by SENTINEL2-A and B data. The rectangular outline shown in red defines the area of analysis.*

#### **Figure 8.**

*Histograms for CHLA concentrations (mg.m*�*<sup>3</sup> ) during the period January 2–12, 2021 detected by SENTINEL2- A and B data.*

#### **Figure 9.**

*Combined histogram of CHLA concentrations (mg.m*�*<sup>3</sup> ) for January 02–12, 2021 detected by SENTINEL2-A and B data.*

#### **Figure 10.**

*SENTINEL2-A & B derived CHLA concentration (mg.m*�*<sup>3</sup> ) on January 07, 2021 (a); CHLA January climatology derived from MERIS data [14] (b); merged CHLA levels for the period January 02–12, 2021 (c). The rectangular outline shown in red defines the area of analysis.*

**Figure 11.**

*SENTINEL2-A & B derived TSM concentration (g.m*�*<sup>3</sup> ) on 07/01/2021 (a); TSM January climatology (b); and merged TSM levels for the period January 02–12, 2021 (c).*

*Soil Erosion Risk Analysis of a Small Watershed DOI: http://dx.doi.org/10.5772/intechopen.111424*

**Figure 12.** *Histograms showing TSM (g.m*�*<sup>3</sup> ).*

**Figure 13.** *Combined histogram of TSM (g.m*�*<sup>3</sup> ).*


#### **Table 4.**

*Comparative extent between the rainstorm events and the respective climatological levels for the Ramla coastal waters next to the valley mouth.*
