**7. References**

Bajracharya, K., and Barry, D. A. (1992). "Mixing cell models for nonlinear non-equilibrium single species adsorption and transport." *Water Res*., 29 (5), 1405-1413

Bajracharya, K., and Barry, D. A. (1993). "Mixing cell models for nonlinear equilibrium single species adsorption and transport." J. of Contaminant Hydrology, 12, 227-243

Simulation of non-equilibrium exchange of non-conservative pollutant between main channel and stagnation zone is vital. As we have considered conservative pollutant in this chapter, the maximum concentrations of pollutant at different locations were same due to mass conservation, but the residence times were different. Thus, this study also gives a retrospect for the extension of the model considering non-equilibrium condition of decaying

AP, AM1, AM2 – interface areas of the hyporheic zone and the mainstream flow under plug

CP, CM1, CM2 – Pollutant concentrations at the end of plug flow, first and second well mixed

pollutant exchange for natural streams.

flow, first and second well mixed cells respectively C(x, t) – Concentration of pollutant in the main stream

CR – Input pollutant concentration of a hybrid unit

Ms – Mass of the pollutant trapped in hyporheic zone

D – Depth of effective soil layer/hyproheic zone

DL – Longitudinal dispersion co-efficient

K(t) – Unit step response of a hybrid unit k (t) – Unit impulse response of a hybrid unit

T1 – Residence time of first well mixed cell T2 – Residence time of second well mixed cell

F – Proportionality constant

RD – Mass exchange rate constant

α – Residence time of plug flow cell

Δx – Size of control volumes within plug flow cell.

Cs(x, t) – Concentration of Pollutant trapped in the hyporheic zone

V0 , V1, V2 – Volumes of mainstream plug flow, first and second well mixed cells

WP – Wetted perimeter at the interface of hyporheic zone and the main stream

δM1, δM2 – Ramp kernel co-efficient of first and second well mixed cells respectively

V0\*, V1\*, V2\* - Volumes of hyporheic zones under plug flow, first and second well mixed cells

Bajracharya, K., and Barry, D. A. (1992). "Mixing cell models for nonlinear non-equilibrium single species adsorption and transport." *Water Res*., 29 (5), 1405-1413 Bajracharya, K., and Barry, D. A. (1993). "Mixing cell models for nonlinear equilibrium

single species adsorption and transport." J. of Contaminant Hydrology, 12, 227-243

**6. Nomenclature** 

cells respectively

n – Number of cells Q – Stream discharge R – Retardation factor

u – Stream flow velocity U ( ) – Unit step function

Δt – Small time interval

t – Time

x – Distance

φ – Porosity

**7. References** 


**8** 

*India* 

**Wetlands for Water Quality Management** 

*1Department of Mathematics, Faculty of Science, Jazan University, Jazan, KSA;* 

*3Department of Applied Mathematics, Indian School of Mines, Dhanbad, Jharkhand;* 

Wetlands are defined as water systems with marsh or fen and with water that is static or flowing, fresh or brackish, the depth of which at low tide is below 6m [5]. Natural wetlands are characterized by emergent aquatic vegetation such as cattails (typha), rushes (Scirpus) and reeds (Phragmites), and by submerged and floating plant species. Wetlands are categorized into three main categories: (1) fresh water coastal wetlands, (2) flood – plain wetlands and (3) constructed wetlands. These are valuable ecosystems as they support services which contribute significantly to human well - being. Some of these services are fish and fiber, water supply, water purification, flood regulation, recreational opportunities and

In this chapter, we focus our attention to potential of wetlands as water purifiers. This is important because harmful substances enter into wetland systems through animal waste from farms, toxic chemicals from factories and pesticides present in rain water. The large and diverse population of bacteria which grow on the submerged roots and stems of aquatic plants play an important role in removing BOD5 from waste water. Wetland plants take up harmful substances into their roots and change the harmful substances into the less harmful ones before they are released into the water body. Harmful substances partly get buried in the wetland soil. The soil bacteria convert these into substances, which are not harmful. Soil microbes (*Bacillus subtilis* and *Pseudomonas fluorescens*) convert pesticides into simpler nontoxic compounds. This process of degradation of pesticides and subsequent conversion into non-toxic compounds is known as "biodegradation". The biodegradation is influenced by

The chapter is organized as follows. In the next section, we present a study of a natural wetland of flood – plain type. This section summarizes a previous study of this natural wetland by the author and presents some new results. Section 3 discusses the design and

factors such as moisture, temperature, pH and organic matter content.

construction of constructed wetlands.

**1. Introduction** 

tourism.

 **– The Science and Technology** 

Vikas Rai1, A. M. Sedeki1, Rana D. Parshad2, R. K. Upadhyay3 and Suman Bhowmick3

*2Applied Mathematics and Computational Science, King Abdullah University of Science and Technology,* 

*Thuwal 23955 – 6900, KSA;* 

