EVALUATING WATER EROSION RISKS IN SOME WADIS OF NORTHWESTERN COAST ZONE – EGYPT

Field experiments were conducted in 2015 – 2016 winter season, at wadi El- Raml area. Wadi El – Raml is located southwest, Mersa Matruh city, Egypt. Slope of the experimental site is about 5 percent in south – north direction. The treatments were as follows: Bare soil, traditional cultivation without soil conditioners, cultivation with Ceramic conditioner at rate of 20, 40, and 80 t.fed-1, cultivation with bokashi conditioner at rate of 20, 40, and 80 t.fed-1 and coal ash conditioner at rate of 20, 40, and 80 t.fed-1. The total number of treatments was 11. Each treatment was replicated 3 times. The soil conditioners was added on the soil surface after carrying out tillage operation and then mixed with the soil surface layer. Thirty-three bounded plots having edges of soil with approximately 20 cm height were used to determine soil loss associated with runoff. Each plot was 21 m length and 2 m width. At the down slope end, Gerlash trough were placed, 0.5 m long and 0.2 m wide, closed at the sides and covered with movable lid. An outlet pipe extended from the base of the gutter to the collection containers present below the soil surface. Rainfall amounts, duration, and intensity were measured for every rainstorm with an automatic rain gauge at the site of experiment. The amount of soil loss and runoff water for every rainstorm was determined by maintaining the containers undisturbed for a sufficient time, so that, the solid constituents in the runoff water could precipitate. The precipitated solids were collected and measured gravimetrically after drying at 105°C overnight.
Soils of wadi El Raml are mainly sandy loam in texture with deep soil profile. The climatic conditions of the area is defined as arid Mediterranean type, it is characterized by short rainy seasons during October to March. About 75 percent of the total annual rainfall as recorded from November to February. The remaining period of the year is characterized by long dry season (6-7months), except for few rainy storms in April, May and September. The average annual rainfall is 175.4mm. the  effective storms were sex storms the runoff coefficient of 3% seams reassemble. However, the lowest runoff yield was obtained when adding Bokashi conditioner with rate of 80 t.fed-1 under all storms,). It is clear that runoff values associated with bare soil were higher than those for the soil treated by non-traditional soil conditioners. From another point, Ceramic conditioner added on the soil surface with the rate of 20, 40 and 80t.fed-1 led to reduce runoff by 37, 49 and 56.5%, respectively, as compared with cultivated soil . With respect to adding bokashi as soil conditioner on the soil surface with the rate 20, 40 and 80 t.fed-1, runoff values under all storms was reduced to 45.2, 59.6 and 67.7%, respectively, The influence of the applied traditional cultivation and applied some soil conditioners on the amount of soil loss under natural rainfall. The highest rates of soil losses resulted from bare soil treatment 1.23 ton/fed. Year this rate lies within the permissible limits of soil loss by erosion, which range from 1 to 5 tams per acre per yeas, With respect to planting without soil conditioners, it is clear that such practice reduced the amount of soil loss by 24.2% relative to that for bare soil treatment, This behavior could be attributed to the fact that plants protect a portion of the soil surface from the energy of rainfall impact, thereby, soil detachment decreased. Growing plants also create obstructions to eater flow over land, slowing down runoff velocity and consequently its carrying capacity and thus, reducing soil loss.