Artificial Recharge in Coastal Plain Aquifer in Israel--Further Findings: ABSTRACT

Abstract

Artificial groundwater recharge operations till the end of 1966 have been described in the Bulletin of the International Association of Scientific Hydrology, Annex No. 1, March 1967. The present paper reviews artificial recharge practices followed in Israel since 1967. The coastal plain aquifer is at present recharged through 99 wells and through 8 spreading grounds with a total area of 180 acres. The average yearly rate of recharge to this aquifer amounts to about 80 MCM/acre (64,000 acre-ft). Recharge is practiced mostly during winter months, November through March, and sometimes also during April and October. The main source is mixed Lake Kinneret water, this supplying 68% of the recharged water; about 17% is storm runoff and 15% groundwater withdrawn from a limestone aquifer. Recharge rates into wells range between 50 and 400 cu m/hour (220-880 gpm) and infiltration rates in the spreading grounds range between 0.2 and 3.0 m/day (0.7-10.5 ft/day), though initial infiltration rates in spreading grounds are usually lower for storm runoff water than for water from Lake Kinneret. Recharge and infiltration rates decrease during recharge seasons; this decrease varies with the type of recharge installation and the type of water used. The decrease in well recharge rates is observed mostly when single-purpose wells (unequipped wells drilled for recharge only) are recharged with Lake Kinneret water. Redevelopment of these wells over a short period does not suffice to restore the original recharge rates. The same Lake Kinneret water, when recharged into dual-purpose wells (wells that are normally pumped throughout the summer), causes only a small decrease in the recharge rate during the recharge period. Recharging the aquifer through both dual and single-purpose wells with groundwater from the limestone aquifer causes almost no decrease in recharge rates. To assist in restoring infiltration recharge rates, the basins are dried out after each season, the upper layer of soil and silt removed, and the basin cultivated. This results generally in restoration of the infiltration rates to their original values. In the dual-purpose wells, the first batch of water pumped after recharge had ceased for a short period was contaminated. This contamination (odor, turbidity, high counts of coliform bacteria) is due probably to the high content of organic matter in the recharged water. To overcome this pollution, short and intensive pumping for a few hours was carried out and the water discarded. Later, chlorination was applied for a few days. End_of_Article - Last_Page 1605------------