An-Najah Staff

Zimar stream has become since the 1950's a sewage drain. Xe stream extends over 27 km from the west of Nablus
City to Tulkarem City northwest of West Bank. Xere are lost opportunities for streams’ water bene]cial use, and
nature conservation principals have been severely violated for the Zimar watershed, in addition to public health
and biodiversity threats. Xis paper was prepared to predict the water quality of the Zimar’s stream under current
and proposed future conditions, and under di:erent scenarios. Dissolved Oxygen was taken as the main quality
parameter, and depending on steady state solutions of Streeter-Phelp’s equation. QUAL2Kw model was used to
predict the behavior of the stream. Water samples were collected, and ]eld measurements were conducted for eight
di:erent critical locations along the stream, and during the wet and dry seasons of 2011–2012. Several scenarios
were simulated, taking in consideration the inbuences of the under-construction wastewater treatment plant in
the western area of Nablus city, proposing additional wastewater treatment plant at Anabta village, and proposing
constructing of three arti]cial weirs. It was found that the stream has signi]cant self-puri]cation capacity as the
dissolved oxygen concentration doubled from Nablus city to Anabta village; midway to Tulkarem. Xe Biological
oxygen demand between those two points decreased to values up to 11% from the original value. Xis paper supports
proposed solutions of the stream to improve its water quality, and enhance aesthetic views in the catchment.