The Eresma River starts in Valsaín valley of the
Sierra de Guadarrama, where the confluence of several streams forms the river. Most of these streams descend from the slopes of mountains like Peñalara,
Siete Picos, and
Montón de Trigo. Its most important tributaries are Moros and the Voltoya that flow northward. After passing through
San Ildefonso and
Palazuelos, it reaches the city of
Segovia, which it surrounds in a closed
meander. Eresma river then runs northwest, passing near
Hontanares,
Los Huertos,
Bernardos,
Navas de Oro, Coca, and
Villeguillo. It enters the province of Valladolid through
Olmedo, Pedrajas,
Alcazarén, and Hornillos. Later it flows from the right into the
Adaja in
Matapozuelos. The Eresma River has a
pluvio-nival regime, which means that it has a period of high water flow in the autumn and winter season in proportion to precipitation and a short, violent water flow in the spring when the snow melts. == References ==