تقويم مدى صلاحية المياه الجوفية للري في قطاع غزة - فلسطين(بالغة الانجليزية).

Abstract

The Gaza Strip is entirely dependent on groundwater resources. This Study aims at evaluating if groundwater in Gaza Strip ( the study area) for irrigation during the period 2002/2003. This paper discusses water quality considerations for irrigation and determines some chemical characteristics of waters used for irrigation in Gaza Strip. The study depends on 240 water samples collected from irrigation wells, and analyzed chemically by the water Department in the ministry of Agriculture where the values of electrical conductivity (EC) and cations (Ca , Mg , Na, and K) were measured. Some parameters were calculated by the researcher to determine the suitability of water for irrigation such as Soluble Sodium Percentage (SSP), and Sodium Adsorption Ratio ( SAR ). The suitability of irrigation water id classified according to the Wilcox diagram and the diagram by the U.S. Department of Agriculture. Excluding the Northern Governorate, the data obtained from the study shows that irrigation water used in Gaza Strip is of bad quality. According to the classification by Wilcox, more than 50 % ( including the samples which fall beyond the limits if the Wilcox classification) of total well water samples in Gaza Strip is considered unsuitable for irrigation, while 29.6 % of it is classified as good – to – permissible. As is shown in this paper, 13.3 % and 4.2 % of well water samples are classified as doubtful- to – unsuitable and permissible- to – doubtful respectively. Form the values of EC and SAR for the water samples obtained from the different governorates and using U.S. salinity diagram, it is clear that the majority of the water samples fall in the C4- S4 and C4 –S3 classes. They form 22.5 % and 14.2 % of the total samples respectively. C4-S4 class is considered unsuitable for irrigation. Also, more that 15 % of the total samples fall beyond the limits of the U.S. salinity diagrams and do not appear on them, and are not generally suitable for irrigation. About 26% of the total samples in Gaza Strip fall in the C3-S1 class. This class belongs to the low sodium and high salinity water group, which can be used for irrigation on almost all soils with good drainage but is not good for sodium – sensitive crops. A few samples were in the C2- S1 ( 1.7%), C2- S2 (0.4%), C3-S2 (8.3%), C3-S3 (1.7%), C4 – S1 (3.3%) , and C4- S2 (6.3%) classes. Due to the rapid expansion of irrigated agriculture, excrescent use of the salinity water in Gaza Strip is becoming more vital. However, water salinity is a major problem due to its negative influence in the area and yields of many crops. Gaza Strip suffers from a reduction of crop yields, especially those crops that are not tolerant to salt like citrus trees and other fruit trees. Keywords: Gaza Strip, water quality, irrigation, cations, electrical conductivity, sodium adsorption ratio.