Summary:
The Basin of Spercheios River belongs to East Sterea Ellada and is a ditch-like
narrow strip with longitudinal axis that, in general, coincides with the river
bed. Spercheios Rived is 82.5 km long and the total surface of the water
catchment basin is 1,660.91 km2.
From administrative point of view the Spercheios basin belong to the Prefecture
of Fthiotida. It begins in the Tymfristos (2,312 m), Vardousia, Othrys, Oite
and Kallidromos Mountains and falls in the Maliakos Gulf, where its delta is
formed. In the water catchment basin there are steep slopes and on the whole
the average slope is 33%.
The future reduction of the sediment yield of the Spercheios River in
combination with the simultaneous reduction of the surface runoff is estimated
that it will result to the retreat of the delta’s coastline of the river and to
the lack of parts of the delta’s plain.
The surface runoff was calculated through the several parameters of the water
balance as well as through the use of software that is freely available by U.S.
Geological Survey (USGS) and which is extensively described by McCabe and
Markstrom (2007). Thus, the surface runoff for evapotranspiration coefficient
35% is equal to 468.756 106 m3 (1st approach) while the one corresponding to
soil moisture 100 mm (2nd approach) is equal to 519.098 106 m3.
The assessment of sediment yield (per unit area) was calculated on the basis of
the equations of Jansen & Painter (1978), Renfro (1972) and Probst (1992.) The
risen load is estimated about 171-248 tones/km2 while the total load varies
between 214-312 tones/km2.
The estimation of future levels of surface runoff and sediment yield per unit
area of Spercheios River was based on simulations of monthly rainfall and
temperature levels according to the regional climate model RAMCO-2 (KNMI) from
the European Project ENSEMBLES and are related to near future 2021-2050 and
distant future 2071-2100 in relation to the reference period 1961-1990. The
results show reduction of surface runoff by 6.19% for the period 2021-2050 and
by 33.35% for the period 2071-2100. Accordingly the sediment yield per unit
area is expected to be reduced by 11.03% for the period 2021-2050 and by
2071-2100% for the period 2071-2100.
Keywords:
Surface runoff, Sediment yield, Sperchios, Climate model
