T. M. Abu-Sharar

Water Resources Management under Competitive Sectoral Demand A Case Study from Jordan

Abstract Jordan is a country plagued with water scarcity. The annual per capita share of water is currently estimated at 170 m3 and the figure is expected to drop to 90 m3 in the year 2020 as a result of the disproportional increase in population relative to water resources development. Moreover, about 70 percent of the countrys water resources are consumed in irrigated agriculture. For most crops growing in all areas and seasons and managed with different production technologies, analysis of net return from unit volume of irrigation water showed, with few exceptions, low values pertaining to production under protected agriculture. Such a result indicated unjustified waste of water in the agricultural sector at the expense of the domestic sector. This paper reviews current challenges facing water management in the country and proposes short- and long-term alternative solutions.

Water chemistry of the Dhuleil aquifer (Jordan) as influenced by long-term pumpage

Abstract The Dhuleil aquifer is located in the northwest of Jordan and represents a major groundwater resource for domestic and agricultural purposes. At present, there are more than 80 wells extracting water from basaltic or limestone formations. Long-term observations have indicated an increase in the groundwater salinity. Chemical analyses of water samples collected from seven wells over a minimum of 12 years have been employed to characterize and determine the cause(s) of increasing water salinity. The results show that the electrical conductivity of each wells water is linearly associated with Cl concentration. Slopes of such relations are almost identical for the basaltic well waters and, thus, reflect the influence of the geological formations on water chemistry. Increasing water salinity was mainly due to increasing Cl salts of Na, Ca, and Mg as indicated by the linear relation between the concentration factor of each cation (a given cation concentration divided by the reported minimum cation concentration) and that of the Cl anion. The SO 4 concentration factors for all well waters did not increase in harmony with these of Cl. The Cl fractional negative charge tended to increase to an average steady-state value of ≈0.8 for all basaltic wells, irrespective of the variation in irrigation practices. These observations suggest that return flow of irrigation leachate was not the cause of the increasing water salinity. Alternatively, deterioration in water quality was hypothesized to be due to excessive pumpage which rendered the exhausted aquifer more susceptible to the limited rainwater infiltrating the natively saline parent materials. This conclusion is further supported by the results of chemical speciation which indicate that all well waters were always undersaturated with respect to gypsum (ion activity products of (Ca 2+ )(SO 2− 4 ) were smaller than K sp of gypsum by more than one order of magnitude). In addition, all well waters were undersaturated with respect to caclite with only a few cases where the waters were in equilibrium with that solid phase. After 25 years of irrigation, soil solution chemistry became similar to that of the DH-16 well water employed in irrigation.

Sorption-desorption characteristics of methyl parathion by clays.

Methyl parathion (O,O-dimethylO-(4-nitrophenyl) phosphorothioate) adsorption was studied on montmorillonite, kaolinite, halloysite, natural zeolite, ion exchange resins and calcium carbonate. Methyl parathion was highly adsorbed by montmorillonite, followed by zeolite, and very little adsorption was obtained on kaolinite and halloysite. Calcium carbonate did not exhibit any adsorption. The values of the partial molar free energy “Δ¯G” were calculated for all systems. For the montmorillonite-methyl parathion system, the calculated partial molar heat of adsorption “Δ¯H”, and the conformity of the data to Freundlich equation indicated a possible physical mechanism of adsorption. Increasing acetone concentration decreases methyl parathion adsorption and dehydration increased adsorption in the nonaqueous system. Moreover, the increased adsorption on the swollen clay indicated that methyl parathion was adsorbed on the interlamellar surfaces of the clay. This was also in agreement with the results of the desorption studies, since the insecticide was not desorbed using the same aqueous acetone solution. This indicated that methyl parathion was adsorbed as a water-insoluble organic compound.

THE CHALLENGES OF LAND AND WATER RESOURCES DEGRADATION IN JORDAN: DIAGNOSIS AND SOLUTIONS

Desertification is the loss of complexity of biological and/or economic productivity of crop-, range- or wood-lands. Reasons of such a loss is mainly due to climatic change and unsustainable human activities. The arid and semi-arid lands of Jordan are sensitive to human interference that resulted in a severe depletion of its natural resources and in different forms of land degradation due to multiple interaction of socio-economic factors. Further, degradation will continue if human activities are not carefully controlled and managed. Almost 90% of the land area of Jordan receives less than 200 mm of rainfall annually. This is reflected in poor structural stability of soils and the subsequent vulnerability to excessive erosion following shallow rainstorm events. Such a fragile ecosystem has also been manifested by non sustainable land use patterns and poor vegetative cover of the range land and the remaining forest batchs. Therefore, most of the economic activities take place on the remaining 10% of the land area and the competition between different user groups for these lands is, therefore, intense. Factors such as livestock and grazing practices, inappropriate agricultural and irrigation techniques, the marginalizing of lands, poor socio-economic conditions and a high population growth rate as well as weak institutional arrangements need to be considered in a comprehensive and integrated framework. Rangelands are deteriorating at an accelerated rate due to widespread overgrazing, uncontrolled herd movements, firewood collection, unsuitable cultivation practices, and persisted periodic droughts, all of which worsen ecological conditions. Cultivation of marginal lands, and unsound practices such as ploughing down slopes, and use of heavy farm machinery have accelerated rate of soil erosion and lowered land productivity. Urbanisation is also steadily encroaching onto good quality agricultural land in the higher rainfall areas of the Jordanian highlands, reducing the traditional production areas of food crops such as wheat and barley.

Thermodynamic Chemical Equilibria of Cadmium and Lead in the Aquatic System of the King Talal Reservoir (Jordan)

Abstract The King Talal Reservoir (KTR) is partially recharged with sewage water effluent produced from the Khirbit-Es-Samra Treatment Plant. Because of the enrichment of the KTR water with nutrients, and the subsequent eutrophication, the effect of biochemical activity on the thermodynamic chemical equilibria of Cd(II) and Pb(II) was investigated. Twenty water samples were periodically collected from both surface and bottom waters of the KTR during the period 13/5/1986—9/11/1987. The water samples were analyzed for major chemical constituents, including Cd and Pb. Ionic speciation of each sample was carried out using the GEOCHEM program. The results indicated that surface and bottom waters were undersaturated with respect to CdCO3 and Cd(OH)2. The surface water was in equilibrium with PbCO3 for the samples having log {(H+)/(HCO3 −)} lower than — 4.4. At values higher than — 4.4, Pb(II) was probably precipitated as lead phosphate. The bottom water was, in general, in equilibrium with PbCO3. However, some ...

MULTCOMP: A computer program for preparation and chemical speciation of multicomponent saline solutions

A computer program “MULTCOMP*” was developed to provide a prescription for the preparation of multicomponent electrolyte solutions which allow the study of plant response to osmotic stress and/or specific ion toxicity. The solutions may comprise five components (Ca, Mg, Na, Cl, and SO4) of any desired Ca:Mg and Cl:SO4 stoichiometric ratio and sodium adsorption ratio (SAR). The program also carries out chemical speciation of the prescribed solutions, or solutions of similar composition, taking into consideration 12 chemical species (Ca2+, CaCl+, CaSO4, Mg2+, MgCl+, MgSO4, Na+, NaCl, NaSO4−, Na2SO4, Cl−, and SO42−). Consequently, the obtained activity of each chemical species may further help in understanding a plant’s response to specific ion toxicity. The program is written in FORTRAN and compiled by a FORTRAN compiler (version VAX/VMS) to allow its running on IBM or compatible personal computers.