Prioritization of a Micro-basin of the Daule River Sub-basin with Strong Erosional Problems and Their Effect to the Turbidity of the Water in the City of Guayaquil, Coastal Ecuador

The drinking water intake of the city of Guayaquil is located on the Daule River, supplying 2.7 million inhabitants who are affected by the turbidity of the water, even leading INERGAGUA to suspend the service with high economic losses. Given this, water erosion and the effects of land use were calculated using the Universal Soil Loss Equation (USLE), estimating the Erosivity factor (R) through the Fournier climatic aggressiveness index. Mean monthly and annual rainfall data from 14 stations in the basin were used. The other variables such as soil erodibility factor (K), slope length and gradient (LS), coverage factor (C), use factor and soil management (P), were quantified with a mathematical analysis of the variables. Initially, the sub-basin was considered as a global model and then as a distributed model, subdividing it into 88 micro-basins, allowing a more accurate estimate of an average annual water erosion of 130.04 t/ha/year. To determine the type and level of erosion, the FAO scale was used, observing 14 micro-basins with erosion rates ranging from 154.3487 t/ha/year to 846.3418 t/ha/year, whose range of erosion goes from very severe to catastrophic, which results to the requirement of immediate intervention. Applying the sediment delivery factor (SDF), it was estimated that 5.12% of the total eroded, that is, 8,089 tons/ha/year reaches the river.