Hydrogeochemistry ﺟﯾوﮐﻣﯾﺎء اﻟﻣﯾﺎه (G441)

Hydrogeochemistry جيوكمياء المياه (G441)

Dr. Esam Abu El Sebaa Osman Ismail اعزائى الطالب برجاء التواصل عن طريق االيميل التالى • [email protected] المحاضرة االولى Hydrogeochemistry

.The chemistry of ground and surface waters, particularly the relationship between the chemical characteristics and quality of waters and the areal and regional geology. .The study of the chemical composition of natural waters. .Chemistry of ground water and surface water. Surface water

• Surface water is water on the surface of the planet such as in a river, lake, wetland, or ocean. • Non-saline surface water is replenished by precipitation and by recruitment from ground-water. It is lost through evaporation, seepage into the ground where it becomes ground-water, used by plants for transpiration, extracted by man kind for agriculture, living, industry etc. or

discharged to the sea where it becomes saline. Groundwater

• Groundwater is the water present beneath Earth's surface in soil pore spaces and in the fractures of rock formations. • A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. • The depth at which soil pore spaces or fractures and voids in rock become completely saturated with water is called the water table. Water cycle • The water cycle, also known as the hydrological cycle or the hydrologic cycle, describes the continuous movement of water on, above and below the surface of the Earth. • The mass of water on Earth remains fairly constant over time but the partitioning of the water into the major reservoirs of ice, fresh water, saline water and atmospheric water is variable depending on a wide range of climatic variables. The water moves from one reservoir to another, such as from river to ocean, or from the ocean to the atmosphere, by the physical processes of evaporation, condensation, precipitation, infiltration, surface runoff, and subsurface flow. In doing so, the water goes through different forms: liquid, solid (ice) and vapor.

المحاضرة الثانية GROUNDWATER EXPLORATION USING ELECTRICAL RESISTIVITY METHOD

• Electrical resistivity method is useful to investigate the nature of subsurface formations by studying the variations in their resistance to flow of electrical current and hence determine the occurrence of groundwater. • The objectives of this method in the field of groundwater exploration are to locate groundwater bearing formations, estimation of depth to the water table, thickness and lateral extent of aquifers, depth to bed rock, delineation of weathered zone, structures and stratigraphic conditions such as fractures, dykes etc., distribution and configuration of saltwater/fresh water interface, etc. GROUNDWATER EXPLORATION USING ELECTRICAL RESISTIVITY METHOD

• The electrical resistivity method has particular advantage in hydrogeology because of its low cost, easy operation and efficacy to detect the water bearing formations. • Resistivity of geological formations vary significantly between their dry and saturated states. Resistivity values of rocks are controlled by chemical composition of the minerals, density, porosity, water content, water quality and temperature. GROUNDWATER EXPLORATION USING ELECTRICAL RESISTIVITY METHOD

• The main aim of electrical resistivity survey is the measurement of electrical resistivity of the subsurface formations. In general, four electrodes are required to measure the resistivity of subsurface formations. Current T is sent through the earth formation through one pair of electrodes (A & B) called current electrodes. The potential difference (AV) produced as a result of current flow is measured across a second pair of electrodes (M&N) called potential electrodes. Sample collection

• Surface water sampling • Groundwater sampling Sampling Problems

• The first problem is the extent to which the sample may be representative of the water source of interest. Many water sources vary with time and with location. The measurement of interest may vary seasonally or from day to night or in response to some activity of man or natural populations of aquatic plants and animals. The measurement of interest may vary with distances from the water boundary with overlying atmosphere and underlying or confining soil. The sampler must determine if a single time and location meets the needs of the investigation, or if the water use of interest can be satisfactorily assessed by averaged values with time and location, or if critical maxima and minima require individual measurements over a range of times, locations or events. The sample collection procedure must assure correct weighting of individual sampling times and locations where averaging is appropriate. Sampling Problems • The second problem occurs as the sample is removed from the water source and begins to establish chemical equilibrium with its new surroundings – the sample container. Sample containers must be made of materials with minimal reactivity with substances to be measured; and pre-cleaning of sample containers is important. The water sample may dissolve part of the sample container and any residue on that container, or chemicals dissolved in the water sample may sorb onto the sample container and remain there when the water is poured out for analysis. Similar physical and chemical interactions may take place with any pumps, piping, or intermediate devices used to transfer the water sample into the sample container. Water collected from depths below the surface will normally be held at the reduced pressure of the atmosphere; so gas dissolved in the water may escape into unfilled space at the top of the container. Atmospheric gas present in that air space may also dissolve into the water sample. Other chemical reaction equilibria may change if the water sample changes temperature. Finely divided solid particles formerly suspended by water turbulence may settle to the bottom of the sample container, or a solid phase may form from biological growth or chemical precipitation. Microorganisms within the water sample may biochemically alter concentrations of oxygen, carbon dioxide, and organic compounds. Changing carbon dioxide concentrations may alter pH and change solubility of chemicals of interest. These problems are of special concern during measurement of chemicals assumed to be significant at very low المحاضرة الثالثة Field work

• Temperature (OC):Water temperature naturally fluctuates both daily and seasonally varies with air temperature. Temperature affects the speed of chemical reaction; aquatic plants photosynthesize interaction of pollutants with aquatic residents, it can influence the solubility of dissolved oxygen (DO) Field work • Dissolved Oxygen (DO): Oxygen is required for the metabolism of aerobic organism. It influences inorganic chemical reaction. Oxygen is used as an indicator of water quality, that high concentration of oxygen indicates good water quality. Oxygen enters water through diffusion across the water’s surface by rapid movement as aeration. The amount of dissolved oxygen gas highly depends on temperature and sometimes on atmospheric pressure. Salinity influences the dissolved oxygen concentration which oxygen is low in highly saline water. The amount of any gas including the dissolved oxygen in water is inversely proportional to the temperature of the water; as temperature increase, the amount of dissolved oxygen decreases Field work • Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD): Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) are measures of water quality that reflect the degree of organic matter pollution. BOD is measure the amount of oxygen by aerobic micro-organism for their metabolic requirements during the break down of organic matter, with high BOD tends to have low dissolved oxygen concentrations. COD is measured of oxygen equivalent of the organic matter in water samples are susceptible to oxidation by strong chemical oxidant, such as dichromate. Field work • Hydrogen ion - concentration (pH): The pH of aqueous solution is controlled by interrelated chemical reactions that produced or consume hydrogen ions. Water

+ - (H2O) molecules dissociate and form (H ) and hydroxyl (OH ) ions. If hydrogen ions more than hydroxyl ions, the water are acidic. If hydroxyl ions are abundant, the water is alkaline. The pH in the groundwater depends mainly on the composition of the rock and sediment which the water are migrating during it. . is a numeric scale used to specify the acidity or basicity of an aqueous solution. It is approximately the negative of the base 10 logarithm of the molar concentration, measured in units of moles per liter, of hydrogen ions. More precisely it is the negative of the logarithm to base 10 of the activity of the hydrogen ion. Solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are basic. Pure water is neutral, at pH 7 (25°C), being neither an acid nor a base. Field work

• Electrical conductivity (E.C): Electrical conductivity measures the capacity of water to conduct an electrical current and it is a function of the types and quantities of dissolved substances in water. As concentration of dissolved ions increase, electrical conductivity of water also increases. It is expressed in units of micro mhos/cm at 25 degree Celsius or micro semen’s/cm. Field work

• Total dissolved solids (TDS) is a measure of the combined content of all inorganic and organic substances contained in a liquid in molecular, ionized or micro-granular (colloidal sol) suspended form. • Total dissolved solids (TDS) Measurement • Total dissolved solids (TDS) Units Field work

TDS classification according to Hem (1985) Water type TDS fresh water < 1000 mg/1 Slightly Sal. 1000 – 3000 Moderately Sal. 3000 - 10000 Very Saline 10000 - 35000 Brine > 35000 المحاضرة الرابعة Total Hardness

• Hard water is water that has high mineral content (in contrast with "soft water"). Hard water is formed when water percolates through deposits of limestone and chalk which are largely made up of calcium and magnesium carbonates. Types of water hardness • Temporary hardness is a type of water hardness caused by the presence of dissolved bicarbonate minerals (calcium bicarbonate and magnesium bicarbonate). When dissolved, these minerals yield calcium and magnesium cations (Ca2+, Mg2+) and

2− − carbonate and bicarbonate anions (CO3 , HCO3 ). The presence of the metal cations makes the water hard. this "temporary" hardness can be reduced either by boiling the water, or by the addition of lime (calcium hydroxide) through the process of lime softening. Boiling promotes the formation of carbonate from the bicarbonate and precipitates calcium carbonate out of solution, leaving water that is softer upon cooling. Types of water hardness

• Permanent hardness is hardness that cannot be removed by boiling. • It is usually caused by the presence of calcium sulphate /calcium chloride and/or magnesium sulphate/magnesium chloride in the water, which do not precipitate out as the temperature increases. • Ions causing permanent hardness of water can be removed using a water softener, or ion exchange. • Total Permanent Hardness = Calcium Hardness + Magnesium Hardness • The calcium and magnesium hardness is the concentration of calcium and magnesium ions expressed as equivalent of calcium carbonate. • Total permanent water hardness can be calculated with the following formula:

2+ 2+ • TH (CaCO3) = 2.5(Ca ) + 4.1(Mg ) (ppm). Hardness water classification according to Hem (1985).

• Water type classification • Soft 0-60 mg/l • Moderately 61-120 mg/l • Hard 121-180 mg/1 • Very hard >180 mg/1 Chemical analysis المحاضرة الخامسو Distributions of major ions

• Distribution of calcium ion (Ca+2) • Calcium is the most abundant element in the earth’s crust and soil. It may be leached out by rain water, so it is present in all surface water at varying concentrations. Calcium occurs

naturally as calcite (CaCO3), anorthite (CaAl2Si2O8), gypsum

(CaSO42H2O), dolomite CaMg(CO3)2. Calcium is a major constituent of many common rock minerals in the form of carbonate (limestone and dolomite). Distributions of major ions

• Distribution of magnesium (Mg+2) • The distribution of magnesium ions is similar to that of calcium ions. Magnesium occurs in many rock types however, the concentration is usually significantly less than for calcium in natural fresh water. The main source of magnesium in water is

mainly present as dolomite Ca Mg (CO3)2 and magnesite (Mg

CO3). In some aspects for water chemistry, calcium and magnesium may be considered as having similar effects. Distributions of major ions

• Distribution of Sodium and Potassium (Na+ and K+) • Sodium doesn’t exist in native state but is present only as compounds in a rocks and deposits such as halite (NaCl), apatite

(NaSiO8). Sodium contents of surface and groundwater samples is depending on the geology of the catchments area and weathering process of rocks and soils. In arid regions, all natural waters contain sodium and potassium in high concentrations, particularly in shale and clay sediments. The sodium ion is the most alkali metal in water. The distribution of K is mainly depending on the existence of clay minerals and also the weathering of K-bearing minerals. Distributions of major ions

- • Distribution of bicarbonate (HCO3 ) • The natural water sources of carbonate and bicarbonate are the

sedimentary rocks; included CO2 from atmosphere. CO2 produced by biota of soil or activity of sulfate reducer and other bacteria in deeper formation. Sodium carbonate can accumulate as evaporate in closed basins causing high carbonate level in groundwater. Bicarbonate concentrations of more than 200 mg/l are common in

groundwater, and higher concentrations can occur where CO2 is produced within the aquifer. The limestone and dolomite are considered the main source of carbonate and bicarbonate ions in the groundwater. Distributions of major ions

- • Distribution of sulfate (SO4 ) • Sulfates occurs in the earth's crust mainly in the form of gypsum

mineral (CaSO4.2H2O) and anhydrite (CaSO4). Also, the oxidation of sulfide ores represents a source of sulfate in water. Sulfate ions are widely distributed in surface waters. They are coming from leaching of rocks and soils, from atmospheric precipitates and from sewage and industrial discharge. • In natural waters the sulfate concentration is usually below 300 mg/l except in wells affected by acid mine drainage. In some brines, the sulfate concentration may be up to 200,000 mg/l Distributions of major ions

• Distribution of chloride (Cl-) • Chloride is present in nearly all natural waters, although concentrations are normally low. Primary sources of chloride are evaporates. A chloride ion is widely distributed in environmental mainly as its salts with sodium potassium and calcium, as halite (NaCl), sulfite (KCl) and carnallite

(KMgCl3.6H2O). Chloride may originate from natural evaporate deposits of salts. Chloride content is primarily originate in land areas from a mixed seawater trapped in sediments at the time of deposition and in coastal area from a mixed sea water and fresh water in productive aquifer. High chloride concentrations are undesirables, because the water would be less useable as a drinking water resource. Distributions of major ions

- • Distribution of nitrates (NO3 ) • In the surface water, the most common identified contaminant is

- dissolved nitrogen in the form of nitrate (NO3 ) in water are

nitrogen fertilizer as ammonium sulfate (NH4)2SO4, ammonium

nitrate (NH4) NO3 and urea CONH2. The nitrogen fertilizer provide plant with nitrate, the excess nitrogen fertilizer causes nitrogen contamination in groundwater. The high concentration of nitrate is due to the different variety of nitrogen fertilizers and sewage. Distributions of major ions

3- • Distribution of phosphorous (PO4 ) • Phosphorus is a component of sewage where the element is essential in metabolism, and it is always present in animal metabolic waste. Phosphorus includes inorganic and organic materials, manufacture of soaps and detergents, pesticides, alloys, animal feed supplements, catalysts, lubricants and corrosion inhabit ion. Phosphorus is rather common element in igneous rock and it is also fairly abundant in sediments. المحاضرة السادسة Distribution of trace constituents

• The terms "minor" and "trace" used in reference to solute in natural water cannot be precisely defined. Commonly, the terms are used for substances that always or nearly always occur in concentration less than 1.0 mg/l. The determined concentrations of the trace constituents depended on the water resources. Trace constituents are actually or potentially of vital importance to human health, plant nutrition. Distribution of trace constituents • Boron (B) • Boron is essentially presents in trace quantities in plants, but becomes toxic to some of them when present in amounts more than1.0 mg/l in irrigation water. The high concentrations of boron (up to 0.5 mg/l) are coming from industrial wastes recharge and runoff agricultural land • Iron (Fe) • The main source of iron in natural surface water results from the wreathing and leaching of rocks and soils. It is also discharge into stream from mines and waste water from metals foundries. Corrosion of well casing and other pipes may also contribute iron in to the groundwater. Distribution of trace constituents • Copper (Cu) • Most copper is released to land by mining operations, agriculture, solid waste, and sludge from sewage treatment plants. Copper is released to water from soil and industrial and sewage treatment discharge. Much of this copper is attached to dust and other air particles. • Zinc (Zn) • Zinc is present not only in rock and soil, but also in air, water and biosphere, plants, animals and humans. Distribution of trace constituents • Manganese (Mn) • The main source of manganese in natural water is the leaching of rocks and soils. It is also, discharged to surface waters from mines and industrial wastes. • Cobalt (Co) • Cobalt compounds are also present in iron and manganese ores. Cobalt enters environment by leaching from acid coal mine drainage and emissions to the atmosphere from coal burning. It is an essential element for living organism, in high concentration cobalt can be toxic. Distribution of trace constituents • Mercury (Hg) • The increasing of some values is coming from the chemical manufacturing industry. • Nickel (Ni) • Nickel is more abundant in crustal rocks than cobalt. Nickel is an important industrial metal. It is used extensively in stainless steel and other corrosion-resistant alloys and to a lesser extent for other purposes. Distribution of trace constituents

• Aluminum (Al) • Aluminum occurs in substantial amount in many silicate igneous rocks mineral such as feldspars, feldspthoids, mica and many amphiboles. • Lead (Pb) • The presence of lead in water indicates contamination from metallurgical wastes or from lead containing industries. Lead enters water from atmospheric fallout; runoff or wastewater. Distribution of trace constituents • Aluminum (Al) • Aluminum occurs in substantial amount in many silicate igneous rocks mineral such as feldspars, feldspthoids, mica and many amphiboles. • Lead (Pb) • The presence of lead in water indicates contamination from metallurgical wastes or from lead containing industries. Lead enters water from atmospheric fallout; runoff or wastewater. • Cadmium (Cd) • Cadmium is often present in artificial fertilizers where heavy metals may accumulate in soils in areas that have been used for agriculture for long period. Cadmium occurs in igneous and some sedimentary rocks and is generally associated with Zn ore minerals like Cu minerals. المحاضرة السابعة Ion dominance

• Ca>Mg>Na / HCO3>Cl>SO4

• Mg>Ca>Na / HCO3> SO4 >Cl

• Na> Mg >Ca / HCO3> SO4>Cl

• Na> Mg >Ca / Cl> SO4>HCO3 water type

• The dominant cation, and the dominant anions Ca (HCO3)2,

Mg (HCO3)2 , NaHCO3, Ca (HCO3)2. Hypothetical salt combinations المحاضرة الثامنة Piper diagram A piper diagram is a graphical representation of the chemistry of a water sample or samples. Anions are plotted in the lower right triangle and cations are plotted in the lower left triangle. The single point plotted in the diamond field indicates the overall character of the points in the cation and anion triangles. Piper classified the diamond shaped into six sub-areas. 1-Sub-area 1: alkaline earths exceed alkalis, (Ca+2+Mg+2)> (Na++ K+). 2-Sub-area 2: Alkalis exceed alkaline earths, (Na+ + K+) > (Ca+2+ Mg+2).

------3-Sub-area 3: Weak acids exceed strong acids, (CO3 +HCO3 )> (SO4 +C1 ) -2 - -2 - 4-Sub-area 4: Strong acids exceed weak acids, (SO4 +C1 )> (CO3 +HCO3 ). 5-Sub-area 5: Carbonate hardness (secondary alkalinity) exceeds 50%. 6-Sub-area 6: Non-carbonate hardness (secondary alkalinity) exceeds 50%.Consequently Piper diagram Stiff diagram A Stiff diagram, or Stiff pattern, is a graphical representation of chemical analyses, first developed by H.A. Stiff in 1951. It is widely used by hydrogeologists and geochemists to display the major ion composition of a water sample. A polygonal shape is created from four parallel horizontal axes extending on either side of a vertical zero axis. Cations are plotted in milliequivalents per liter on the left side of the zero axis, one to each horizontal axis, and anions are plotted on the right side. Stiff patterns are useful in making a rapid visual comparison between water from different sources. An alternative to the Stiff diagram is the Maucha diagram. Stiff diagrams can be used: 1) to help visualize ionically related waters from which a flow path can be determined, or;2) if the flow path is known, to show how the ionic composition of a water body changes over space and/or time. Stiff diagram Sulin diagram

Sulin (1946) diagram consists of two equal squares. The upper right one represents the marine water genesis (MgCl2 and CaCl2). It has ((rNa /rCl) < 1). While, the lower left square represents the meteoric water genesis (NaHCO3 and Na2SO4). It has ((rNa/rCl) > 1). The two squares are subdivided where each one has two triangles. Sulin diagram المحاضرة التاسعة Durov Diagram

The Durov Diagram is an alternative to the Piper Diagram. In the two triangles, it plots the major ions as percentages of milliequivalents. The totals of both the cations and anions are set to 100% and the data points in the two triangles are projected onto a square grid which lies perpendicular to the third axis in each triangle. Durov Diagram Schocller’s Diagram

Schoeller’s diagram is a linear pattern diagram which is based on a system developed in part by the French investigator (Schoeller, 1962). A line represent an analysis may be drawn on this diagram by connect points representing concentration of ions. Concentration values are expressed on a series of logarithmic scales and arranged, where the sheet can serve as a monograph for conversion of data to equivalent per million. The logarithmic scale has some dis-advantages for water of low dissolved solids concentration. On this graph, the cations and anions (Ca++, Mg++, Na+ +K+, Cl-, SO4-- and HCO3- +CO3--) are arranged according to their mobility by mill-equivalents values. Schocller’s Diagram

100 100 100 100 100 100 100 100

300 300 300 300 300 300 300 300

200 200 200 200 200 200 200 200

100 100 100 100 100 100 100 100 90 90 90 90 90 90 90 90 80 80 80 80 80 80 80 80 70 70 70 70 70 70 70 70 60 60 60 60 60 60 60 60 50 50 50 50 50 50 50 50 40 40 40 40 40 40 40 40

30 30 30 30 30 30 30 30

20 20 20 20 20 20 20 20

10 10 10 10 10 10 10 10 9 9 9 9 9 9 9 9 8 8 8 8 8 8 8 8 7 7 7 7 7 7 7 7 6 6 6 6 6 6 6 6 5 5 5 5 5 5 5 5

4 4 4 4 4 4 4 4

3 3 3 3 3 3 3 3

2 2 2 2 2 2 2 2

1 1 1 1 1 1 1 1 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5

0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4

0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3

0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2

0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 EPM Ca Mg Na Cl SO4 HCO3 EPM

River Nile, Bahr Youssefi, El Ibrahemia and El Sabkha canals samples El Moheet drain and its branches samples Groundwater samples Fig. (2.76):Scholler diagram of the studied water samples Grid system diagram grid system diagram, this diagram is divided into nine equally sized main grids. A further subdivision is possible based on cations or anions, which present small amounts. The results of the investigated water samples are plotted in the grids, where each point represents a sample. The pattern of distribution immediately gives an idea about the major and minor classes of the waters encountered. Grid system diagram

Mg - Na Ca Na - Mg

Ca - Na Mg Na - Ca

Ca - Mg Na

Mg - Ca

S C

River Nile, Bahr Youssefi, El Ibrahemia, El Sabkha canals samples El Moheet drain and its branches samples Groundwater samples Fig. (2.77) : Grid system classifacation of the studied water samples Gibbs diagram

Gibbs (1970) suggested a diagram in which the ratio of dominant anions and cations are plotted against the value of TDS. This diagram help to know the groundwater chemistry and the relationship of the chemical components of the water to their respective aquifers, such as the chemistry of the rock types, the chemistry of precipitated water, and the rate of evaporation. Gibbs diagram المحاضرة العاشرة Evaluation of groundwater quality for irrigation use • Salinity index or salinity hazard • US Salinity Laboratory Staff • Sodium percent (Na %) • Sodium adsorption ratio (SAR) • Residual sodium carbonate (RSC) • Magnesium hazard (MH) • Kelley’s ratio (KR) • Soluble sodium percentage (SSP) • Potential salinity (PS) • Permeability Index (PI) Kelley’s ratio (KR)

• all ions in meq/l • In general, groundwater with Kelly’s ratio greater than one is unfit for irrigation. Salinity index or salinity hazard • high concentrations of salinity in irrigation water affect crop yield through the inability of the plant to complete with ions in the soil solution for water.

EC (μS/cm) Water salinity range < 250 Excellent quality

251–750 Good quality

750 –2000 Permissible quality

2001–3000 Doubtful

>3000 Unsuitable US Salinity Laboratory Staff Sodium percent (Na %)

Na %= (Na+K))/((Ca+Mg+Na+K))×100 all ions in meq/l 100

Permissible to Doubtful

70 Permissible to Doubful t

n 60

e P

P 50

s o

40 e

e i

30 E

20 e

D G 10

0 0 500 1000 1500 2000 2500 3000 3500 4000 Electerical ElectricalConductivity Conductivity (Micro Simense/cm) (µS/cm) at 25ºC at 25 degree centigrate River Nile, Bahr Youssefi, El Ibrahemia and El Sabkha canals samples El Moheet drain and its branches samples Groundwater samples Fig.(2.81): Percent sodium vs. EC plot ( after Wilcox, 1995) Sodium adsorption ratio (SAR) ions in meq/l

Water class SAR (epm) Excellent 0 -10 Good 10 - 18 Fair 18 - 26 Poor > 26 Residual sodium carbonate (RSC)

• RSC = (CO3 + HCO3) – (Ca + Mg) (epm) • According to USSL diagram, an RSC value <1.25 meq/L is probably safe for irrigation. If it is >2.5 meq/L, it is not suitable for irrigation. المحاضرة الحادية عشر Magnesium hazard (MH)

• all ions in meq/l • when MH values< 50, water is considerably suitable; and when MH>50, water is considered harmful and unsuitable for irrigation purposes. Soluble sodium percentage (SSP)

SSP=((Na+ + K+ )/ (K+ + Na+ + Ca2+ +Mg2+ )) ×100 • all ions in meq/l SSP < 50percent good quality and suitable for irrigation SSP>50percent poor quality water and unsuitable for irrigation Potential salinity (PS)

• PS=Cl+ √SO4 all ions in meq/l

PS Water quality

<5 Excellent to Good

5-10 Good to Injurious

>10 Injurious to Unsatisfactory Permeability Index (PI) Permeability Index (PI)

y y

60 t

)

r e

50 e

(

s CLASS- I

i i

r 40

5 5

o T 20

10 CLASS - III CLASS - II 0 120 100 80 60 40 20 0 Permeability Index (P1) Groundwater samples Fig. (2.82): Doneen (1964) classification for irrigation water based on the permeability index المحاضرة الثانية عشر Isotope Hydrology

Water Management Isotope Hydrology

• Isotope hydrology is a tool using to understanding hydrological processes such are recharge rate and recharge mechanism, surface water groundwater interaction, time scale of processes, origin of pollution etc. • Isotope hydrology could provide the much needed knowledge for water resources management. • Isotope techniques are effective tools for fulfilling critical hydrological information needs such as:  The origin of water.  The determination of its age, velocity, and direction of flow.  The interrelations between surface waters and groundwater.  The possible interconnections between different aquifers.  Aquifer characteristics such as porosity, transmissivity. Isotope Hydrology • Applications of isotopes in hydrology are based on the general concept of “tracing,” in which either intentionally introduced isotopes or naturally occurring (environmental) isotopes are employed. • Environmental isotopes (either radioactive or stable) have the distinct advantage over injected (artificial) tracers that they facilitate the study of various hydrogeological processes on a much larger temporal and spatial scale through their natural distribution in a hydrological system. Isotope Hydrology • Environmental isotopes, both stable and radioactive, occur in the atmosphere and the hydrosphere in varying concentrations. So far, the most frequently used environmental isotopes include those of the water molecule, hydrogen (2H or D, and 3H) and oxygen (18O), as well as carbon (13C and 14C) occurring in water as constituents of dissolved inorganic and organic carbon compounds. Isotope Hydrology Isotope Hydrology Isotope Hydrology Isotope Hydrology Isotope Hydrology Isotope Hydrology Isotope Hydrology Isotope Hydrology Isotope Hydrology Isotope Hydrology Isotope Hydrology Isotope Hydrology Isotope Hydrology