
Figure 1.
Edku Lake

Figure 2.
Field measurement locations in Lake Edku zones A, B, C, and D

Figure 3.
Observed DO data during four seasons in Lake Edku zones
TABLE I.
USED LANDSAT 8 (OLI) SCENES AND DATES OF ACQUISITION
| Scene ID (path177/row38) | Date Acquired |
|---|---|
| “LC81770382016071LGN01” | 11-Mar-2016 |
| “LC81770382016151LGN01” | 30-May-2016 |
| “LC81770382016231LGN01” | 18-Aug-2016 |
| “LC81770382016343LGN01” | 8-Dec-2016 |
TABLE II.
LANDSAT 8 (OLI) SPECTRAL BANDS CONSIDERED IN THIS STUDY
| Landsat 8 (OLI) bands | Spectral range (μm) |
|---|---|
| Band 2 (Visible) | 0.450 - 0.51 |
| Band 3 (Visible) | 0.53 - 0.59 |
| Band 4 (Visible) | 0.64 - 0.67 |
| Band 5 (Near-Infrared) | 0.85 - 0.88 |
| Thermal Infrared Sensor (TIRS) | |
| Thermal Infrared (Band 10) | 10.6 - 11.19 |
| Thermal Infrared (Band 11) | 11.5 - 12.51 |

Figure 4.
Spatial distribution of derived Temperature (ºC) within Lake Edku in spring, 2016

Figure 5.
Spatial distribution of derived Turbidity (NTU) within Lake Edku in spring, 2016

Figure 6.
Spatial distribution of derived TSS (mg/L) within Lake Edku in spring, 2016

Figure 7.
Spatial distribution of derived Chlorophyll-a (mg/m3) within Lake Edku in spring, 2016
TABLE III.
SENSITIVITY ANALYSIS FOR OPTIMAL DO RETRIEVAL ALGORITHM MODEL
| Seasons | Input Parameters | Regression Coefficient (R2) |
|---|---|---|
| Spring & Fall & Winter | Turb, TSS, Chl, Ln-temp | 0.618 |
| Summer & Fall & Winter | Turb, TSS, Chl, Ln-temp | 0.630 |
| Spring & Summer & Fall | Turb, TSS, Chl, Ln-temp | 0.657 |
| Summer & Fall | Turb, TSS, Chl, Ln-temp | 0.781 |
| Spring & Fall | Turb, TSS, Chl, Ln-temp | 0.751 |
| Spring & Winter | Turb, TSS, Chl, Ln-temp | 0.651 |
| Spring & Summer & Fall | Turb, TSS, Ln-temp | 0.613 |
| Summer & Fall & Winter | Turb, TSS, Ln-temp | 0.601 |
| Spring & Fall & Winter | Turb, TSS, Ln-temp | 0.584 |
| Spring & Fall | Turb, TSS, Chl | 0.644 |
| Spring & Fall | TSS, Chl, Ln-temp | 0.676 |
| Spring & Winter | TSS, Chl, Ln-temp | 0.554 |
| Summer & Fall | Turb, TSS, Ln-temp | 0.766 |
| Summer & Fall | Turb, Chl, Ln-temp | 0.798 |
| Summer & Fall | TSS, Ln-temp | 0.756 |
| Summer & Fall | Turb, Ln-temp | 0.792 |

Figure 8.
Predictive capacity of developed algorithm model for DO Satellite-based retrieval

Figure 9.
Validation of the developed model for DO retrieval
TABLE IV.
DESCRIPTIVE STATISTICS FOR OBSERVED VERSUS DERIVED YEARLY DO LEVELS WITHIN LAKE EDKU
| Descriptive Statistics | Do (mg/L) | |
|---|---|---|
| Observed | Modeled | |
| Mean | 10.440 | 9.064 |
| Minimum | 1.560 | 4.552 |
| Maximum | 18.107 | 20.271 |
| Standard Deviation | 4.042 | 3.841 |

Figure 10.
Observed versus derived DO concentrations during four seasons in Lake Edku

Figure 11.
Retrieved DO concentrations in Lake Edku during winter season